Se efectúa en piezas vitales y desvitalizadas, intra y extra camerales, en la clínica del profesional o en casa; se usa peróxido de hidrógeno o peróxido de carbamida (y como verán más abajo, alguna que otra alternativa); a la forma de gel, dentífricos, cintas… en fin, modalidades formas y concentraciones varias. Los efectos adversos no son muchos y se refieren principalmente a la sensibilidad dentaria durante y/o post tratamiento e irritación gingival y en los casos de blanqueamiento intracameral, endorizalisis. Finalmente otros reportan cambios en la dureza del esmalte y diferencias en los niveles de adhesividad de materiales.
La cantidad de publicaciones es importante.
Dr. Jorge Garat.
Photomed Laser Surg. 2010 Sep 23. [Epub ahead of print]
Enamel Susceptibility to Coffee and Red Wine Staining at Different Intervals Elapsed from Bleaching: A Photoreflectance Spectrophotometry Analysis.
Liporoni PC, Souto CM, Pazinatto RB, Cesar IC, de Rego MA, Mathias P, Cavalli V.
1 University of Taubaté , Department of Dentistry, Taubaté, SP, Brazil .
Abstract
Abstract Objective: This study aimed to investigate bleached enamel susceptibility to coffee and red-wine staining at different time periods after bleaching. Background data: Although hydrogen peroxide is effective for dental bleaching, little is known regarding color stability immediately after bleaching. Materials and Methods: Fifty-four standardized bovine enamel slabs were obtained and assigned to the following treatments (n = 9): (CO) control: sound enamel surface submitted only to bleaching with 35% hydrogen peroxide (HP); (C30’) enamel submitted to HP and coffee immersion at 30 min after bleaching; (C150’) enamel submitted to HP and coffee immersion at 150 min after bleaching; (W30’) enamel submitted to HP and red-wine immersion at 30 min after bleaching; and (W150’) enamel submitted to HP and red-wine immersion at 150 min after bleaching. The color of treated enamel was determined by means of photoreflectance spectroscopy at baseline (T<inf>0</inf>) and after the described treatments (T<inf>f</inf>), and data were statistically analyzed with ANOVA and Tukey tests (p < 0.05). Results: No differences were observed between the exposure times of 30 and 150 min after bleaching for both beverages (p > 0.05). Although coffee did not stain the surface, red wine significantly darkened previously bleached enamel (p < 0.05). Conclusion: Bleached enamel was susceptible to red-wine staining at both 30 and 150 min after bleaching procedures, whereas coffee did not interfere with the bleaching process.
J Conserv Dent. 2010 Apr;13(2):76-9.
Efficacy of casein phosphopeptide-amorphous calcium phosphate to prevent stain absorption on freshly bleached enamel: An in vitro study.
Singh RD, Ram SM, Shetty O, Chand P, Yadav R.
Department of Prosthodontics, Faculty of Dental Sciences, C.S.M. Medical University, Lucknow, Uttar Pradesh, India.
Abstract
BACKGROUND: Teeth when subjected to bleaching bring about the desiccation of the enamel, making it more susceptible to stain absorption. While subjecting the freshly bleached enamel surface to various surface treatments of Fluoride and Casein Phosphopeptide – Amorphous Calcium phosphate (CPP-ACP) brought about the reduction in stain absorption, which is assessed in this study.
AIMS: The study aims to evaluate the tea stain absorption on freshly bleached enamel surface of extracted human teeth with varied surface treatment. The stain absorption was evaluated at the end of one hour and 24 hours post bleaching.
MATERIALS AND METHODS: Forty extracted human permanent maxillary central incisors were subjected to bleaching with 10% carbamide peroxide for eight days. They were divided into four groups of 10 each. Group I was control group. Group II was immersed in tea solution without surface treatment, while Group III and IV were immersed in tea solution with surface treatment of topical Fluoride and CPP-ACP respectively. Spectrophotometer was used for color analysis.
RESULTS: Surface treatment with CPP-ACP and topical fluoride on freshly beached enamel surface, significantly reduced the stain absorption.
CONCLUSION: Remineralizing agents reduce stain absorption after tooth bleaching.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2010 Aug;28(4):361-3.
[Effect of cold-light bleaching technique on human permanent teeth enamel surface]
[Article in Chinese]
Huang JW, Shi XC, Zhou JL, Li W.
State Key Laboratory of Oral Diseases, Sichuan Sichuan University, Chengdu 610041, China.
Abstract
OBJECTIVE: To study the effects of the cold-light bleaching technique on crystals and microstructure of the dental enamel.
METHODS: The human premolars extracted for orthodontic reasons were treated by a standard cold-light bleaching procedure. After the treatment, all samples were detected by high resolution micro-area X-ray diffractometer, Fourier transform infrared spectroscope and scanning electron microscope.
RESULTS: After the permanent teeth were treated with cold-light bleaching technique, the enamels’ crystal dimension, crystallinity decreased and irregular surfaces and shallow disk pits appeared.
CONCLUSION: The cold-light bleaching technique could lead to the changes of crystals and microstructure in the surface layer of dental enamel.
J Clin Pediatr Dent. 2010 Summer;34(4):303-8.
Spectrophotometric analysis on bleaching efficacy of blood stained demineralized and deproteinized dentin–an in vitro study.
Ghousia S, Sathyajith NN, Reddy VV.
Department Pedodontic & Preventive Dentistry, AECS Maaruti College of Dental Sciences and Research Centre, Bengaluru. drghousia786@gmail.com
Abstract
BACKGROUND AND OBJECTIVE: The objectives of this in vitro study, is to evaluate the influence of various dentin treatment procedures prior to bleaching namely, demineralization and demineralization in conjunction with deproteinization on the dentin permeability and bleaching efficacy.
METHOD: The study used a total of 40 sound premolars, which were sectioned longitudinally, and their color coefficients and absorption spectrum was recorded and used as control values for the later study. These dentin samples were then discolored by blood and their color coefficients and absorption spectrum were calibrated. They were then divided into two Groups with 20 samples each per group. Group A–dentin samples were demineralized prior to bleaching. Group B–dentin samples were deproteinized also in conjunction to demineralization prior to bleaching. The values of color coefficient and absorption spectrum were determined using Spectrophotometer for samples of each group respectively.
RESULTS: There were significantly higher color coefficient and absorption spectrum values in the group where dentin was treated with demineralization in conjunction with deproteinization prior to bleaching when compared to the group where dentin was treated by demineralization alone prior to bleaching.
CONCLUSION: Demineralization in conjunction with deproteinization has proven to be a good method of increasing dentin permeability for achieving a higher bleaching efficacy.
J Am Dent Assoc. 2010 Jun;141(6):639-46.
Use of tray-applied 10 percent carbamide peroxide gels for improving oral health in patients with special-care needs.
College of Dental Medicine, Western University of Health Sciences, 309 E. Second St., Pomona, CA 91766-1854, USA. dlazarchik@westernu.edu
Abstract
BACKGROUND: Plaque accumulation and resulting caries or periodontal disease is a frequent problem in patients with special-care needs. Tray-applied 10 percent carbamide peroxide (CP) is a tooth-bleaching agent that has positive effects on plaque, gingival health and caries.
METHODS: The authors review the antibacterial properties of CP and the effects of CP on saliva, plaque, caries and gingival health. They also review tray fabrication options and techniques, application methods, safety and side effects. Finally, they address the challenges involved in and research needed regarding use of tray-applied CP materials in special-care patients.
RESULTS: In their literature review and clinical experience, the authors found 10 percent CP delivered in a custom-fitted tray to be an effective treatment for caries in patients with compromised oral hygiene. Plaque suppression and caries control result from a CP-induced increase in salivary and plaque pH caused by CP’s urea component, and from possible antimicrobial action via physical debridement and the direct chemical effect of hydrogen peroxide.
CONCLUSIONS: Tray-applied 10 percent CP may hold great promise for improving the oral health of many special-care patients, including elderly patients, patients with cancer and patients with dry mouth. Further research is needed to verify the potential benefits, specifics of treatment times and protocols and most cost-effective products for use in various patient groups.
CLINICAL IMPLICATIONS: Application of 10 percent CP in a custom-fitted tray may reduce caries by elevating the pH above the level at which the caries process can occur, in addition to debriding the teeth and improving gingival health.
Br Dent J. 2010 Jun;208(12):571-7. Epub 2010 May 28.
Effect of chewing gum on tooth sensitivity following whitening.
Department of Primary Care Dentistry, King’s College London Dental Institute, Denmark Hill Campus, Bessemer Road, London, SE5 9RW, UK.
Abstract
OBJECTIVE: Transient sensitivity is the most common side-effect associated with tooth whitening. The purpose of this randomised, controlled clinical study was to determine if a chewing gum containing Recaldent (CPP-ACP) was effective in reducing tooth sensitivity associated with in-office whitening procedures.
MATERIALS AND METHODS: Eighty-eight patients were recruited and had their teeth lightened using a single-visit, in-office whitening treatment with 15% hydrogen peroxide augmented by light for a treatment period of one hour. Following the procedure, each patient was randomly assigned to one of three study groups: Group A, who used a sugar-free chewing gum with CPP-ACP; Group B, who did not use any desensitising agent; and Group C, who used a sugar-free chewing gum without CPP-ACP. The participants were requested to return for a 24 hour follow-up visit, at which the colour changes were measured using a value-oriented Vita classic shade guide. They also reported on the incidence, duration and intensity of tooth sensitivity experienced by completing a post-treatment questionnaire.
RESULTS: The average Vita shade unit reduction was 4.8 and 88.6% of the patients were satisfied with their treatment outcomes. However, 85.2% of them experienced tooth sensitivity at some point following the whitening procedures. Both Group A and Group C experienced significantly less intense tooth sensitivity than Group B following the whitening procedures. However, Group A did not have a statistically significant reduction in the incidence, duration or intensity of sensitivity when compared to Group C. All sensitivity ceased at the 24 hour follow-up visits.
CONCLUSION: This study suggested that using a sugar-free chewing gum (both with and without CPP-ACP) could reduce the intensity of tooth sensitivity associated with in-office whitening procedures. However, it failed to demonstrate conclusively that using a sugar-free chewing gum with CPP-ACP could provide additional therapeutic benefits.
Gen Dent. 2010 May-Jun;58(3):258-63; quiz 264-5.
Reversal of reduced bond strength after bleaching.
Comlekoglu ME, Gokce B, Kaya AD, Turkun M, Ozpinar B.
Department of Prosthodontics, School of Dentistry, University of Ege, Izmir, Turkey.
Abstract
This article investigated how the shear bond strength of a luting resin to dentin was affected by antioxidant treatment and delayed bonding after bleaching with carbamide peroxide. Using a lowspeed diamond saw, 40 flat dentin surfaces were prepared from freshly extracted human molars and divided into three bleaching groups (n = 10) and a control group (n = 10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent (10% sodium ascorbate), while Group 3 specimens were immersed in artificial saliva for one week after bleaching. Specimens in Group 4 were not bleached but were immersed in artificial saliva for one week before bonding. Forty ceramic blocks were prepared and luted to teeth using a dual-curing resin cement. The specimens were thermocycled and the shear bond strength tests were performed using a universal testing machine. Fracture analysis was performed using a scanning electron microscope. While the Group 1 samples demonstrated the lowest shear bond strengths (11.9 +/- 3 MPa) (p < 0.05), no significant differences were found among samples in Group 2 (26.3 +/- 7.1 MPa), Group 3 (20.7 +/- 6.5 MPa), and Group 4 (22.1 +/- 2.5 MPa) (p = 0.05).
Am J Dent. 2010 Jun;23(3):171-4.
Peroxide penetration from the pulp chamber to the external root surface after internal bleaching.
Palo RM, Valera MC, Camargo SE, Camargo CH, Cardoso PE, Mancini MN, Pameijer CH.
Department of Endodontics, São Paulo State University, Araraquara, SP, Brazil.
Abstract
PURPOSE: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique.
METHODS: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml.
RESULTS: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.
Am J Dent. 2010 Jun;23(3):168-70.
Influence of acid etching on hydrogen peroxide diffusion through human dentin.
Camps J, Pommel L, Aubut V, About I.
Laboratory IMEB, Faculty of Odontology, Université de la Méditerranée, Marseille, France. Jcamps2035@aol.com
Abstract
PURPOSE: To evaluate the influence of dentin etching with phosphoric acid on hydrogen peroxide diffusion through human dentin in internal bleaching.
METHODS: 46 human premolars were extracted for orthodontic reasons from adolescents. The teeth were endodontically treated and a flat defect was created at the enamel-cementum junction. The teeth were divided into two groups: the access cavity was etched for 30 seconds with 35% H3PO4 in the first group and left intact in the second group. The teeth were filled with 20 microL of 35% hydrogen peroxide gel. The receiving medium on the other side was renewed at Day 1, Day 2 and Day 7 to quantify the diffusing hydrogen peroxide. An analysis of variance was performed to compare the diffusion between the two groups.
RESULTS: This work demonstrated a higher hydrogen peroxide diffusion when the access cavity was etched (P < 0.01).
Oper Dent. 2010 Jul-Aug;35(4):381-8.
Comparison of at-home and in-office tooth whitening using a novel shade guide.
da Costa JB, McPharlin R, Paravina RD, Ferracane JL.
Oregon Health & Science University, Restorative Dentistry, Portland, OR, USA. dacostaj@ohsu.edu
Abstract
OBJECTIVE: This study evaluated the time necessary for at-home whitening (HW) to match the results of an in-office (OW) treatment, side effects and patients’ preferences/perceptions.
METHODS: The tooth color change of 20 subjects was measured using a shade guide (BSG) and spectrophotometer (ES). Color difference was calculated: delta E* = [(delta L*)2 + (delta a*ab)2 + (delta b*ab)2]1/2. The whitening treatments were randomly applied to the right or left maxillary anterior teeth, in-office, with 25% hydrogen peroxide or at-home, overnight, with 10% carbamide peroxide. The tooth color was evaluated at baseline, one day after OW, six days (five days after HW) and at 20 days (14 days after HW and 19 days OW). Subjects rated their tooth and soft tissue sensitivity (1-10 scale). The results were analyzed by two-way RM ANOVA/Tukey’s and Mann-Whitney (p<0.05).
RESULTS: At six days, the teeth that were treated with HW and OW presented delta E* = 5.2 and 6.6, respectively, delta BSG = 3, and at 20 days, they presented delta E* = 6.2 and 6.6, respectively, delta BSG = 3. Less than 40% of the subjects experienced tooth sensitivity after OW and HW. No subjects experienced tooth and gingival sensitivity at 20 days. Seventy-four percent preferred HW over OW, 63% recommended OW and 100% recommended HW.
CONCLUSION: While there was a subtle difference in delta E* between HW and OW at six days, the measurement of delta E* and delta BSG agreed that five days of home whitening produced the same results as a single in-office treatment. The tissue and teeth sensitivity were mild and transient. Subjects preferred and would recommend HW over OW.
Kokubyo Gakkai Zasshi. 2010 Jun;77(2):121-7.
[Development of low-concentration hydrogen peroxide whitening agent using visible light-responsive titania photocatalyst]
[Article in Japanese]
Department of Inorganic Materials, Division of Biomaterials, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University.
Abstract
Although highly concentrated hydrogen peroxide (HP) has been used to bleach vital discolored teeth during office whitening, low-concentration HP was recognized to have insufficient whitening ability. We demonstrated that using a visible light-responsive titania photocatalyst (VLRTP) and a vis-Nd : YAG laser, 3 wt% HP-bleached oxytetracycline (OTC)-stained teeth models were more efficient than 30 wt% HP. The stained samples were prepared by soaking synthetic hydroxyapatite ceramic disks in OTC aqueous solutions. Color images of the OTC-stained models before and after whitening were taken with a conventional flatbed scanner and calibrated using a photocell colorimeter. By VLRTP treatment with vis-Nd : YAG laser irradiation, the lightness value (L*) significantly increased and the yellowness index (b*) significantly approached zero. This suggests that a diluted HP agent with VLRTP can more efficiently decolorize stained teeth by visible light irradiation.
Acta Odontol Latinoam. 2010;23(1):27-31.
Effects of five carbamide peroxide bleaching gels on composite resin microhardness.
Briso AL, Tuñas IT, de Almeida LC, Rahal V, Ambrosano GM.
Department of Restorative Dentistry, Araçatuba Dental School-UNESP, Araçatuba, São Paulo, Brazil. alfbriso@foa.unesp.br
Abstract
The purpose of this study was to evaluate the effects of five home bleaching products containing 15-16% carbamide peroxide on the microhardness of microhybrid composite resin Z-250 (3M/Espe). A total of 72 specimens were fabricated in cylindrical acrylic matrices (4 x 2 mm), filled with composite resin and photo-activated for 40 seconds. They were divided in 6 study groups (n = 12), according to the bleaching product: Review (SS White), Magic Bleaching (Vigodent), Opalescence (Ultradent), Whiteness Perfect (FGM), Claridex (Biodinâmica), and a control group (not bleached). Specimens were exposed to 1 cc of bleaching gel for 6 hours daily for 2 weeks. The control group specimens were kept in artificial saliva throughout this time. All the specimens were then analyzed in a microhardness tester. Knoop hardness measurements were performed, and the results were submitted to parametric statistical analysis (analysis of variance and Tukey’s test). Mean Knoop values and standard deviation were: baseline, 68.52a (4.28); control, 63.42b (7.16); Whiteness Perfect, 57.57c (1.81); Magic Bleaching, 57.22c (3.84); Opalescence, 57.03cd (4.00); Claridex, 53.64de (3.33); Review 51.45e (2.82). Identical letters mean statistical equality according to Tukey’s test at the 5% significance level. The products significantly decreased Z-250 (3M/Espe) microhardness.
Oper Dent. 2010 Jul-Aug;35(4):463-9.
Effect of carbamide peroxide bleaching gel concentration on the bond strength of dental substrates and resin composite.
Barcellos DC, Benetti P, Fernandes VV Jr, Valera MC.
Department of Restorative Dentistry, São Paulo State University, SP, Brazil. daphnecbarcellos@hotmail.com
Abstract
PURPOSE: This study evaluated the effect of bleaching gel containing 10%, 15% and 20% carbamide peroxide (CP) on the bond strength of dental enamel or dentin and resin composite restorations. METHODS: The buccal surfaces of 12 bovine tooth crowns were conditioned with 37% phosphoric acid, and the adhesive resin Single Bond 2 and the resin composite Filtek Z350 were used to perform the restorations. The blocks were sectioned to obtain bar specimens. Each specimen group (enamel-E, dentin-D) was divided into four subgroups (n=15): S-artificial saliva; 10-10% CP bleaching; 15-15% CP bleaching; 20-20% CP bleaching. CP was applied for six hours daily for two weeks. The specimens were submitted to the sigma test in a universal testing machine. The data were analyzed by one-way ANOVA and the Tukey post-hoc test and a correlation analysis (r) was performed. RESULTS: For Group E, the mean value (+/- standard-deviation) was 21.86 (+/- 6.03)a, 18.91 (+/- 8.31)ab, 15.43 (+/- 7.44)b and 10.6 (+/- 4.94)c for ES, E10, E15 and E20, respectively. For Group D, the a values were 34.73 (+/- 4.68)a, 35.12 (+/- 13.43)a, 29.67 (+/- 6.84)ab and 24.56 (+/- 6.54)b for DS, D10, D15 and D20, respectively. A negative correlation between the CP concentration and mean values was observed for both the enamel (r=-0.95) and dentin (r=-0.85) groups. CONCLUSION: In the current study, the bond strength of the restoration to enamel and the restoration to dentin were influenced by the application of CP and was dependent on the CP concentration in the bleaching gel.
Oper Dent. 2010 Jul-Aug;35(4):405-11.
Effects of bleaching agents on human enamel light reflectance.
Markovic L, Fotouhi K, Lorenz H, Jordan RA, Gaengler P, Zimmer S.
University of Witten/Herdecke, Operative and Preventive Dentistry, Witten, Germany. Ljubisa.Markovic@uni-wh.de
Abstract
OBJECTIVES: Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. METHODS: Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student’s paired t-test and one-way variance analysis. RESULTS: Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with p<0.0001. At 750 nm (red), significant changes only occurred in enamel from adults and seniors (p<0.04). However, the efficacy of bleaching was significantly increased in the blue and green light spectra as compared to the red spectra (p<0.0001). CONCLUSIONS: The results of the current study showed that the exclusive assumption of the “chromophore effect” in dental bleaching could not be sustained, because whitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.
Oper Dent. 2010 Jul-Aug;35(4):405-11.
Effects of bleaching agents on human enamel light reflectance.
Markovic L, Fotouhi K, Lorenz H, Jordan RA, Gaengler P, Zimmer S.
University of Witten/Herdecke, Operative and Preventive Dentistry, Witten, Germany. Ljubisa.Markovic@uni-wh.de
Abstract
OBJECTIVES: Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. METHODS: Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student’s paired t-test and one-way variance analysis. RESULTS: Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with p<0.0001. At 750 nm (red), significant changes only occurred in enamel from adults and seniors (p<0.04). However, the efficacy of bleaching was significantly increased in the blue and green light spectra as compared to the red spectra (p<0.0001). CONCLUSIONS: The results of the current study showed that the exclusive assumption of the “chromophore effect” in dental bleaching could not be sustained, because whitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.
Acta Odontol Latinoam. 2010;23(1):27-31.
Effects of five carbamide peroxide bleaching gels on composite resin microhardness.
Briso AL, Tuñas IT, de Almeida LC, Rahal V, Ambrosano GM.
Department of Restorative Dentistry, Araçatuba Dental School-UNESP, Araçatuba, São Paulo, Brazil. alfbriso@foa.unesp.br
Abstract
The purpose of this study was to evaluate the effects of five home bleaching products containing 15-16% carbamide peroxide on the microhardness of microhybrid composite resin Z-250 (3M/Espe). A total of 72 specimens were fabricated in cylindrical acrylic matrices (4 x 2 mm), filled with composite resin and photo-activated for 40 seconds. They were divided in 6 study groups (n = 12), according to the bleaching product: Review (SS White), Magic Bleaching (Vigodent), Opalescence (Ultradent), Whiteness Perfect (FGM), Claridex (Biodinâmica), and a control group (not bleached). Specimens were exposed to 1 cc of bleaching gel for 6 hours daily for 2 weeks. The control group specimens were kept in artificial saliva throughout this time. All the specimens were then analyzed in a microhardness tester. Knoop hardness measurements were performed, and the results were submitted to parametric statistical analysis (analysis of variance and Tukey’s test). Mean Knoop values and standard deviation were: baseline, 68.52a (4.28); control, 63.42b (7.16); Whiteness Perfect, 57.57c (1.81); Magic Bleaching, 57.22c (3.84); Opalescence, 57.03cd (4.00); Claridex, 53.64de (3.33); Review 51.45e (2.82). Identical letters mean statistical equality according to Tukey’s test at the 5% significance level. The products significantly decreased Z-250 (3M/Espe) microhardness.
Microsc Res Tech. 2010 Jul 9. [Epub ahead of print]
Shear bond strength and ultrastructural interface analysis of different adhesive systems to bleached dentin.
Ferreira EA, Souza-Gabriel AE, Silva-Sousa YT, Sousa-Neto MD, Silva RG.
School of Dentistry, University of Ribeirão Preto, Ribeirão Preto, Brazil.
Abstract
Background: It remains unclear as to whether or not dental bleaching affects the bond strength of dentin/resin restoration. Purpose: To evaluated the bond strength of adhesive systems to dentin submitted to bleaching with 38% hydrogen peroxide (HP) activated by LED-laser and to assess the adhesive/dentin interfaces by means of SEM. Study design: Sixty fragments of dentin (25 mm(2)) were included and divided into two groups: bleached and unbleached. HP was applied for 20 s and photoactivated for 45 s. Groups were subdivided according to the adhesive systems (n = 10): (1) two-steps conventional system (Adper Single Bond), (2) two-steps self-etching system (Clearfil standard error (SE) Bond), and (3) one-step self-etching system (Prompt L-Pop). The specimens received the Z250 resin and, after 24 h, were submitted to the bond strength test. Additional 30 dentin fragments (n = 5) received the same surface treatments and were prepared for SEM. Data were analyzed by ANOVA and Tukey’s test (alpha = 0.05). Results: There was significant strength reduction in bleached group when compared to unbleached group (P < 0.05). Higher bond strength was observed for Prompt. Single Bond and Clearfil presented the smallest values when used in bleached dentin. SEM analysis of the unbleached specimens revealed long tags and uniform hybrid layer for all adhesives. In bleached dentin, Single Bond provided open tubules and with few tags, Clearfil determined the absence of tags and hybrid layer, and Prompt promoted a regular hybrid layer with some tags. Conclusions: Prompt promoted higher shear bond strength, regardless of the bleaching treatment and allowed the formation of a regular and fine hybrid layer with less deep tags, when compared to Single Bond and Clearfil. Microsc. Res. Tech., 2010. (c) 2010 Wiley-Liss, Inc.
Eur J Dent. 2010 Jul;4(3):238-44.
Protective Effect of Sodium Ascorbate on MDPC-23 Odontoblast-Like Cells Exposed to a Bleaching Agent.
Lima AF, Lessa FC, Hebling J, de Souza Costa CA, Marchi GM.
DDS, MS, PhD Student, Department of Restorative Dentistry, Piracicaba School of Dentistry, State University of Campinas-UNICAMP, Piracicaba, SP, Brazil.
Abstract
OBJECTIVES: To evaluate the cytotoxic effects of a bleaching agent composed of 0.01% carbamide peroxide (CP; 2.21mug/ml H(2)O(2)) on the MDPC-23 odontoblastic cell line, and to determine whether sodium ascorbate (SA) is capable of reducing, or even eliminating, the toxic effects caused by this bleaching agent. METHODS: The cells were seeded in wells and incubated for 48 hours. CP and SA were dissolved in a culture medium (DMEM) in order to obtain experimental extracts. Six groups of cells (n=10) were treated as follows: G1: no treatment (control); G2: 0.25 mM SA/60 min; G3: 0.5 mM SA/60 min; G4: 0.25 mM SA+0.01% CP/60 min; G5: 0.5 mM SA+0.01% CP/60 min; and G6: 0.01% CP/60 min. The cell metabolism was evaluated by MTT assay, and the cell morphology was assessed by scanning electron microscopy. The data obtained were analyzed by 2-way ANOVA and post-hoc Tukey’s test (alpha=5%). RESULTS: THE PERCENTAGES OF CELL METABOLISM WERE AS FOLLOWS: G1 (control)=100%; G2=110.06%, G3=108.57%, G4=90.35%, G5=97.63%, and G6=66.88%. Group 6 presented a statistically lower cell metabolism than did the other groups, and the cells that remained on the substrate exhibited changes in their morphology. SA decreased the cytotoxic effects caused by CP, demonstrating its protective effect against the toxic components of this dental product. CONCLUSIONS: It was concluded that CP gel has cytopathic effects on MDPC-23 odontoblastic cells, even at low concentrations such as 0.01%. SA at 0.25 mM, and that 0.5 mM is able to protect these cultured cells against the cytotoxic effects of CP.
Am J Dent. 2010 Apr;23(2):113-5.
Effect of the diffusion of bleaching agents through enamel on dentin bonding at different depths.
Lima AF, Fonseca FM, Cavalcanti AN, Aguiar FH, Marchi GM.
Department of Restorative Dentistry, Piracicaba School of Dentistry, State University of Campinas, Piracicaba, Brazil.
Abstract
PURPOSE: To evaluate the influence of two concentrations of bleaching agents applied over enamel surfaces on the dentin bonding at different depths. METHODS: Twenty-four bovine incisors were sectioned, obtaining three fragments per tooth (4×4 mm). Each fragment presented a 0.7 mm enamel thickness; and the dentin thickness varied according to the experimental group: 0.5 mm, 1 mm or 1.5 mm. Fragments from each dentin-thickness were allocated into three groups (n=8): G1: Control (no bleaching); G2: 16% carbamide peroxide (6 hours/14 days); G3: 35% hydrogen peroxide (three 15-minute treatments). 24 hours after enamel bleaching, the adhesive system was applied and dentin surfaces were restored with resin composite cylinders (2 mm diameter and 1 mm height). The micro-shear testing was performed immediately after restorative procedures, at a speed of 0.5 mm/minute until failure. Bond strength values, in MPa, were statistically analyzed (split-plot ANOVA/Tukey alpha=0.05). RESULTS: Means obtained were: G1-0.5 mm: 13.5, G1-1 mm: 9.48, G1-1.5 mm: 9.01; G2-0.5 mm: 9.64, G2-1 mm: 9.44, G2-1.5 mm: 9.27; G3-0.5 mm: 11.68, G3-1 mm: 11.64, G3-1.5 mm: 7.63. Regardless of the dentin thickness, bleached groups presented bond strengths similar to that of control groups. Nevertheless, significant differences among dentin depths were detected (P=0.02); and the lowest bond strength was observed on the deepest dentin (1.5 mm). The diffusion of bleaching agents through enamel surfaces did not affect the bond strength to dentin, which is highly dependent on the morphology/depth of the substrate.
J Dent. 2010 Sep;38(9):757-764. Epub 2010 Jun 23.
Bioadhesion and retention of non-aqueous delivery systems in a dental hard tissue model.
Department of Pharmacy, King’s College London, UK.
Abstract
OBJECTIVES: Effective delivery of active agents to dental hard tissues is critical to product performance and pertinent to biofilm control, caries, erosion, hypersensitivity and tooth bleaching. The aim of this study was to investigate in vitro the bioadhesion and retention behaviour of non-aqueous delivery systems (NADS) based on glycerol, PEG 400, Carbopol 974P and triclosan. METHODS: Tensile testing was employed to calculate the work of adhesion (WOA) and maximum force of detachment (F(max)) for formulations applied to hydroxyapatite (HA) and pellicle-coated HA surfaces (HAP). Formulation substantivity under conditions of dynamic flow was studied by monitoring the release of incorporated triclosan. The release data were fitted to a first-order model to generate a removal half-life (t(1/2))(.) RESULTS: Tensile testing showed a clear positive relationship between Carbopol concentration and bioadhesion. Increasing the PEG 400 concentration in formulations containing glycerol, 2% (w/w) Carbopol and 0.30% triclosan produced a local minimum for both WOA and F(max) at 10% (w/w). Values for WOA and F(max) decreased threefold in the presence of a salivary pellicle. Good correlations were obtained between (i) WOA and F(max) and (ii) WOA and t(1/2) and (iii) the elastic modulus of the formulations and t(1/2). CONCLUSION: The presence of a salivary pellicle markedly reduced the bioadhesive interaction between the NADS and the substrate. Increased Carbopol content appeared to be the dominant factor in promoting the WOA, elasticity and retention of NADS to HA surfaces. Such formulations might provide a suitable platform for developing systems suitable for promoting retention to hard surfaces within the oral cavity. Copyright © 2010 Elsevier Ltd. All rights reserved.
Oper Dent. 2010 May-Jun;35(3):300-7.
Influence of carbamide peroxide on the flexural strength of tooth-colored restorative materials: an in vitro study at different environmental temperatures.
Yu H, Li Q, Lin Y, Buchalla W, Wang Y.
Department of Prosthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
Abstract
The current study investigated the influence of carbamide peroxide on the flexural strength of tooth-colored restorative materials at two environmental temperatures. Seven restorative materials were used, including four resin composites (Filtek Z350, Filtek Z250, Synergy Flow and Filtek P60), a polyacid-modified composite (Dyract AP), a conventional glass-ionomer cement (Ketac Molar Easymix) and a ceramic (Vitablocs Mark II). For each type of material, 80 bar-shaped specimens were fabricated and divided into four groups (n = 20): bleaching group at 25 degrees C, control group at 25 degrees C, bleaching group at 37 degrees C and control group at 37 degrees C. The specimens in the bleaching groups were treated with 10% carbamide peroxide gel for eight hours/day, while the control specimens in their respective groups were stored in deionized water. After 14-day treatment, the flexural strength of the specimens was determined using a universal testing machine. All the results were analyzed with ANOVA and the Tukey’s post-hoc test. The data were also submitted to Weibull distribution. The flexural strength and its Weibull distribution of polyacid-modified composite and glass-ionomer cement were more seriously affected by bleaching agents than the resin composite and ceramic, especially at the higher environmental temperature.
Eur J Esthet Dent. 2010 Summer;5(2):216-24.
Clinical efficacy of a bleaching system based on hydrogen peroxide with or without light activation.
Calatayud JO, Calatayud CO, Zaccagnini AO, Box MJ.
Departamento de Estomatología II, Facultad de Odontología, Universidad Complutense de Madrid, Spain. dentaloteo@telefonica.net
Abstract
The objective of the present study was to assess the clinical efficacy of a dental bleaching system based on hydrogen peroxide with or without light activation. This randomized controlled trial evaluated the effect of the light when applied to the hydrogen peroxide by using a split-mouth design with 21 patients, with light activation in one hemi-arch but not in the other. The bleaching agent was QuickWhite 35% hydrogen peroxide and activation was conducted with a diode lamp (Luma Cool). The Classic Vita Guide was used to score tooth shades. Two consecutive applications of hydrogen peroxide were made to one hemi-arch, each light-activated for 10 min. The other hemi-arch was then identically treated but without light activation. After removal of the bleaching agent, the shade was re-scored and the Wilcoxon signed ranks test was used to compare differences in tooth shade values. The bleaching treatment produced significant shade changes (P < 0.01) in both hemi-arches. After treatment, there were no statistically significant differences between light-treated and non-light-treated tooth types (central incisors, lateral incisors, and canines). However, taking central incisor, lateral incisor, and canine as a group, comparison between each hemi-arch showed a significant effect in the hemi-arch with light activation (P < 0.05). The use of diode light with a 35% hydrogen peroxide gel slightly improved the dental bleaching.
Oper Dent. 2010 May-Jun;35(3):287-94.
In vitro assessment of chemical activation efficiency during in-office dental bleaching.
Travassos AC, Rocha Gomes Torres C, Borges AB, Barcellos DC.
Restorative Dentistry Department, São José dos Campos School of Dentistry, São Paulo State University, UNESP, SP, Brazil.
Abstract
PURPOSE: This study compared five types of chemical catalyzing agents added to 35% hydrogen peroxide gel, with regard to their capacity of intensifying in-office dental bleaching results. METHODS: One-hundred and twenty bovine incisors were used, of which the crowns and roots were cut in the incisor-apical direction, to acquire the dimensions of a human central incisor. The specimens were sectioned in the mesiodistal direction by means of two longitudinal cuts, the lingual halves being discarded. The vestibular halves received prophylaxis with a bicarbonate jet, ultrasound cleaning and acid etching on the dentinal portion. Next, the specimens were stored in receptacles containing a 25% instant coffee solution for two weeks. After the darkening period, initial measurement of the shade obtained was taken with the Easy Shade appliance, which allowed it to be quantified by the CIELab method. The samples were divided into six groups, corresponding to the chemical activator used: a) none (CON); b) ferric chloride (CF); c) ferrous sulphate (SF); d) manganese gluconate (GM); e) manganese chloride (CM); f) mulberry root extract (RA). Each group received three 10-minute applications of the gels containing the respective activating agents. Next, a new shade measurement was made. RESULTS: The Analysis of Variance and Tukey tests (alpha = 5%) showed statistically significant differences for the shade perception values (p = 0.002). Groups GM, CM and RA showed significantly higher means than the control group. CONCLUSION: The presence of some chemical activators is capable of resulting in a significant increase in tooth shade variation.
J Am Dent Assoc. 2010 Apr;141(4):449-54.
An in vivo study of the effect of a 38 percent hydrogen peroxide in-office whitening agent on enamel.
Cadenaro M, Navarra CO, Mazzoni A, Nucci C, Matis BA, Di Lenarda R, Breschi L.
Division of Dental Sciences and Biomaterials, Department of Biomedicine, University of Trieste, Piazza Ospedale, 1, 34129 Trieste, Italy. m.cadenaro@fmc.units.it
Abstract
BACKGROUND: In an in vivo study, the authors tested the hypothesis that no difference in enamel surface roughness is detectable either during or after bleaching with a high-concentration in-office whitening agent. METHODS: The authors performed profilometric and scanning electron microscopic (SEM) analyses of epoxy resin replicas of the upper right incisors of 20 participants at baseline (control) and after each bleaching treatment with a 38 percent hydrogen peroxide whitening agent, applied four times, at one-week intervals. The authors used analysis of variance for repeated measures to analyze the data statistically. RESULTS: The profilometric analysis of the enamel surface replicas after the in vivo bleaching protocol showed no significant difference in surface roughness parameters (P > .05) compared with those at baseline, irrespective of the time interval. Results of the correlated SEM analysis showed no relevant alteration on the enamel surface. CONCLUSIONS: Results of this in vivo study support the tested hypothesis that the application of a 38 percent hydrogen peroxide in-office whitening agent does not alter enamel surface roughness, even after multiple applications. CLINICAL IMPLICATIONS: The use of a 38 percent hydrogen peroxide in-office whitening agent induced no roughness alterations of the enamel surface, even after prolonged and repeated applications.
J Mech Behav Biomed Mater. 2010 May;3(4):339-46. Epub 2010 Feb 21.
Alteration of dentin-enamel mechanical properties due to dental whitening treatments.
Zimmerman B, Datko L, Cupelli M, Alapati S, Dean D, Kennedy M.
School of Materials Science and Engineering, Clemson University, 161 Sirrine Hall, Clemson, SC 29634, United States.
Abstract
The mechanical properties of dentin and enamel affect the reliability and wear properties of a tooth. This study investigated the influence of clinical dental treatments and procedures, such as whitening treatments or etching prior to restorative procedures. Both autoclaved and non-autoclaved teeth were studied in order to allow for both comparison with published values and improved clinical relevance. Nanoindentation analysis with the Oliver-Pharr model provided elastic modulus and hardness across the dentin-enamel junction (DEJ). Large increases were observed in the elastic modulus of enamel in teeth that had been autoclaved (52.0 GPa versus 113.4 GPa), while smaller increases were observed in the dentin (17.9 GPa versus 27.9 GPa). Likewise, there was an increase in the hardness of enamel (2.0 GPa versus 4.3 GPa) and dentin (0.5 GPa versus 0.7 GPa) with autoclaving. These changes suggested that the range of elastic modulus and hardness values previously reported in the literature may be partially due to the sterilization procedures. Treatment of the exterior of non-autoclaved teeth with Crest Whitestrips, Opalescence or UltraEtch caused changes in the mechanical properties of both the enamel and dentin. Those treated with Crest Whitestrips showed a reduction in the elastic modulus of enamel (55.3 GPa to 32.7 GPa) and increase in the elastic modulus of dentin (17.2 GPa to 24.3 GPa). Opalescence treatments did not significantly affect the enamel properties, but did result in a decrease in the modulus of dentin (18.5 GPa to 15.1 GPa). Additionally, as expected, UltraEtch treatment decreased the modulus and hardness of enamel (48.7 GPa to 38.0 GPa and 1.9 GPa to 1.5 GPa, respectively) and dentin (21.4 GPa to 15.0 GPa and 1.9 GPa to 1.5 GPa, respectively). Changes in the mechanical properties were linked to altered protein concentration within the tooth, as evidenced by fluorescence microscopy and Fourier transform infrared spectroscopy. Published by Elsevier Ltd.
J Am Dent Assoc. 2010 Mar;141(3):300-6.
Influence of in situ postbleaching times on shear bond strength of resin-based composite restorations.
Bittencourt ME, Trentin MS, Linden MS, de Oliveira Lima Arsati YB, França FM, Flório FM, Basting RT.
Department of Restorative Dentistry, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil.
Abstract
BACKGROUND: The authors conducted an in situ study of the influence of various time intervals after tooth bleaching with 35 percent hydrogen peroxide on the bond strength of resin-based composite restorations. METHODS: After selecting 20 participants, the authors randomly fixed enamel and dentin blocks onto the buccal surfaces of posterior maxillary teeth one week before performing tooth bleaching with 35 percent hydrogen peroxide. After the bleaching treatment, they removed one block of dentin or enamel and prepared it for the bond strength tests according to these time intervals: no bleaching treatment (controls), immediately after bleaching, seven days after bleaching, 14 days after bleaching and 21 days after bleaching. RESULTS: The analysis of variance and Tukey test showed significant differences between times (P<.05), and shear bond strength values of resin-based composite to enamel and dentin were lower immediately after the bleaching treatment. CONCLUSIONS: The authors found that 35 percent hydrogen peroxide reduces the bond strength to enamel and dentin and that it is necessary to wait seven days before performing adhesive restorative procedures. CLINICAL IMPLICATIONS: The results of this study suggest that clinicians should allow seven days to elapse after completion of in-office bleaching with 35 percent hydrogen peroxide before placing adhesive restorations.
Med Oral Patol Oral Cir Bucal. 2010 Mar 1;15(2):e413-6.
Effect of calcium hydroxide dressing on microleakage of composite restorations in endodontically treated teeth subsequent to bleaching.
Rahimi S, Shahi S, Kimyai S, Khayyam L, Abdolrahimi M.
Department of Endodontics, School of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
Abstract
OBJECTIVE: This study evaluates the effect of calcium hydroxide dressing on microleakage of composite restorations following non-vital bleaching. METHODS: A total of 45 sound extracted human maxillary central incisors underwent endodontic treatment. The teeth were randomly divided into three groups (n=15). In group 1, access cavities were restored with composite. In group 2, the teeth underwent a bleaching procedure for one week before being restored with composite. In group 3, following a bleaching procedure, calcium hydroxide paste was placed in the pulp chamber for one week. The teeth were then restored with composite. The specimens were subjected to a dye leakage test. The data was analyzed using Kruskal-Wallis and Mann-Whitney U tests. RESULTS: There were significant differences between the groups (P<0.0005). No statistically significant differences were found between groups 2 and 3, while the differences between other groups were significant. CONCLUSIONS: The bleaching agent increased microleakage of composite restorations in non-vital bleaching, whereas microleakage was not found to be increased by calcium hydroxide.
J Am Dent Assoc. 2010 Jun;141(6):639-46.
Use of tray-applied 10 percent carbamide peroxide gels for improving oral health in patients with special-care needs.
College of Dental Medicine, Western University of Health Sciences, 309 E. Second St., Pomona, CA 91766-1854, USA. dlazarchik@westernu.edu
Abstract
BACKGROUND: Plaque accumulation and resulting caries or periodontal disease is a frequent problem in patients with special-care needs. Tray-applied 10 percent carbamide peroxide (CP) is a tooth-bleaching agent that has positive effects on plaque, gingival health and caries. METHODS: The authors review the antibacterial properties of CP and the effects of CP on saliva, plaque, caries and gingival health. They also review tray fabrication options and techniques, application methods, safety and side effects. Finally, they address the challenges involved in and research needed regarding use of tray-applied CP materials in special-care patients. RESULTS: In their literature review and clinical experience, the authors found 10 percent CP delivered in a custom-fitted tray to be an effective treatment for caries in patients with compromised oral hygiene. Plaque suppression and caries control result from a CP-induced increase in salivary and plaque pH caused by CP’s urea component, and from possible antimicrobial action via physical debridement and the direct chemical effect of hydrogen peroxide. CONCLUSIONS: Tray-applied 10 percent CP may hold great promise for improving the oral health of many special-care patients, including elderly patients, patients with cancer and patients with dry mouth. Further research is needed to verify the potential benefits, specifics of treatment times and protocols and most cost-effective products for use in various patient groups. CLINICAL IMPLICATIONS: Application of 10 percent CP in a custom-fitted tray may reduce caries by elevating the pH above the level at which the caries process can occur, in addition to debriding the teeth and improving gingival health.
Schweiz Monatsschr Zahnmed. 2010;120(4):306-13.
Bleaching of nonvital teeth: a clinically relevant literature review.
Klinik für Zahnerhaltung, Präventiv- und Kinderzahnmedizin, Zahnmedizinische Kliniken, Universität Bern, Switzerland.
Abstract
Today, the bleaching of nonvital, discolored teeth is a low-risk routine treatment for improving esthetics. This review article focuses on the etiology of tooth discolorations, different treatment techniques, and risks of bleaching procedures. Some tooth discolorations in endodontically treated teeth are caused by dental treatments. The three most popular techniques for nonvital tooth bleaching are the walking bleach technique, inside/outside bleaching, and in-office bleaching. The walking bleach technique is a relatively reliable, fairly simple technique for dentists and patients. Inside/outside bleaching can be used additionally when internal and external bleaching must be combined. Inoffice bleaching seems to be a short-term solution, the effects of which can largely be attributed to dehydration of the teeth. There are still some open questions concerning the bleaching agents. Improved safety seems desirable with regard to adding thiourea as a scavenger of radicals or newer materials such as sodium percarbonate. The thermocatalytic technique, insufficient cervical sealing, and high concentrations of bleaching agents should be avoided, as this can increase the risk of cervical root resorptions. Patients should be informed about the low predictability of bleaching success and the risk of recurrent discoloration. The risk of cervical root resorption should be discussed with the patient. There is a strong correlation between root resorption and dental trauma.
Quintessence Int. 2010 Jun;41(6):505-16.
In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products.
Dietschi D, Benbachir N, Krejci I.
Abstract
Objective: Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficiency is unknown. The aim of this in vitro study was to evaluate the ability of bleaching products and protocols to lighten enamel and dentin. Method and Materials: Bovine tooth specimens of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thickness) were prepared and stained with whole blood and hemolysate before being submitted to seven supervised or self-directed bleaching regimens: tray-based bleaching using 10% (Opalescence, Ultradent; Nite White, Discus Dental) or light-activated 30% (Metatray, Metatray) carbamide peroxide (CP); 6% (Zoom, Discus Dental) or 9% (TresWhite, Ultradent) hydrogen peroxide (HP); strips (Whitening Strips, Oral B-Rembrandt); and paint-on gel (Paint on Plus, Ivoclar Vivadent) containing 8.1% and 6% HP, respectively. Colorimetric measurements were performed on each specimen side, according to the CIE L*a*b* system, before and after staining, as well as after 5, 10, and the recommended number of bleaching applications. Results: Color change after recommended number of applications (DEr) varied from 15.72 (Metatray) to 29.67 (Nite White) at enamel and 14.91 (Paint on Plus) to 41.43 (Nite White) at dentin side; Nite White (10% CP) and TresWhite (9% HP) were more effective than Metatray (30% CP) and Paint on Plus (6% HP) after 5 or the recommended number of applications. Conclusion: In this in vitro study based on bovine teeth, tray-based systems produced the faster and better bleaching effect, regardless of the product and concentration used, at both enamel and dentin sides. (Quintessence Int 2010;41:505-516).
Am J Dent. 2010 Feb;23(1):19-22.
Effect of hydrogen peroxide on microhardness and color change of resin nanocomposites.
Kwon YH, Shin DH, Yun DI, Heo YJ, Seol HJ, Kim HI.
Department of Dental Materials, School of Dentistry, Pusan National University, Yangsan 626-870, Korea. y0k0916@pusan.ac.kr
Abstract
PURPOSE: To examine the effect of hydrogen peroxide on the microhardness and color change of resin composites containing nanofillers. METHODS: Three resin nanocomposites with three different shades and two different tooth whitening agents were used. The specimens were given a 3-week treatment with one of three protocols: (1) 7 hours/day treatment of carbamide peroxide (CP) + 17 hours/day immersion in distilled water (DW); (2) 1 hour/week treatment of hydrogen peroxide (HP) + immersion in DW for the rest of the week; and (3) immersion in DW for 24 hours/day. The microhardness and color changes were measured after treatment. RESULTS: After treatment with the whitening agents, there was an 8.1-10.7% decrease in the original microhardness. These values were similar to those obtained from the samples treated with distilled water. In the same resin product, the decrease was similar regardless of the test agents used. In most cases, the color change was only slight (deltaE*=0.5-1.4). Hydrogen peroxide enhanced the color change but the absolute color change values were similar in the same product and shade, regardless of the test agent used.
J Am Dent Assoc. 2010 May;141(5):546-51.
Erosion and abrasion of enamel and dentin associated with at-home bleaching: an in vitro study.
Engle K, Hara AT, Matis B, Eckert GJ, Zero DT.
Biology Department, Wabash College, Crawfordsville, IN, USA.
Abstract
BACKGROUND: Bleaching and erosive processes have been reported to soften dental surfaces, possibly increasing their susceptibility to toothbrush abrasion. The authors conducted an investigation of the effect on enamel and dentin of the interaction among bleaching, erosion and dentifrice abrasivity. METHODS: The authors prepared specimens of human enamel and root dentin and randomly divided them into eight groups that underwent 10 percent carbamide peroxide bleaching, erosion and dentifrice abrasion. The authors submitted the specimens to cycles of erosion, toothbrushing and bleaching for five days. They determined the change in surface loss by means of profilometry. RESULTS: Dental erosion and the more abrasive dentifrice increased toothbrushing wear on enamel surfaces, while bleaching showed no deleterious effect. Dentin wear also increased after subjection to erosion and use of the more abrasive dentifrice. Bleaching increased surface loss on noneroded dentin and decreased loss on eroded dentin when it was brushed with the less abrasive dentifrice. CONCLUSION: Bleaching did not increase the susceptibility of enamel to erosive and abrasive wear, regardless of the dentifrice used. Dentin wear was modulated by the interaction of bleaching, erosion and dentifrice. CLINICAL IMPLICATIONS: Bleaching with 10 percent carbamide peroxide does not increase erosive and abrasive wear of enamel. However, it may change dentin’s abrasive wear, depending on erosive and abrasive challenges.
Oper Dent. 2010 Mar-Apr;35(2):180-6.
Influence of remineralizing gels on bleached enamel microhardness in different time intervals.
Borges AB, Yui KC, D’Avila TC, Takahashi CL, Torres CR, Borges AL.
Department of Restorative Dentistry at São José dos Campos School of Dentistry-UNESP–São Paulo State University, São José dos Campos, SP, Brazil.
Abstract
This study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the post-bleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey’s test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet’s test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.
Oper Dent. 2010 Mar-Apr;35(2):139-46.
In situ study of in-office bleaching procedures using light sources on human enamel microhardness.
Araujo Fde O, Baratieri LN, Araújo E.
Operative Dentistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil. fabianoapraujo_@hotmail.com
Abstract
OBJECTIVE: To evaluate the influence of various light sources on the microhardness of human dental enamel following treatment with an in-office vital bleaching agent (35% hydrogen peroxide). METHODS AND MATERIALS: One-hundred and sixty dental enamel slabs (-2.5 x 2.5 x 1.0 mm) were obtained from 32 recently extracted human third molars, polished and subjected to hardness testing (KHN, 50g-load, 5 seconds) after four time periods (baseline and after 1, 7 and 14 days). The specimens were placed in intraoral appliances and delivered to eight volunteers after being equally divided into five groups each according to the light source treatment to be performed extraorally (n=32): Group LA (35% hydrogen peroxide + argon laser unit); Group HA (35% hydrogen peroxide + halogen light-curing unit); Group LED (35% hydrogen peroxide + LED-laser unit); Group OX (35% hydrogen peroxide + no light source unit); or Group CO (control: saliva only). Microhardness values were analyzed by ANOVA and Tukey’s post-hoc test (alpha = 0.05). RESULTS: Significant decreases in KHN were found in enamel for the HA group one day and seven days after treatment (5.81% and 2.35%, respectively) (p < 0.0001). However, no significant differences were found between the baseline and final microhardness values for all groups submitted to bleaching. CONCLUSION: The different tested light sources did not significantly influence the microhardness of human enamel following treatment with 35% hydrogen peroxide.
Aust Dent J. 2009 Dec;54(4):326-33.
Internal bleaching of teeth: an analysis of 255 teeth.
School of Dentistry, The University of Western Australia, Nedlands WA. paul.v.abbott@uwa.edu.au
Abstract
BACKGROUND: Studies about bleaching have not analysed factors that affect the outcome. This aim of this study was to analyse the outcome of, and the factors associated with bleaching. METHODS: Internal bleaching was done on 255 teeth in 203 patients. Colour was assessed pre-operatively, postoperatively and at recalls. The cause and type of discolouration, number of applications, bleaching outcome, and colour stability were assessed. RESULTS: The most common teeth were upper central (69 per cent) and lateral (20.4 per cent) incisors. Trauma was the most common cause (58.8 per cent), followed by previous dental treatment (23.9 per cent), pulp necrosis (13.7 per cent) and pulp canal calcification (3.6 per cent). Dark yellow and black teeth required more applications of bleach than light yellow and grey teeth. Colour modification was “good” (87.1 per cent) or “acceptable” (12.9 per cent). Teeth restored with glass ionomer cement/composite resin had good colour stability, but this was less predictable with other restorations. No teeth had external invasive resorption. CONCLUSIONS: Bleaching endodontically treated teeth was very predictable, especially for grey or light yellow discolourations. Glass ionomer cement/composite restorations were effective at preventing further discolouration. Patient age and tooth type did not affect treatment outcome and no cases of external invasive resorption were observed.
Eur J Dent. 2010 Apr;4(2):175-82.
Effect of 16% carbamide peroxide bleaching gel on enamel and dentin surface micromorphology and roughness of uremic patients: an atomic force microscopic study.
Mahmoud SH, Elembaby Ael S, Zaher AR, Grawish Mel-A, Elsabaa HM, El-Negoly SA, Sobh MA.
Associate Professor of Operative Dentistry, Head of Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.
Abstract
OBJECTIVES: To investigate the effect of 16% carbamide peroxide bleaching gel on surface micromorphology and roughness of enamel and root dentin of uremic patients receiving hemodialysis using atomic force microscopy (AFM). METHODS: A total of 20 sound molars were collected from healthy individuals (n=10) and uremic patients (n=10). The roots were separated from their crowns at the cemento-enamel junction. Dental slabs (3 mm x 2 mm x 2 mm) were obtained from the buccal surface for enamel slabs and the cervical third of the root surface for dentin slabs. Dental slabs were then flattened and serially polished up to #2500-grit roughness using silicon carbide abrasive papers. Half of the slabs obtained from healthy individuals and uremic patients were stored in artificial saliva and left without bleaching for control and comparison. The remaining half was subjected to a bleaching treatment using 16% carbamide peroxide gel (Polanight, SDI Limited) 8 h/day for 14 days and stored in artificial saliva until AFM analysis was performed. Statistical analysis of the roughness average (Ra) results was performed using one-way ANOVA and Bonferroni post hoc multiple comparisons test. RESULTS: The micromorphological observation of bleached, healthy enamel showed exaggerated prism irregularities more than non-bleached specimens, and this observation was less pronounced in bleached uremic enamel specimens with the lowest Ra. Bleached healthy dentin specimens showed protruded peritubular dentin and eroded intertubular dentin with the highest Ra compared to bleached uremic dentin. CONCLUSIONS: The negative effects of the bleaching gel on uremic tooth substrates are less dramatic and non-destructive compared to healthy substrates because uremia confers different micromorphological surface changes.
Tex Dent J. 2010 Mar;127(3):285-91.
A comparison of shear bond strengths on bleached and unbleached bovine enamel.
Dietrich AM, English J, McGrory K, Ontiveros J, Powers JM, Bussa HI Jr, Salas-Lopez A.
The University of Texas Dental Branch at Houston, Department of Orthodontics, USA.
Abstract
INTRODUCTION: This study investigated whether tooth whitening with two different bleaching systems affects the shear bond strength achieved using an orthodontic self-etching primer. METHODS: The sample of 210 bovine incisors was divided into three groups. One group served as the control, while the other two groups received either an over-the-counter “white strip” bleaching regimen (Opalescence TresWhite) or a “power bleaching” in-office regimen (Opalescence Boost). Each bleaching group was divided into three groups to be tested at three time intervals post-bleaching: immediately, 24 hours, and 7 days. RESULTS: When compared to the control, the shear bond strength attained on Opalescence TresWhite treated specimens was not significantly lower at any time interval post-bleaching. Immediately after bleaching and 24 hours after bleaching, the Opalescence Boost treated groups showed significantly lower shear bond strengths than both the control groups and the Opalescence TresWhite groups. CONCLUSIONS: Bleaching with 38 percent hydrogen peroxide immediately and 24 hours before bonding reduced the shear bond strengths. After seven days the bond strengths were normal. Bleaching with 10 percent hydrogen peroxide in the form of white strip material did not reduce shear bond strengths.
Int J Prosthodont. 2010 Jan-Feb;23(1):29-32.
Analysis of tooth enamel after excessive bleaching: a study using scanning electron microscopy and energy dispersive x-ray spectroscopy.
Souza RO, Lombardo GH, Pereira SM, Zamboni SC, Valera MC, Araujo MA, Ozcan M.
Department of Restorative Dentistry, Division of Prosthodontics, Federall University of Paraíba, João, Pessoa, Brazil. roasouza@yahoo.com.br
Abstract
This study assessed alterations on bovine enamel after excessive bleaching. Coronal portions of bovine teeth (n = 30) were sectioned and divided into three groups (n = 10 per group). The coronal parts were further cut incisocervically into two halves. While one half received no bleaching (control), the other half was subjected to either one (group 1), three (group 2), or five bleaching sessions (group 3) with 35% hydrogen peroxide. The enamel surfaces were then analyzed using scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS). Excessive bleaching affected the surface morphology and chemistry of the bovine enamel. EDS analysis showed the highest decrease in calcium ion percentages in groups 2 and 3 when compared to their nonbleached halves. Oxygen and phosphorus percentages were comparable on both the control and bleached enamel, regardless of the number of bleaching sessions. Consecutive bleaching sessions with 35% hydrogen peroxide may lead to morphologic and specific elemental changes when performed in a short period of time. Calcium ion percentages may decrease when this bleaching agent is used for more than one session. Int J Prosthodontics 2010;23:29-32.
nt Endod J. 2010 Feb;43(2):102-8.
Cytotoxicity and genotoxicity of sodium percarbonate: a comparison with bleaching agents commonly used in discoloured pulpless teeth.
Fernández MR, Carvalho RV, Ogliari FA, Beira FA, Etges A, Bueno M.
School of Dentistry, Institute of Biology, Federal University of Pelotas, Pelotas, RS, Brazil. raquelitafm@gmail.com
Abstract
AIM: To evaluate the cytotoxicity and genotoxicity of sodium percarbonate (SPC) in comparison with bleaching agents used on discoloured pulpless teeth. METHODOLOGY: The cytotoxicity and genotoxicity of bleaching agents were evaluated both in their pure form as well as at concentrations commonly used in clinical practice. Hydrogen peroxide (HP), carbamide peroxide (CP), sodium perborate (SP) and SPC were diluted in Dulbecco’s modified Eagle’s medium (DMEM) in series. To evaluate the cytotoxicity, the survival of 3T3/NIH mouse fibroblasts was measured photometrically using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after a 24 h-exposure period. Genotoxicity was indicated by micronuclei (MN) formation, and modification of the normal cell was analysed by light microscopy (400x). Statistical analysis was performed by one-way anova, followed by a multiple-comparison Tukey post hoc test (P < 0.05). RESULTS: All groups exhibited a dose-dependent cytotoxicity. However, CP showed a similar cytotoxic effect when compared with DMEM-untreated control (UC) group. HP and SPC were significantly more cytotoxic than SP. The genotoxicity test showed that SPC and SP had an intermediate rate of MN frequency when compared with the UC group. The mean rate of MN frequency for HP was higher and statistically more significant than for the other groups tested. No difference was observed when CP and UC groups were compared. CONCLUSIONS: Sodium percarbonate showed cytotoxicity and genotoxicity similar to those of the other products tested. However, before SPC is used clinically, studies should be conducted to confirm its safety in vivo.
J Am Dent Assoc. 2010 Apr;141(4):449-54.
An in vivo study of the effect of a 38 percent hydrogen peroxide in-office whitening agent on enamel.
Cadenaro M, Navarra CO, Mazzoni A, Nucci C, Matis BA, Di Lenarda R, Breschi L.
Division of Dental Sciences and Biomaterials, Department of Biomedicine, University of Trieste, Piazza Ospedale, 1, 34129 Trieste, Italy. m.cadenaro@fmc.units.it
Abstract
BACKGROUND: In an in vivo study, the authors tested the hypothesis that no difference in enamel surface roughness is detectable either during or after bleaching with a high-concentration in-office whitening agent. METHODS: The authors performed profilometric and scanning electron microscopic (SEM) analyses of epoxy resin replicas of the upper right incisors of 20 participants at baseline (control) and after each bleaching treatment with a 38 percent hydrogen peroxide whitening agent, applied four times, at one-week intervals. The authors used analysis of variance for repeated measures to analyze the data statistically. RESULTS: The profilometric analysis of the enamel surface replicas after the in vivo bleaching protocol showed no significant difference in surface roughness parameters (P > .05) compared with those at baseline, irrespective of the time interval. Results of the correlated SEM analysis showed no relevant alteration on the enamel surface. CONCLUSIONS: Results of this in vivo study support the tested hypothesis that the application of a 38 percent hydrogen peroxide in-office whitening agent does not alter enamel surface roughness, even after multiple applications. CLINICAL IMPLICATIONS: The use of a 38 percent hydrogen peroxide in-office whitening agent induced no roughness alterations of the enamel surface, even after prolonged and repeated applications.
Arch Oral Biol. 2010 Apr;55(4):300-8. Epub 2010 Mar 24.
Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.
Tanaka R, Shibata Y, Manabe A, Miyazaki T.
Department of Oral Biomaterials and Technology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Abstract
Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.
Gen Dent. 2010 Mar-Apr;58(2):e74-9.
Changes in surface morphology and mineralization level of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation.
Berger SB, Cavalli V, Ambrosano GM, Giannini M.
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, Sao Paulo, Brazil.
Abstract
The objective of this study was to evaluate the alterations on surface morphology and mineral loss of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation. Dental enamel samples were obtained from human third molars and randomly divided into 10 groups (n = 10). The control group remained untreated. Bleached groups were treated with one of three whitening products. Bleaching was performed in a single session, during which bleaching gel was applied to the enamel surface three times for 10 minutes each time. During treatment, the bleaching agents were either irradiated by a halogen light or an LED/diode laser or were not irradiated at all. Microhardness testing was performed with a Knoop indentor and the surface morphologic observations were carried out by scanning electron microscopy (SEM). Cross-sectional microhardness (CSMH) and polarized light microscopy (PLM) were used to measure the depth of demineralization. The results revealed a significant decrease in surface microhardness values and changes to the enamel morphology after bleaching. CSMH and PLM showed that bleached enamel presented lower volume percentage of mineral up to 40 micrometers from the enamel surface and demineralization areas located in the subsuperficial region of enamel, respectively. It was concluded that 35% hydrogen peroxide can alter the surface morphology and the mineralization level of the dental enamel surface and sub-surface regardless of what type of bleaching light is used.
Int J Periodontics Restorative Dent. 2010 Mar-Apr;30(2):203-11.
Microhardness evaluation of in situ vital bleaching and thickening agents on human dental enamel.
Soldani P, Amaral CM, Rodrigues JA.
Abstract
Bleaching systems and thickening agents lead to changes in the tooth enamel matrix as a result of an unspecific oxidation of the bleaching gel in the enamel. This reaction may result in a loss of mineral content and a decrease in microhardness. The aim of this study was to evaluate the effects of different bleaching systems and their thickening agents on the microhardness of human enamel in situ. Two dental slabs (3 3 3 3 2 mm) obtained from third molars were fixed on the buccal facial aspects of the maxillary first molars in a group of 45 volunteers. The volunteers were treated with 10% carbamide peroxide gel with carbopol as the thickening agent (group 1), 2% carbopol gel (group 2), 10% carbamide peroxide paste with poloxamer as the thickening agent (group 3), poloxamer (group 4), or 6.5% hydrogen peroxide strips for 21 days (group 5) (experimental treatment factor). The effects of the experimental treatment were evaluated by microhardness tests performed both before and after treatment (time factor). Data were submitted to split-plot analysis of variance and Tukey tests. Only time showed a statistically significant difference (P < .0001). All treatments reduced the enamel microhardness during treatment. Clinically, a reduction in microhardness can be expected after dental bleaching. (Int J Periodontics Restorative Dent 2010;30:203-211.).
Clin Oral Investig. 2010 Mar 9. [Epub ahead of print]
Surface characterization of passive film and elemental release analysis of a Ni-Cr alloy during bleaching, part I: effects of different bleaching agents.
Department of Prosthodontics, Ankara University Faculty of Dentistry, 06500, Besevler, Ankara, Turkey, evsen78@yahoo.com.
Abstract
The aim of this study was to evaluate the elemental release from a Ni-Cr dental casting alloy subjected to 10% hydrogen peroxide (HP) or 10% carbamide peroxide (CP) solutions and to determine the composition of surface oxide layer formed on alloy samples. Cylinder-shaped 15 specimens were cast from a Ni-Cr alloy and divided into three groups (n = 5). Samples were exposed either to phosphate-buffer solution, HP, or CP for 30 days, and total mass and individual elements (Ni, Cr, Mo) released into solutions were measured by means of atomic absorption spectrometry. Before and after elemental release measurements, a scanning electron microscope (SEM) accompanied by energy dispersive spectroscopy (EDS) (SEM/EDS) was used to analyze the surface morphology, and surface characterization of passive film formed on alloy samples was also performed by using X-ray photoelectron spectroscopy (XPS). The presence of bleaching agents induced the mass released compared to control group (4.9 mug/cm(2)); this effect was recorded in both HP (171.2 mug/cm(2)) and CP (59.7 mug/cm(2)). XPS data showed that Cr and Ni levels in oxide layers formed on HP group were higher, Mo level was lower than those of CP group.
Am J Dent. 2009 Dec;22(6):393-6.
Effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application on enamel microhardness after bleaching.
Bayrak S, Tunc ES, Sonmez IS, Egilmez T, Ozmen B.
Department of Pediatric Dentistry, Faculty of Dentistry, Ondokuz Mayis University, 55139 Samsun, Turkey. suleb76@yahoo.com
Abstract
PURPOSE: To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CCP-ACP) application on the microhardness of bleached enamel and compare it to that of fluoride application. METHODS: 10 extracted bovine incisors were cut into four sections (4 x 4 x 3 mm) that were randomly distributed among five groups (n = 8). All groups were bleached three times using 38% hydrogen peroxide (HP), with 5-day intervals between bleaching, according to the following treatment protocols: Group A: bleaching only; Group B: bleaching + daily CCP-ACP paste; Group C: bleaching + daily casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACPF) paste; Group D: bleaching + daily 250ppm NaF solution; Group E: bleaching + APF gel (once after final bleaching). Specimens were maintained in artificial saliva throughout the experiment. Baseline and post-treatment Vickers microhardness values were obtained for all specimens. Statistical analysis was performed using one-way ANOVA and post-hoc Tukey tests. RESULTS: Groups B and C showed significant increases in enamel microhardness following treatment (P < 0.001), whereas no statistically significant changes were observed in Groups A, D, or E (P > 0.05). One-way ANOVA of delta Vickers microhardness numbers (deltaVHN) revealed significant differences among groups (P < 0.001), with Group B showing the highest deltaVHN and Group A the lowest.
Am J Dent. 2009 Dec;22(6):387-92.
Influence of in situ post-bleaching times on resin composite shear bond strength to enamel and dentin.
Barbosa CM, Sasaki RT, Flório FM, Basting RT.
Faculty of Dentistry and Dental Research Center São Leopoldo Mandic, Department of Restorative Dentistry – Operative, Rua José Rocha Junqueira, 13 Bairro Swift, Campinas, SP, CEP: 13045-755, Brazil.
Abstract
PURPOSE: To evaluate in situ the influence of time after treatment with a 16% carbamide peroxide home-use bleaching agent on the shear bond strength of resin-based composite to human enamel and dentin. METHODS: 80 enamel slabs (E) and 80 dentin slabs (D) were obtained, embedded, flattened, sterilized and randomly fixed on the buccal surface of teeth in 20 volunteers. These specimens were submitted to treatment with a 16% carbamide peroxide bleaching agent (Pola Night) for 2 hours a day, for 3 weeks. The control group (C) consisted of slabs that were fixed on buccal tooth faces that did not receive any bleaching treatment. For the experimental groups, three slabs of E and three slabs of D were fixed to teeth of the same volunteers, and after bleaching treatment, the slabs were removed at different times: EI–immediate removal; E7–removal 7 days after treatment ended; E14–removal 14 days after treatment ended. After removal, the slabs were again embedded and microhybrid composite resin cylinders (Filtek Z250) were constructed and bonded using a one-bottle adhesive system (Single Bond) for shear bond strength tests. These tests were performed in a universal testing machine, with a speed of 0.5 mm/minute, with the data returned in MPa. The results were submitted to the ANOVA test. RESULTS: There were no significant differences with regards to the timespan for the E and D groups (P > 0.05). For the fracture mode analysis, there was a predominance of adhesive failures for Groups C, EI and E14 in enamel, with the same adhesive failures occurred for all groups in dentin. It was concluded that restorative procedures may be performed immediately after the end of the bleaching treatment.
Am J Dent. 2009 Dec;22(6):324-8.
Effects of tooth bleaching on the color and translucency properties of enamel.
Ma X, Jiang T, Sun L, Wang Z, Zhou Y, Wang Y.
Key Laboratory for Oral Biomedical Engineering, Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, PR China.
Abstract
PURPOSE: To investigate the changes in color and translucency properties of enamel following 14 days treatment with carbamide peroxide. METHODS: 24 extracted premolars were used in this study. Two enamel-dentin specimens were prepared from each tooth and randomly assigned to be bleached with carbamide peroxide for 14 days or stored in artificial saliva as control. A spectrophotometer (Spectrascan PR650) was employed to measure the color of specimens according to the CIELab system. Color measurement of enamel-dentin specimens was performed prior to and after bleaching. After 14 days bleaching, enamel slabs were prepared by removing dentin parts using a low-speed saw. Then the color and translucency parameter (TP) of enamel slabs was measured over a black and a white background. Data between the experimental group and the control group were analyzed by paired t-test. RESULTS: After bleaching, the color of enamel slabs and controls differed significantly both over the black and white background in L* and b* values (all P < 0.001). The translucency parameter (TP) of bleached enamel slabs was significantly lower than that of controls (P < 0.01). Both the deltaE values of enamel on the two backgrounds were significantly correlated to that of enamel-dentin specimens (P = 0.003; P = 0.012).
J Esthet Restor Dent. 2010 Feb;22(1):42-52.
Spectrophotometric analysis of tooth color reproduction on anterior all-ceramic crowns: Part 1: analysis and interpretation of tooth color.
Ishikawa-Nagai S, Yoshida A, Da Silva JD, Miller L.
Department of Restorative Dentistry and Biomaterials Sciences, Harvard School of Dental Medicine, Boston, MA 02115, USA. shigemi_nagai@hsdm.harvard.edu
Color matching of a natural maxillary central incisor is one of the most difficult challenges in clinical dentistry. Accurate color determination and interpretation of tooth color information in ceramic work is an important step in achieving success in ideal color reproduction. In this case study, factors that influence tooth color determination were analyzed, and the process of interpretation of tooth color information was assessed based on scientific color data using a novel dental spectrophotometer system. An all-ceramic crown for a maxillary right central incisor was the subject of this color assessment. The contralateral incisor was an intact natural tooth that was bleached and then used as the target shade for an all-ceramic crown. The dental spectrophotometer (Crystaleye, Olympus, Tokyo, Japan) was used for tooth color measurement and analysis. The target tooth, prepared tooth, maxillary arch, and face images were captured for color information. Tooth color stabilization related to tooth bleaching and tooth dehydration was assessed. Based on tooth color data obtained by the dental spectrophotometer, color was analyzed in several different areas of a tooth using CIELAB (Commission Internationale de l’Eclarirage) color coordinates L*, a*, b*, and color difference Delta E. Interpretation of the tooth color information was made in each of porcelain layers on a blue map, and its intensions for color reproduction were described. Throughout this spectrophotometric assessment, the process of stabilized tooth color determination, tooth color analysis, interpretations, and fabrication of a blue map for porcelain work was clarified with color data as scientific evidence. CLINICAL SIGNIFICANCE: The use of a dedicated dental spectrophotometer allows the evaluation and measurement of the color of a bleached tooth. This allows the laboratory technician to more precisely understand the bleached tooth shade as well as when the bleached tooth color has become stable enough to match to a contralateral all-ceramic crown restoration.
Dent Mater J. 2009 Nov;28(6):693-9.
Effects of light sources and visible light-activated titanium dioxide photocatalyst on bleaching.
Suyama Y, Otsuki M, Ogisu S, Kishikawa R, Tagami J, Ikeda M, Kurata H, Cho T.
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549, Japan. worldclass0221@yahoo.co.jp
The objective of this study was to evaluate, using methylene blue (MB), the effects of various light sources on the bleaching action of hydrogen peroxide (H(2)O(2)) with two titanium dioxide (TiO(2)) photocatalysts – an ultraviolet light-activated TiO(2) photocatalyst (UVTiO(2)) versus a visible light-activated TiO(2) photocatalyst (VL-TiO(2)). Five experimental solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), H(2)O(2), VL-TiO(2), UV-TiO(2)) were prepared by mixing varying concentrations of H(2)O(2 )and/or TiO(2 )photocatalyst with MB solution. For H(2)O(2)-containing solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), and H(2)O(2)), the concentration of H(2)O(2) was adjusted to 3.5%. For the four different light sources, low- and high-intensity halogen lamps and blue LED LCUs were used. All the experimental solutions were irradiated by each of the light sources for 7 minutes, and the absorbance at 660 nm was measured every 30 seconds to determine the concentration of MB as an indicator of the bleaching effect. On the interaction between the effects of light source and bleaching treatment, the high-intensity halogen with VL-TiO(2)+H(2)O(2) caused the most significant reduction in MB concentration. On the effect of light sources, the halogen lamps resulted in a greater bleaching effect than the blue LED LCUs.
Int Dent J. 2009 Oct;59(5):284-8.
A silica toothpaste containing blue covarine: a new technological breakthrough in whitening.
Unilever Oral Care, Bebington, Wirral, UK. Andrew.Joiner@Unilever.com
There continues to be a demand from consumers and patients for products that whiten teeth. These products are generally either peroxide-based bleaching formats to improve intrinsic tooth colour or whitening toothpastes with enhanced physical and chemical cleaning properties to remove and prevent extrinsic tooth stain. Through the understanding of colour science and its application to tooth colour a new approach to tooth whitening is now possible from toothpaste. This is achieved by the deposition of blue covarine onto the tooth surface where it changes the optical properties of the teeth such that their appearance is both measurably and perceivably whiter immediately after treatment. In vitro and in vivo studies confirm the efficacy of this whitening approach in a silica based whitening toothpaste containing blue covarine. In addition, this toothpaste has been shown not to have an undue degree of abrasivity to enamel or dentine compared to other relevant commercially available products, and is an efficacious source of fluoride.
J Appl Oral Sci. 2009 Sep-Oct;17(5):436-9.
Intrapulpal temperature variation during bleaching with various activation mechanisms.
Michida SM, Passos SP, Marimoto AR, Garakis MC, de Araújo MA.
Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, SP, Brazil. silviamasae@yahoo.com
OBJECTIVES: The aim of this study was to evaluate the intrapulpal temperature variation after bleaching treatment with 35% hydrogen peroxide using different sources of activation. MATERIAL AND METHODS: Twenty-four human teeth were sectioned in the mesiodistal direction providing 48 specimens, and were divided into 4 groups (n=12): (G1) Control – Bleaching gel without light activation, (G2) Bleaching gel + halogen light, (G3) Bleaching gel + LED, (G4) Bleaching gel + Nd:YAG Laser. The temperatures were recorded using a digital thermometer at 4 time points: before bleaching gel application, 1 min after bleaching gel application, during activation of the bleaching gel, and after the bleaching agent turned from a dark-red into a clear gel. Data were analyzed statistically by the Dunnet’s test, ANOVA and Tukey’s test (a=0.05). RESULTS: The mean intrapulpal temperature values ( degrees C) in the groups were: G1: 0.617 +/- 0.41; G2: 1.800 +/- 0.68; G3: 0.975 +/- 0.51; and G4: 4.325 +/- 1.09. The mean maximum temperature variation (MTV) values were: 1.5 degrees C (G1), 2.9 degrees C (G2), 1.7 degrees C (G3) and 6.9 degrees C (G4). When comparing the experimental groups to the control group, G3 was not statistically different from G1 (p>0.05), but G2 and G4 presented significantly higher (p<0.05) intrapulpal temperatures and MTV. The three experimental groups differed significantly (p<0.05) from each other. CONCLUSIONS: The Nd:YAG laser was the activation method that presented the highest values of intrapulpal temperature variation when compared with LED and halogen light. The group activated by LED light presented the lowest values of temperature variation, which were similar to that of the control group.
Dent Mater J. 2009 Nov;28(6):693-9.
Effects of light sources and visible light-activated titanium dioxide photocatalyst on bleaching.
Suyama Y, Otsuki M, Ogisu S, Kishikawa R, Tagami J, Ikeda M, Kurata H, Cho T.
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549, Japan. worldclass0221@yahoo.co.jp
The objective of this study was to evaluate, using methylene blue (MB), the effects of various light sources on the bleaching action of hydrogen peroxide (H(2)O(2)) with two titanium dioxide (TiO(2)) photocatalysts – an ultraviolet light-activated TiO(2) photocatalyst (UVTiO(2)) versus a visible light-activated TiO(2) photocatalyst (VL-TiO(2)). Five experimental solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), H(2)O(2), VL-TiO(2), UV-TiO(2)) were prepared by mixing varying concentrations of H(2)O(2 )and/or TiO(2 )photocatalyst with MB solution. For H(2)O(2)-containing solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), and H(2)O(2)), the concentration of H(2)O(2) was adjusted to 3.5%. For the four different light sources, low- and high-intensity halogen lamps and blue LED LCUs were used. All the experimental solutions were irradiated by each of the light sources for 7 minutes, and the absorbance at 660 nm was measured every 30 seconds to determine the concentration of MB as an indicator of the bleaching effect. On the interaction between the effects of light source and bleaching treatment, the high-intensity halogen with VL-TiO(2)+H(2)O(2) caused the most significant reduction in MB concentration. On the effect of light sources, the halogen lamps resulted in a greater bleaching effect than the blue LED LCUs.
J Esthet Restor Dent. 2009;21(6):387-94.
Effect of light irradiation on tooth whitening: enamel microhardness and color change.
Gomes MN, Francci C, Medeiros IS, De Godoy Froes Salgado NR, Riehl H, Marasca JM, Muench A.
Department of Dental Materials, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227,Cidade Universitária, 05508-900 São Paulo, Brazil. maungomes@usp.br
The aim of this study was to evaluate the influence of light exposure associated with 35% hydrogen peroxide (Pola Office, SDI, Melbourne, Vic., Australia) or 15% hydrogen peroxide (BriteSmile, Discus, Culver City, CA, USA) on the microhardness and color changes of bovine enamel. Experimental groups were Britesmile + Light (BL) (15% hydrogen peroxide + plasm arc; 4 x 20 minutes), Britesmile + No Light (BN) (BL, no light), Pola office + Light (PL) (35% hydrogen peroxide + LED; 4 x 8 minutes), and Pola office + No light (PN) (PL, no light). Color changes (DeltaE) and the CIELAB (Commission Internationale de l’ Eclairage, L* a* b* color system) parameters (L*, a*, and b*) were assessed with a spectrophotometer before (B), immediately (A), 1 day and 7 days after bleaching. The microhardness was measured before (B) and after (A), the obtained data were submitted to a two-way analysis of variance, and DeltaE were submitted to t-test for each period. Only Pola Office, in which the peroxide is associated with the light, improved DeltaE when evaluated immediately after bleaching (p < 0.001). Light exposure did not influence DeltaE after 1 day or 7 days for either bleaching system. The enamel microhardness was not altered after bleaching for BriteSmile. However, enamel microhardness was reduced after bleaching for Pola Office, 283 MPa (+/-21) and 265 MPa (+/-27), respectively. It was concluded that these two bleaching systems were efficient regardless of the light systems used. However, the 35% hydrogen peroxide altered the enamel microhardness. CLINICAL SIGNIFICANCE Enamel microhardness was affected by a 35% hydrogen peroxide in-office bleaching therapy. Moreover, the in-office bleaching outcome was not improved by using the light associated with systems tested in this study. (J Esthet Restor Dent 21:387-396, 2009).
Oper Dent. 2009 Sep-Oct;34(5):593-7.
Influence of potentially remineralizing agents on bleached enamel microhardness.
Borges AB, Samezima LY, Fonseca LP, Yui KC, Borges AL, Torres CR.
São Paulo State University, Restorative Dentistry, São Paulo, Brazil. alessandra@fosjc.unesp.br
This study investigated the effect of the addition of calcium and fluoride into a 35% hydrogen peroxide gel on enamel surface and subsurface microhardness. Twenty extracted human third molars were sectioned to obtain enamel fragments and they were divided into four groups (n = 20) according to the bleaching treatment. Group 1 received no bleaching procedure (control). Group 2 was treated with a 35% hydrogen peroxide gel (Total Bleach), Groups 3 and 4 were bleached with Total Bleach modified by the addition of sodium fluoride and calcium chloride, respectively. The microhardness of the enamel surface was assessed using a Vickers microdurometer immediately after the bleaching treatment. The specimens were sectioned in the central portion, polished and evaluated to determine the microhardness of the enamel subsurface to a depth of 125 microm, with an interval of 25 microm between measures. There were significant differences among the groups. In terms of surface microhardness, the bleached group exhibited the lowest means, and the calcium-modified bleached group exhibited the highest means. Regarding subsurface microhardness, there were no significant differences among the groups for the depth and interaction factors. The bleached group exhibited the lowest means, and the calcium-modified bleached group presented the highest means. It was concluded that the bleaching treatment with 35% hydrogen peroxide significantly reduced the surface and subsurface microhardness of the enamel, and the addition of fluoride and calcium in the bleaching agent increased the microhardness means of the bleached enamel.
Oper Dent. 2009 Sep-Oct;34(5):565-70.
Effect of light-activated bleaching on the microleakage of Class V tooth-colored restorations.
Department of Operative Dentistry & Torabinejad Dental Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. khoroushi@dnt.mui.ac.ir
OBJECTIVE: In-office bleaching procedures utilizing highly concentrated 30%-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents are used for tooth whitening. Some recommend that, to enhance the whitening process, light-activation of the bleaching agent should be performed. The current study evaluated the effect of plasma arc bleaching on the microleakage of Class V restorations restored with resin composite, compomer and resin-modified glass ionomer (RMGI). MATERIALS AND METHODS: The buccal surfaces of 72 freshly extracted premolars were prepared with Class V cavities (4 x 2.5 x 1.5 mm) extended 1 mm apical to the CEJ. The prepared teethwere randomly divided into six groups. The cavities were restored with Single Bond and Z100 resin composite (Groups 1 and 2), Prompt L-Pop and F2000 compomer (Groups 3 and 4) and Vitremer RMGI (Groups 5 and 6), respectively. They were then thermocycled for 500 cycles. The samples from Groups 1, 3 and 5 were incubated at 37 degrees C and 100% humidity. Groups 2, 4 and 6 were bleached using in-office bleaching gel and the plasma arc bleaching unit, then incubated. All samples were sealed with nail varnish and immersed in 2% basic fuschin for 24 hours. The restorations were sectioned longitudinally and microleakage was evaluated using a scale ranging from 0 to 3. The data were analyzed using the Kruskal-Wallis test (alpha = 0.05). RESULTS: No statistically significant differences between study groups were observed in both the enamel and dentinal margins (p > 0.05). CONCLUSION: Plasma arc bleaching did not significantly affect the microleakage of existing tooth-colored restorations restored with Z100 resin composite, F2000 compomer and Vitremer RMGI.
Oper Dent. 2009 Nov-Dec;34(6):746-52.
Effect of 10% sodium ascorbate and 10% alpha-tocopherol in different formulations on the shear bond strength of enamel and dentin submitted to a home-use bleaching treatment.
Sasaki RT, Flório FM, Basting RT.
School of Dentistry, São Leopoldo Mandic, Campinas, SP, Brazil.
This in vitro study assessed the shear bond strength of human enamel and dentin submitted to a bleaching treatment with 10% carbamide peroxide and treatment with antioxidant agents containing 10% alpha-tocopherol and 10% sodium ascorbate formulated in solution and gel. Sixty human dental enamel slabs (E) and 60 human dental dentin slabs (D) were randomly divided into six groups (n = 10). Groups E1 and D1 were negative control groups and the bleaching agent was not applied. The bleaching agent was applied daily for two-hours on the dental slabs of all the other groups and, during the remaining 22 hours, the specimens were stored in an artificial saliva solution for a total of 14 days. Groups E2 and D2 were positive control groups and they only received application of the bleaching agents. Antioxidant agents were applied in Groups E3 and D3 (10% sodium ascorbate solution), E4 and D4 (10% alpha-tocopherol solution), E5 and D5 (10% sodium ascorbate gel) and E6 and D6 (10% alpha-tocopherol gel) for two hours. Cylinders were made with microhybrid resin composite and a total-etch adhesive system for shear bond strength tests. These tests were performed in a universal testing machine at a speed of 0.5 mm/minute to obtain the values in MPa. ANOVA (p > 0.05) showed no significant differences among groups E4, E5, E6 and E1. However, groups E3, E5 and E6 presented statistically similar values to group E2. The Kruskal-Wallis test showed no significant differences among D1 and all the other experimental groups; the same values occurred with D2, which did not differ from the experimental groups. Antioxidant treatment with 10% alpha-tocopherol solution was the only effective agent to revert the oxidizing effects of the bleaching treatment on enamel.
Oper Dent. 2009 Nov-Dec;34(6):635-41.
Comparative clinical study of the effectiveness of three different bleaching methods.
Bizhang M, Chun YH, Damerau K, Singh P, Raab WH, Zimmer S.
Heinrich-Heine University, Operative and Preventive Dentistry and Endodontics, Duesseldorf, Germany. mozhgan.bizhang@med.uni-duesseldorf.de
OBJECTIVE: The current study assessed the efficacy of three current bleaching methods. METHODS: Seventy-five healthy subjects (45 female; 30 male) with anterior teeth, having a Vita Shade score of A2 or darker, participated in the study. The subjects were randomly assigned to one of three treatment groups: Group A: home-bleaching (illumine Home, 10% carbamide peroxide, trays, overnight, for two weeks), Group B: in-office bleaching (Illumine Office, 15% hydrogen peroxide, trays for 45 minutes, three times over three weeks), Group C: Whitestrips (strips, twice a day, 30 minutes each for two weeks). Following the screening visit, three weeks prior to the baseline examination, all subjects received a dental prophylaxis. The color of the teeth was determined using a colorimeter (ShadeEye NCC) and a custom-made stent at baseline (E0), immediately after completion of the bleaching (E3) and three months after treatment (E4). All subjects received oral hygiene instructions and a toothbrush and toothpaste for oral home care during the study period. The change of tooth color was determined for each treatment regimen between baseline and E3 and baseline and E4 and was statistically analyzed performing the Kruskal Wallis test and the Mann-Whitney-U test. The significance level was set atp < 0.01. RESULTS: The dropout rate was 0%. Mean (SD) deltaE* (overall color change) from baseline to immediately after treatment was 6.57 (2.13) for Group A, 5.77 (1.72) for Group B and 3.58 (1.57) for Group C. The mean (SD) tooth color change from baseline to three months after treatment deltaE* was: 4.98 (1.34) for Group A, 4.59 (1.42) for Group B and 2.99 (1.39) for Group C. Significant differences were found between home bleaching and Whitestrips, as well as between in-office bleaching and Whitestrips, but not between home-bleaching and in-office bleaching during the same time. CONCLUSION: Using an objective color measurement device, home bleaching and in-office bleaching were found to be superior to Whitestrips. Home bleaching and in-office bleaching were equally efficient for bleaching teeth and maintaining the results for up to three months.
J Appl Oral Sci. 2009 Sep-Oct;17(5):436-9.
Intrapulpal temperature variation during bleaching with various activation mechanisms.
Michida SM, Passos SP, Marimoto AR, Garakis MC, de Araújo MA.
Department of Dental Materials and Prosthodontics, São Paulo State University, São José dos Campos, SP, Brazil. silviamasae@yahoo.com
OBJECTIVES: The aim of this study was to evaluate the intrapulpal temperature variation after bleaching treatment with 35% hydrogen peroxide using different sources of activation. MATERIAL AND METHODS: Twenty-four human teeth were sectioned in the mesiodistal direction providing 48 specimens, and were divided into 4 groups (n=12): (G1) Control – Bleaching gel without light activation, (G2) Bleaching gel + halogen light, (G3) Bleaching gel + LED, (G4) Bleaching gel + Nd:YAG Laser. The temperatures were recorded using a digital thermometer at 4 time points: before bleaching gel application, 1 min after bleaching gel application, during activation of the bleaching gel, and after the bleaching agent turned from a dark-red into a clear gel. Data were analyzed statistically by the Dunnet’s test, ANOVA and Tukey’s test (a=0.05). RESULTS: The mean intrapulpal temperature values ( degrees C) in the groups were: G1: 0.617 +/- 0.41; G2: 1.800 +/- 0.68; G3: 0.975 +/- 0.51; and G4: 4.325 +/- 1.09. The mean maximum temperature variation (MTV) values were: 1.5 degrees C (G1), 2.9 degrees C (G2), 1.7 degrees C (G3) and 6.9 degrees C (G4). When comparing the experimental groups to the control group, G3 was not statistically different from G1 (p>0.05), but G2 and G4 presented significantly higher (p<0.05) intrapulpal temperatures and MTV. The three experimental groups differed significantly (p<0.05) from each other. CONCLUSIONS: The Nd:YAG laser was the activation method that presented the highest values of intrapulpal temperature variation when compared with LED and halogen light. The group activated by LED light presented the lowest values of temperature variation, which were similar to that of the control group.
J Appl Oral Sci. 2009 Aug;17(4):284-8.
Effectiveness of home bleaching agents in discolored teeth and influence on enamel microhardness.
Delfino CS, Chinelatti MA, Carrasco-Guerisoli LD, Batista AR, Fröner IC, Palma-Dibb RG.
Department of Restorative Dentistry, Ribeirão Preto Dental School, University of São Paulo, Ribeirão Preto, SP, Brazil.
OBJECTIVES: This study evaluated the effectiveness of different home bleaching agents on color alteration and their influence on surface and subsurface microhardness of discolored bovine enamel. MATERIAL AND METHODS: Forty-five fragments of bovine incisors were randomly allocated into 3 groups (n=15) according to the bleaching agent: 10% carbamide peroxide gel (CP10), 16% carbamide peroxide gel (CP16) and 6.5%-hydrogen-peroxide-based strip (HP6.5). Before bleaching treatment, initial values of Knoop surface microhardness and color (CIEL a b) were obtained and the fragments were artificially stained in hemolyzed rat blood. Then, bleaching treatments were performed over a 21-day period. Color changes (DeltaE) were assessed at 7, 14 and 21 days, and final surface microhardness reading was done after 21 days. Thereafter, the fragments were bisected to obtain subsurface microhardness. Data were subjected to ANOVA and Tukey’s tests (alpha=5%). RESULTS: Color changes produced by CP16 were similar to those of CP10, and the color changes produced by these materials were significantly superior to those produced by HP6.5. Color changes at 21 days were superior to 7 days and similar to 14 days. The time did not influence color changes for CP16, which showed similarity between the 14- and 21-day results. No statistically significant differences were found among the home bleaching agents for surface and subsurface microhardness. CONCLUSIONS: Microhardness of bovine enamel was not affected by the bleaching agents. The 16% carbamide peroxide gel was the most effective for bleaching the stained substrate.
Am J Orthod Dentofacial Orthop. 2009 Nov;136(5):689-94.
Can intracoronally bleached teeth be bonded safely?
Uysal T, Er O, Sagsen B, Ustdal A, Akdogan G.
Department of Orthodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey. tancanuysal@yahoo.com
INTRODUCTION: Our objective was to determine the effects of intracoronal bleaching on the shear bond strength and failure side location of metallic brackets at 2 times (bleaching immediately before bonding and 30 days before bonding). METHODS: Sixty freshly extracted mandibular incisors were randomly divided into 3 groups; each group contained 20 teeth. After finishing canal preparation and root canal filling, the root fillings were removed to a level 2 mm apical to the cementoenamel junction. Glass ionomer base (Vitrabond, 3 M Dental Products, St Paul, Minn) was placed approximately 2-mm thick. Bleaching agent (Whiteness Perfect, FGM Dental Products, Joinville, Brazil) was placed into the rest of the cavity for 4 days at 2 times. Shear bond strength of these brackets was measured in megapascals. The adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed with analysis of variance (ANOVA), Tukey, and chi-square tests. RESULTS: The bond strengths of the group with no bleaching (mean, 20.25 +/- 7.06 MPa) were significantly higher (P >0.001) than those of the group that had bleaching immediately before bonding (mean, 4.85 +/- 3.22 MPa) and the group that had bleaching 30 days before bonding (mean, 8.70 +/- 4.93 MPa). The results of the chi-square comparisons indicated significant differences among the 3 groups. In the group with no bleaching, there was a higher frequency of ARI scores of 2 to 4, indicating cohesive failures in the resin. In the other 2 groups, the failures were mostly adhesive at the resin-enamel interface (ARI scores of 4 and 5). CONCLUSIONS: Intracoronal bleaching with carbamide peroxide adversely affected the shear bond strength and changed the site of failure during debonding when bonding was done immediately or 30 days after bleaching.
Indian J Dent Res. 2009 Jul-Sep;20(3):304-7.
The effect of combined bleaching techniques on oral microbiota.
Franz-Montan M, Ramacciato JC, Rodrigues JA, Marchi GM, Rosalen PL, Groppo FC.
Department of Physiological Sciences, Piracicaba Dentistry School, UNICAMP, Brazil.
AIMS: To evaluate the antimicrobial activity of 10% and 37% carbamide peroxide during dental bleaching in three different modes. MATERIALS AND METHODS: This five-week double-blind randomized controlled trial included 32 volunteers assigned to four groups (n = 8). Each group received bleaching agents or placebo as an in-office and at-home treatment. The dental bleaching techniques were: In-office bleaching (37% carbamide peroxide: CP37); at-home bleaching (10% carbamide peroxide: CP10) and the association of both (CP37 and CP10). Saliva samples were collected right before (baseline), right after, 12 hours after, and seven days after the treatment. Counts of total microorganisms, Streptococci, and Mutans streptococci were carried out. Friedman test (alpha = 0.05) was used to compare the microorganism counts. RESULTS: The number of the all oral microorganisms remained stable during all experiment. CONCLUSIONS: No bleaching agent (CP37, CP10 or the combination of both) was able to reduce the oral microorganisms tested.
Photomed Laser Surg. 2009 Oct 27. [Epub ahead of print]
Effects of Combined Use of Light Irradiation and 35% Hydrogen Peroxide for Dental Bleaching on Human Enamel Mineral Content.
Berger SB, Cavalli V, Martin AA, Soares LE, Arruda MA, Brancalion ML, Giannini M.
1 Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas , Piracicaba, São Paulo, Brazil .
Abstract Objective: The objective of this study was to evaluate the effects of the combined use of light irradiation (LIR, halogen light, or LED/diode laser) and 35% hydrogen peroxide (35%HP) on human enamel mineral content. Background Data: The use of high-intensity light has been indicated for acceleration of the rate of chemical bleaching; however, it is not known whether LIR can promote additional effects on enamel surfaces during the bleaching. Materials and Methods: One hundred enamel samples were obtained from third molars and randomly divided into 10 groups (n = 10). The control group (CG) remained untreated. Three whitening products were used: Whiteness HP Maxx, Pola Office, and Opalescence Xtra. Bleaching consisted of one session, and the products were applied three times to each specimen for 10 min each. The products were subjected, or not, to LIR during treatment with halogen light or LED/diode laser. The mineral concentration of enamel was determined before and after treatments using an FT-Raman spectroscope (FT-RS), and the amount of calcium lost from the bleached enamel surfaces was quantified with an atomic absorption spectrometer (AAS). Results: FT-RS results showed a decreased mineral content after all treatments, with the exception of Pola Office when irradiated with LED/diode laser and the CG. The losses of calcium detected for Pola Office and Opalescence Xtra were similar for the three situations (without or with light irradiations), whereas for Whiteness HP Maxx the lowest calcium loss was detected without LIR. Conclusion: Most of the bleaching treatments investigated, in combination with LIR or not, can reduce the mineral content of enamel surface. LIR increased the calcium loss for Whiteness HP Maxx; no effects were observed for Pola Office and Opalescence Xtra.
Oper Dent. 2009 Sep-Oct;34(5):565-70.
Effect of light-activated bleaching on the microleakage of Class V tooth-colored restorations.
Department of Operative Dentistry & Torabinejad Dental Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. khoroushi@dnt.mui.ac.ir
OBJECTIVE: In-office bleaching procedures utilizing highly concentrated 30%-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents are used for tooth whitening. Some recommend that, to enhance the whitening process, light-activation of the bleaching agent should be performed. The current study evaluated the effect of plasma arc bleaching on the microleakage of Class V restorations restored with resin composite, compomer and resin-modified glass ionomer (RMGI). MATERIALS AND METHODS: The buccal surfaces of 72 freshly extracted premolars were prepared with Class V cavities (4 x 2.5 x 1.5 mm) extended 1 mm apical to the CEJ. The prepared teethwere randomly divided into six groups. The cavities were restored with Single Bond and Z100 resin composite (Groups 1 and 2), Prompt L-Pop and F2000 compomer (Groups 3 and 4) and Vitremer RMGI (Groups 5 and 6), respectively. They were then thermocycled for 500 cycles. The samples from Groups 1, 3 and 5 were incubated at 37 degrees C and 100% humidity. Groups 2, 4 and 6 were bleached using in-office bleaching gel and the plasma arc bleaching unit, then incubated. All samples were sealed with nail varnish and immersed in 2% basic fuschin for 24 hours. The restorations were sectioned longitudinally and microleakage was evaluated using a scale ranging from 0 to 3. The data were analyzed using the Kruskal-Wallis test (alpha = 0.05). RESULTS: No statistically significant differences between study groups were observed in both the enamel and dentinal margins (p > 0.05). CONCLUSION: Plasma arc bleaching did not significantly affect the microleakage of existing tooth-colored restorations restored with Z100 resin composite, F2000 compomer and Vitremer RMGI.
Eur J Oral Sci. 2009 Aug;117(4):435-41.
Effect of fluoridated carbamide peroxide gels on enamel microtensile bond strength.
Chuang SF, Chen HP, Chang CH, Liu JK.
Institute of Oral Medicine, National Cheng Kung University, Tainan, Taiwan. sfchuang@mail.ncku.edu.tw
The aim of this study was to examine the resin bond strength on enamel treated with different fluoridated bleaching agents. Forty-eight bovine incisors were divided into four groups to receive bleaching treatments, over a 14-d period, as follows: no treatment; 10% carbamide peroxide (CP) bleaching; 10% CP containing 0.11% fluoride; and 10% CP containing 0.37% fluoride. Immediately, and 7 and 14 d after bleaching, the enamel surfaces were respectively bonded with composite and sectioned to create resin-enamel beams. These beams were subjected to the microtensile bond strength (microTBS) test, then assessed for failure mode under scanning electron microscopy. The results showed that the 0.37% fluoridated group demonstrated a microTBS equivalent to that of the unbleached group at all stages. Non-fluoridated and 0.11% fluoridated groups showed a weaker microTBS after bleaching but regained the bond strength after 14 or 7 d of storage, respectively. In the non-fluoridated group, adhesive failure was the predominant fracture pattern that comprised the enamel prism demineralization change and widely dispersed voids on the resin-enamel interfaces. No evident enamel erosion and fewer microporosities were found in the 0.37% fluoridated group. Accordingly, treatment with 0.37% fluoridated CP maintained the microTBS as effectively as the unbleached enamel. Additional fluoride in the bleaching agents may facilitate subsequent restorative treatment by inhibiting enamel demineralization.
J Dent. 2009;37 Suppl 1:e27-33. Epub 2009 May 14.
Color and contrast ratio of resin composites for whitened teeth.
da Costa J, Vargas M, Swift EJ Jr, Anderson E, Ritter S.
Department of Restorative Dentistry, Oregon Health and Sciences University, Portland, OR 97239-3097, USA. dacostaj@hsu.edu
OBJECTIVES: The purpose of this study was to determine the optical properties, color and contrast ratio (CR) of commercially available resin composites marketed for the restoration of whitened teeth. METHODS: Twenty-six resin composites designed for restoration of whitened teeth and four shade B1 (control) were evaluated. Five resin composite disks (d=12mm, h=1.54mm) were fabricated for each shade of composite and were stored in water at 37 degrees C for at least 24h. A colorimeter was used to measure specimen color over both white and black backgrounds. CIELAB and CIExyY color spaces were used. The CIELAB color notation system provides values for L*a*b*. The CIExyY system provides lightness and chromaticity values, where Y represents lightness and xy chromaticity. The contrast ratio (CR) was assessed using, CIE xyY, of the specimens against black (Yb) and white (Yw) backgrounds, with CR=Yb/Yw. The data for L*, a*, b* and CR were analyzed by one-way ANOVA, Tukey’s test, and the correlation L* and CR was analyzed by Pearson correlation test (alpha=0.05). RESULTS: Significantly different L*, a*, b* values and CR were observed. Premise XL2 had the highest L* and CR values and Vit-l-escence PS had the lowest. Vit-l-escence PS had the highest a* value and Point 4XL2 had the lowest, Premise XL1 had the highest b* value and Supreme WB the lowest. The L* and CR correlation was positive and statistically significant. CONCLUSIONS: Composites designated for whitened teeth have different levels of color and contrast ratio. Awareness of the optical properties of the composites allows the operator to choose the appropriate materials to mimic the remaining tooth structure.
Angle Orthod. 2009 Jul;79(4):777-83.
Tooth whitening effects on bracket bond strength in vivo.
Mullins JM, Kao EC, Martin CA, Gunel E, Ngan P.
OBJECTIVE: To test the hypothesis that there is no difference between the bracket survival rate of brackets bonded to bleached and unbleached teeth. MATERIALS AND METHODS: Thirty-eight patients who required comprehensive orthodontic treatment were included in the study. A split mouth technique was used with one arch exposed to in-office whitening gel containing 38% hydrogen peroxide for 30 minutes, while the unbleached arch served as the control. Patients were divided into two groups: Brackets bonded within 24 hours after bleaching and brackets bonded 2-3 weeks after bleaching. The bracket survival rate was computed using the log-rank test (Kaplan-Meier Analysis). RESULTS: A significantly higher rate of bracket failure was found with bleached teeth (16.6%) compared with unbleached teeth (1.8%) after 180 days. Brackets bonded within 24 hours of bleaching resulted in significantly higher clinical failure (14.5%) compared with those bonded after 3 weeks (2.1%). Adhesive Remnant Index scores of failed brackets revealed that the majority of failure in bleached teeth occurred in the enamel/resin interface. CONCLUSIONS: The hypothesis was rejected. Brackets bonded within 24 hours after bleaching have a significantly higher risk for bond failure. Orthodontic bonding should be delayed for 2-3 weeks if patients have a history of in-office bleaching with 38% hydrogen peroxide.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009 Sep;108(3):458-64.
Cytotoxic effect of a 35% hydrogen peroxide bleaching gel on odontoblast-like MDPC-23 cells.
Dias Ribeiro AP, Sacono NT, Lessa FC, Nogueira I, Coldebella CR, Hebling J, de Souza Costa CA.
Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, São Paulo State University, Araraquara, Brazil.
OBJECTIVE: This study evaluated transenamel and transdentinal cytotoxic effects of a bleaching gel on the MDPC-23 cell line. STUDY DESIGN: Discs obtained from bovine incisors were placed in a metallic device to simulate an in vivo pulp chamber. Groups were formed according to the enamel surface treatment: G1: 35% H(2)O(2) bleaching gel; G2: 35% H(2)O(2) bleaching gel + halogen light; G3: halogen light; and G4: control. Cell metabolism was evaluated by the methyltetrazolium assay and cell morphology by scanning electron microscopy. RESULTS: Cell metabolism decreased by 31.7%, 41.6%, and 11.5% in G1, G2, and G3, respectively. Cytotoxic effects observed in G2 were significantly more severe compared with G3 and G4. In G1 and G2, a smaller number of viable cells with major morphologic alterations remained adhered to dentin. CONCLUSION: The bleaching gel associated with light presented transenamel and transdentinal cytotoxic effects characterised by direct damage to odontoblasts and decrease of their metabolic activity.
Photomed Laser Surg. 2009 Aug 28. [Epub ahead of print]
Diode Laser Effect on Enamel Microhardness After Dental Bleaching Associated with Fluoride.
de Magalhães MT, Basting RT, de Almeida ER, Pelino JE.
1 Department of Restorative Dentistry, School of Dentistry , São Leopoldo Mandic, Campinas, SP, Brazil .
Abstract Objective: The aim of this in vitro study was to evaluate the effects of diode laser irradiation on human dental enamel treated by bleaching and acidulated phosphate fluoride gels (APF) according to microhardness analysis. Background Data: The high interest of patients for aesthetics in cosmetic dentistry has led to new bleaching materials and the development of new techniques. Materials and Methods: Sixty embedded, flattened human third molar enamel fragments were randomly assigned to three groups (n = 20). Group 1 received topical application of 1.23% APF photoactivated using a diode laser. Group 2 received three applications of 35% hydrogen peroxide for 5 min and was photoactivated with laser for 30 s in each application. Group 3 treated the same as group 2 plus a 1.23% APF application for 1 min after bleaching followed by 30 s of laser irradiation. Microhardness analyses were performed before and after all the treatments. Results: Analysis of variance followed by Tukey and Student statistical t-tests (p < 0.05) showed significantly higher microhardness values for group 1 after treatment. No significant differences were shown before and after treatments for groups 2 and 3. Conclusion: No change was observed in enamel microhardness after treatment with hydrogen peroxide gel photoactivated using diode laser with or without APF. There was an increase in microhardness when enamel was treated only with APF photoactivated using a laser.
J Prosthet Dent. 2009 Sep;102(3):148-54.
Effect of vital tooth bleaching on solubility and roughness of dental cements.
Londono J, Abreu A, Nelson S, Hernandez J, Torres C, Mettenburg D, Looney S, Rueggeberg F.
Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia and School of Graduate Studies, Medical College of Georgia, Augusta, Ga, USA.
STATEMENT OF PROBLEM: Vital tooth bleaching may affect properties of dental cements used for fixed prostheses. PURPOSE: The purpose of this study was to examine the effect of a combined in-office and at-home bleaching regimen on changes in surface roughness and depth loss of a variety of commercially available dental cements. MATERIAL AND METHODS: Five cement classifications were tested: glass ionomer, resin-modified glass ionomer, resin,self-adhesive resin cement, and zinc phosphate. Cements were placed in multiple wells in plastic blocks. After setting,the surface profile of each block was determined, and average roughness and vertical height of cement surface from the specimen holder were recorded. Blocks were water stored (control) or subjected to in-office and at-home bleaching(n=12). Surfaces were rescanned and pre- and posttest parameter changes were calculated. Statistical analysis consisted of Mann-Whitney-Wilcoxon Rank Sum and Student t tests applied to control and bleaching parameterc hanges within the same cements. A family-wise alpha of .05 was maintained by using a Bonferroni-adjusted level of significance preset to .01 per test. RESULTS: Zinc phosphate showed the only significant depth increase (P=.004) from bleaching: 0.9 +/- 0.7 microm deeper than the water-control group. Only resin-modified glass ionomer showed a significant (P=.004) increase in roughness from bleaching; values increased by 0.05 +/- 0.03 microm over the water-control group. CONCLUSIONS: In-office and at-home bleaching significantly increased depth loss of zinc phosphate and increased resinmodified glass ionomer roughness. However, the absolute values of differences observed, as compared to the wateronly control, were considered to be clinically insignificant. (J Prosthet Dent 2009;102:148-154)
Rom J Morphol Embryol. 2009;50(3):435-40.
The use of scanning electron microscopy in evaluating the effect of a bleaching agent on the enamel surface.
Dudea D, Florea A, Mihu C, Câmpeanu R, Nicola C, Benga G.
Department of Dental Propaedeutics, Faculty of Dental Medicine, “Iuliu Hatieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania. ddudea@umfcluj.ro.
In this paper we present the results of an experiment with a commercial gel containing carbamide peroxide (CP) 15% (Opalescence 15% PF), aimed to assess the effects of this bleaching agent on the enamel surface of extracted human teeth, by using scanning electron microscopy (SEM). Opalescence 15% PF was applied on two quadrants of twelve extracted permanent, decay-free, human teeth, for 3 hours or 8 hours; for four teeth the application was performed once, while for eight teeth the treatment was repeated daily for 14 days (in order to simulate the usual clinical protocol of at-home bleaching). One quadrant of each tooth was used for control and the remaining quadrant was etched for 40 seconds with a gel containing 37% phosphoric acid. No differences concerning the micromorphology of tooth surface were observed by SEM, on the samples treated with Opalescence 15% PF once, for 3 or 8 hours, when compared to the control. Various, mainly minor changes occurred in samples treated with Opalescence 15% PF for 3 hours or 8 hours daily, for 14 days. On the other hand, the acid-etched samples had an irregular surface, which suggests important alterations of the prismatic structure of the enamel. These are the first studies of this type performed in Romania.
Dent Mater J. 2009 May;28(3):315-23.
Influence of peroxide treatment on bovine enamel surface–cross-sectional analysis.
Ushigome T, Takemoto S, Hattori M, Yoshinari M, Kawada E, Oda Y.
Department of Dental Materials Science, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan.
Carbamide peroxide and hydrogen peroxide are used as the main agents in vital tooth bleaching. In this study, the influence of peroxide treatment on cross-sectional morphology and mechanical property was investigated. A 3 x 5-mm window of enamel on the labial surface of a bovine tooth was exposed to immersion in 10% or 30% carbamide peroxide or hydrogen peroxide for 30 or 180 min. After immersion, the cross-sectional structure of each specimen was examined by nanoindentation and SEM. Nanohardness in the enamel showed a decrease at 2 microm below the surface, but none at 50 microm. High concentrations of peroxide caused erosion to a depth of 5 microm below the surface. In conclusion, decrease in nanohardness and change in morphology were limited to an area less than 50 microm below the surface, regardless of either concentration of peroxide or period of immersion.
J Dent. 2009 Aug 4. [Epub ahead of print]
Reaction kinetics of sodium ascorbate and dental bleaching gel.
Freire A, Souza EM, de Menezes Caldas DB, Rosa EA, Bordin CF, de Carvalho RM, Vieira S.
School of Dentistry, Pontifical Catholic University of Parana, Curitiba, Parana, Brazil.
OBJECTIVE: The aim of this study was to establish the reaction kinetics of 35% hydrogen peroxide and sodium ascorbate and to determine the mass of antioxidant required to neutralize the bleaching gel. METHODS: The method used to quantify sodium ascorbate was based on the United States Pharmacopeia (1995)(26). Oxidation-reduction titration was used to confirm the concentration of hydrogen peroxide and sodium ascorbate and to determine the reaction kinetics between them. RESULTS: The results indicated a direct correlation between the mass of hydrogen peroxide and that of the antioxidant agent. In addition, 5min of contact was sufficient to neutralize the hydrogen peroxide used. CONCLUSION: This in vitro study showed that the amount of sodium ascorbate required for reduction of hydrogen peroxide is directly related to the concentration of the latter. In addition, the reaction kinetics between oxidant and antioxidant showed that a longer application time for sodium ascorbate does not influence the effectiveness of the reaction and that 5min is sufficiently long for this antioxidant to exert an antioxidant effect.
Eur J Esthet Dent. 2009 Spring;4(1):82-8.
Penetration of 35% hydrogen peroxide into the pulp chamber in bovine teeth after LED or Nd:YAG laser activation.
Camargo SE, Cardoso PE, Valera MC, de Araújo MA, Kojima AN.
School of Dentistry, Department of Oral Pathology São Paulo State University – UNESP, São José dos Campos, São Paulo, Brazil. samiraafonso@uol.com.br
This aim of the present study was to evaluate the pulp chamber penetration of 35% hydrogen peroxide activated by LED (light-emitting diode) or Nd:YAG laser in bovine teeth, after an in-office bleaching technique. Forty-eight bovine lateral incisors were divided into four groups, acetate buffer was placed into the pulp chamber and bleaching agent was applied as follows: for group A (n = 12), activation was performed by LED; for group B (n = 12), activation was performed by Nd:YAG laser (60 mJ, 20 Hz); group C (n = 12) received no light or laser activation; and the control group (n = 12) received no bleaching gel application or light or laser activation. The acetate buffer solution was transferred to a glass tube and Leuco Crystal Violet and horseradish peroxidase were added, producing a blue solution. The optical density of this solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. The results were analysed using ANOVA and Tukey’s test (5%). It was verified that the effect of activation was significant, as groups activated by LED or laser presented greater hydrogen peroxide penetration into the pulp chamber (0.499 +/- 0.622 microg) compared with groups that were not (0.198 +/- 0.218 microg). There was no statistically significant difference in the penetration of hydrogen peroxide into the pulp chamber between the two types of activation (LED or laser). The results suggest that activation by laser or LED caused an increase in hydrogen peroxide penetration into the pulp chamber.
J Prosthodont. 2009 Apr;18(3):223-9.
The effect of a bleaching system on properties related to different ceramic surface textures.
Department of Fixed Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.
PURPOSE: This study examined the effect of a manufacturer’s proposed bleaching protocol on surface properties of a low-fusing ceramic. MATERIALS AND METHODS: Forty ultra low-fusing ceramic samples (Ducera LFC) were constructed for this study. Half the discs were autoglazed, and the other half were overglazed. The two main groups (autoglaze, overglaze) were further divided into subgroups of four. Group I: autoglazed (control group I), bleached autoglaze, diamond polished, diamond polished and bleached. The same division was applied to Group II: overglazed (control group II), bleached overglazed, diamond polished, diamond polished and bleached. The total number of subgroups was eight. Control groups I and II (n = 10) were both immersed in distilled water, which was changed daily for 1 week. The other six subgroups (n = 30) were subjected to the following protocol: 2-hour bleaching using carbamide peroxide 35%, followed by six 8-hour bleaching applications using 15% carbamide peroxide gel. Every two bleaching procedures were interrupted by a 10-hour fluoride gel application. At the end of each bleaching step, the treated specimens were washed under running water in readiness for the next application. RESULTS: Bleaching did not significantly affect the surface roughness of the autoglazed group; however, it significantly increased the roughness of the overglazed ceramic, especially after polishing. Regarding whiteness, the overglazed group had significantly increased values compared to the autoglazed group. It appeared that bleaching whitened the overglazed specimens significantly, whereas polishing alone showed less whiteness. There appeared to be a strong inverse relation between the roughness and the whiteness of the autoglazed specimens as affected by the bleaching. On the other hand, a weak inverse relation was found between the roughness and whiteness of the overglazed specimens, as affected by the bleaching. CONCLUSIONS: In-office bleaching with 35% carbamide peroxide, followed by home bleaching with 15% carbamide peroxide and a fluoride gel may affect the roughness and whiteness of overglazed and polished/overglazed Duceram LFC restorations. No significant change in roughness or whiteness was detected by this bleaching system on autoglazed Ducera LFC. Ceramic restorations should be protected before any bleaching for fear of altering their roughness and whiteness. Patients should be advised that their existing porcelain restorations may not match their natural teeth after bleaching.
J Prosthodont. 2009 Apr;18(3):249-54. Epub 2009 Feb 2.
In vitro evaluation of the effectiveness of bleaching agents activated by different light sources.
Lima DA, Aguiar FH, Liporoni PC, Munin E, Ambrosano GM, Lovadino JR.
Department of Restorative Dentistry, Piracicaba School of Dentistry, Campinas State University, Sao Paulo, Brazil. debora1201@yahoo.com.br
PURPOSE: This study evaluated the efficacy of tooth whitening and color stability at different time periods after treatment. MATERIALS AND METHODS: Blocks obtained from human molars were divided into 15 groups (n = 5) by bleaching agents: 35% hydrogen peroxide (Whiteness HP and Opalescence Xtra) and 37% carbamide peroxide (Whiteness Super); and light sources: halogen lamp and plasma arc lamp (bleach mode), LED/diode laser, argon laser, and no light source. The efficacy of bleaching was measured using a spectrophotometer. Six bleaching sessions were performed (times 1 to 6). The specimens were submitted to another reading 7, 15, and 30 days after the end of bleaching (times 7, 8, and 9). The results were submitted to ANOVA followed by Tukey test and polynomial regression (p < 0.05). RESULTS: Carbamide peroxide significantly differed from hydrogen peroxide, presenting low reflectance values. Activated versus non-activated bleaching did not differ significantly for any gel tested, except for Whiteness HP activated by argon laser, which presented the lowest mean reflectance values. The results obtained with hydrogen peroxide revealed a decrease in reflectance values one month after the end of treatment. For carbamide peroxide, this decrease was not observed. CONCLUSION: The halogen lamp presented the same or higher efficacy than non-activated bleaching, which had a longer gel contact period. When hydrogen peroxide was used, a decrease in reflectance values was observed 30 days after the end of bleaching.
Braz Oral Res. 2008 Apr-Jun;22(2):106-11.
In vitro assessment of the effectiveness of whitening dentifrices for the removal of extrinsic tooth stains.
Lima DA, Silva AL, Aguiar FH, Liporoni PC, Munin E, Ambrosano GM, Lovadino JR.
Department of Restorative Dentistry, Vale do Paraíba University, SP, Brazil. debora1201@yahoo.com.br
This in vitro study evaluated the effectiveness of whitening dentifrices for the removal of extrinsic tooth stains. Twenty dental blocks (4 x 4 mm), including enamel and dentine, removed from freshly extracted bovine incisors, were randomly divided into 4 groups: G1–distilled water, G2–Colgate, G3–Crest Extra Whitening and G4–Rapid White. In all specimens, the dentin was covered with colorless nail polish, and the enamel was left exposed. Next, the specimens were immersed in a solution of black tea, which was changed every 24 h, for a period of 6 days. After this period, a photo-reflectance reading was taken (Time 1) with a spectrometer. The stained specimens were then submitted to linear brushing movements (5,000 cycles) using brushes (Oral B-Soft) coupled to an automatic toothbrushing machine, under a static axial load of 200 g and with a speed of 4 movements/second, at 37 degrees C, with the dentifrice or water being injected every 60 s. When toothbrushing ended, a second photo-reflectance reading was taken (Time 2). The results were submitted to two-criteria analysis of variance (ANOVA) and to the Tukey test ( = 0.05). When the two times for a same group were compared, Time 2 presented the highest reflectance values with statistical difference only for G3 and G4. Among the dentifrices tested, only the Rapid White group differed from the control group, presenting the highest reflectance values. Only the whitening dentifrice Rapid White was effective for the removal of extrinsic stains.
Clin Oral Investig. 2009 Jun 20. [Epub ahead of print]
Undesirable and adverse effects of tooth-whitening products: a review.
Goldberg M, Grootveld M, Lynch E.
EA2496, Faculté de Chirurgie Dentaire, Université Paris Descartes, 1, rue Maurice Arnoux, 92120, Montrouge, France, mgoldod@aol.com.
Hydrogen peroxide (H(2)O(2)) is a powerful oxidising agent. It gives rise to agents known to be effective bleaching agents. The mechanisms of bleaching involve the degradation of the extracellular matrix and oxidation of chromophores located within enamel and dentin. However, H(2)O(2) produces also local undesirable effects on tooth structures and oral mucosa. In clinical conditions, the daily low-level doses used to produce tooth whitening never generate general acute and sub-acute toxic effects. Genotoxicity and carcinogenicity only occur at concentrations that are never reached during dental treatments. Some transient adverse effects have been reported on the oral mucosa and the digestive tract if the product is swallowed. Local effects may occur on the oral mucosa and dental tissues during whitening, namely, pulp sensitivity, cervical resorption, release of selected components of dental restorative materials, and alteration of the enamel surface. Most of the local effects are dependent of the technique and concentration of the product so far used, but as the results of bleaching obtained are not stable, repeated treatments add to the adverse effects. The informed decision to administer or not and the control of bleaching effects should stand in the hand of dental surgeons and certainly not as it appears at present, as cosmetics sold without any restriction despite the potential health hazards of peroxides.
J Adhes Dent. 2009 Feb;11(1):35-40.
Can the hydrogel form of sodium ascorbate be used to reverse compromised bond strength after bleaching?
Türkün M, Celik EU, Kaya AD, Arici M.
Ege University School of Dentistry, Department of Restorative Dentistry and Endodontics, Izmir, Turkey.
PURPOSE: To assess the effect of the hydrogel form of different concentrations (2.5%, 5%, and 10%) of sodium ascorbate on the shear bond strength of composite after bleaching of the enamel with 10% carbamide peroxide gel. MATERIALS AND METHODS: Sixty flat buccal enamel surfaces obtained from 30 bovine incisors were divided into 6 treatment groups: group I, control (nonbleached); group II, no antioxidant treatment after bleaching; group III, 10% sodium ascorbate solution after bleaching; group IV, 2.5% sodium ascorbate hydrogel after bleaching; group V, 5% sodium ascorbate hydrogel after bleaching; group VI, 10% sodium ascorbate hydrogel after bleaching. The specimens were bonded with Clearfil SE Bond, then thermocycled and subjected to the shear test until failure. Fracture analysis of the bonded enamel surfaces was examined using a stereomicroscope. Statistical analysis was carried out using Kruskal-Wallis and the Mann-Whitney U-test. RESULTS: While the samples that were not treated with antioxidant after bleaching (group I) demonstrated significantly lower shear bond strengths and the 10% sodium ascorbate gel group (group VI) demonstrated significantly higher bond strengths than the control group (p < 0.05), no significant differences were found between the other groups and control group (p > 0.05). Among the antioxidant groups, only the groups treated with the 10% solution and the 10% hydrogel form of sodium ascorbate (group III and VI) revealed significantly higher bond strengths than the bleached group without antioxidant (group II) (p < 0.05). Higher scores were obtained with 10% sodium ascorbate gel (group VI) when compared with the other antioxidant-treated groups (p < 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that the 10% hydrogel form of sodium ascorbate may be used in clinical procedures instead of its solution form. However, using sodium ascorbate hydrogel with concentrations lower than 10% may not be as reliable as using this agent in 10% concentration for reversing the compromised bond strength.
J Dent. 2009 Mar;37(3):185-90. Epub 2008 Dec 23.
Effect of home bleaching systems on enamel nanohardness and elastic modulus.
Azer SS, Machado C, Sanchez E, Rashid R.
Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, OH 43218-2357, USA. azer.1@osu.edu
OBJECTIVES: The purpose of this study was to evaluate the nanohardness and elastic modulus of human enamel after treatment with tray and strip bleaching systems. METHODS: Fifty-five human enamel samples were exposed to five different bleaching agents. Nanoindentations were made before and after bleaching treatments following the manufacturer’s directions using a Nanoindenter XP (MTS Systems Corporation, Oak Ridge, TN, USA). Nanohardness and elastic modulus measurements were obtained and the results were statistically analyzed using a repeated measures analysis of variance with a post-hoc Tukey-Kramer multiple comparison test. RESULTS: Nanohardness and elastic modulus measurements showed decrease of mean values for each group except the control which remained the same. There were significant differences due to time (before and after treatment) and material effects in nanohardness (P<0.0001) and elastic modulus (P=0.0241). Measurements after treatment showed significant decrease in nanohardness between all groups and the control group. There was a significant difference in hardness between CP and TO after treatment. Additionally, there were significant differences in elastic modulus between the control group when compared to OB and TO after treatment. While there were significant changes in the elastic modulus due to treatment for both CP and TO, there were no significant differences between any of the groups after treatment. CONCLUSIONS: Nanohardness and elastic modulus of human enamel were significantly decreased after the application of home-bleaching systems.
Braz Dent J. 2009;20(1):48-53.
Effect of 10% carbamide peroxide bleaching on sound and artificial enamel carious lesions.
Pinto CF, Paes Leme AF, Cavalli V, Giannini M.
Departament of Restorative Dentistry, Dental School of Piracicaba, State University of Campinas, Piracicaba 13414-903, SP, Brazil.
This study evaluated the effect of 10% carbamide peroxide (CP) bleaching on Knoop surface microhardness (KHN) and morphology of sound enamel and enamel with early artificial caries lesions (CL) after pH-cycling model (pHcm). Human dental enamel blocks were
randomly divided into 6 groups (n=10): 1 – sound enamel bleached (S) with CP (Rembrandt/Den-Mat); 2 – S and submitted to pHcm; 3 – CL bleached with CP; 4 – CL stored in artificial saliva and submitted to pHcm; 5 – CL treated with placebo gel and submitted to pHcm; 6 – CL bleached with CP and submitted to pHcm. Enamel blocks with known initial KHN values were demineralized (groups 3 to 6) and submitted to 12 day pHcm (groups 2, 4, 5 and 6). After demineralization and treatments, KHN was determined and the specimens were examined using scanning electron microscopy (SEM). Data were analyzed statistically by ANOVA and Tukey’s test at 5% significance level. The results showed that among CL groups (3 to 6) only the group 3 presented remineralization after treatments. S groups (1 and 2) showed higher KHN and presented less formation of porosities on enamel surface than CL groups after treatments. In conclusion, bleaching procedures on enamel with CL did not exacerbate the demineralization, but should be indicated with caution.
Int Endod J. 2009 Jun;42(6):516-24.
Trans-enamel and trans-dentinal cytotoxic effects of a 35% H2O2 bleaching gel on cultured odontoblast cell lines after consecutive applications.
Trindade FZ, Ribeiro AP, Sacono NT, Oliveira CF, Lessa FC, Hebling J, Costa CA.
Departments of Dental Materials and Prosthodontics, Araraquara School of Dentistry, São Paulo State University, Araraquara, SP, Brazil.
AIM: To evaluate the trans-enamel and trans-dentinal cytotoxic effects of a 35% H(2)O(2) bleaching gel on an odontoblast-like cell lines (MDPC-23) after consecutive applications. METHODOLOGY: Fifteen enamel/dentine discs were obtained from bovine central incisor teeth and placed individually in artificial pulp chambers. Three groups (n = 5 discs) were formed according to the following enamel treatments: G1: 35% H(2)O(2) bleaching gel (15 min); G2: 35% H(2)O(2) bleaching gel (15 min) + halogen light (20 s); G3: control (no treatment). After repeating the treatments three consecutive times, the extracts (culture medium + gel components that had diffused through enamel/dentine discs) in contact with the dentine were collected and applied to previously cultured MDPC-23 cells (50 000 cells cm(-2)) for 24 h. Cell metabolism was evaluated by the MTT assay and data were analysed statistically (alpha = 5%; Kruskal-Wallis and Mann-Whitney U-test). Cell morphology was analysed by scanning electron microscopy. RESULTS: Cell metabolism decreased by 92.03% and 82.47% in G1 and G2 respectively. G1 and G2 differed significantly (P < 0.05) from G3. Regardless of halogen light activation, the application of the bleaching gel on the cultured odontoblast-like cells caused significantly more severe cytotoxic effects than those observed in the nontreated control group. In addition, significant morphological cell alterations were observed in G1 and G2. CONCLUSION: After three consecutive applications of a 35% H(2)O(2) bleaching agent, the diffusion of the gel components through enamel and dentine caused severe toxic effects to cultured pulp cells.
Lasers Med Sci. 2009 May 9. [Epub ahead of print]
Laser-assisted in-office bleaching using a neodymium:yttrium-aluminum-garnet laser: an in vivo study.
Strobl A, Gutknecht N, Franzen R, Hilgers RD, Lampert F, Meister J.
Department of Conservative Dentistry, Periodontology and Preventive Dentistry, Medical Faculty, Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
The desire for perfect and white teeth can be accomplished in aesthetical dentistry by modern tooth bleaching methods. Within the scope of a clinical study, laser assisted in-office bleaching was applied to the teeth of 20 individual patients with a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (lambda = 1.064 microm, average power 4 W, pulse repetition rate 10 Hz, pulse duration 320 micros). The treatment was carried out in a split-mouth design, each patient having two appointments with 1 week in between. Laser activation of the bleaching agent was performed on teeth 14-11 and 34-31 per session, with a total irradiation time of 30 s per tooth. The initial and the final color of the teeth were ascertained by VITA Colorsticks and the dental chromatometer ShadeEye NCC(R). Whitening was detected in the laser-activated and in the non-activated quadrants. Statistical evaluation showed that the additional activation of the bleaching agent by the Nd:YAG laser had produced no significant influence on the whitening (P > 0.05). The results achieved in this study should be scrutinized critically. They give cause for one to reconsider the treatment conditions or the laser parameters used, or even to query the application of the Nd:YAG laser in general during in-office bleaching.
Quintessence Int. 2009 Mar;40(3):195-202.
Effect of reservoirs on gingival inflammation after home dental bleaching.
Kirsten GA, Freire A, de Lima AA, Ignácio SA, Souza EM.
School of Dentistry, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil.
OBJECTIVE: To evaluate the influence of reservoirs on the gingival mucosa of patients submitted to at-home bleaching with 16% carbamide peroxide. METHOD AND MATERIALS: Nineteen nonsmoking male patients, 18 to 25 years of age, were submitted to home bleaching with a 16% carbamide peroxide gel for 2 consecutive hours for 21 days. The custom-made mouth trays were made with a reservoir on only the left side and cut anatomically 1 mm beyond the gingival margin. Smears of the gingival mucosa were obtained by the exfoliation cytology in liquid media technique before (control), immediately after, and 30 and 45 days after treatment. The samples were processed in the laboratory and evaluated according to Papanicolaou’s criteria of malignity. Statistical analysis was carried out by McNemar test, 2 proportions test, and Wilcoxon test with a level of significance of 1%. RESULTS: The presence of a reservoir in the custom tray resulted in an increase of inflammation only immediately after the bleaching procedure. After 30 and 45 days, the difference between inflammation on the sides with and without a reservoir was not statistically significant. Significant differences were found in the degree of inflammation, classified as predominantly mild on the nonreservoir side and moderate on the reservoir side (P < .01). CONCLUSIONS: A 16% carbamide peroxide bleaching gel caused gingival inflammation immediately after the procedure and persisted until 45 days after the bleaching treatment. The use of a reservoir in the custom tray for home bleaching resulted in higher rates and higher intensity of gingival inflammation.
Oper Dent. 2009 Mar-Apr;34(2):142-9.
A clinical evaluation of two in-office bleaching regimens with and without tray bleaching.
Matis BA, Cochran MA, Wang G, Eckert GJ.
Clinical Research Section, Indiana University School of Dentistry, Department of Restorative Dentistry, Indianapolis, IN, USA.
This study evaluated the degree of color change of teeth, the rebound effect and the sensitivities of teeth and gingiva associated with the use of an in-office bleaching agent followed by an at-home bleaching agent to lighten stained teeth in an in vivo study. Thirty-seven subjects who met the Inclusion/Exclusion criteria were divided into two cells. Twenty-five subjects received three 15-minute in-office bleaching treatments in succession with 36% hydrogen peroxide (HP) on the maxillary anterior teeth, followed by at-home overnight bleaching with 15% carbamide peroxide (CP) for seven days on one side of the dental arch. Twelve other subjects received a 40-minute in-office bleaching treatment on their maxillary anterior teeth, followed by at-home overnight bleaching for seven days on one side of the dental arch with the same product. The cells of teeth on the other side of the dental arch received the same in-office treatment but were not bleached overnight for seven days. Color was subjectively evaluated using the Vitapan Classical Shade Guide and was objectively evaluated using the Chroma Meter at the baseline appointment, immediately after in-office bleaching and at 4, 7 and 14 days and 3 months after the in-office treatment. For two weeks, the subjects completed sensitivity evaluations of gingival tissues and hard tooth tissues. The cells that did not receive the at-home bleaching had significantly less color change than the cells that received at-home bleaching. The cell that was bleached for 40 minutes and received the at-home treatment had significantly less overall change (deltaE) at 14 days and 3 months than the cell that received three 15-minute treatments with the at-home treatment. Throughout the study, the subjects in the three 15-minute treatment cells had less gingival and tooth sensitivity than the other cells.
Oper Dent. 2009 Jan-Feb;34(1):72-82.
Effects of carbamide peroxide on the staining susceptibility of tooth-colored restorative materials.
Yu H, Pan X, Lin Y, Li Q, Hussain M, Wang Y.
Department of Prosthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
This study investigated the effects of an at-home bleaching gel containing 15% carbamide peroxide on the susceptibility of tooth-colored restorative materials to different staining solutions. The tooth-colored restoratives used in this study were a nano resin composite (Filtek Z350), a packable resin composite (Filtek P60), a polyacid-modified composite (Dyract AP) and a glass-ionomer cement (Ketac Molar Easymix). Each material was equally divided into two groups (n = 34): the bleaching group and the control group. This study included two treatment segments. In the first part (days 1-14), the specimens of the bleaching group were bleached with 15% carbamide peroxide gels for eight hours daily, while the specimens in the control group were stored in deionized water. Subsequently, four specimens from each group were randomly selected for observation under an environmental scanning electron microscope. In the second part (days 15-42), the samples were not bleached. Instead, they were stored in five different kinds of solutions. Color measurements for each sample were taken at six different time periods using a spectrophotometer. The data was then analyzed using SPSS statistical software. After two-weeks of bleaching, all the specimens showed statistically significant color changes compared with the control specimens. Furthermore, the bleaching agents seriously affected the surface morphology of Dyract AP and Ketac Molar Easymix. Following exposure to the staining solutions, it was found that the bleached restorative materials exhibited greater staining susceptibility than the control materials. Filtek Z350 and P60 exhibited the best color stability, while Dyract AP exhibited the least color stability.
An evaluation of the color stability of tooth-colored restorative materials after bleaching using CIELAB color technique.
Rao YM, Srilakshmi V, Vinayagam KK, Narayanan LL.
Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospitals, Chennai, India. ymr357@yahoo.com
AIMS AND OBJECTIVE: The aim of this laboratory study was to evaluate the effect of three home bleaching agents: Vivastyle Paint On, Vivastyle, and Opalascence PF on the color stability of the microfilled composite Durafill, the nanofilled composite Filtek Z 350, and the glass ionomer cement Fuji II. MATERIALS AND METHODS: There were 3 groups in this study (n=40)-Group I: durafill, Group II: Filtek Z 350, and Group III: Fuji II. Each group was further subdivided into 4 subgroups (n=10), Subgroup A: bleaching with Vivastyle Paint On, Subgroup B: bleaching with Vivastyle, Subgroup C: bleaching with Opalascence PF, and Subgroup D: control specimens stored in distilled water. Bleaching was carried out following the manufacturer’s instructions for a period of 14 days. At the end of the bleaching regimen, the specimens were tested for color change using the CIELAB technique and a reflectance spectrophotometer. RESULTS: The data was subjected to statistical analysis. A Kruskal-Wallis variance analysis and Mann Whitney U test were done to determine the significant color change of the restorative materials. All restorative materials demonstrated a significantly higher color change (DeltaE) with Vivastyle (P < 0.0001). The mean color change of GIC (11.4 +/- 0.3) was the highest among the materials followed by Durafill (7.5 +/- 0.1). Filtek z 350 (0.3 +/- 0.1) showed the least color change with all the bleaching agents. CONCLUSION: Glass ionomer cement showed the highest color change followed by the microfilled composite. The nanofilled composite was found to be highly stable in terms of color.
J Dent Res. 2009 Mar;88(3):239-43.
Effects of bleaching on mercury ion release from dental amalgam.
School of Dentistry, The University of Manchester, Manchester, UK. samira.al-salehi@manchester.ac.uk
The chemical reactions that take place at the amalgam surface when exposed to bleaching agents are not well-understood. It is known, however, that mercury ions are released from dental amalgam when bleached. We hypothesized that increasing concentrations of hydrogen peroxide are more effective than water at increasing mercury ion release from dental amalgam. We prepared dental amalgam discs (n = 65) by packing amalgam into cylindrical plastic molds and divided them into 13 equal groups of 5 discs each. The discs in each group were individually immersed in either 0%, 3.6%, 6%, or 30% (w/v) hydrogen peroxide at exposure periods of 1, 8, 48, and 168 hrs. Samples were taken for mercury ion release determination by inductively coupled plasma mass spectrometry. There were significant increases in mercury release between control and all other hydrogen peroxide concentrations at all exposure times (p < 0.05).
Am J Dent. 2009 Feb;22(1):23-9.
Whitening effect and morphological evaluation of hydroxyapatite materials.
Dabanoglu A, Wood C, García-Godoy F, Kunzelmann KH.
Ludwig Maximilians University, Faculty of Dentistry, Department of Operative Dentistry and Periodontology, Goethe Str. 70, D-80336 Munich, Germany.
PURPOSE: To measure the efficacy of the whitening effect of non-oxidizing and non-acidic nano- and micro-hydroxyapatite materials on the enamel surface and to evaluate the surface changes after treatment. METHODS: Three hydroxyapatite suspensions and two hydroxyapatite mixtures in dissolvable polymer films were applied to a total of 30 extracted caries-free human premolars. After the last material application, a hydrodynamic shear force was generated and applied for 2 minutes to all teeth to simulate mechanical loading of the surface. The tooth color was measured with a dental spectrophotometer. The mean changes of the L*a*b* values between different measurements in each group were expressed as delta E and were analyzed with ANOVA and the Tukey’s post-hoc test. RESULTS: The groups of the nano-hydroxyapatite, the hydroxyapatite-nanocrystals and the tricalcium-phosphate exhibited significant delta E values between baseline and after hydrodynamic shear force application (P<0.05). In conclusion, the materials used in the study are very promising alternatives to oxidizing bleaching agents.
Quintessence Int. 2009 Jan;40(1):47-52.
Pigmentation susceptibility of teeth after bleaching with 2 systems: an in vitro study.
Setien V, Roshan S, Cala C, Ramirez R.
Department of Genral Dentistry, Baylor College Of Dentitry, Dallas, Texas 75246, USA.
OBJECTIVE: To determine the susceptibility of teeth to darken after bleaching with 35% hydrogen peroxide and 16%carbamideperoxide. METHOD AND MATERIALS: Thirty-eight premolars were covered with varnish and the mesiobuccal facets polished up to 0.04 microm, leaving a flat surface. Thirty-six of these premolars were then randomly assigned to 3 groups and the shade of the polished surfaces recorded using a Vita shade guide set in a value disposition. According to the manufacturers’instructions, 12 samples were bleached with 35% hydrogen peroxide (in-office group) and 12 samples with 16%carbamide peroxide (at-home group). The 12 samples in the control group were not bleached. Two days later, the shades of the bleached teeth were recorded; all samples were immersed in silver nitrate 50% for 4 hours,rinsed, and fixed (using a dithioxamidesolution) for 24 hours. Polished surfaces were cleaned and the samples’ shade recorded and analyzed using ANOVA. The remaining 2 premolars were bleached the same as those in the test group and analyzed using atomic force microscopy. RESULTS: The mean shade values were 6.2, 3.7, and 10.9 for in-office samples; 8.8, 1.7, and 6.1 for at-home samples; and 7.8 and 9.4 for the control group. After pigmentation, the at-home group had a lighter shade than the in-office group (P=or<.001). Atomic force microscopy showed no significant surface differences. CONCLUSION: While all the samples were susceptible to pigmentation, this tendency was greater following application of 35% hydrogen peroxide
Int Endod J. 2008 Dec;41(12):1054-8.
Ex vivo antimicrobial activity of several bleaching agents used during the walking bleach technique.
Oliveira DP, Gomes BP, Zaia AA, Souza-Filho FJ, Ferraz CC.
Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil. danifop@hotmail.com
AIM: To investigate ex vivo the antimicrobial activity of a paste of sodium perborate associated with various vehicles comparing it with 37% carbamide peroxide and 35% hydrogen peroxide. METHODOLOGY: The antimicrobial activity of these agents was evaluated against three microorganisms: Enterococcus faecalis, Streptococcus mutans and Candida albicans. One millilitre of each tested substance was placed on the bottom of wells of 24-well cell culture plates. Six wells were used for each time period and group. Two millilitres of the microbial suspension was ultrasonically mixed for 10 s with the bleaching pastes and placed in contact with them for 10, 30, 45 s; 1, 3, 5, 10, 20, 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared brain heart infusion agar + neutralizers. Agar plates were inoculated in appropriate gaseous conditions. Data were analysed statistically by the Kruskal-Wallis test with the level of significance set at P < 0.05. RESULTS: In all groups containing chlorhexidine (groups 3, 5 and 7), the antimicrobial activity of the bleaching paste was significantly increased when compared with groups with other kinds of vehicle (groups 1, 2, 4, 6 and 8). For all tested groups, the most resistant microorganism was E. faecalis. CONCLUSIONS: Chlorhexidine when used as a vehicle for sodium perborate enhanced its antimicrobial activity.
In vitro efficacy and risk for adverse effects of light-assisted tooth bleaching.
Bruzell EM, Johnsen B, Aalerud TN, Dahl JE, Christensen T.
Nordic Institute of Dental Materials (NIOM), NO-1305, Haslum, Norway.
The use of optical radiation in the so-called light-assisted tooth bleaching procedures has been suggested to enhance the oxidizing effect of the bleaching agent, hydrogen peroxide. Documentation is scarce on the potential adverse effects of bleaching products and on optical exposure risks to eyes and skin. The efficacy of seven bleaching products with or without simultaneous use of seven different bleaching lamps was investigated using extracted human teeth. The bleaching effect was determined immediately after treatment and one week later. Tooth surfaces were examined for adverse alterations after bleaching using a scanning electron microscope. Source characteristics of eight lamps intended for tooth bleaching were determined. International guidelines on optical radiation were used to assess eye and skin exposure hazards due to UV and visible light emission from the lamps. Inspection of teeth one week after bleaching showed no difference in efficacy between teeth bleached with or without irradiation for any of the products. Scratches, probably from the cleaning procedure were frequently seen on bleached enamel irrespective of irradiation. Maximum permissible exposure time (t(max)) and threshold limit values were exceeded for about half the bleaching lamps investigated. One lamp exceeded t(max) even for reflected blue light within the treatment time. This lamp also exceeded t(max) values for UV exposure. The lamps were classified as “low risk” and as borderline to “moderate risk” according to a relevant lamp standard.
J Dent. 2009 Feb 21. [Epub ahead of print]
Single site meta-analysis of 6% hydrogen peroxide whitening strip effectiveness and safety over 2 weeks.
Gerlach RW, Barker ML, Karpinia K, Magnusson I.
The Procter & Gamble Company, 8700 Mason-Montgomery Road, Mason, OH 45040-8006, USA.
OBJECTIVES: This research evaluated efficacy and safety of 6% hydrogen peroxide whitening strips from a clinical trials database accumulated over a multi-year period at a single site. METHODS: The inclusive meta-analysis involved seven different randomized clinical trials at one dental school. Each study used 6% hydrogen peroxide whitening strips twice daily for 30min over a 2-week period. Common efficacy (digital images) and safety (examination and interview) methods were used across studies. Pooled subject-level data were analyzed using a general linear mixed model to determine overall response and effects of treatment duration on whitening. RESULTS: The 148 treated subjects were 18-71 years old, with b* (yellowness) ranging from 12 to 22, and L* (lightness) ranging from 69 to 80. After 1-week strip use, the adjusted mean (S.E.) for Deltab* was -1.6 (0.08), differing significantly from baseline (p<0.0001). After 2 weeks, the adjusted mean (S.E.) for Deltab* was -2.3 (0.07), differing significantly from Week 1 (p<0.0001). The estimated correlation between Weeks 1 and 2 for Deltab* was 0.74. Study-to-study variation contributed less than 2% of Deltab* variability. Results were similar for DeltaL*, with Weeks 1 and 2 estimated means (S.E.) of 1.5 (0.13) and 2.0 (0.12). Occurrence of oral irritation (22%) and tooth sensitivity (20%) did not adversely affect whitening. Other side effects were unremarkable, and only 1 subject (0.7%) discontinued treatment early due to an adverse event. CONCLUSIONS: The meta-analysis of multiple studies conducted at a single clinical site over several years establishes consistent, effective and safe vital bleaching with 6% hydrogen peroxide whitening strips.
J Prosthodont. 2009 Jan 30. [Epub ahead of print]
The Effect of a Bleaching System on Properties Related to Different Ceramic Surface Textures.
Professor, Department of Fixed Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.
Abstract Purpose: This study examined the effect of a manufacturer’s proposed bleaching protocol on surface properties of a low-fusing ceramic. Materials and Methods: Forty ultra low-fusing ceramic samples (Ducera LFC) were constructed for this study. Half the discs were autoglazed, and the other half were overglazed. The two main groups (autoglaze, overglaze) were further divided into subgroups of four. Group I: autoglazed (control group I), bleached autoglaze, diamond polished, diamond polished and bleached. The same division was applied to Group II: overglazed (control group II), bleached overglazed, diamond polished, diamond polished and bleached. The total number of subgroups was eight. Control groups I and II (n = 10) were both immersed in distilled water, which was changed daily for 1 week. The other six subgroups (n = 30) were subjected to the following protocol: 2-hour bleaching using carbamide peroxide 35%, followed by six 8-hour bleaching applications using 15% carbamide peroxide gel. Every two bleaching procedures were interrupted by a 10-hour fluoride gel application. At the end of each bleaching step, the treated specimens were washed under running water in readiness for the next application. Results: Bleaching did not significantly affect the surface roughness of the autoglazed group; however, it significantly increased the roughness of the overglazed ceramic, especially after polishing. Regarding whiteness, the overglazed group had significantly increased values compared to the autoglazed group. It appeared that bleaching whitened the overglazed specimens significantly, whereas polishing alone showed less whiteness. There appeared to be a strong inverse relation between the roughness and the whiteness of the autoglazed specimens as affected by the bleaching. On the other hand, a weak inverse relation was found between the roughness and whiteness of the overglazed specimens, as affected by the bleaching. Conclusions: In-office bleaching with 35% carbamide peroxide, followed by home bleaching with 15% carbamide peroxide and a fluoride gel may affect the roughness and whiteness of overglazed and polished/overglazed Duceram LFC restorations. No significant change in roughness or whiteness was detected by this bleaching system on autoglazed Ducera LFC. Ceramic restorations should be protected before any bleaching for fear of altering their roughness and whiteness. Patients should be advised that their existing porcelain restorations may not match their natural teeth after bleaching.
J Dent. 2009 Feb 7. [Epub ahead of print]
Color and surface analysis of carbamide peroxide bleaching effects on the dental restorative materials in situ.
Key Laboratory for Oral Biomedical Engineering of Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237# Luo Yu Road, Wuhan, China.
OBJECTIVES: The aim of this in vivo study was to evaluate the effects of a home-bleaching agent on the color and surface properties of four tooth-colored restorative materials. METHODS: Two composite resins (a nano-hybrid and a packable), a polyacid-modified composite and a conventional glass-ionomer were tested. Specimens were inserted into custom-fabricated trays, and underwent a routine home-bleaching treatment. CIE Lab* color coordinates of the specimens were obtained using a spectrophotometer. Ultra-structural effects were investigated by SEM and ATR-FTIR. The color data were analyzed with ANOVA and Tukey’s post hoc analysis. RESULTS: Significant color changes were found among all the materials after bleaching. However, the color differences decreased and fell into the clinically acceptable range (except for the compomer) after withdrawal of the bleaching treatment. Surface dissolution was detected in the polyacid-modified composite and glass-ionomer cement. ATR-FTIR analyses found chemical composition alterations in the polyacid-modified composite. SIGNIFICANCE: A 15% carbamide peroxide home-bleaching gel did not cause color changes in the composites and glass-ionomer cement. However, significant color and chemical composition alterations were found in the polyacid-modified composite.
Quintessence Int. 2008 Apr;39(4):299-306.
Spectrophotometric evaluation of the efficacy of a new in-office bleaching technique.
Benbachir N, Ardu S, Krejci I.
Dental School, University of Geneva, Switzerland. nacer.benbachir@medecine.unige.ch
OBJECTIVE: To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to lighten tooth color in clinical situations and to evaluate the change of the tooth color six months after the bleaching procedure. METHOD AND MATERIALS: Ten adult subjects requesting tooth bleaching were selected to participate in this randomized clinical trial involving a new in-office bleaching technique using VivaStyle Paint On Plus (Ivoclar Vivadent), originally designed as an over-the-counter bleaching gel. Digital images and CIE Lab spectrophotometric measurements were taken at baseline (I), after the bleaching treatment (PB), and 6 months after bleaching (6M). Differences in Lab values were tested with a repeated measures analysis of variance (ANOVA). Differences in Delta E values were tested with a factorial ANOVA. RESULTS: Significant (P < .05) differences were detected in L, as well as in a and b values, between initial (I) and post-bleaching (PB) and between initial (I) and 6 months post-op (6M). In contrast, there was no significant difference between post-bleaching (PB) and 6 months post-op (6M). CONCLUSION: This new bleaching technique proved to be efficient over a period of 6 months. It could be a less aggressive and more convenient alternative to traditional bleaching techniques.
Braz Oral Res. 2008 Jan-Mar;22(1):90-5.
Spectrophotometric assessment of the effects of 10% carbamide peroxide on enamel translucency.
Vieira GF, Arakaki Y, Caneppele TM.
Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
Tooth shade results from the interaction between enamel color, enamel translucency and dentine color. A change in any of these parameters will change a tooths color. The objective of this study was to evaluate the changes occurring in enamel translucency during a tooth whitening process. Fourteen human tooth enamel fragments, with a mean thickness of 0.96 mm (+/- 0.3 mm), were subjected to a bleaching agent (10% carbamide peroxide) 8 hours per day for 28 days. The enamel fragment translucency was measured by a computer controlled spectrophotometer before and after the bleaching agent applications in accordance with ANSI Z80.3-1986–American National Standard for Ophthalmics–nonprescription sunglasses and fashion eyewear-requirements. The measurements were statistically compared by the Mann-Whitney non-parametric test. A decrease was observed in the translucency of all specimens and, consequently, there was a decrease in transmittance values for all samples. It was observed that the bleaching procedure significantly changes the enamel translucency, making it more opaque.
Angle Orthod. 2009 Jan;79(1):122-6.
Bond strength of metallic brackets after dental bleaching.
Patusco VC, Montenegro G, Lenza MA, Alves de Carvalho A.
Department of Orthodontics, Federal University of Goiania, Goiania, Brazil. virnapatusco@hotmail.com
OBJECTIVE: To test the hypothesis that there is no difference between the action of at-home and in-office vital bleaching on the shear bond strength of metallic brackets bonded with composite resin 24 hours after bleaching. MATERIALS AND METHODS: Forty-five human upper premolars were randomly divided into three groups: (1) control, (2) 10% carbamide peroxide at-home bleached, and (3) 35% hydrogen peroxide in-office bleached. Twenty-four hours after bleaching the teeth were pumiced, bonded with metallic brackets, and stored in distilled water. One day after bonding the shear bond strength of the brackets was determined. RESULTS: The mean shear bond strength of Group 1 (control) and Group 2 (carbamide peroxide bleached) were not statistically different. Group 3 (hydrogen peroxide bleached) had a significantly lower mean shear bond strength than Group 1 and Group 2. CONCLUSIONS: The hypothesis is rejected. Use of 10% carbamide peroxide bleaching does not significantly alter shear bond strength values. On the other hand, use of 35% hydrogen peroxide bleaching significantly reduces these values and diminishes the amount of resin remnant on the tooth surface after bracket debonding.
Oper Dent. 2008 Nov-Dec;33(6):606-12.
Efficacy and safety of 10% and 16% carbamide peroxide tooth-whitening gels: a randomized clinical trial.
Meireles SS, Heckmann SS, Leida FL, dos Santos Ida S, Della Bona A, Demarco FF.
Federal University of Pelotas, Pelotas, RS, Brazil.
This double-blind randomized clinical trial evaluated the efficacy and safety of two carbamide peroxide concentrations used in at-home vital bleaching. Ninety-two volunteers with a shade mean of C1 or darker for the six maxillary anterior teeth were randomized into two balanced groups (n=46) according to bleaching agent concentration: 10% (CP10) or 16% (CP16) carbamide peroxide. The patients were instructed to use the whitening agent in a tray for two hours once a day for three weeks. Shade evaluations were done with a value-oriented shade guide and a spectrophotometer at baseline and one week post-bleaching (four-week evaluation). Tooth sensitivity was measured daily using a scale ranging from 0 (no sensitivity) to 4 (severe sensitivity). At the end of the study, the volunteers filled out a questionnaire with seven questions aimed to give their opinion about the adopted treatment regimen. Both carbamide peroxide concentrations resulted in significantly lighter teeth at the four-week evaluation compared to the baseline for all color parameters (p < 0.0001) and shade median (p < 0.001). There was no significant difference between the two groups in terms of shade change difference with either the spectrophotometer (p = 0.1) or the shade guide (p = 0.7). Also, no statistically significant difference was found in relation to deltaL* (p = 0.7), delta a* and deltaE* (p = 0.5). A significant reduction in yellowness (delta b*) was observed for CP16 compared to CP10 (p = 0.05) in crude analysis, which disappeared after controlling for b* parameter at baseline. The group treated with CP16 experienced more tooth sensitivity during the first (p = 0.02) and third (p = 0.01) weeks of treatment compared to the CP10 group. However, no major difference was observed (p = 0.09) when the degree of tooth sensitivity between groups was compared. Both 10% and 16% carbamide peroxide concentrations were equally effective and safe for a three-week at-home tooth-bleaching treatment.
Vital tooth bleaching: biologic adverse effects-a review.
Department of Restorative Dentistry, Faculty of Dentistry, Université Louis Pasteur, Strasbourg, France. minoux@igbmc.u-strasbg.fr
Depending on etiology, the esthetic treatment of dyschromia may involve vital tooth- bleaching techniques. Hydrogen peroxide is the active molecule used for such procedures; however, its action mechanism is not clearly understood. Moreover, a variety of contradictory studies make difficult the evaluation of the safety of bleaching techniques. The purpose of this article is therefore to review the available literature (1) to describe the physicochemical properties of hydrogen peroxide and (2) to assess the safety of its use as a vital tooth-bleaching agent. Indeed, based on hydrogen peroxide’s capacity to generate free radicals that diffuse throughout the dental hard tissues, concerns have been addressed regarding the adverse effects that bleaching products can induce on the enamel and dentin structures, pulp, and bonding to a composite resin system. Moreover, during self-application of home bleaching products, hydrogen peroxide is released into the oral cavity and ingested. Some questions have therefore arisen concerning its toxicity and its possible carcinogenicity.
J Appl Oral Sci. 2008 Oct;16(5):355-9.
In vitro study of the pulp chamber temperature rise during light-activated bleaching.
Carrasco TG, Carrasco-Guerisoli LD, Fröner IC.
Department of Restorative Dentistry, Dental School of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.
This study evaluated in vitro the pulp chamber temperature rise induced by the light-activated dental bleaching technique using different light sources. The root portions of 78 extracted sound human mandibular incisors were sectioned approximately 2 mm below the cementoenamel junction. The root cavities of the crowns were enlarged to facilitate the correct placing of the sensor into the pulp chamber. Half of specimens (n=39) was assigned to receive a 35% hydrogen peroxide gel on the buccal surface and the other halt (n=39) not to receive the bleaching agent. Three groups (n=13) were formed for each condition (bleach or no bleach) according to the use of 3 light sources recommended for dental bleaching: a light-emitting diode (LED)laser system, a LED unit and a conventional halogen light. The light sources were positioned perpendicular to the buccal surface at a distance of 5 mm and activated during 30 s. The differences between the initial and the highest temperature readings for each specimen were obtained, and, from the temperature changes, the means for each specimen and each group were calculated. The values of temperature rise were compared using Kruskal-Wallis test at 1% significance level. Temperature rise varied significantly depending on the light-curing unit, with statistically significant differences (p<0.01) among the groups. When the bleaching agent was not applied, the halogen light induced the highest temperature rise (2.38+/-0.66 degrees C). The LED unit produced the lowest temperature increase (0.29+/-0.13 degrees C); but there was no significant difference between LED unit and LED-laser system (0.35+/-0.15 degrees C) (p>0.01). When the bleaching agent was applied, there were significant differences among groups (p<0.01): halogen light induced the highest temperature rise (1.41+/-0.64 degrees C), and LED-laser system the lowest (0.33+/-0.12 degrees C); however, there was no difference between LED-laser system and LED unit (0.44+/-0.11 degrees C). LED and LED-laser system did not differ significantly from each other regardless the temperature rise occurred with or without bleaching agent application. It may be concluded that during light-activated tooth bleaching, with or without the bleaching agent, halogen light promoted higher pulp chamber temperature rise than LED unit and LED-laser system. The tested light-curing units provided increases in the pulp chamber temperature that were compatible with pulpal health.
J Appl Oral Sci. 2008 Jun;16(3):201-4.
Enamel susceptibility to red wine staining after 35% hydrogen peroxide bleaching.
Berger SB, Coelho AS, Oliveira VA, Cavalli V, Giannini M.
Department of Restorative Dentistry, Dental School of Piracicaba, Stare University of Campinas, Piracicaba, SP, Brazil.
Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10). Specimens of all groups were immersed in red wine for 48 h at 37 degrees C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher’s PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments.
J Dent. 2008 Dec 10. [Epub ahead of print]
Effect of fluoridated bleaching gels on the remineralization of predemineralized bovine enamel in vitro.
Tschoppe P, Neumann K, Mueller J, Kielbassa AM.
Department of Operative Dentistry and Periodontology, University School of Dental Medicine, CharitéCentrum 3, Germany.
OBJECTIVES: This study evaluated possible differences regarding the remineralization of predemineralized enamel after exposure to fluoridated or non-fluoridated bleaching gels. METHODS: 120 enamel specimens were prepared from sixty bovine incisors; before and after demineralization (37 degrees C; pH 4.95; 10d), one-quarter of each specimen’s surface was covered with nail varnish (control sound/demineralized). Subsequently, the specimens were stored for 16h daily in a remineralizing solution (pH 7.0; 14d), while for the remaining time (8h) various bleaching gels were applied: (1) no treatment (control), (2) Opalescence regular (O, Ultradent), (3) Opalescence PF (O-PF), (4) Nite White ACP (NW-ACP, Discus Dental) and (5) Nite White ACPF (NW-ACPF). Following, half of the bleached parts were nail-varnished and stored for another 3-weeks period in a remineralizing solution. Differences in mineral losses (DeltaDeltaZ) and lesion depths (DeltaLD) before and after treatment/remineralization period were evaluated from microradiographs. DeltaDeltaZ(surface) values (mineral loss of the outer 18mum of the lesion) were calculated. RESULTS: After 2 and 5 weeks DeltaDeltaZ/DeltaLD values of the bleaching groups did not differ significantly from the controls. Treatment with NW-ACPF for 2 weeks resulted in significantly lower DeltaDeltaZ values compared to NW-ACP (p=0.032) and NW-ACPF in higher values than Opalescence regular (p=0.006). Two weeks treatment with O and O-PF resulted in decreased DeltaDeltaZ(surface) values compared to control (p<0.0005), whereas with NW-ACPF no significant differences could be observed (p=0.062). Application of NW-ACP induced significantly increased DeltaDeltaZ(surface) values compared to control (p=0.001). CONCLUSIONS: No supporting influence of fluoride-containing bleaching gels on remineralization could be observed.
Quintessence Int. 2008 Apr;39(4):299-306.
Spectrophotometric evaluation of the efficacy of a new in-office bleaching technique.
Benbachir N, Ardu S, Krejci I.
Dental School, University of Geneva, Switzerland. nacer.benbachir@medecine.unige.ch
OBJECTIVE: To quantitatively test the hypothesis that a new paint-on bleaching gel has the potential to lighten tooth color in clinical situations and to evaluate the change of the tooth color six months after the bleaching procedure. METHOD AND MATERIALS: Ten adult subjects requesting tooth bleaching were selected to participate in this randomized clinical trial involving a new in-office bleaching technique using VivaStyle Paint On Plus (Ivoclar Vivadent), originally designed as an over-the-counter bleaching gel. Digital images and CIE Lab spectrophotometric measurements were taken at baseline (I), after the bleaching treatment (PB), and 6 months after bleaching (6M). Differences in Lab values were tested with a repeated measures analysis of variance (ANOVA). Differences in Delta E values were tested with a factorial ANOVA. RESULTS: Significant (P < .05) differences were detected in L, as well as in a and b values, between initial (I) and post-bleaching (PB) and between initial (I) and 6 months post-op (6M). In contrast, there was no significant difference between post-bleaching (PB) and 6 months post-op (6M). CONCLUSION: This new bleaching technique proved to be efficient over a period of 6 months. It could be a less aggressive and more convenient alternative to traditional bleaching techniques.
Appl Spectrosc. 2008 Nov;62(11):1274-9.
Effects of in-office and at-home bleaching on human enamel and dentin: an in vitro application of Fourier transform infrared study.
Severcan F, Gokduman K, Dogan A, Bolay S, Gokalp S.
Department of Biology, Middle East Technical University, 06531 Ankara, Turkey. feride@metu.edu.tr
In-office and at-home bleaching techniques are widely used methods for the whitening of teeth. However, the safety of these techniques has not been clarified yet. The aim of the current study is to investigate the in-office- and at-home-bleaching-induced structural and quantitative changes in human enamel and dentin at the molecular level, under in vitro conditions. The Fourier transform mid-infrared (mid-FT-IR) spectroscopic technique was used to monitor bleaching-induced structural changes. Band frequency and intensity values of major absorptions such as amide A, amide I, phosphate (PO(4)), and carbonate (CO(3)(-2)) bands, for treatment groups and control, were measured and compared. The results revealed that both procedures have negligible effects on dentin constituents. In office-bleached enamel, in addition to demineralization, a decrease in protein and polysaccharide concentrations, mineral-to-protein ratio, and the strength of hydrogen bonds around NH groups, as well as a change in protein secondary structure were observed. The protein structure changed from beta-sheet to random coil, which is an indication of protein denaturation. However, no significant variations were observed for at-home bleached enamel. The control, at-home, and in-office bleached enamel samples were differentiated with a high accuracy using cluster analysis based on FT-IR data. This study revealed that office bleaching caused deleterious alterations in the composition and structure of enamel that significantly affected the crystallinity and mineralization of the tissue. Therefore, at-home bleaching seems to be much safer than in-office bleaching in terms of molecular variations.
J Dent Child (Chic). 2008 Sep-Dec;75(3):229-34.
Color and surface temperature variation during bleaching in human devitalized primary teeth: an in vitro study.
Gontijo IT, Navarro RS, Ciamponi AL, Miyakawa W, Zezell DM.
Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
This study’s purpose was to make an in vitro assessment of 2 whitening techniques in primary teeth, regarding color and temperature surface variation, during dental bleaching using different catalytic sources. Twenty-one extracted human upper central deciduous incisors were used in this in vitro study. The teeth were darkened with human blood for a period of 21 days. After preparing the teeth, they were randomly distributed into 2 groups, according to bleaching source of activation: (1) a diode laser (DL) group; and (2) a halogen lamp (HL) group. The bleaching process was performed, according to the manufacturer’s guidelines, using Whiteness HP (FGM, Joinville, Brazil). The color was assessed by spectrophotometer (CIELab) and the VITA scale (3M) before and immediately after tooth whitening. The temperature increase in the radicular surface during the bleaching was registered with a thermographic camera ThermaCAM SC 3000 (Flir Systems, Danderyd, Sweden) at the Nuclear and Energy Research Institute, IPEN-CNEN (São Paulo, Brazil). There was no significant difference between the groups in terms of color changes, but there was a statistically significant difference for temperature variation. The use of a diode laser and halogen lamp both promoted whitening in devitalized primary teeth in vitro. As a catalytic source of energy, the diode laser–with the applied parameters–promoted a smaller temperature increase compared to the halogen lamp during the bleaching procedure on nonvital primary teeth.
J Endod. 2008 Dec;34(12):1462-5. Epub 2008 Oct 31.
The effect of tooth bleaching on substance P expression in human dental pulp.
Caviedes-Bucheli J, Ariza-García G, Restrepo-Méndez S, Ríos-Osorio N, Lombana N, Muñoz HR.
Department of Endodontics, School of Dentistry, Pontificia Universidad Javeriana, Bogotá, Colombia. javiercaviedes@cable.net.co
The purpose of this study was to quantify the effect of tooth bleaching on substance P (SP) expression in healthy human dental pulp. Forty pulp samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Thirty of these premolars were assigned into three different tooth-bleaching protocols: group 1 (n = 10): Opalescence Xtra Boost (Ultradent Products, South Jordan, UT) (38% H(2)O(2)) for 15 minutes; group 2 (n = 10): Lase Peroxide (DMC, Brazil) (35% H(2)O(2)) activated with infrared laser diode (Biolux; BioArt, Brazil) for 3 minutes, and group 3 (n = 10): Zoom! Whitening System (Discuss Dental, Culver City, CA) (25% H(2)O(2)) light activated for 20 minutes. The remaining 10 healthy premolars serve as a control group. Teeth were anesthetized immediately after bleaching and were extracted 10 minutes later. All pulp samples were processed and SP was measured by radioimmunoassay. Greater SP expression was found in the Zoom! Whitening System, followed by the Lase Peroxide group, Opalescence Xtra Boost, and the lower SP values were for the control group. Analysis of variance showed statistically significant differences between groups (p = 0.0001). Tukey HSD post hoc tests showed significant differences in the light (p < 0.01) and laser (p < 0.05) activated bleaching systems when compared with control values. It can be concluded that light- and laser-activated tooth-bleaching systems increase SP expression in human dental pulp significantly higher than normal values.
SADJ. 2008 Jun;63(5):282-4, 286.
Effect of four different opalescence tooth-whitening products on enamel microhardness.
Majeed A, Grobler SR, Moola MH, Rossouw RJ, van Kotze TJ.
Oral and Dental Research Institute, Faculty of Dentistry, University of the Western Cape, Tygerberg, South Africa.
OBJECTIVES: The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. METHODS AND MATERIALS: Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer’s instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. RESULTS: All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test). CONCLUSION: All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).
Int Dent J. 2008 Aug;58(4):208-12.
The susceptibility of bleached enamel to staining as measured by Quantitative Light-induced Fluorescence (QLF).
Adeyemi A, Pender N, Higham SM.
School of Dental Sciences, The University of Liverpool, UK. A.A.Adeyemi@liverpool.ac.uk
OBJECTIVES: To report the use of Quantitative Light-induced Fluorescence (QLF) to determine if there was a tendency for bleached enamel to take up extrinsic stains more than unbleached enamel. METHODS: Bovine teeth devoid of stains were selected, the roots removed and enamel gently pumiced. Each tooth was sectioned into two and each half randomly assigned to two groups (bleached or unbleached). Windows were created on each half using clear acid resistant varnish. 38% Hydrogen peroxide gel was applied to the exposed windows of the bleached group for 1 hour. The teeth were rinsed and dried. Bleached and unbleached halves of the same teeth were then mounted on glass rods attached to pot lids using green stick. QLF images were taken. The teeth were subjected to a cycle of artificial saliva, chlorhexidine and tea (2 minutes in each solution). This was repeated 5 times. QLF images were taken at the end of each cycle. RESULTS: The uptake and progression of stain was detected in all the sections by QLF. Using paired t- test (SPSS) there was no significant difference between the two groups for the change from baseline to the final stain cycle (p > 0.05), however there was variability in stain uptake within the groups as the cycles progressed. CONCLUSION: Bleaching of enamel in vitro does not appear to increase the susceptibility of enamel to extrinsic staining.
J Esthet Restor Dent. 2008;20(4):266-73; discussion 274-5.
Effect of curing lights and bleaching agents on physical properties of a hybrid composite resin.
Lima DA, De Alexandre RS, Martins AC, Aguiar FH, Ambrosano GM, Lovadino JR.
Department of Restorative Dentistry, Piracicaba School of Dentistry-Campinas State University, SP, Brazil.
The aim of this in vitro study was to evaluate the microhardness (MH) and diametral tensile strength (DTS) of a minifill hybrid composite (Filtek Z250, 3M ESPE), polymerized with halogen lamp or second generation light-emitting diode (LED), submitted to different bleaching agents. Composite resin specimens were randomly polymerized according to experimental groups (halogen, 550 mW/cm(2)/20 seconds; LED, 550 mW/cm(2)/25 seconds) and subdivided into three subgroups (N=8): A, without bleaching (control); H, 35% hydrogen peroxide; and C, 16% carbamide peroxide. After that, the MH test and DTS test were performed. Two-way analysis of variance (whitening x light) and Tukey’s tests (alpha=5%) were performed. For DTS, there were no statistical differences among the bleaching agents and the control group; however, the halogen group presented statistically lower DTS (p<0.05) than the LED group. For the MH test, the carbamide peroxide group presented statistically lower MH means (p<0.05) than the control groups, and there were no statistical differences among the light-curing units. Sixteen percent carbamide peroxide reduced the MH of the hybrid composite tested. The second generation LED presented a performance similar to or better than the halogen lamp for hardness and DTS, respectively. CLINICAL SIGNIFICANCE: Repolishing of minifill hybrid composite is suggested, as the alteration caused after the contact with 16% carbamide peroxide was limited to the material surface. The second generation light-emitting diode is a good option for a curing light device when the polymerization initiator of composite resin is camphorquinone.
J Clin Dent. 2008;19(2):59-63.
In-use peroxide kinetics of 10% hydrogen peroxide whitening strips.
Gerlach RW, Barker ML, Sagel PA, Ralston CS, McMillan DA.
The Procter & Gamble Company Mason, OH, USA. gerlach.rw@pg.com
OBJECTIVE: Clinical research was conducted to establish the peroxide degradation profile of a very thin 10% hydrogen peroxide bleaching gel delivered on a flexible polyethylene strip. METHODS: Sixteen subjects participated in this study of Crest Whitestrips Premium, a thin layer of 10% hydrogen peroxide gel. Application was supervised, and strips were removed after five, 10, 30, and 60 minutes. Samples were collected from the strips, teeth, gingiva, and saliva, and peroxide levels were derived using a colorimetric peroxide assay. RESULTS: At five minutes, median peroxide concentrations were 7.3%, 6.4%, and 0.7% for strips, teeth, and gingiva, respectively, declining to 4.6%, 2.9%, and 0.1% at 30 minutes. Salivary samples never exceeded a median concentration of 0.014% at any time point. Samples differed significantly (p < 0.01) with respect to the 30- and 60-minute area-under-the-curve calculations, with the highest concentrations on the strip and teeth, and the lowest on the gingiva and in saliva. Median peroxide concentrations on strips and teeth remained above 2% over 60 minutes. At all post-treatment time points, the gingival peroxide concentration was an order of magnitude lower than the teeth samples. CONCLUSION: Use of 10% hydrogen peroxide whitening strips yielded appreciable peroxide on teeth over a 60-minute period, with rapid peroxide degradation on the gingiva, and exceedingly low accumulation in saliva anytime during use.
J Dent. 2008 Sep 1.
Beneficial effects of hydroxyapatite on enamel subjected to 30% hydrogen peroxide.
Jiang T, Ma X, Wang Z, Tong H, Hu J, Wang Y.
Key Laboratory for Oral Biomedical Engineering, Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, PR China; Institute of Analytical and Biomedical Science, Wuhan University, Luojia Hill, Wuhan 430072, PR China.
OBJECTIVES: To evaluate the effect of combination of hydroxyapatite (HA) and hydrogen peroxide (HP) on color, microhardness and morphology of human tooth enamel. METHODS: Forty-eight human dental blocks were obtained from 12 pairs of premolars and were randomly divided into four groups. Group DW was treated with distilled water, group HP with 30% HP, group HA+DW with HA mixed with distilled water and group HA+HP with HA mixed with 30% HP. Baseline and final color measurements and microhardness test were carried out before and after bleaching experiments. Two specimens from each group were selected for morphological investigation after final tests. RESULTS: The DeltaE of group HP and HA+HP were significantly higher than those of group DW (p=0.000 and p=0.000) and group HA+DW (p=0.000 and p=0.000). The percentage microhardness loss of group HA+HP was significantly lower than that of group HP (p=0.047), but significantly higher than those of group DW (p=0.000) and group HA+DW (p=0.000). The obvious variation of morphology was only observed on enamel surfaces in group HP. CONCLUSIONS: This study suggested that combination of HA and HP was effective in tooth whitening. HA could significantly reduce the microhardness loss of enamel caused by 30% HP and keep enamel surface morphology almost unchanged.
Gen Dent. 2008 Jul-Aug;56(5):481-6; quiz 487-8, 495-6.
In vitro assessment of pulp chamber temperature of different teeth submitted to dental bleaching associated with LED/laser and halogen lamp appliances.
Torres CR, Caneppele TM, Arcas FC, Borges AB.
Sao Jose dos Campos School of Dentistry, Sao Paulo State University, SP, Brazil.
This study sought to assess the pulp chamber temperature in different groups of human teeth that had been bleached using hydrogen peroxide gel activated with halogen lamps or hybrid LED/laser appliances. Four groups of ten teeth (maxillary central incisors, mandibular incisors, mandibular canines, and maxillary canines) were used. A digital thermometer with a K-type thermocouple was placed inside pulp chambers that had been filled with thermal paste. A 35% hydrogen peroxide-based red bleaching gel was applied to all teeth and photocured for a total of three minutes and 20 seconds (five activations of 40 seconds each), using light from an LED/laser device and a halogen lamp. The temperatures were gauged every 40 seconds and the data were analyzed by three-way ANOVA, followed by Tukey’s test. Regardless of the light source, statistically significant differences were observed between the groups of teeth. The mean temperature values (+/- SD) were highest for maxillary central incisors and lowest for mandibular canines. The halogen lamp appliance produced more pulp chamber heating than the LED/laser appliance. The increase in irradiation time led to a significant increase in temperature.
Oper Dent. 2008 Jul-Aug;33(4):441-7.
Department of Restorative Dentistry and Endodontics, Ege University, School of Dentistry, Izmir, Turkey. draysegulkaya@yahoo.com
Many studies have shown a considerable reduction in the enamel bond strength of resin composite restorations when the bonding procedure is carried out immediately after bleaching. These studies claim that a certain waiting period is needed prior to performing the restoration in order to attain the original bond strength values. This study determined the most effective time duration for the application of sodium ascorbate prepared in gel form. The labial surfaces of 70 bovine incisors were polished with 600-grit silicon carbide paper on a water-irrigated metallurgical polishing wheel. The specimens were randomly divided into seven groups: 1) bleaching (10% Rembrandt Xtra-Comfort +) immersed in artificial saliva for seven days, 2) bonded immediately after bleaching, 3) bleaching + 10% sodium ascorbate (SA) gel for 10 minutes, 4) bleaching + 10% SA gel for 60 minutes, 5) bleaching + 10% SA gel for 120 minutes, 6) bleaching + 10% SA gel for 240 minutes and 7) bleaching + 10% SA gel for 480 minutes. After preparation, a standard-shaped resin composite was applied to all specimens. The teeth were stored in distilled water at 37 degrees C for 24 hours and a universal testing machine determined their shear bond strength. The data were evaluated using ANOVA and Tukey tests. Antioxidant gel proved to be effective for increasing the shear bond strength of the resin composite to enamel. For maximum effectiveness, antioxidant gel should be applied to enamel for at least 60 minutes. As the application period of the antioxidant increased, the bond strength of the composite on enamel tissue also increased. The increase noticed in Groups 5, 6 and 7 was statistically significant (p<0.05). Application of the antioxidant gel by the patient shortens the time spent in the clinic.
Br Dent J. 2008 Jun 28;204(12):691-5; discussion 668.
Preoccupation with one’s appearance: a motivating factor for cosmetic dental treatment?
De Jongh A, Oosterink FM, van Rood YR, Aartman IH.
Department of Social Dentistry and Behavioural Sciences, Academic Centre for Dentistry Amsterdam, Universiteit van Amsterdam, Louwesweg 1, 1066 EA Amsterdam, The Netherlands. a.de.jongh@acta.nl
BACKGROUND: It has been estimated that among patients presenting for cosmetic treatments up to 15% suffer from Body Dysmorphic Disorder (BDD), a psychiatric condition characterised by a preoccupation with an imagined defect in appearance. OBJECTIVES: The main purpose of the current study was to establish the relationship between presence of BDD characteristics and interest in aesthetically motivated dental treatments. METHODS: Data were obtained by means of a survey within a sample of 879 Dutch citizens of 16 years and older. Characteristics of BDD were assessed based on DSM-IV criteria. RESULTS: Only one of the BDD features (ie a preoccupation with a defect of appearance) emerged as a significant predictor of undergoing cosmetic dental treatments. Patients with such preoccupation were nine times more likely to consider tooth whitening, and six times more likely to consider orthodontic treatment. They were also five times more likely to be dissatisfied about their most recent treatment. CONCLUSIONS: The results suggest that preoccupation with one’s physical appearance is a motivating factor for undergoing certain types of cosmetic dental procedures.
J Am Dent Assoc. 2008 May;139(5):592-7; quiz 626-7.
The effect of fluoride gel use on bleaching sensitivity: a double-blind randomized controlled clinical trial.
Armênio RV, Fitarelli F, Armênio MF, Demarco FF, Reis A, Loguercio AD.
Dental Materials and Operative Dentistry, University of West of Santa Catarina, Joaçaba, Santa Catarina, Brazil.
BACKGROUND: Fluoride has been recognized as a desensitizer; however, no study has addressed its effects to decrease tooth sensitivity when compared with a placebo in a double-blind randomized clinical study. METHODS: The authors divided 30 participants into two groups: one that received a placebo and another that was treated with fluoride. All patients used 16 percent carbamide peroxide (CP) in a custom-fitted tray until their teeth achieved shade A1 or lighter. After daily removal of CP, the patients wore a tray containing either sodium fluoride or placebo for four minutes. The authors statistically analyzed the perception of the intensity of tooth sensitivity and the weekly shade changes for both groups, as well as the intensity of tooth sensitivity (alpha = .05). RESULTS AND CONCLUSIONS: The use of fluoride gel did not affect the whitening efficacy of the CP. The authors observed no difference between the groups receiving the placebo and the fluoride treatment in terms of tooth sensitivity experience (P > .05); however, patients who received the placebo had a higher-intensity tooth sensitivity than that of patients who received the fluoride (P < .001). CLINICAL IMPLICATIONS. The use of 1.23 percent sodium fluoride after each bleaching regimen does not affect the bleaching efficacy of CP. Also, the use of sodium fluoride gel reduces the intensity of tooth sensitivity.
Int Endod J. 2008 Jun;41(6):485-92. Epub 2008 Apr 12.
Ex vivo evaluation of the effectiveness of bleaching agents on the shade alteration of blood-stained teeth.
Yui KC, Rodrigues JR, Mancini MN, Balducci I, Gonçalves SE.
Department of Restorative Dentistry, São José dos Campos School of Dentistry, São Paulo State University, São Paulo, Brazil. karenyui@fosjc.unesp.br
AIM: To evaluate ex vivo effectiveness of the three formulations of bleaching materials for intracoronal bleaching of root filled teeth using the walking bleach technique. METHODOLOGY: Extracted premolar teeth were stained artificially with human blood. After biomechanical preparation, the root canals were filled and a 3-mm thick intermediate base of zinc phosphate cement was placed at the level of the cementoenamel junction. The teeth were divided into four groups (n = 12): C (control, without bleaching material), A1 (sodium perborate + distilled water), A2 (sodium perborate + 10% carbamide peroxide) and A3 (sodium perborate + 35% carbamide peroxide). The bleaching materials were changed at 7 and 14 days. Evaluation of shade was undertaken with aid of the VITA Easyshadetrade mark (DeltaE*ab) and was performed after tooth staining and at 7, 14 and 21 days after bleaching, based on the CIELAB system. Data were analysed by anova for repeated measurements, Tukey and Dunnett tests (alpha = 0.05). RESULTS: The Tukey test revealed that group A1 (10.58 +/- 4.83 DeltaE*ab) was statistically different from the others (A2, 19.57 +/- 4.72 DeltaE*ab and A3, 17.58 +/- 3.33 DeltaE*ab), which were not different from each other. At 7 days: A1 was significantly different from A2; at 14 and 21 days: A2 and A3 were significantly better than A1; the Dunnett test revealed that the control group was different from A1, A2 and A3 at all periods (P < 0.05). CONCLUSION: Sodium perborate associated with both 10% and 35% carbamide peroxide was more effective than when associated with distilled water.
J Clin Dent. 2008;19(1):33-6.
Effect of bleaching treatments on microleakage of Class I restorations.
White DJ, Duschner H, Pioch T.
Health Care Research Center, The Procter and Gamble Company, Mason, Ohio, USA. white.dj.1@pg.com
OBJECTIVE: To test the effect of bleaching agents on microleakage of composite restorations. METHODS: Sixty extracted human molar class I cavities were restored using Scotchbond 1 and Filtek Z250 composite according to the manufacturer’s instructions. The teeth were randomly divided into four groups (n = 15 each). Group 1 was the control group, which was not bleached. Group 2 had a once-daily bleaching treatment with 20% carbamide peroxide gel for eight hours. Group 3 had a bleaching of 6% H2O2 for 30 minutes twice a day. Group 4 had a bleaching treatment once per day with 19% percarbonate gel for eight hours. The bleaching was carried out at 37 degrees C for 14 days. Nail varnish was applied on the apical portion of the teeth only, and the specimens were immersed in a 0.1% rhodamin-B-isothiocyanate for 24 hours at 37 degrees C. After thorough rinsing with tap water, the specimens were embedded in self-curing methacrylate resin. The blocks were sectioned with a water-cooled microtome saw into three to five slices. The cuts were positioned centrally through the restorations and approximately parallel to the long axis of the tooth in the mesiodistal direction. Microleakage was evaluated at the occlusal margins of the class I restorations using a stereo microscope. RESULTS: Microleakage occurred in all groups. The percentage of sections showing leakage was 20% (Group 1), 11% (Group 2), 15% (Group 3), and 18% (Group 4). The statistical evaluation (Kruskal-Wallis test) showed no significant difference between groups (p = 0.537). CONCLUSION: Bleaching with the materials tested has no influence on microleakage of Filtek composite bonded with Scotchbond I.
J Clin Dent. 2008;19(1):14-7.
The effects of high concentration tooth whitening bleaches on microleakage of Class V composite restorations.
Klukowska MA, White DJ, Gibb RD, Garcia-Godoy F, Garcia-Godoy C, Duschner H.
Health Care Research Center, The Procter and Gamble Company, Mason, OH, USA. Klukowska.m@pg.com
OBJECTIVE: To explore the effects of high-concentration hydrogen peroxide bleaching agents on the microleakage of composite restorations. METHODS: In 60 extracted human molars, Class V restorations were prepared with Scotchbond 1/Filtek Z250 composite. Teeth were randomly divided into four groups: (1) no bleaching; (2) bleaching with 14% hydrogen peroxide gel from Crest Whitestrips; (3) bleaching with 20% carbamide peroxide gel from Opalescence PF 20; and (4) bleaching with 38% hydrogen peroxide gel Opalescence Xtra Boost. Bleaching procedures were carried out at 37 degrees C for 21 days/42 hours (2); seven days/42 hours (3); one day/45 minutes (4). Varnish was applied on the apical portion of the teeth only, excluding the restoration, prior to immersion in a 0.1% rhodamin-B-isothiocyanate solution for 24 hours at 37 degrees C. After rinsing, specimens were embedded in methacrylate blocks, and sectioned with a water-cooled microtome with three restoration cuts positioned centrally parallel to the long axis of the tooth. Microleakage was evaluated at the occlusal margins of the Class V restorations using a stereo microscope, separate for dentin and enamel margins. RESULTS: Over 90% of enamel margins exhibited no microleakage following cycling. Bleaching agents had almost no effect on numerical averages. Eighty-eight percent of the dentin margins were free of microleakage for the non-treated control group. Bleaching treatments collectively had slight numerical reductions to around 80%. The statistical evaluation (Kruskal-Wallis-test) showed no significant difference in microleakage between groups for enamel or dentin. CONCLUSION: Bleaching with the materials tested had no influence on microleakage of Filtek Z250 composite bonded with Scotchbond 1.
J Endod. 2008 May;34(5 Suppl):e111-6.
Bleaching in endodontics: an online study guide.
JOE Editorial Board.
JEndodontics@UTHSCSA.edu
The Editorial Board of the Journal of Endodontics has developed a literature-based study guide of topical areas related to endodontics. This study guide is intended to give the reader a focused review of the essential endodontic literature and does not cite all possible articles related to each topic. Although citing all articles would be comprehensive, it would defeat the idea of a study guide. This section presents bleaching of endodontically treated teeth, bleaching of teeth with vital pulps, and cervical resorption associated with bleaching.
Dent Mater. 2008 Jul 15. [Epub ahead of print]
Influence of study design on the impact of bleaching agents on dental enamel microhardness: A review.
Attin T, Schmidlin PR, Wegehaupt F, Wiegand A.
Clinic for Preventive Dentistry, Periodontology and Cariology, University Zurich, Zurich, Switzerland.
OBJECTIVE: Numerous studies investigated the impact of bleaching procedures on enamel microhardness. The outcomes of these studies reveal inconsistencies regarding the fact whether a microhardness reduction due to bleaching occurs or not. Aim of the present review was to summarize the existing literature of external bleaching therapies, which used microhardness tests for evaluation of possible effects on enamel and to weigh up different parameters of the study designs with respect to the outcome of these studies. METHODS: The data from original scientific full papers listed in PubMed or ISI Web of Science (search term: enamel and (bleaching or peroxide) and (hardness or microhardness or Knoop or Vickers)) and received by additional hand-search meeting the inclusion criteria were included in the review. Influences of different parameters on the outcome of the bleaching treatments were analyzed with the Fisher’s-exact-test. RESULTS: A total of 55 studies were identified with 166 hardness measurements conducted directly after bleaching and 69 measurements performed after a post-treatment episode. Directly after bleaching, 84 (51%) treatments showed microhardness reduction compared to baseline, whereas 82 (49%) did not yield microhardness reduction. After the post-treatment episode, 20 (29%) treatments showed hardness reduction and 49 (71%) did not. A significant higher number of bleaching treatments resulting in enamel microhardness reduction were observed, when artificial instead of human saliva was used for storage of the enamel samples in the intervals between the bleaching applications and when no fluoridation measures were applied during or after the bleaching phase. SIGNIFICANCE: The review shows that in those studies, which simulated the intraoral conditions as closely as possible, the risk of enamel microhardness decrease due to bleaching treatments seems to be reduced. Nevertheless more in situ- and in vivo-studies are needed to verify this observation.
J Contemp Dent Pract. 2008 Jul 1;9(5):17-24.
The effect of in-office in combination with intracoronal bleaching on enamel and dentin bond strength and dentin morphology.
Amaral C, Jorge A, Veloso K, Erhardt M, Arias V, Rodrigues JA.
Department of Restorative Dentistry, Dental Research and Graduate Studies Division, School of Dentistry, Guarulhos University, Guarulhos, Brazil. crismariote@yahoo.com
AIM: The aim of this study was to evaluate in vitro effects of the combination of in-office and intracoronal bleaching on enamel and dentin bond strength and on dentin morphology. METHODS AND MATERIALS: Bleaching treatment was performed on 128 bovine teeth for three weeks. Intracoronal bleaching was performed in groups G1 to G3, and in the other groups a combination of in-office and intracoronal bleaching was performed. The following agents and materials were used (n=16): G1- sodium perborate and water (SP); G2- 37% carbamide peroxide (CP); G3- 35% hydrogen peroxide (HP); G4- HP + cotton pellet soaked in water (CPW); G5- HP + SP; G6- HP + CP; G7- HP + HP; and G8- CPW (control). Seven days after bleaching treatment the teeth were sectioned into two halves. One half of each tooth was ground to obtain a flat dentin surface. Dentin and enamel fragments were treated with a dentin/enamel resin adhesive. Resin composite was inserted in two increments and polymerized for 20 seconds. Following the restorative procedures, specimens were sectioned into beams with a rectangular cross-sectional area of approximately 1 mm2. Microtensile testing was performed in a universal testing machine. Bond strengths (in MPa) were calculated and the data were submitted to an analysis of variance (ANOVA) and the Tukey test (a=0.05). For the scanning electron microscopy (SEM) observation, the exposed pulp chambers (n=5) were fixed, dehydrated, dried in a Critical Point dryer, and gold-sputter coated for analysis at standardized magnifications (500X, 1000X, and 2000X). RESULTS: None of the bleaching techniques reduced the enamel bond strength, the best results observed were with the intracoronal treatments with SP and HP. In dentin all bleaching techniques reduced the bond strength with the exception of the in-office HP application technique. The SEM results demonstrated similar dentin surfaces for the G1, G3, G6, and G7 groups with more open dentin tubules found than in the other groups. CONCLUSION: None of the bleaching techniques tested reduced the bond strength of enamel, but they all reduced the bond strength of dentin with the exception of the group only treated with in-office bleaching using 35% HP. The worst bond strength results to dentin were observed in groups that received intracoronal bleaching with SP.
J Clin Pediatr Dent. 2008 Spring;32(3):185-7.
In-office dental bleaching and enamel microabrasion for fluorosis treatment.
Bertassoni LE, Martin JM, Torno V, Vieira S, Rached RN, Mazur RF.
Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, UCSF, 707 Parnassus Ave, San Francisco, CA 94143-0758, USA. luiz.bertassoni@ucsf.edu
Recently, mostly as a result of drinking water fluoridation, the number of young patients affected by fluorosis increased considerably. This study describes a minimally invasive technique, using in-office dental bleaching (35% hydrogen peroxide) and enamel microabrasion (silicon carbide and 12% hydrochloric acid) to eliminate fluorosis like stains. The association of techniques was efficient and can be recommended as a good conservative alternative for the treatment of fluorosis affected teeth.
Oper Dent. 2008 Mar-Apr;33(2):127-34.
Effect of two in-office whitening agents on the enamel surface in vivo: a morphological and non-contact profilometric study.
Cadenaro M, Breschi L, Nucci C, Antoniolli F, Visintini E, Prati C, Matis BA, Di Lenarda R.
Department of Biomedicine, Division of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy. mcadenaro@fmc.units.it
This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% carbamide peroxide (CP) (Rembrandt Quik Start). The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T0: first application, T1: second application at one week, T2: third application at two weeks and T3: fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.
J Clin Pediatr Dent. 2008 Spring;32(3):185-7.
In-office dental bleaching and enamel microabrasion for fluorosis treatment.
Bertassoni LE, Martin JM, Torno V, Vieira S, Rached RN, Mazur RF.
Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, UCSF, 707 Parnassus Ave, San Francisco, CA 94143-0758, USA. luiz.bertassoni@ucsf.edu
Recently, mostly as a result of drinking water fluoridation, the number of young patients affected by fluorosis increased considerably. This study describes a minimally invasive technique, using in-office dental bleaching (35% hydrogen peroxide) and enamel microabrasion (silicon carbide and 12% hydrochloric acid) to eliminate fluorosis like stains. The association of techniques was efficient and can be recommended as a good conservative alternative for the treatment of fluorosis affected teeth.
J Dent. 2008 May 19. [Epub ahead of print]
The effect of bleaching, varying the shade or thickness of composite veneers on final colour: An in vitro study.
Jarad FD, Griffiths CE, Jaffri M, Adeyemi AA, Youngson CC.
Restorative Dentistry, Liverpool University Dental Hospital, Pembroke Place, Liverpool L3 5PS, United Kingdom.
OBJECTIVE: To investigate whether bleaching prior to placement of a composite veneer had an effect on the final shade of the restoration and whether this was affected by the thickness or shade of the veneer. METHODS: Twenty bovine teeth were collected, sectioned and divided into two groups. One group was the non-bleached control, while the other was the bleached group. A colour reading was recorded using a spectrophotometer. The bleached group then underwent external bleaching with 38% hydrogen peroxide and a colour reading was recorded. Each of these two groups were further sub-divided into four subgroups, on which composite veneers were placed. These subgroups were: 0.5mm thick A1, 1mm thick A1, 0.5mm thick A4 and 1mm thick A4 composite veneers. Colour readings were recorded after veneer placement. Statistical significance was assessed using analysis of variance. RESULTS: There was a difference between the colour produced for the same veneer properties, between the bleached and non-bleached groups. For a thin (0.5mm) A4 veneer bleaching produced a statistically significant difference in the amount of colour change (DeltaE) compared to veneering alone. For A1, non-bleached group there is a significant difference in the DeltaE produced by altering the thickness of the veneer. CONCLUSION: Within the limitations of this study, we can conclude that bleaching prior to placement of a thin A4 dark veneer produces a significant difference in colour change. If no bleaching is performed, altering the thickness of an A1 veneer produces a significant colour difference DeltaE. However, if bleaching is carried out there is no significant difference.
Aust Dent J. 2008 Jun;53(2):128-32.
Effect of ozone and Tooth Mousse on the efficacy of peroxide bleaching.
Manton DJ, Bhide R, Hopcraft MS, Reynolds EC.
Cooperative Research Centre for Oral Health Science, School of Dental Science and the Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria.
Background: The aim of this in vitro study was to investigate the effect of Tooth Moussetrade mark (TM) and ozone on the bleaching effectiveness of peroxide (P). Methods: Sixty enamel specimens were stained by tea infusion. P (8% carbamide peroxide solution) and the P/TM (50:50) blend were prepared freshly as required. The specimens were divided randomly into six groups: Group A – ozone followed by P; Group B – ozone concurrently with P; Group C – P alone; Group D – ozone followed by P/TM; Group E – ozone concurrently with P/TM; and Group F – P/TM alone. Ozone exposure was of 40 seconds duration. Digital photographic images were recorded at baseline and endpoint under standardized lighting and desiccation conditions. CIELAB L*a*b* values were determined. Results: The addition of TM to P or the application of ozone with P did not significantly affect bleaching effectiveness compared with P alone. The application of ozone prior to P significantly decreased bleaching effectiveness as indicated by the DeltaL*, Deltaa*, DeltaE and %L* values. The addition of TM to the P did enhance the aesthetic by increasing the lustre and translucency of the treated enamel. Conclusions: The results of this study suggest that Tooth Mousse may be applied concurrently with the bleach, and not reduce bleaching effectiveness.
Med Oral Patol Oral Cir Bucal. 2008 Apr 1;13(4):E266-9.
Effect of external tooth bleaching on dental plaque accumulation and tooth discoloration.
Gursoy UK, Eren DI, Bektas OO, Hurmuzlu F, Bostanci V, Ozdemir H.
Institute of Dentistry and Department of Oral & Maxillofacial Surgery, University of Helsinki, BIOMEDICUM, Helsinki University Central Hospital, Helsinki, Finland. ulvi.gursoy@helsinki.fi
OBJECTIVES: Treatment of dental discolorations with external bleaching is becoming very common in dentistry, however, possible irreversible alterations on enamel surface due to bleaching procedures is a topic of discussion. The aim of this study was to evaluate the clinical effects of bleaching by measuring the dental plaque accumulation on human enamel and tooth discoloration in vivo. STUDY DESIGN: Forty-four teeth in eleven patients not revealing any restorations or periodontal problems were enrolled in this study. Bleaching agent applied only to labial surfaces of incisors using commercial 35% hydrogen peroxide gel. Dental plaque and tooth color measured in the same group of participants, at the end of non-brushing periods lasting 3 and 5 days, respectively, before and after bleaching. RESULTS: The results of the comparison of pre- and post-bleaching measurements showed that, after a non-brushing period lasting 3 day, discoloration scores and plaque accumulation scores for bleached surfaces were lower than the non-bleached surface scores. However, at the end of a non-brushing period lasting 5 day, even the color measurement score in post-bleaching period was lower than the pre-bleaching counterpart, plaque index measurements showed higher plaque accumulation scores in the bleached group. CONCLUSIONS: According to these results, bleaching with 35% hydrogen peroxide seem to favor plaque accumulation after non-brushing period lasting 5 day and tooth discoloration after bleaching is not in correlation with the amount of plaque accumulation.
J Can Dent Assoc. 2008 Mar;74(2):163-163e.
Effectiveness of nightguard vital bleaching with 10% carbamide peroxide — a clinical study.
dos Santos Medeiros MC, de Lima KC.
Department of Dentistry, Universidade Federal do Rio Grande do Norte, Natal, Brazil. cristinamedeiros@digizap.com.br
OBJECTIVE: To use the criteria set by the American Dental Association to evaluate the effectiveness of nightguard vital bleaching with 10% carbamide peroxide through a controlled randomized clinical trial.MATERIALS AND METHODS: Fifty volunteers allocated to either an experimental group(Opalescence PF 10%; OPA) or a control group (placebo; PLA) used a gel for 21 days.Observations of tooth colour were recorded at baseline, immediately after 3 weeks of use(day 21), and 30 days (day 30) and 6 months (day 180) after the treatment was finished.Colour was evaluated with the Vitapan classical shade guide and from the volunteers’ degree of satisfaction. Tooth sensitivity and gingival bleeding were also assessed.Results: The median increase in the lightness of the teeth in the OPA group was 3 units,based on the value-ordered Vitapan shade guide. This improvement in lightness was maintained for 6 months in 88% of this group. In the PLA group, 8% had a 2-unit reduction in tooth colour at day 21. Tooth sensitivity occurred in the OPA (36%) and PLA (8%)groups. Gingival bleeding was not associated with gel use. Volunteers’ satisfaction was 92% for the OPA and 8% for the PLA group.CONCLUSIONS: With the protocol used, nightguard vital bleaching was an effective technique that had minimal and transient side effects that disappeared after treatment without causing sequelae or complications.
Dent Traumatol. 2008 Apr;24(2):220-3.
The effect of a 10% carbamide peroxide bleaching agent on the phosphate concentration of tooth enamel assessed by Raman spectroscopy.
Santini A, Pulham CR, Rajab A, Ibbetson R.
The University of Edinburgh, Edinburgh, UK. ariosantini@hotmail.com
The study assessed changes in phosphate concentrations of surface enamel treated with a proprietary bleaching agent (‘PEROXIDE’) containing 10% carbamide peroxide over a 28-day period using Raman spectroscopy. Six non-carious human molar teeth (age range 12-21 years), extracted for orthodontic reasons, were used. From the enamel face of each half tooth, a near flat enamel section, approximately 2 x 2 mm, was cut, providing 12 specimens. Each specimen was treated with 10% carbamide peroxide for 8 h day(-1) for 28 consecutive days, with Raman spectra being obtained prior to bleaching and after 7, 14, 21 and 28 days. Raman spectra were acquired on a confocal LabRam 300 spectrometer fitted with an Olympus B microscope (Olympus, Middlesex, UK).The difference in the maximum peak values for phosphate group concentrations were tested using the Friedman test (non-parametric anova) and Dunn’s multiple comparison test. An intense broad band at 980 cm(-1), characteristic of phosphate groupings, was always observed. At 7 and 14 days, and again at 28 days, there was a significant decrease in the phosphate group concentration compared with base-line measurements (P < 0.05) but not at 21 days (P > 0.05). Ideally, bleaching should not be continued to a point where surface enamel is lost, and the present study suggests that a regime using 10% carbamide peroxide should not extend to 7 days.
Oper Dent. 2008 Jan-Feb;33(1):15-22.
Clinical evaluation of in-office dental bleaching treatments with and without the use of light-activation sources.
Marson FC, Sensi LG, Vieira LC, Araújo E.
Department of Operative Dentistry, Faculty Uningá, Maringá, Pr, Brazil. doutorfabiano@hotmail.com
This study clinically evaluated the alteration of color, color stability, dental sensitivity and gingival irritation on patients undergoing dental bleaching using varying bleaching methods and light-activation sources. According to pre-established criteria, 40 patients were selected and randomly divided into four groups (n=10): Group 1–35% Hydrogen Peroxide (HP); Group 2–35% HP plus Halogen Curing Light XL 3000 (3M/ESPE); Group 3–35% HP plus Demetron LED (Kerr) and Group 4–35% HP plus LED/LASER (Bio-art). For all groups, there were two sessions of bleaching with 35% HP, with a one week break between sessions. At each bleaching session, three applications of the bleaching gel were used. Two methods of shade evaluation were performed before and after the first week, second week, first month and after six months of the bleaching treatment. These methods were VITA Easyshade Spectrophotometer and Vita Classical Shade Guide. Statistical analysis using ANOVA demonstrated equality between the participating groups when evaluating the group and time variables. The In-Office dental bleaching treatments of vital teeth with 35% HP did not prove to be more effective when light sources were used. There was no difference in color stability between groups until the sixth month of evaluation.
J Oral Rehabil. 2008 Apr;35(4):276-82.
The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.
Al-Salehi SK, Hatton PV, Johnson A, Cox AG, McLeod C.
Department of Adult Dental Care, School of Clinical Dentistry, University of Sheffield, Sheffield, UK. s.k.al-salehi@sheffield.ac.uk
There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P < 0.05). Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.
Dent Mater J. 2008 Jan;27(1):105-16.
Effect of bleaching on color change and refractive index of dental composite resins.
Hubbezoglu I, Akao?lu B, Dogan A, Keskin S, Bolayir G, Ozçelik S, Dogan OM.
Department of Endodontics, Faculty of Dentistry, Cumhuriyet University, Sivas, Turkey.
This study investigated the effects of three bleaching agents (Whiteness Perfect, Whiteness Super, and Whiteness HP) on the color change and refractive index of three dental composites (Admira, Durafill VS, and Gradia Direct). Twenty disk-shaped specimens (10 x 2 mm) of each composite were prepared and divided into four subgroups (n=5). An unbleached group was used as a control, while the remaining specimens in the three subgroups were bleached with one of the bleaching agents respectively. Color change was assessed according to CIELAB color system and refractive indices were determined by phase modulated spectroscopic ellipsometry. Color differences between bleaching and baseline value (DeltaE) were less than 3.3 for all groups. However, bleaching with Whiteness HP led to noticeable color changes for Admira and Durafill VS. While this agent had no effect on the refractive indices of these composites, the other two agents containing carbamide peroxide increased their refractive indices. Therefore, results suggested that replacement of such composite restorations may be required after bleaching.
J Biomed Mater Res A. 2008 Feb 19
Side effects of a non-peroxide-based home bleaching agent on dental enamel.
Wang X, Mihailova B, Klocke A, Fittschen UE, Heidrich S, Hill M, Stosch R, Güttler B, Broekaert JA, Bismayer U.
Mineralogisch-Petrographisches Institut, University of Hamburg, Grindelallee 48, D-20146 Hamburg, Germany.
Changes in the chemistry and structure of enamel due to a non-peroxide-based home bleaching product (Rapid White) were studied in vitro using attenuated total reflectance-infrared spectroscopy, Raman spectroscopy, electron probe microanalysis, flame atomic absorption spectroscopy, and total reflection X-ray fluorescence. The results revealed that the citric-acid-containing gel-like component of the bleaching system substantially impacts on the dental hard tissue. Enamel is affected on several levels: (i) the organic component is removed from superficial and deeper enamel layers and remnants of the bleaching gel are embedded in the emptied voids; (ii) cracks and chemical inhomogeneities with respect to Ca and P occur on the surface; and (iii) within a submicron layer of enamel, the Ca–O bond strength in apatite decreases, thus enhancing calcium leakage from the bleached enamel hard tissue. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008.
J Contemp Dent Pract. 2008 Feb 1;9(2):81-8.
Influence of time on bond strength after bleaching with 35% hydrogen peroxide.
Barbosa CM, Sasaki RT, Florio FM, Basting RT.
School of Dentistry and Dental Research Center, São Leopoldo Mandic, Campinas, SP, Brazil. dra_cinthia@hotmail.com
AIM: The aim of this in vitro study was to evaluate the influence of time after treatment with a 35% hydrogen peroxide bleaching agent on the shear bond strength between composite resin and sound enamel and dentin. METHODS AND MATERIALS: Eighty dental slabs – 40 enamel (E) slabs and 40 dentin (D) slabs – were embedded, flatted, and divided into four groups (n=10). In G1 the E and D slabs were kept in artificial saliva for 14 days. For the G2, G3, and G4 groups the E and D slabs were submitted to bleaching treatment with a 35% hydrogen peroxide bleaching agent. At different times after bleaching treatments (G2=immediate; G3=seven days; G4= fourteen days), composite resin cylinders were made using an adhesive system. Tests were performed in a universal testing machine at a speed of 0.5 mm/min to obtain the values in MPa. RESULTS: For enamel, the Kruskal-Wallis test and Dunn Method showed G1 differed significantly from G2 (G1=13.40 a; G2=6.64 b; G3=16.76 a; G4=11.64 ab). For dentin, the analysis of variance (ANOVA) and Tukey tests showed that G1 differed significantly from G2 and G3 (G1=12.11 a; G2=4.97 b; G3=8.67 c; G4=11.86 ac). CONCLUSION: It is recommended adhesive restorative procedures in enamel be delayed for seven days post-bleaching treatment with 35% hydrogen peroxide, while restorations in dentin should be delayed for 14 days following bleaching treatment.
J Dent. 2007 Dec;35(12):889-96. Epub 2007 Oct 26.
Review of the effects of peroxide on enamel and dentine properties.
Joiner A.
Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, UK. Andrew.Joiner@Unilever.com
OBJECTIVES: To review the available literature investigating the effects of peroxide-based products and solutions on enamel and dentine properties. SOURCES: All original scientific full papers listed in ISI Web of Science and Medline were included in this review using the search terms peroxide AND (enamel OR dentin*) up to the end of 2006. CONCLUSIONS: The majority of studies indicate that peroxide containing products and solutions have no significant deleterious effects on enamel and dentine surface morphology and chemistry, surface microhardness, subsurface enamel and dentine microhardness or ultrastructure. In addition, in vitro studies indicate that they have no significant clinically relevant effects on subsequent enamel and dentine loss caused by acidic erosive challenges, toothpaste abrasion or caries lesion formation. The contrasting studies that do show an effect on some of the above properties, in general, have some limitations in the in vitro methods used which do not accurately reflect the in vivo situation or use products/solutions that have a particularly low pH where acidic erosive processes are likely to dominate and explain the observed changes in enamel and dentine.
Cochrane Database Syst Rev. 2006 Oct 18;(4):CD006202.
Home-based chemically-induced whitening of teeth in adults.
Hasson H, Ismail AI, Neiva G.
University of Michigan, Department of Cariology, Restorative Sciences, and Endodontics,1011 N University, D2361, Cariology/Dentistry, University of Michigan, Ann Arbor, Michigan 48109-1078, USA. hanahass@umich.edu
(Meta análisis)
BACKGROUND: During the last decade tooth whitening products have become widely available in the USA for sale over-the-counter or dispensed by dentists for use at home. With the current rapid growth in demand for tooth whitening it is imperative that the dental community base its recommendations to patients on sound scientific evaluations conducted in well-designed and independent studies. OBJECTIVES: To evaluate the effectiveness (versus a placebo or another active product) and side effects of over-the-counter or dentist-dispensed chemically-based tooth whitening products designed for home use. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 3); MEDLINE (January 1966 to September week 2 2005); and EMBASE (1988 to week 39 2005). The tables of content of selected dental journals published since 1995 were searched for additional references. Written requests for additional studies and information were mailed to experts in this area of research. After a final set of studies was identified, the list of references reported in the included reports was reviewed to identify additional studies. Studies published in English and non-English were considered in this review. SELECTION CRITERIA: Randomised controlled trials and quasi-randomised controlled trials of dentist-dispensed or over-the-counter tooth whitening products with a chemical action (rather than abrasive action), for home use. DATA COLLECTION AND ANALYSIS: Screening of titles and abstracts, data extraction and quality assessment were undertaken independently and in duplicate. MAIN RESULTS: A total of 416 articles were identified, 25 of which met the inclusion criteria and presented data that could be used in the analysis. All included trials measured effectiveness immediately after 2 weeks of product application. Only 13 studies reported outcome data 1 week after the 2-week application period, and of those only six reported outcome data after 1 month or longer. Four of the included trials were assessed as at moderate risk of bias and the remainder at high risk of bias. All trials were sponsored by the manufacturers of tooth whitening products.Six trials compared different whitening products (gel in trays, paint-on films and whitening strips) with placebo/no treatment and all analyses showed the products to be effective, although most comparisons were based on single trials. Nineteen trials compared different whitening products with each other. There was only one meta-analysis which included more than one trial which showed statistically significant differences between the different whitening products. Strips (5.5% to 6.5% hydrogen peroxide(HP)) are more effective than gel in tray at 10% carbamide peroxide (CP) mean difference 1.82 (95% confidence interval (CI) 0.26 to 3.38). All of these trials were assessed as of high risk of bias. ‘Mild’ to ‘moderate’ tooth sensitivity and gingival irritation were the most common side effects. The whitening strips and products with high concentrations of HP caused more users to complain from tooth sensitivity. The protocols for preparation of participants prior to bleaching were inconsistent among the studies. Data on baseline scores of whiteness were not reported by the majority of the studies. The current evidence base on tooth whitening products suffers from methodological and publication biases. AUTHORS’ CONCLUSIONS: There is evidence that whitening products work when compared with placebo/no treatment. There are differences in efficacy between the products, mainly due to the levels of active ingredients, hydrogen peroxide and carbamide peroxide. All trials were however short term and the majority of the studies were judged to be at high risk of bias and were either sponsored or conducted by the manufacturers. There is a need for pragmatic long-term and independent clinical studies that include participants representing diverse populations. There is also a need to evaluate long-term harms. Several studies reported (where measured) the common side effects of tooth sensitivity and gingival irritation, and people should be informed of this.
mp Dent Pract. 2008 Feb 1;9(2):81-8.
Influence of time on bond strength after bleaching with 35% hydrogen peroxide.
Barbosa CM, Sasaki RT, Florio FM, Basting RT.
School of Dentistry and Dental Research Center, São Leopoldo Mandic, Campinas, SP, Brazil. dra_cinthia@hotmail.com
AIM: The aim of this in vitro study was to evaluate the influence of time after treatment with a 35% hydrogen peroxide bleaching agent on the shear bond strength between composite resin and sound enamel and dentin. METHODS AND MATERIALS: Eighty dental slabs – 40 enamel (E) slabs and 40 dentin (D) slabs – were embedded, flatted, and divided into four groups (n=10). In G1 the E and D slabs were kept in artificial saliva for 14 days. For the G2, G3, and G4 groups the E and D slabs were submitted to bleaching treatment with a 35% hydrogen peroxide bleaching agent. At different times after bleaching treatments (G2=immediate; G3=seven days; G4= fourteen days), composite resin cylinders were made using an adhesive system. Tests were performed in a universal testing machine at a speed of 0.5 mm/min to obtain the values in MPa. RESULTS: For enamel, the Kruskal-Wallis test and Dunn Method showed G1 differed significantly from G2 (G1=13.40 a; G2=6.64 b; G3=16.76 a; G4=11.64 ab). For dentin, the analysis of variance (ANOVA) and Tukey tests showed that G1 differed significantly from G2 and G3 (G1=12.11 a; G2=4.97 b; G3=8.67 c; G4=11.86 ac). CONCLUSION: It is recommended adhesive restorative procedures in enamel be delayed for seven days post-bleaching treatment with 35% hydrogen peroxide, while restorations in dentin should be delayed for 14 days following bleaching treatment.
Dent Mater J. 2007 Nov;26(6):875-81.
Improvement of bonding to bleached bovine tooth surfaces by ascorbic acid treatment.
Muraguchi K, Shigenobu S, Suzuki S, Tanaka T.
Department of Fixed Prosthetic Dentistry, Advanced Therapeutic Course, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan. gutch@denta.hal.kagoshima-u.ac.jp
The purposes of this study were twofold: (1) to examine the effects of bleaching on the bond strength of an adhesive to bovine tooth surfaces; and (2) to explore the effectiveness of an ascorbic acid application in preventing the deterioration of bonding ability due to bleaching. In the experimental groups, ascorbic acid was applied to the bleached bovine tooth surfaces. In the control groups, the tooth specimens were bleached but no ascorbic acid application was carried out. All bonded specimens were subjected to shear bond test, and the data were statistically analyzed with two-way ANOVA and Bonferroni’s test (p=0.05). Bond strengths to the bleached specimens were significantly lower than those of non-bleached specimens. No statistical differences were found in bond strength between the bleached and non-bleached groups when the ascorbic acid treatment was carried out. Results of this study suggested that ascorbic acid application was effective in preventing the reduction of bonding ability to bleached teeth.
J Dent. 2007 Nov;35(11):845-50. Epub 2007 Sep 14.
The effect of 24h non-stop hydrogen peroxide concentration on bovine enamel and dentine mineral content and microhardness.
Al-Salehi SK, Wood DJ, Hatton PV.
Centre for Biomaterials & Tissue Engineering, Department of Adult Dental Care, School of Clinical Dentistry, University of Sheffield, Claremont Crescent, Sheffield S10 2TA, UK. s.k.al-salehi@sheffield.ac.uk
OBJECTIVES: Tooth bleaching agents may adversely affect tooth structure. The aim of this study was to investigate the effect of hydrogen peroxide concentration on mineral loss and microhardness of bovine teeth. METHODS: Twenty-six freshly extracted intact bovine incisor teeth were stored in distilled water. Five teeth were sectioned and four samples (2 mm x 2 mm x 1.5 mm) each of enamel and dentine were obtained from each tooth. The samples of enamel and dentine were divided into four groups and immersed in either 0%, 3%, 10% or 30% (w/v) hydrogen peroxide solutions for 24h at 37 degrees C. Samples from the solutions were taken for ion release analysis using inductively coupled plasma mass spectrometry. The remaining 21 teeth were mounted in epoxy resin and the upper surface of the specimens were ground and polished to expose the enamel and dentine for microhardness measurements. These specimens were randomly divided into three equal groups and Vickers microhardness values were recorded on the enamel and dentine surfaces of each group before and after bleaching. RESULTS: The differences in ion release concentration after treatment with 0% (control) and each of 3%, 10% and 30% hydrogen peroxide (w/v) were statistically significant (p<0.025). The release of calcium and phosphorous ions increased with increasing hydrogen peroxide concentrations. A significant reduction (p<0.05) in Vickers microhardness values for enamel was recorded after bleaching. CONCLUSIONS: Ion release from both enamel and dentine increased with increasing hydrogen peroxide concentration. Microhardness of enamel decreased significantly with bleaching.
Gen Dent. 2007 Nov;55(7):669-74.
Randomized controlled trial of professional at-home tooth whitening in teenagers.
Donly KJ, Segura A, Henson T, Barker ML, Gerlach RW.
Department of Pediatric Dentistry, University of Texas Health Science Center, San Antonio, USA.
A randomized controlled clinical trial was conducted to compare two professional at-home tooth whitening systems in a teenage population. Informed consent and child assent were obtained from 60 teenagers aged 12-17 (mean age = 14.8). After baseline measurements, subjects were randomized to one of two groups, using either 14% hydrogen peroxide whitening strips or 10% carbamide peroxide in a custom bleaching tray. Strips were used for 30 minutes twice daily, while the tray was worn overnight. Treatment took place for 14 days sequentially, first on the maxillary arch and then on the mandibular arch; all use was unsupervised. Efficacy was measured objectively by L*a*b* color change from digital images obtained at baseline and end of treatment, using combined color measures for both arches. Both professional whitening systems had significant (p < 0.0001) reductions in yellowness (Deltab*) and increased lightness (DeltaL*) after two weeks of treatment on each arch. At the end of treatment, Deltab* or DeltaL* did not differ significantly between the groups (p > 0.28). Tooth sensitivity and mild oral irritation represented the most common adverse events, with only one subject discontinuing treatment as a result. Teenagers who used either bleaching method for two weeks experienced significant tooth whitening without serious adverse events.
Oper Dent. 2007 Nov-Dec;32(6):610-5.
Effect of different fluoridation regimes on the microhardness of bleached enamel.
Wiegand A, Schreier M, Attin T.
Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zürich, Zürich, Switzerland. annette.wiegand@zzmk.unizh.ch
PURPOSE: This in vitro study evaluated the effects of toothpaste fluoridation and toothpaste plus gel fluoridation and influence of the time period of fluoride gel application on the microhardness of bleached enamel. METHODS: Ninety bovine enamel samples were distributed among nine groups (A-I), each having 10 samples. Half of each surface was bleached with 10% carbamide peroxide gel (8 hours/daily) for 14 days, while the remaining surface was not bleached and served as the control. Groups A-H were fluoridated with toothpaste twice daily throughout the experiment (42 days) and assigned to fluoride gel treatment during the pre-bleaching period (14 days), during the bleaching period and/or during the post-bleaching period (14 days): A: prior, B: during, C: post, D: prior+during, E: during+post, F: prior+post, G: prior+during+post, H: no gel. Group I was neither fluoridated by toothpaste nor gel. The Knoop microhardness (KHN) of each specimen was determined at baseline, after pre-bleaching (day 14), after bleaching (day 28) and after post-bleaching (day 42). Statistical analysis of the percentage of change at baseline KHN was performed by ANOVA and t-test (p < 0.05). RESULTS: Bleaching led to a significant decrease of KHN in Group I (unfluoridated) compared to Groups A-H, where microhardness did not fall below baseline values. Fluoridation treatment in Groups A-H increased microhardness in bleached and unbleached samples, but additional supplementation of fluoride gel in Groups A-G was not superior to toothpaste fluoridation only (H). After the post-bleaching period, the microhardness of the bleached and unbleached surfaces was not significantly different in Groups A-H. CONCLUSION: Regular toothpaste fluoridation prevents microhardness loss due to bleaching treatment in vitro. The additional supplementation of fluoride gel did not enhance the beneficial effect of toothpaste fluoridation, and microhardness was not influenced by the time period of gel fluoridation.
J Dent Res. 2007 Dec;86(12):1193-7.
Effects of direct and indirect bleach on dentin fracture toughness.
Tam LE, Noroozi A.
Restorative Dentistry, Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON, Canada M5G 1G6. laura.tam@utoronto.ca
There are concerns that tooth-whitening procedures irreversibly damage tooth structure. We investigated the hypothesis that dental bleaches significantly affect dentin structural integrity. The objective was to evaluate the effects of peroxide bleaches on dentin fracture toughness. Compact test specimens, composed of human dentin, were used (n = 10/group). Bleach (16% or 10% carbamide peroxide or 3% hydrogen peroxide) or control material, containing 0.1% sodium fluoride, was applied directly or indirectly to dentin through enamel (6 hrs/day) for 2 or 8 weeks. Fracture toughness results were analyzed by ANOVA and Fisher’s LSD test (p < 0.05). There were significant decreases in mean fracture toughness after two- and eight-week direct (19-34% and 61-68%, respectively) and indirect (up to 17% and 37%, respectively) bleach application. The in vitro reduction in dentin fracture toughness caused by the application of peroxide bleaches was greater for the direct application method, longer application time, and higher bleach concentration.
Am J Dent. 2007 Oct;20(5):324-8.
Enamel microhardness and shear bond strength after treatment with an 18% carbamide peroxide bleaching varnish.
Sasaki RT, Barbosa MC, Flório FM, Basting RT.
Department of Restorative Dentistry, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil.
PURPOSE: To evaluate the microhardness and shear bond strength of human enamel treated with an 18% carbamide peroxide bleaching varnish. METHODS: 40 dental enamel slabs were embedded and ground flat, dividing them into four groups (n=10) which received the varnish application for 14 consecutive days: (G1) one daily varnish application; (G2) two daily varnish applications with an interval of 15 minutes; (G3) two daily varnish applications with an interval of 5 hours. After varnish application, the slabs were immersed in artificial saliva changed daily. The control group (G4) consisted of slabs (n=10) that did not receive any varnish treatment and were maintained in artificial saliva for 14 days. Microhardness tests were performed with Knoop indentation with a load of 25 grams for 5 seconds at the beginning of the treatment (baseline values) and after 7 and 14 days. Cylinders were made with microhybrid resin composite and one-bottle adhesive system for shear bond strength tests. Using a universal testing machine with a speed of 0.5 mm/minute to obtain the values in MPa. RESULTS: The Kruskal-Wallis test showed no changes in microhardness values among groups after 7-day varnish application, although there was a decrease in microhardness values when using an 18% carbamide peroxide varnish twice a day with a time-interval of 5 hours between applications (P < 0.05). For enamel shear bond strength, ANOVA test (P > 0.05) did not show significant differences among the groups (G1=15.8; G2=15.2; G3=19.0; G4=15.1).
Am J Dent. 2007 Oct;20(5):319-23.
Shear bond strength of resin composite to enamel and dentin submitted to a carbamide peroxide dentifrice.
da Silva BM, Flório FM, Basting RT.
São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil.
PURPOSE: To assess the shear bond strength of resin composite to human enamel and dentin after using a whitening dentifrice containing carbamide peroxide for 21 days. METHODS: Thirty enamel and 30 dentin slabs were embedded, flattened and randomly divided into three groups (n=10) that received different treatments: carbamide peroxide containing dentifrice (Rembrandt Plus), fluoride containing dentifrice (Close Up with fluoride), and immersion in artificial saliva as the control group. Applications were made for a 15-minute period daily, immersing the slabs in a suspension with distilled water and dentifrice in the ratio of 3:1 (weight) for 21 days. For the rest of the time, the slabs were kept in an artificial saliva solution. After the last application, an adhesive system (Single Bond) was used to bond resin-based composite cylinders (Z100) to the enamel and dentin surfaces for the shear bond strength tests. These tests were carried out in a universal testing machine at a speed of 0.5 mm/minute. RESULTS: ANOVA and the Tukey test for enamel and Kruskal-Wallis and the Dunn Method for dentin, showed significant differences between slabs treated with Rembrandt Plus (REM) and the artificial saliva control group, with higher values for REM (P < 0.05). There were no differences in mean bond strengths of enamel and dentin treated with Close Up with fluoride (CLO) and REM, nor were any differences shown between CLO and the artificial saliva control group. A whitening dentifrice containing carbamide peroxide increased the bond strength of restorative systems.
Am J Dent. 2007 Oct;20(5):315-8.
A randomized controlled trial of home tooth-whitening products.
Lo EC, Wong AH, McGrath C.
Faculty of Dentistry, The University of Hong Kong, 34 Hospital Road, Hong Kong. edward-lo@hku.hk
PURPOSE: To evaluate the effectiveness of two marketed home tooth-whitening products. METHODS: A randomized controlled clinical trial involving 87 adults who were randomly allocated into one of three groups: (1) 6% hydrogen peroxide whitening strips, (2) 18% carbamide peroxide whitening gel, and (3) a placebo (fluoride toothpaste) control group. Subjects were instructed individually and then used the given product daily for 2 consecutive weeks. Color was determined in brightness (L*), yellowness (b*) and redness (a*) [color space] at baseline and 8 weeks after dispensing the product by employing a high resolution digital camera (Fuji HC1000 CCD) to image the subject’s anterior maxillary teeth under standard polarized lighting conditions. The subjects also completed a questionnaire on self-satisfaction with the treatment outcome. RESULTS: One-way ANOVA (Bonferroni test) demonstrated significant differences in color between the three groups with changes in brightness (L*, P< 0.001), yellowness (b*, P< 0.001) and redness (a*, P < 0.001). Changes in L* a* b* was greatest among those who used the 6% hydrogen peroxide whitening strips. Subjects in the whitening strip group also rated that product significantly (P < 0.01) more favorably than other groups with respect to the amount of whiteness improvement, as well as whitening satisfaction and overall impression while there is no significant difference between the whitening gel and the placebo groups.
Eur J Prosthodont Restor Dent. 2007 Sep;15(3):131-4.
The microhardness of bleached dentine and its bond strength to a dentine bonding agent.
Dadoun MP, Bartlett DW.
Prosthodntics, Guy’s, King’s and St. Thomas’ Dental Institute, King College, Guy’s Tower, London.
The aim of this study was to measure the hardness of a bleached dentine surface and its bond strength to a dentine-bonding agent. Thirty teeth were randomly divided into a test and control group. The teeth were hemi-sectioned, the cut surfaces ground flat and the test surfaces bleached with a 10% aqueous solution of carbamide peroxide continuously for 4 days. Hardness was determined using a Vickers microhardness test. The bond between Coltene ‘One Coat Bond’ and bleached and unbleached dentine was evaluated by measuring shear bond strength using an Instron machine. The mean hardness of dentine before and after bleaching was 62.5 (10.2) and 53.6 (7.3) and this difference was statistically different (p<0.001). For the controls immersed in water the hardness was before 60.8 (standard deviation: 7.2) and after 59.6 (8.2) respectively. The mean shear bond strength for the unbleached was 5.5MPa (1.6) and for the bleached samples was 3.3MPa (1.8) and this difference was statistically significant (p<0.002). Under these study conditions the Vickers hardness and bond strength to dentine was reduced by bleaching.
Oper Dent. 2007 Sep-Oct;32(5):427-36.
Clinical evaluation of 15% carbamide peroxide on the surface microhardness and shear bond strength of human enamel.
Metz MJ, Cochran MA, Matis BA, Gonzalez C, Platt JA, Pund MR.
Indiana University School of Dentistry, Indianapolis, IN, USA. michael.metz@med.navy.mil
PURPOSE: This clinical evaluation compared a neutral sodium fluoridated whitening product to a neutral non-fluoridated whitening product in terms their effects on human enamel surface microhardness (SMH) and human enamel/resin composite shear bond strength (SBS) following various treatment times. MATERIALS AND METHODS: Subjects were evaluated for enamel SMH and enamel/resin SBS following 15% carbamide peroxide (CP) with and without potassium nitrate and fluoride (PF). Twenty subjects (80 first or second premolars), who were treatment-planned for premolar extraction due to orthodontic therapy, were allocated into two groups, A and B. Group A received 15% CP, while Group B received 15% CP with PF. Each patient had a control tooth, a 14-day treatment + 14-day recovery tooth, a 14-day treatment + no recovery tooth and a 4-day + no recovery tooth. Each tooth was further divided into two testing surfaces; the facial surface was used for SMH, while the lingual surface was used for SBS. RESULTS: The results of this study determined that there was no statistically significant difference between the effects of the two products on SMH and enamel/resin SBS. Additionally, there was no statistically significant difference between the treatment specimens compared to the controls in terms of SMH. However, there was a significant difference between the treatment groups compared to the controls in terms of enamel/resin SBS. CONCLUSION: Within the limitations of this clinical study, 15% CP with and without PF does not seem to alter the SMH of human enamel. However, 15% CP with and without PF significantly reduced enamel/resin SBS immediately following tooth whitening therapy, up to 14 days post-treatment.
Am J Dent. 2007 Aug;20(4):245-9.
Effect of bleaching on the cemento-enamel junction.
Esberard R, Esberard RR, Esberard RM, Consolaro A, Pameijer CH.
Department of Pathology, Bauru Dental School, University of São Paulo, Brazil. roesberard@hotmail.com
PURPOSE: To evaluate the effect of various bleaching agents on the cemento-enamel junction (CEJ) of human teeth by scanning electron microscopy (SEM) analysis. METHODS: 30 intact teeth were selected and longitudinally sectioned, yielding 60 specimens. Thirty specimens served as controls; the other 30 were divided into six groups with five specimens each (n = 5) and bleached according to six protocols (Group 1: External bleaching with 10% carbamide peroxide; Group 2: External bleaching with 35% hydrogen peroxide; Group 3: External bleaching with 35% hydrogen peroxide; Group 4: Internal/external bleaching with 35% hydrogen peroxide; Group 5: Internal/external bleaching with 35% hydrogen peroxide; and Group 6: Intracoronal bleaching with a paste of sodium perborate mixed with 9% hydrogen peroxide). After treatment the specimens were prepared and examined in a scanning electron microscope. RESULTS: The bleaching agents used in this study caused morphological changes in the CEJ and increased dentin exposure.
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