Composites Posteriores Bibliografía.

La búsqueda de un material restaurador del sector posterior se ha centrado en los composites. Con justicia, Leinfelder ha dicho al respecto que los actuales materiales no son un sustituto de la amalgama, sino una alternativa. De la revisión actual, puede desprenderse que los actuales composites tienen un promedio de permanencia en boca de alrededor de 8 años, (Vs 15 de la amalgama). Esfuerzos están siendo hechos para aumentar la resistencia y el desgaste de los composites agregando partículas y variando el tamaño de ellas. El material ideal aún está lejos.

Dr. Jorge Garat.

Quintessence Int. 2009 Sep;40(8):631-8.

Selected mechanical and physical properties and clinical application of a new low-shrinkage composite restoration.

Duarte S Jr, Botta AC, Phark JH, Sadan A.

Department of Comprehensive Care, Case Western Reserve University, School of Dental Medicine, Cleveland, Ohio 44106-4905, USA. sillas.duarte@case.edu

Polymerization shrinkage is a major concern for bonded direct posterior restorations. Recently, a new low-shrinkage composite resin restorative material was developed. However, few data are available regarding clinical manipulation of this composite. Silorane-based composites represent an alternative to conventional methacrylate-based composites for direct posterior restorations. This article critically discusses the latest peer-reviewed reports related to polymerization, bonding, polishing, and color stability of silorane composite, focusing on its clinical application. Initial evaluation of this new category of composite material shows acceptable mechanical and physical properties.

Oper Dent. 2009 Nov-Dec;34(6):697-702.

Properties of hybrid resin composite systems containing prepolymerized filler particles.

Blackham JT, Vandewalle KS, Lien W.

Tyndall AFB, Panama City, FL, USA.

This study compared the properties of newer hybrid resin composites with prepolymerized-filler particles to traditional hybrids and a microfill composite. The following properties were examined per composite: diametral tensile strength, flexural strength/modulus, Knoop microhardness and polymerization shrinkage. Physical properties were determined for each Jason T Blackham, DMD, USAF, General Dentistry, Tyndall composite group (n = 8), showing significant differences between groups per property (p < 0.001). In general, the traditional hybrid composites (Z250, Esthet-X) had higher strength, composites containing pre-polymerized fillers (Gradia Direct Posterior, Premise) performed more moderately and the microfill composite (Durafill VS) had lower strength. Premise and Durafill VS had the lowest polymerization shrinkage.

Clin Oral Investig. 2009 Sep;13(3):301-7. Epub 2008 Nov 8.

Three-year results of a randomized controlled clinical trial of the posterior composite QuiXfil in class I and II cavities.

Manhart J, Chen HY, Hickel R.

Department of Restorative Dentistry, School of Dentistry, Ludwig-Maximilians-University, 80336 Munich, Germany. manhart@manhart.com

This longitudinal randomized controlled clinical trial evaluated direct composite restorations for clinical acceptability as posterior restoratives in single- or multi-surface cavities and provides a survey of the 3-year results. Three dentists placed 46 QuiXfil (Xeno III) and 50 Tetric Ceram (Syntac Classic) composite restorations in stress-bearing class I and II cavities in first or second molars (43 adult patients). Clinical evaluation was performed at baseline and after 3 years by two other dentists using modified US Public Health Service criteria. At the last recall period, 40 QuiXfil and 46 Tetric Ceram restorations were assessed. A total of 92.5% of QuiXfil and 97.8% of Tetric Ceram posterior composites were assessed to be clinically excellent or acceptable with predominating alpha scores. Up to the 3-year recall, three QuiXfil restorations failed because of bulk fracture, partial tooth fracture, and postoperative symptoms. One Tetric Ceram restoration was lost due to problems with tooth integrity. No significant differences between both composites could be detected at 3 years for all evaluated clinical criteria (p > 0.05). The comparison of restoration performance with time within both groups yielded a significant increase in marginal discoloration (p = 0.007) and deterioration of marginal integrity (p = 0.029) for QuiXfil and significant increase in marginal discoloration (p = 0.009) for Tetric Ceram. However, both changes were mainly effects of scoring shifts from alpha to bravo. Clinical assessment of stress-bearing QuiXfil and Tetric Ceram posterior composite restorations exhibited for both materials good clinical results with predominating alpha scores.

Nanomedicine. 2009 Jun;5(2):232-9. Epub 2009 Feb 14.

New nano-sized Al2O3-BN coating 3Y-TZP ceramic composites for CAD/CAM-produced all-ceramic dental restorations. Part I. Fabrication of powders.

Yang SF, Yang LQ, Jin ZH, Guo TW, Wang L, Liu HC.

Department of Stomatology, The PLA General Hospital, Beijing, China. yangyangfeifei@yahoo.com.cn

Partially sintered 3 mol % yttria-stabilized tetragonal zirconium dioxide (ZrO(2), zirconia) polycrystal (3Y-TZP) ceramics are used in dental posterior restorations with computer-aided design-computer-aided manufacturing (CAD/CAM) techniques. High strength is acquired after sintering, but shape distortion of preshaped compacts during their sintering is inevitable. The aim of this study is to fabricate new machinable ceramic composites with strong mechanical properties that are fit for all-ceramic dental restorations. Aluminum oxide (Al(2)O(3))-coated 3Y-TZP powders were first prepared by the heterogeneous precipitation method starting with 3Y-TZP, Al(NO(3))(3) . 9H(2)O, and ammonia, then amorphous boron nitride (BN) was produced and the as-received composite powders were coated via in situ reaction with boric acid and urea. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to analyze the status of Al(2)O(3)-BN on the surface of the 3Y-TZP particles. TEM micrographs show an abundance of Al(2)O(3) particles and amorphous BN appearing uniformly on the surface of the 3Y-TZP particles after the coating process. The size of the Al(2)O(3) particles is about 20 nm. The XRD pattern shows clearly the peak of amorphous BN among the peaks of ZrO(2).

Clin Oral Investig. 2009 Aug 8. [Epub ahead of print]

Three-year randomised clinical trial to evaluate the clinical performance, quantitative and qualitative wear patterns of hybrid composite restorations.

Palaniappan S, Elsen L, Lijnen I, Peumans M, Van Meerbeek B, Lambrechts P.

Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, 3000, Leuven, Belgium.

The aim of the study was to compare the clinical performance, quantitative and qualitative wear patterns of conventional hybrid (Tetric Ceram), micro-filled hybrid (Gradia Direct Posterior) and nano-hybrid (Tetric EvoCeram, TEC) posterior composite restorations in a 3-year randomised clinical trial. Sixteen Tetric Ceram, 17 TEC and 16 Gradia Direct Posterior restorations were placed in human molars and evaluated at baseline, 6, 12, 24 and 36 months of clinical service according to US Public Health Service criteria. The gypsum replicas at each recall were used for 3D laser scanning to quantify wear, and the epoxy resin replicas were observed under scanning electron microscope to study the qualitative wear patterns. After 3 years of clinical service, the three hybrid restorative materials performed clinically well in posterior cavities. Within the observation period, the nano-hybrid and micro-hybrid restorations evolved better in polishability with improved surface gloss retention than the conventional hybrid counterpart. The three hybrid composites showed enamel-like vertical wear and cavity-size dependant volume loss magnitude. Qualitatively, while the micro-filled and nano-hybrid composite restorations exhibited signs of fatigue similar to the conventional hybrid composite restorations at heavy occlusal contact area, their light occlusal contact areas showed less surface pitting after 3 years of clinical service.

Quintessence Int. 2009 Aug;40(8):631-8.

Selected mechanical and physical properties and clinical application of a new low-shrinkage composite restoration.

Duarte S Jr, Botta AC, Phark JH, Sadan A.

Int Dent J. 2009 Jun;59(3):148-54.

Placement of posterior composite restorations in United Kingdom dental practices: techniques, problems, and attitudes.

Gilmour AS, Latif M, Addy LD, Lynch CD.

Cardiff University School of Dentistry, Health Park, Cardiff, UK.

OBJECTIVE: To investigate the range of techniques used by U.K. general dental practitioners when placing posterior composites, their attitudes and opinions and problems encountered. METHODS: A pre-piloted questionnaire was distributed to 500 UK GDPs selected at random from the U.K. Dentists Register requesting specific information on attitudes, use and problems encountered in relation to posterior composite placement. RESULTS: 254 useable replies were returned (response rate= 51%). Over 95% of respondents would consider placing posterior composites, but only 33% (n=84) would regularly or often place composite in the occlusal surface of a molar tooth. 62% of respondents (n=157) are influenced by articles in peer-reviewed journals when deciding to place a posterior composite, while 95% (n=241) reported that they are not influenced by advertising. Techniques for managing operatively exposed dentine vary, and are related to the depth of the dentine cavity: 79% (n=201) use a ‘dentine-bonding’ technique (i.e., no base/liner) approach for shallow cavities, while only 9% (n=23) would consider this approach for a deep dentine cavity. Only 10% of respondents (n=25) use a sectional metal matrix system for restoring occlusoproximal cavities, while 29% (n=74) use transparent matrix systems, and 61% (n=155) use a circumferential metal matrix system. More than one-half (52%, n=132) of practitioners reported they experienced problems with food packing in more than one in four posterior composites placed. CONCLUSIONS: Despite having been previously discouraged by financial guidelines and with probable limited exposure to posterior composite instruction at dental school, U.K. GDPs are placing posterior composites with reasonable reference to current best available evidence. Diverse opinions exist on the management of certain clinical scenarios, such as of operatively exposed dentine.

Dent Clin North Am. 2009 Jan;53(1):71-6, ix.

Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite.

Kovarik RE.

Department of Oral Health Science, University of Kentucky College of Dentistry, Room 402, Health Science Research Building, 800 Rose Street, Lexington, KY 40536-0297, USA. rekova2@uky.edu

This article reviews the current use of amalgam versus resin composite in posterior restorations and the evidence-base for choosing between these two treatment options. While much research has been published on the issue of the clinical use of amalgam versus resin composite, there are several issues that limit the true evidence-base on the subject. Furthermore, while the majority of published studies on posterior composites would seem to indicate equivalent clinical performance of resin composite to amalgam restorations, the studies that should be weighted much more heavily (randomized controlled trials) do not support the slant of the rest of the literature. As part of an evidence-based approach to private practice, clinicians need to be aware of the levels of evidence in the literature and need to properly inform patients of the true clinical outcomes that are associated with the use of amalgam versus resin composite for posterior restorations, so that patients are themselves making informed decisions about their dental care.

J Am Dent Assoc. 2009 Apr;140(4):447-54.

Clinical evaluation of two packable posterior composites: a five-year follow-up.

Fagundes TC, Barata TJ, Carvalho CA, Franco EB, van Dijken JW, Navarro MF.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Brazil.

BACKGROUND: Research has suggested that packable resin-based composites inserted with a placement technique similar to amalgam condensation can reduce the sensitivity associated with posterior restorations. The authors evaluated the clinical performance, including associated sensitivity, of two packable composites in a randomized five-year clinical trial. METHODS: A single operator randomly placed two restorations in each of 33 patients: one restoration consisting of Alert (Jeneric/Pentron, Wallingford, Conn.) and the other consisting of SureFil (Dentsply/Caulk, Milford, Del.). There were 30 Class I and 36 Class II restorations. Two independent evaluators evaluated the restorations by using modified U.S. Public Health Service criteria. The authors analyzed data by means of the Fisher, chi(2) and McNemar tests at P < .05. RESULTS: Of 60 restorations evaluated at five years, two Class II restorations (one SureFil, one Alert) failed. All other restorations received the highest score possible for sensitivity and vitality. The only difference between the composites at the five-year recall was the significantly better surface texture of SureFil. The authors observed significantly different scores between the baseline and at five years for marginal discoloration (Alert and SureFil), surface texture (Alert and SureFil) and color (SureFil). CONCLUSIONS: Both packable resin-based composites showed excellent durability during the five-year follow-up. CLINICAL IMPLICATIONS: The investigated resin-based composites are suitable for posterior restorations.

Oper Dent. 2009 Jan-Feb;34(1):11-7.

Six-year clinical evaluation of packable composite restorations.

Kiremitci A, Alpaslan T, Gurgan S.

Hacettepe University, School of Dentistry, Department of Restorative Dentistry, Ankara, Turkey.

OBJECTIVE: For decades, resin composites have been used with increasing frequency as posterior restorative materials, because of the demand for aesthetic restoration. This study evaluated the six-year clinical performance of Filtek P60 (3M ESPE) packable composite restorations in combination with a one-bottle etch and rinse adhesive, Single Bond (3M ESPE), in Class II restorations. METHODS: A total of 47 restorations were placed in the Class II cavity preparations (27 premolars and 20 molars) of 33 patients (22 female/11 male; mean age 34) by the same operator. The restorations were evaluated by two examiners at baseline and 1, 2, 3 and 6 years according to the method developed by Ryge, which also is known as the United States Public Health Service (USPHS) criteria. The following characteristics were observed: marginal adaptation, anatomical form, surface texture, marginal discoloration, surface staining, post-operative sensitivity and secondary caries. The Chi-square and Wilcoxon signed rank test with Bonferroni adjustment were used for statistical analysis (p = 0.05). RESULTS: All the restorations received Alpha scores at baseline assessment, except for one restoration, which showed post-operative sensitivity. At the three-year recall examination, two patients, with a total of three restorations, were not included. From baseline to three years, only two of the 44 restorations changed from Alpha to Bravo, for numerous reasons. At the six-year recall, 44 restorations were available for examination. The majority of restorations exhibited Alpha or Bravo scores for the evaluated criteria. No significant differences were found for any of the clinical criteria (p > 0.05). Only two restorations needed to be repaired due to caries that began independently from the restorations. Three or four restorations showed slight surface staining and marginal discoloration. CONCLUSIONS: The clinical performance of the posterior composite restorations that were evaluated was acceptable after six years of service.

J Am Dent Assoc. 2009 Apr;140(4):447-54.

Clinical evaluation of two packable posterior composites: a five-year follow-up.

Fagundes TC, Barata TJ, Carvalho CA, Franco EB, van Dijken JW, Navarro MF.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Brazil.

Rev Belge Med Dent. 2008;63(4):135-46.

Black or white–Which choice for the molars? Part 2. Which does one choose for the restoration of posterior teeth: amalgam or composite?

De Moor R, Delmé K.

Service de Dentisterie Opératoire et d’Endodontle. Département de Médecine Dentaire & Clinique de Médecine Dentaire, Stomatologie et Chirurgie maxillo-faciale, Universiteit Gent, De Pintelaan 185 (P8) 8-9000 Gand. roeland.demoor@ugent.be

The two direct dental restorative materials most commonly used today are silver-mercury amalgam and resin-based composite. The survival of dental amalgam restorations is twice as high than for composite fillings: polymerisation shrinkage, deficient marginal adaptation, higher wear rates, defective contact points leading to food impaction, insufficiently converted composite at the bottom of the cavity are problems that cannot be underestimated when using resin-composite. This does not imply that there is no weakness for amalgam: the need for retentive cavities at the cost of healthy tooth substance, weakening of the tooth’s strength by cutting through the tooth crown’s ridges, the risk of fracture of remaining tooth substance (mostly buccal and lingual surfaces) as the result of the cavity design, and the lack of adhesion between amalgam and tooth substance. Retaining a tooth’s strength by the replacement of amalgam by resin-composites is not always the correct solution. In this respect, it can be questioned whether it is not appropriate to repair failing (extensive) amalgam restorations as to replace them with resin-composites. Research in this respect has demonstrated that dentists still are not convinced of this treatment option. Restoring a tooth in its original build-up or structure and function within the oral cavity is the basis of the biomimetic principle: the use of composite appears to be more obvious than restoring with amalgam. In the present survey pro’s and con’s of amalgams and resin-composites for the restoration of posterior teeth are weighted. The conclusion demonstrates that there is still a place for dental amalgam in modern restorative dentistry when plastic filling materials are used for the direct tooth repair or restoration.

Quintessence Int. 2008 Oct;39(9):757-65.

Clinical performance of the posterior composite QuiXfil after 3, 6, and 18 months in Class 1 and 2 cavities.

Manhart J, Chen HY, Neuerer P, Thiele L, Jaensch B, Hickel R.

Department of Restorative Dentistry, School of Dentistry, Ludwig-Maximilians University, Munich, Germany. manhart@manhart.com

OBJECTIVE: This longitudinal randomized controlled clinical trial evaluated direct composite restorations for clinical acceptability of posterior restoratives in single- or multisurface cavities and provided a preliminary survey of the 3-, 6-, and 18-month results. METHOD AND MATERIALS: Three clinicians placed 46 QuiXfil (Xeno III; Dentsply DeTrey) and 50 Tetric Ceram (Syntac Classic; Vivadent) composite restorations in stress-bearing Class 1 and 2 cavities in first or second molars (43 adult patients). Clinical evaluation was performed at baseline and after 3, 6, and 18 months by 2 other clinicians using modified US Public Health Service criteria. At the final recall period, 45 QuiXfil and 49 Tetric Ceram restorations were assessed. RESULTS: A total of 97.8% of QuiXfil and 100% of Tetric Ceram posterior composites were assessed to be clinically excellent or acceptable with predominating Alpha scores. At the 18-month recall, 1 QuiXfil restoration had failed because of bulk fracture. No significant differences between either composite could be detected at 18 months for all evaluated clinical criteria (P > .05). Small QuiXfil restorations exhibited significantly less marginal discoloration (P = .003) and better restoration integrity (P = .008) than large restorations. The comparison of restoration performance with time within both groups yielded a significant increase in marginal discoloration for QuiXfil (P = .011) and significant deterioration for anatomic form at the marginal step for Tetric Ceram (P = .011). However, both changes were only effects of scoring shifts from Alpha to Bravo. CONCLUSION: Clinical assessment of stress-bearing QuiXfil and Tetric Ceram posterior composite restorations exhibited for both materials good clinical results with predominating Alpha scores.

Rev Belge Med Dent. 2008;63(4):135-46

De Moor R, Delmé K.

J Oral Rehabil. 2009 Feb 10. [Epub ahead of print]

Teaching of posterior composites in dental schools in Japan.

Hayashi M, Seow LL, Lynch CD, Wilson NH.

Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.

Summary The teaching of posterior composites has undergone considerable refinement and development in western countries in recent years. However, little information exists on this teaching in other parts of the world. The aim of this paper is to investigate the teaching of posterior composites to undergraduate dental students in Japan. In late 2007/early 2008, a questionnaire seeking information on the teaching of posterior composites was distributed by email to the person responsible for teaching operative dentistry in each of the 29 dental schools having undergraduate dental degree programmes in Japan. Twenty-three completed responses were returned (response rate = 79%). While all 23 schools taught the placement of composite in occlusal cavities in premolars and molars, 7 schools did not teach the placement of two-surface occlusoproximal composites in premolars (n = 1) and molars (n = 6) and 14 schools and 15 schools do not teach placement of three surface occlusoproximal composites in premolars and molars, respectively. While composite at the time of the survey accounted for 45% of posterior direct restorations placed by students, it is anticipated that this proportion will increase to 59% in 5 years time. Variations were noted between schools in the teaching of principles of cavity design, techniques for restoring proximal contours and light-curing technologies; however, more consistency was observed in techniques used for protecting operatively exposed dentine than that observed in western countries. Despite variations between dental schools being noted in the teaching of certain techniques for posterior composites, the overall extent and content of teaching of posterior composites in Japan could be described as comparable, if not exceeding, than that observed in western countries.

Dent Clin North Am. 2009 Jan;53(1):71-6, ix.

Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite.

Kovarik RE.

Department of Oral Health Science, University of Kentucky College of Dentistry, Room 402, Health Science Research Building, 800 Rose Street, Lexington, KY 40536-0297, USA. rekova2@uky.edu

Acta Odontol Scand. 2009 Feb;67(1):44-9.

Finnish dentists’ perceptions of the longevity of direct dental restorations.

Palotie U, Vehkalahti MM.

City of Helsinki Health Centre, Dental Care Department, Helsinki, Finland. ulla.palotie@helsinki.fi

OBJECTIVES: To evaluate Finnish dentists’ perceptions of the longevity of direct dental restorations; to assess the possible impacts of dentists’ characteristics on these perceptions; and to compare the present longevity estimates with those of recent European reports. METHODS: A questionnaire to 592 general practitioners, systematically sampled from the Finnish Dental Association’s membership list, was posted in April 2004 and data collection was finished by the end of June. The question “In general, what is your estimate for the mean age of restoration in permanent teeth?” pointed restorations: Class II and MOD composites and amalgam in a posterior tooth and Class III composites in an incisor. Dentists’ gender, main work, and year of graduation served as background information. Of the 339 (57%) respondents, only public and private dentists were included; 11 were excluded. Three studies fulfilled the inclusion criteria for recent reports on restoration longevity. Statistical evaluation was by one-way ANOVA, with p=0.05 as the level of significance. RESULTS: The mean of the estimates for all types of composite was 9.0 years (SD 3.6; 95% CI 8.6-9.3) and 18.7 years for amalgam (SD 7.3; 95% CI 18.0-19.5). Male dentists gave longer estimates than female dentists for posterior composites, but shorter estimates for amalgam. Compared to public dentists, private dentists gave longer estimates for posterior composites. All estimates were longer than those reported in the recent literature. CONCLUSION: Dentists’ perceptions of posterior composite longevity are significantly longer among males than among females and among private than public sector dentists, and exceed the median longevity reported in recent studies.

Oper Dent. 2009 Jan-Feb;34(1):11-7.

Six-year clinical evaluation of packable composite restorations.

Kiremitci A, Alpaslan T, Gurgan S.

Hacettepe University, School of Dentistry, Department of Restorative Dentistry, Ankara, Turkey.

J Appl Oral Sci. 2009 Feb;17(1):21-6.

Effect of different polishing systems on the surface roughness of microhybrid composites.

Scheibe KG, Almeida KG, Medeiros IS, Costa JF, Alves CM.

Department of Biomaterials and Oral Biochemistry, Dental School, University of São Paulo, SP, Brazil.

The use of composite resins in dentistry is well accepted for restoring anterior and posterior teeth. Many polishing protocols have been evaluated for their effect on the surface roughness of restorative materials. This study compared the effect of different polishing systems on the surface roughness of microhybrid composites. Thirty-six specimens were prepared for each composite $#91;Charisma (Heraeus Kulzer), Fill Magic (Vigodent), TPH Spectrum (Dentsply), Z100 (3M/ESPE) and Z250 (3M/ESPE)] and submitted to surface treatment with Enhance and PoGo (Dentsply) points, sequential Sof-Lex XT aluminum oxide disks (3M/ESPE), and felt disks (TDV) combined with Excel diamond polishing paste (TDV). Average surface roughness (Ra) was measured with a mechanical roughness tester. The data were analyzed by two-way ANOVA with repetition of the factorial design and the Tukey-Kramer test (p<0.01). The F-test result for treatments and resins was high (p<0.0001 for both), indicating that the effect of the treatment applied to the specimen surface and the effect of the type of resin on surface roughness was highly significant. Regarding the interaction between polishing system and type of resin used, a p value of 0.0002 was obtained, indicating a statistically significant difference. A Ra of 1.3663 was obtained for the Sof-Lex/TPH Spectrum interaction. In contrast, the Ra for the felt disk+paste/Z250 interactions was 0.1846. In conclusion, Sof-Lex polishing system produced a higher surface roughness on TPH Spectrum resin when compared to the other interactions.

J Adhes Dent. 2008 Aug;10(4):315-22.

Two-year clinical evaluation of ormocer, nanohybrid and nanofill composite restorative systems in posterior teeth.

Mahmoud SH, El-Embaby AE, AbdAllah AM, Hamama HH.

Department of Conservative Dentistry, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. dr_salahhasab@yahoo.com

PURPOSE: To evaluate and compare the 2-year clinical performance of an ormocer, a nanohybrid, and a nanofill resin composite with that of a microhybrid composite in restorations of small occlusal cavities made in posterior teeth. MATERIALS AND METHODS: Thirty-five patients, each with 4 occlusal restorations under occlusion, were enrolled in this study. A total of 140 restorations was placed, 25% for each material: an ormocer-based composite, Admira; a nanohybrid resin composite, Tetric EvoCeram; a nanofill resin composite, Filtek Supreme; and a microhybrid resin composite, Tetric Ceram. Two operators placed all restorations according to the manufacturers’ instructions. One week after placement, the restorations were finished/polished and patients were advised to return for follow-up at 6 months, 1 year, and 2 years. All patients attended the 2-year visit where the clinical performance of all restorations was evaluated. Two independent examiners made all evaluations according to the USPHS modified Ryge criteria immediately after placement of restorations and at subsequent recall visits. The changes in the USPHS parameters during the 2-year period were analyzed with the Friedman test. Comparison of the baseline scores with those at the recall visits was made using the Wilcoxon signed rank test. The level of significance was set at p < 0.05. RESULTS: All materials showed only minor changes, and no differences were detected between their performance at baseline and after 2 years. Only one ormocer and one microhybrid composite restoration had failed after 2 years. No failure was detected in nanohybrid and nanofill composite restorations. Regarding the clinical performance, there were no statistically significant differences among the materials used (p > 0.05). CONCLUSION: After 2 years, the ormocer, nanohybrid, and nanofill composites showed acceptable clinical performance similar to that of the microhybrid resin composite.

Acta Odontol Scand. 2008 Nov 27:1-6.

Finnish dentists’ perceptions of the longevity of direct dental restorations.

Palotie U, Vehkalahti MM.

Dental Care Department, City of Helsinki Health Centre, Helsinki, Finland.

Objectives. To evaluate Finnish dentists’ perceptions of the longevity of direct dental restorations; to assess the possible impacts of dentists’ characteristics on these perceptions; and to compare the present longevity estimates with those of recent European reports. Methods. A questionnaire to 592 general practitioners, systematically sampled from the Finnish Dental Association’s membership list, was posted in April 2004 and data collection was finished by the end of June. The question “In general, what is your estimate for the mean age of restoration in permanent teeth?” pointed restorations: Class II and MOD composites and amalgam in a posterior tooth and Class III composites in an incisor. Dentists’ gender, main work, and year of graduation served as background information. Of the 339 (57%) respondents, only public and private dentists were included; 11 were excluded. Three studies fulfilled the inclusion criteria for recent reports on restoration longevity. Statistical evaluation was by one-way ANOVA, with p=0.05 as the level of significance. Results. The mean of the estimates for all types of composite was 9.0 years (SD 3.6; 95% CI 8.6-9.3) and 18.7 years for amalgam (SD 7.3; 95% CI 18.0-19.5). Male dentists gave longer estimates than female dentists for posterior composites, but shorter estimates for amalgam. Compared to public dentists, private dentists gave longer estimates for posterior composites. All estimates were longer than those reported in the recent literature. Conclusion. Dentists’ perceptions of posterior composite longevity are significantly longer among males than among females and among private than public sector dentists, and exceed the median longevity reported in recent studies.

Clin Oral Investig. 2008 Nov 8.

Three-year results of a randomized controlled clinical trial of the posterior composite QuiXfil in class I and II cavities.

Manhart J, Chen HY, Hickel R.

Department of Restorative Dentistry, School of Dentistry, Ludwig-Maximilians-University, Goethe Street 70, 80336, Munich, Germany, manhart@manhart.com.

Am J Dent. 2008 Jun;21(3):148-52.

36-month clinical evaluation of two adhesives and microhybrid resin composites in Class I restorations.

Swift EJ Jr, Ritter AV, Heymann HO, Sturdevant JR, Wilder AD Jr.

Department of Operative Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450, USA. ed_swift@dentistry.unc.edu

PURPOSE: To compare the clinical performance of a self-etching adhesive with that of a popular etch-and-rinse adhesive in Class I posterior composite restorations. METHODS: 60 Class I resin composite restorations (30 per group) were placed in matched pairs using either the self-etch adhesive Xeno III and the microhybrid resin composite Esthet-X or the etch-and-rinse adhesive OptiBond Solo Plus and Point 4 microhybrid resin composite. Subjects were interviewed via telephone 1 week after restoration placement to assess early post-operative sensitivity. In addition, the restorations were evaluated clinically for post-operative sensitivity, marginal quality, wear, and other characteristics immediately after placement and at 6, 12, 18, and 36 months from baseline. RESULTS: During the first week after placement, subjects reported that 23% of restorations in each group had post-operative sensitivity. Sensitivity decreased greatly with time, and differences between the two groups were never statistically significant. Marginal integrity and discoloration were similar for each group at each recall evaluation. Wear of both resin composites increased over time, but mean wear remained at less than 100 microm for each resin composite at 3 years.

J Adhes Dent. 2008 Aug;10(4):315-22.

Two-year clinical evaluation of ormocer, nanohybrid and nanofill composite restorative systems in posterior teeth.

Mahmoud SH, El-Embaby AE, AbdAllah AM, Hamama HH.

Department of Conservative Dentistry, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. dr_salahhasab@yahoo.com

Am J Dent. 2008 Jun;21(3):148-52.

36-month clinical evaluation of two adhesives and microhybrid resin composites in Class I restorations.

Swift EJ Jr, Ritter AV, Heymann HO, Sturdevant JR, Wilder AD Jr.

Department of Operative Dentistry, University of North Carolina, Chapel Hill, NC 27599-7450, USA. ed_swift@dentistry.unc.edu

Oper Dent. 2007 Jul-Aug;32(4):336-40.

A study of microleakage in Class II composite restorations using four different curing techniques.

Gharizadeh N, Moradi K, Haghighizadeh MH. Department of Operative and Esthetic Dentistry, School of Dentistry, Jundishapour University of Medical Sciences, Ahwaz, Iran. gharizadehn@yahoo.com

There are several incremental techniques for the placement of posterior composites in Class II cavities that were introduced to overcome clinical failures associated with these restorations. This study evaluated microleakage in Class II cavities restored with four different curing techniques. On 40 non-carious, freshly extracted human premolars, Class II cavities were prepared following a standard pattern in which the mesial cavities had a cervical margin 1.0 mm above the CEJ, and for distal cavities, 1.0 mm below the CEJ. The specimens were randomly divided into four groups. Each cavity surface was conditioned with 35% phosphoric acid and rinsed to remove the excess water, followed by a dental bonding agent (PQ1) being used for all the cavities. The teeth were then restored with a fiber reinforced resin-based composite (Neulite F), using four different techniques: Group 1, metal matrix with wooden wedge; Group 2, transparent matrix with reflective wedge; Group 3, metal matrix with wooden wedge and light tip and Group 4, metal matrix with wooden wedge and bio-glass cylinder. Then, the restorations were finished and polished, rebonded, thermocycled (2000 times, 5 degrees C to 55 degrees C, 30 second dwell time), stained, sectioned vertically and viewed under a stereomicroscope (40x). They were then scored on a 0-4 scale based on microleakage at the gingival margins. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. The results showed that Group 1 demonstrated the most leakage, while the other three groups showed less leakage than Group 1. There was no significant difference between the enamel and dentin gingival margin groups. As a result of these findings, the authors concluded that restoration with metal matrices, using light conducting instruments, results in significantly less microleakage at the gingival margins of Class II resin composite restorations.

J Am Dent Assoc. 2007 Jun;138(6):775-83.

Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial.

Bernardo M, Luis H, Martin MD, Leroux BG, Rue T, Leitão J, DeRouen TA. Community and Preventive Dentistry, Faculdade de Medicina Dentária, Universidade de Lisboa, Portugal.

BACKGROUND: Failure of dental restorations is a major concern in dental practice. Replacement of failed restorations constitutes the majority of operative work. Clinicians should be aware of the longevity of, and likely reasons for the failure of, direct posterior restorations. In a long-term, randomized clinical trial, the authors compared the longevity of amalgam and composite. SUBJECTS, METHODS AND MATERIALS: The authors randomly assigned one-half of the 472 subjects, whose age ranged from 8 through 12 years, to receive amalgam restorations in posterior teeth and the other one-half to receive resin-based composite restorations. Study dentists saw subjects annually to conduct follow-up oral examinations and take bitewing radiographs. Restorations needing replacement were failures. The dentists recorded differential reasons for restoration failure. RESULTS: Subjects received a total of 1,748 restorations at baseline, which the authors followed for up to seven years. Overall, 10.1 percent of the baseline restorations failed. The survival rate of the amalgam restorations was 94.4 percent; that of composite restorations was 85.5 percent. Annual failure rates ranged from 0.16 to 2.83 percent for amalgam restorations and from 0.94 to 9.43 percent for composite restorations. Secondary caries was the main reason for failure in both materials. Risk of secondary caries was 3.5 times greater in the composite group. CONCLUSION: Amalgam restorations performed better than did composite restorations. The difference in performance was accentuated in large restorations and in those with more than three surfaces involved. CLINICAL IMPLICATIONS: Use of amalgam appears to be preferable to use of composites in multisurface restorations of large posterior teeth if longevity is the primary criterion in material selection.

J Am Dent Assoc. 2007 Jun;138(6):763-72.

The longevity of amalgam versus compomer/composite restorations in posterior primary and permanent teeth: findings From the New England Children’s Amalgam Trial.

Soncini JA, Maserejian NN, Trachtenberg F, Tavares M, Hayes C. The Forsyth Institute, Boston, MA, USA.

BACKGROUND: Limited information is available from randomized clinical trials comparing the longevity of amalgam and resin-based compomer/composite restorations. The authors compared replacement rates of these types of restorations in posterior teeth during the five-year follow-up of the New England Children’s Amalgam Trial. METHODS: The authors randomized children aged 6 to 10 years who had two or more posterior occlusal carious lesions into groups that received amalgam (n=267) or compomer (primary teeth)/composite (permanent teeth) (n=267) restorations and followed them up semiannually. They compared the longevity of restorations placed on all posterior surfaces using random effects survival analysis. RESULTS: The average+/-standard deviation follow-up was 2.8+/-1.4 years for primary tooth restorations and 3.4+/-1.9 years for permanent tooth restorations. In primary teeth, the replacement rate was 5.8 percent of compomers versus 4.0 percent of amalgams (P=.10), with 3.0 percent versus 0.5 percent (P=.002), respectively, due to recurrent caries. In permanent teeth, the replacement rate was 14.9 percent of composites versus 10.8 percent of amalgams (P=.45), and the repair rate was 2.8 percent of composites versus 0.4 percent of amalgams (P=.02). CONCLUSION: Although the overall difference in longevity was not statistically significant, compomer was replaced significantly more frequently owing to recurrent caries, and composite restorations required seven times as many repairs as did amalgam restorations. CLINICAL IMPLICATIONS: Compomer/composite restorations on posterior tooth surfaces in children may require replacement or repair at higher rates than amalgam restorations, even within five years of placement. —–

Oper Dent. 2007 May-Jun;32(3):212-6.

Effect of restoration size on the clinical performance of posterior “packable” resin composites over 18 months.

Brackett WW, Browning WD, Brackett MG, Callan RS, Blalock JS. Department of Oral Rehabilitation, School of Dentistry, Medical College of Georgia, Augusta, GA, USA. wbrackett@mail.mcg.edu

Fifty predominantly moderate or large Class II or multiple-surface Class I resin composite restorations were placed in molars under rubber dam isolation. The restorative systems used were: Alert Condensable (Jeneric/Pentron) and SureFil (Dentsply/Caulk). The restorations were classified according to size, with 7 small, 25 moderate and 18 large, of which 8 were cusp replacement restorations. Baseline, 6, 12 and 18-month double-blinded clinical evaluations were carried out using modified USPHS criteria. The independent variables: restorative material, restoration size and three other clinical factors, were tested using a Multiple Logistic Regression procedure to determine if any were predictive of failure. Of the 50 restorations, four failed by the 18-month recall, three failed due to fracture of the restoration and one due to secondary caries. Both restorative systems demonstrated a 92% success rate. No association between restoration size (p = 0.99) or restorative material (p = 0.65) and failure was found. Similarly, the additional variables, occlusal contact type, presence of occlusal wear facets and first or second molar, were not predictive of failure.

J Adhes Dent. 2007 Apr;9(2):209-16.

Clinical performance of novel resin composites in posterior teeth: 18-month results.

Ergücü Z, Türkün LS. Ege University School of Dentistry, Department of Restorative Dentistry, Izmir, Turkey. zergucu@yahoo.com

PURPOSE: The aim of this study was to evaluate the clinical success potential of two nanocomposites placed in posterior teeth using an antibacterial adhesive system over 18 months. METHODS: A total of 49 Class I and 47 Class II restorations were placed in the permanent teeth of thirty adult patients. The carious lesions were restored with Grandio (Voco) or Filtek Supreme (3M ESPE) using a two-step self-etching antibacterial adhesive system Clearfil Protect Bond (Kuraray). The restorations were finished with fine-grit diamond burs, Enhance polishing system, and Sof-Lex finishing brushes. The restorations were evaluated at baseline, 6, 12, and 18 months after placement using modified Ryge criteria for color stability, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. RESULTS: The changes in the parameters were assessed using the Cochran Q test and the McNemar test at a significance level of p < 0.05. All restorations were classified as clinically satisfactory after 18 months. Statistical analysis demonstrated differences only in superficial roughness, with Grandio exhibiting more surface roughness than Filtek Supreme (p < 0.05). CONCLUSION: Posterior restorations built up with the novel nanocomposites using an antibacterial self-etching system showed satisfactory results at the 18-month recall appointment relative to all criteria except the surface texture in the case of Grandio. Further evaluations are necessary for a more in-depth analysis.

J Mater Sci Mater Med. 2007 Jan;18(1):143-7.

Comparative study of the wear behavior of composites for posterior restorations.

Turssi CP, Faraoni-Romano JJ, de Menezes M, Serra MC. Departamento de Odontologia Restauradora-FORP/USP Av. do Café, s/n, Ribeirão Preto, SP, Brazil. cturssi@yahoo.com

This investigation sought to compare the abrasive wear rates of resin composites designed for posterior applications. Seventy-five specimens were fabricated with conventional hybrid (Charisma and Filtek Z250) or packable composites (Filtek P60, Solitaire II and Tetric Ceram HB), according to a randomized complete block design (n = 15). Specimens were finished and polished metallographically and subjected to abrasive wear which was performed under a normal load of 13N at a frequency of 2 Hz using a pneumatic device (MSM/Elquip) in the presence of a mucin-containing artificial saliva. Wear was quantified profilometrically in five different locations of each specimen after 1,000, 5,000, 10,000, 50,000 and after every each 50,000 through 250,000 cycles. A split-plot ANOVA showed a significant difference between the wear resistance of composites (alpha = 0.05). Tukey’s test ascertained that while the composites Filtek Z250 and Charisma wore significantly less than any other of the materials tested, Tetric Ceram HB experienced the greatest wear rates. Filtek P60 and Solitaire II showed intermediate rates of material removal. The wear pattern of composites proved to be biphasic with the primary phase having the faster wear rate. In conclusion, packable resin composites may not have superior wear compared to conventional hybrid composites.

Oper Dent. 2007 Jan-Feb;32(1):94-8.

Composite veneering of complex amalgam restorations.
Demarco FF, Zanchi CH, Bueno M, Piva E. Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil. fdemarco@ufpel.edu.br In

large posterior cavities, indirect restorations could provide improved performance when compared to direct restorations, but with higher cost and removal of sound tooth structure. Improved mechanical properties have resulted in good clinical performance for amalgam in large cavities but without an esthetic appearance. Resin composites have become popular for posterior restorations, mainly because of good esthetic results. A restorative technique is presented that combines the esthetic properties of directly bonded resin composite and the wide range of indications for amalgam in stress-bearing areas.

Clin Oral Investig. 2003 Jun;7(2):63-70. Epub 2003 May 27.

Meta-análisis

Longevity of direct resin composite restorations in posterior teeth.
Brunthaler A, König F, Lucas T, Sperr W, Schedle A. School of Dentistry, University of Vienna, Vienna, Austria.

This review is a survey of prospective studies on the clinical performance of posterior resin composites published between 1996 and 2002. Material, patient- and operator-specific data, observation periods, isolation methods of the operative field, and failure rates are detailed in tables. The data were evaluated statistically in order to assess the role of materials (filler size, bonding system, base materials [e.g. glass ionomer cements], and lining materials), study design, and personnel on failure rates. The primary reasons for composite failure were secondary caries, restoration fracture, and marginal defects. The influence of different commercial material brands on failure rates was not evaluated due to the great variety of test substances and the lack of material-specific documentation. Effects of the isolation method of the operative field (rubber dam or cotton rolls) and the professional status of operators (university or general dentist) on composite failure rates were not found to be significant. Observation periods varied from 1 to 17 years, and failure rates ranged between 0% and 45%. A linear correlation between failure rate and observation period was found (P<0.0001). Thirteen of 24 studies were terminated after 3 years, while seven studies continued for more than 10 years, indicating that favourable results for composite materials are frequently based on short-term results, despite higher dropout rates in longer studies. To determine accurately the risk for patients, long-term, randomised, controlled clinical trials of treatment outcomes with composites used in posterior teeth are clearly needed.

J Adhes Dent. 2001 Spring;3(1):45-64.

Meta-análisis  Longevity of restorations in posterior teeth and reasons for failure.
Hickel R, Manhart J. Department of Restorative Dentistry and Periodontology, Ludwig Maximilians University, Munich, Germany. hickel@dent.med.uni-muenchen.de PURPOSE:

This article compiles a survey on the longevity of restorations in stress-bearing posterior cavities and assesses possible reasons for failure. MATERIALS AND METHODS: The dental literature predominantly of the last decade was reviewed for longitudinal, controlled clinical studies and retrospective cross-sectional studies of posterior restorations. Only studies investigating the clinical performance of restorations in permanent teeth were included. Longevity and annual failure rates of amalgam, direct composite restorations, glass ionomers and derivative products, composite and ceramic inlays, and cast gold restorations were determined for Class I and II cavities. RESULTS: Annual failure rates in posterior stress-bearing restorations are: 0% to 7% for amalgam restorations, 0% to 9% for direct composites, 1.4% to 14.4% for glass ionomers and derivatives, 0% to 11.8% for composite inlays, 0% to 7.5% for ceramic restorations, 0% to 4.4% for CAD/CAM ceramic restorations, and 0% to 5.9% for cast gold inlays and onlays. CONCLUSION: Longevity of dental restorations is dependent upon many different factors that are related to materials, the patient, and the dentist. The principal reasons for failure were secondary caries, fracture, marginal deficiencies, wear, and postoperative sensitivity. A distinction must be made between factors causing early failures and those that are responsible for restoration loss after several years of service.

Am J Dent. 1994 Jun;7(3):167-74

Meta-análisis

Pooling of long term clinical wear data for posterior composites.
Taylor DF, Bayne SC, Leinfelder KF, Davis S, Koch GG. Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill 27599-7450.

Clinical studies to evaluate the wear of posterior composite restorations are complicated by the large number of factors which influence the findings. A multi-factorial equation has been developed which successfully normalizes the effects of these factors within studies. This equation is not capable of normalizing these effects for other investigations reported in the literature because study characteristics essential to the analysis are rarely reported. Quantitative estimates of wear rate often differ dramatically between studies and between groups of investigators. The objective of this study was to investigate a potential solution to this problem by ranking materials within studies, using common materials to relate rankings across studies, and achieving an overall pooled ranking for products. An intensive literature search disclosed 78 articles and 46 abstracts on clinical posterior composite wear. All studies were analyzed which involved: (1) more than five restorations per material, (2) Class I or II restorations in posterior adult teeth, (3) characterized commercial products, (4) 2 or 3-year wear data, and (5) information on more than one composite material per study. There were 10 2-year studies involving 25 materials, and 10 3-year studies with 26 materials. Within each study the materials were ranked by wear, and the rankings were converted to centered modified ridits. A meta-analysis combining the data across studies was conducted using ANOVA. Although caution is needed for interpreting significance levels because of the small numbers of products evaluated per study, a high level of agreement in rank correlation of 28 products across qualifying studies was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

J Dent. 1994 Feb;22(1):33-43.

Meta-análisis

Meta-analysis on long-term clinical performance of posterior composite restorations.
el-Mowafy OM, Lewis DW, Benmergui C, Levinton C. Restorative Department, Faculty of Dentistry, University of Toronto, Ontario, Canada.

Meta-analysis is a formalized method of combining results of different studies to provide conclusions about the effectiveness of a treatment modality. The aims of this study were to use meta-analysis to determine the clinical performance of posterior composite restorations using the assessment criteria of the USPHS guidelines by combining data from selected multiple studies and to estimate the overall survival rates of posterior composite restorations over time. A computer-aided search of the literature revealed 97 publications on clinical trials of posterior composites in the last 10 years. Following specific selection criteria, which included the year and language of publication, duration of study, class of cavities restored and type of resin composite material used and clinical characteristics assessed; 16 studies were found to be suitable for, and included in a meta-analysis. These involved eight different resin composite materials. Assessment criteria data were extracted from each selected study and tabulated on the basis of years of follow-up and materials. The criteria were coded as binary variables. Homogeneity amongst studies was assessed using Woolf’s statistic prior to combining the data. Weighted average proportions and standard errors were determined for each of the assessment criteria. Using Kaplan-Meier estimates, survival analyses of individual assessment criteria (outcomes) for two posterior composite materials were conducted and the resultant survival curves for these outcomes for the two materials are presented. Considering the limited number of studies of variable length available for meta-analysis, the results indicate generally high clinical performance of the various posterior composites for the number of outcomes analysed.

Pract Proced Aesthet Dent 2002 Jan-Feb;14(1):87-94; quiz 96

Direct posterior composite restorations: simplified success through a systematic approach.

Koczarski MJ, Corredor AC.

University of the Pacific School of Dentistry, San Francisco, California, USA. DrMike@email.msn.com

Posterior resin-based composites have become an indispensable part of the aesthetic restorative armamentarium. The creation of a functional, anatomical contact, however, remains a challenge for many clinicians. In order to meet both aesthetic and functional demands in the posterior quadrant, a composite resin with enhanced physical and handling properties must be used. This article demonstrates a predictable technique for creating proximal contact using a resin microfill that will allow clinicians to gain confidence in their ability to provide aesthetic and functional Class II restorations.

Am J Dent 2001 Oct;14(5):304-8

Clinical evaluation of posterior composite restorations: 6-year results.

Busato AL, Loguercio AD, Reis A, de Oliveira Carrilho MR.

Department of Restorative Dentistry, Dental School University Luterana of Brazil (ULBRA), Canoas, Rio Grande do Sul, Brazil. aloguercio@hotmail.com

PURPOSE: To evaluate the wear resistance of resin restorations (Z100; Tetric; Charisma) in posterior teeth (Class I and II) after 6 years. MATERIAL AND METHODS: One operator placed 103 restorations in 13 patients. Each patient had at least three restorations with three different resin-based composites. All restorations were made using rubber dam isolation and the cavity design was restricted to the elimination of carious tissue. Deeper cavities were covered with calcium hydroxide and/or glass ionomer cement and in shallow and medium cavities only an adhesive system was used. Each composite was placed according to the manufacturer’s instructions. In Class II cavities the resin placement followed the Krejci et al or Opdam et al technique, according to the cavity size. One week later, the restorations were finished/polished and stone dies were immediately built from the impressions. Eleven patients attended the 6-year recall, and 90 restorations were evaluated based on new stone dies. The 6-year stone dies were compared with the baseline ones by two examiners. The evaluation was based on the modified Mahler et al. criteria and Busato et al, using six different scores. The scores were statistically analyzed. RESULTS: A total of 87% of the restorations were analyzed after 6 years. Only 15% (6 for Tetric and 7 for Charisma) of the 90 evaluated restorations had been already replaced. No statistical difference was found in the wear rate of the composites used in this study. None of the patients complained of any symptom after the placement of the composite (baseline data) nor after 6 years.

J Am Dent Assoc 2001 Aug;132(8):1099-104

Using packable composites for direct posterior placement.

Nash RW, Lowe RA, Leinfelder K.

Medical College of Georgia School of Dentistry, USA.

BACKGROUND: Although dentists have been using resin-based composites successfully to restore posterior teeth in Class II situations for several years, creating a functional, anatomical proximal contact remains a clinical challenge for many clinicians. OVERVIEW: This article presents a step by-step technique for creating a predictable proximal contact using a packable resin-based composite as the restorative material. Using a technique that is similar to that for amalgam will enable the dentist to make a successful transition to using composite as an alternative to amalgam in some posterior teeth. PRACTICE IMPLICATIONS: More patients today are well-informed about dental care and are seeking tooth-colored restorative alternatives. Excellent materials and proven techniques are making the transition from traditional metallic restorations easier and more predictable. With this article, the authors aim to help dentists gain confidence in their technique and enable them to provide this service for their patients.

J Am Dent Assoc 2001 May;132(5):639-45

The suitability of packable resin-based composites for posterior restorations.

Manhart J, Chen HY, Hickel R.

Department of Restorative Dentistry, Dental School of the Ludwig Maximilians University, Goethestrasse 70, D-80336, Munich, Germany.

BACKGROUND: Packable composites, promoted for the restoration of stress-bearing posterior teeth, have captured clinicians’ interest. METHODS: The authors tested three packable composites (Alert, Jeneric/Pentron; Solitaire, Heraeus Kulzer, Wehrheim, Germany; SureFil, Dentsply De Trey, Konstanz, Germany); a new packable organically modified ceramic, or ormocer (Definite, Degussa AG, Hanau, Germany); a hybrid composite (Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) and an ion-releasing composite (Ariston pHc, Ivoclar Vivadent, Schaan, Liechtenstein). They determined modulus of elasticity according to EN 24049:1993 of the European Committee for Standardization. They measured Vickers hardness using a 200-gram load for 40 seconds. To determine the materials’ depth of cure, they used both a scraping method (International Standards Organization standard CD 4049:1997) and a hardness profiling method. RESULTS: The authors calculated means and standard deviations from 10 replications of each test and used one-way analysis of variance and post hoc Tukey tests (alpha = .05). The materials had significant differences (P < .001) in all characteristics. Solitaire had the significantly lowest elastic modulus and microhardness; Alert had the highest values for these characteristics. Ariston pHc exhibited the significantly lowest depth of cure. There was a significant correlation between the two methods of measuring depth of cure (r2 = 0.9945; P = .021). CONCLUSIONS: The material group of packable composites is rather inhomogeneous in terms of mechanical and physical data. Our data suggest that bulk curing of packable composites in deep cavities still is not recommendable. CLINICAL IMPLICATIONS: The clinician needs to select packable composites carefully, as it seems that not all of these materials quality for stress-loaded posterior restorations.

Oper Dent 2001 May-Jun;26(3):302-7

Microleakage of posterior packable resin composites with and without flowable liners.

Leevailoj C, Cochran MA, Matis BA, Moore BK, Platt JA.

Faculty of Dentistry, Department of Operative Dentistry, Chulalongkorn University, Henridunant Rd, Pathumwan, Bangkok 10330, Thailand.

The use of flowable composites as liners in Class II packable composites has been suggested by some manufacturers. However, the contributions of this technique are unproven. This study evaluated marginal microleakage in Class II packable composite restorations with and without the use of a flowable composite liner. A conventional microhybrid composite was used as a control. Microleakage at occlusal and gingival margins of Class II cavities was evaluated using 45Ca and autoradiographs. Fifty non-carious, restoration-free human molar teeth were used. Separate mesio-occlusal and disto-occlusal Class II cavity preparations were made in each tooth. Gingival margins of all cavities were placed 1 mm apical to the cementoenamel junction (CEJ). Four Packable composites (Alert, Surefil, Pyramid and Solitaire) and one conventional microhybrid composite (Renew) with their respective manufacturer’s bonding agents were used to restore the cavities. One side of each tooth was restored with composite alone, while the other side was restored with the composite lined with that manufacturer’s flowable liner. The restored teeth were thermally stressed and 45Ca was used to evaluate microleakage. Two independent evaluators scored leakage based on the autoradiographs. The results showed flowable composites helped reduce microleakage at gingival margins of Class II restorations (p < 0.05). Gingival margins had higher microleakage than occlusal margins (p < 0.05). Without flowable liners, three packable composites (Alert, Pyramid and Surefil) showed higher leakage (p < 0.05) than the microhybrid control. Only Solitaire packable composite without liner showed no significant difference in microleakage to the control (p > 0.05). Although the flowable liners help reduce microleakage, Alert and Pyramid packable composites with liners still showed higher leakage than the control (p < 0.05). Surefil and Solitaire packable composites with flowable liners showed no significant difference in microleakage (p > 0.05) to the control.

Am J Dent 2001 Feb;14(1):34-8

Post-operative sensitivity in glass-ionomer versus adhesive resin-lined posterior composites.

Akpata ES, Sadiq W.

Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia. akpata@ksu.edu.sa

PURPOSE: To compare objective and subjective assessments of post-operative sensitivity when class 1 cavities, lined with glass-ionomer or adhesive bonding system, were restored with resin-based composite (RBC). MATERIALS AND METHODS: Occlusal cavities on homologous contra-lateral posterior teeth in 44 male patients attending primary health centers in Riyadh, Saudi Arabia were restored with RBC after a cavity lining of either a light cured glass-ionomer cement (Vitrebond) or an adhesive bonding system (One-Step). RESULTS: Cold response measurements 24 hrs, 7 days and 1 month post-operatively showed that the threshold of pulpal response was significantly lower (P< 0.05) in the restored teeth when the adhesive bonding system served as cavity liner. In addition, based on the patients’ subjective assessments, the prevalence of mild or severe post-operative sensitivity was significantly higher (P< 0.05), 24 hrs and 7 days post-operatively, in the teeth with the adhesive bonding system as a cavity liner. After a post-operative period of 1 month, however, there was no significant difference (P> 0.05) between the prevalence of post-operative sensitivity when the restored teeth received a lining of either glass-ionomer or adhesive bonding system.

J Am Dent Assoc 2001 Feb;132(2):196-203; quiz 224-5

Twenty-four-month clinical evaluation of different posterior composite resin materials.

Turkun LS, Aktener BO.

Department of Restorative Dentistry and Endodontics, School of Dentistry, Ege University, 35100, Bornova, Izmir, Turkey. sebnemturkun@hotmail.com

BACKGROUND: In a 24-month clinical trial, the authors compared three brands of light-cured composite resins that were used to restore the posterior teeth of 38 patients. METHODS: A total of 88 Class I and 32 Class II restorations were made using Z100 (3M Dental Products Div.), Clearfil Ray-Posterior (Kuraray Co. Ltd.) and Prisma TPH (Caulk/Dentsply). Quadrant impressions were taken using a polyvinyl siloxane impression material, and stone casts were obtained every six months for indirect evaluations of anatomical form and marginal adaptation. The restorations were evaluated directly by three clinicians using the Ryge criteria. RESULTS: The authors statistically evaluated parameters at each recall period, using a chi 2 test; compared baseline scores with the recall scores, using a McNemar test; and evaluated changes in the parameters, using the Cochran Q test. Color match, cavosurface margin discoloration and secondary caries remained unchanged at the end of the 24-month recall period for all materials (P > or = .05). A total of 11.5 percent of the Z100 restorations and 16.7 percent of the Prisma TPH restorations showed a slight crevice along the margin (P < or = .05). The surface texture was scored as Bravo only for Clearfil Ray-Posterior restorations at the end of the study (P < or = .05). The authors found that the indirect evaluation results were different from the direct evaluations for Z100 and Prisma TPH. CONCLUSIONS: According to these findings, all the materials used are suitable for posterior restorations. The difference between the two evaluation methods can be attributed to the level of sensitivity. CLINICAL IMPLICATIONS: With the improvement in materials, careful case selection and application of the restorative techniques, posterior composites placed under appropriate conditions and monitored routinely can be expected to last 10 years or longer.

J Adhes Dent 2001 Spring;3(1):45-64
Longevity of restorations in posterior teeth and reasons for failure.

Hickel R, Manhart J.

Department of Restorative Dentistry and Periodontology, Ludwig Maximilians University, Munich, Germany. hickel@dent.med.uni-muenchen.de

PURPOSE: This article compiles a survey on the longevity of restorations in stress-bearing posterior cavities and assesses possible reasons for failure. MATERIALS AND METHODS: The dental literature predominantly of the last decade was reviewed for longitudinal, controlled clinical studies and retrospective cross-sectional studies of posterior restorations. Only studies investigating the clinical performance of restorations in permanent teeth were included. Longevity and annual failure rates of amalgam, direct composite restorations, glass ionomers and derivative products, composite and ceramic inlays, and cast gold restorations were determined for Class I and II cavities. RESULTS: Annual failure rates in posterior stress-bearing restorations are: 0% to 7% for amalgam restorations, 0% to 9% for direct composites, 1.4% to 14.4% for glass ionomers and derivatives, 0% to 11.8% for composite inlays, 0% to 7.5% for ceramic restorations, 0% to 4.4% for CAD/CAM ceramic restorations, and 0% to 5.9% for cast gold inlays and onlays. CONCLUSION: Longevity of dental restorations is dependent upon many different factors that are related to materials, the patient, and the dentist. The principal reasons for failure were secondary caries, fracture, marginal deficiencies, wear, and postoperative sensitivity. A distinction must be made between factors causing early failures and those that are responsible for restoration loss after several years of service.

Am Coll Dent 2001;68(2):31-40

Informed consent: direct posterior composite versus amalgam.

Dlugokinski M, Browning WD.

Department of Oral Rehabilitation, Medical College of Georgia, School of Dentistry, 1459 Laney Walker Blvd., Augusta, Georgia, USA. mdlugoki@mail.mcg.edu

Survey data were obtained from 144 dentists and 116 patients concerning their attitudes and preferences toward direct composite and amalgam restorations in the posterior segment. Some dentists report that they take the initiative in recommending direct composites in these cases and others report that patients request them. Selection criteria for direct composite posterior restorations are similar to those advocated in the dental literature. Those characteristics of alternative materials emphasized in obtaining informed consent mirror the characteristics of the materials dentists report most often performing. Patients report an interest in tooth-colored restorations and trust dentists’ professional opinion, but also express a strong desire for full information as part of informed consent.

J Prosthet Dent 2000 Sep;84(3):353-9
In vivo evaluation of the surface of posterior resin composite restorations: a pilot study.

Pesun IJ, Olson AK, Hodges JS, Anderson GC.

School of Dentistry, University of Minnesota, Minneapolis, USA. pesun001@tc.umn.edu

STATEMENT OF PROBLEM: Several methods have been used to determine the surface characteristics of resin composites in vivo and compare composite wear rates with enamel wear rates. PURPOSE: This pilot study describes the surface characteristics of resin composites and the wear of resin composites and enamel during 1 year of in vivo service. MATERIAL AND METHODS: A single Class II posterior resin composite restoration (Z100) was placed in 10 patients. Restored teeth and unrestored adjacent control teeth were measured for wear 4 times within the first year. A null point contact stylus profiler and fitting software were used to measure epoxy casts. Maximum depth of wear, average depth of wear, and characteristics of the restoration margin were determined. Paired t tests were used to compare the control and restored teeth, and ANOVA was used to assess the progression of wear over time (P<.05). RESULTS: After 1 year, maximum depth of wear over the entire preparation region was on average 204.8 microm (+/- 129.8), significantly greater than the 36. 8 microm (+/- 10.1) average maximum depth of wear of enamel at occlusal contact areas on control teeth (P=.009). Maximum depth of wear progressed over time (P=.009). Fracture of excess composite, commonly called flash fracture, occurred in 50% of the restored teeth extending over the preparation margin. CONCLUSION: Composite restorations wore significantly faster than enamel contact areas on control teeth. Also of concern were the marginal flash fractures that could facilitate secondary caries.

J Dent 2000 Aug;28(6):375-82

Direct composite inlays versus conventional composite restorations: 5-year follow-up.

Wassell RW, Walls AW, McCabe JF   Department of Restorative Dentistry, The Dental School, Newcastle upon Tyne, UK. r.w.wassell@ncl.ac.uk  OBJECTIVES: To determine at 5 year follow-up the failure rate, wear rates and other aspects of clinical performance of direct composite inlays compared with conventional composite restorations placed incrementally. METHODS: 100 matched pairs of restorations were originally entered into the trial. Each pair consisted of a direct composite inlay and a conventional composite restoration made from the same material. At 5 years it was possible to recall 65 pairs, of which 54 were complete. Clinical assessments were made using USPHS criteria (indirect measurements of occlusal wear were made using Ivoclar standard dies) and annual bite wing radiographs. RESULTS: There was a trend to more failure of inlays than conventional composites (17.4 c.f. 7.5%) but this was not significant. The clinical performance of both types of restoration was similar and compared favourably with the results of studies of other materials. Secondary decay was diagnosed in only one restoration. Between 3 and 5 years there was some deterioration in cavo-marginal discoloration, marginal adaptation (occlusally) and surface roughness (occlusally). There was no apparent deterioration in colour match, proximal contact, shim stock contacts and Gingival Index. Wear rates of both types of restoration showed no significant difference and were essentially linear with a mean of 33-34 microm per year. CONCLUSIONS: Both inlays and conventional composite restorations complied with ADA specification minimum requirements for posterior composite restorations. In this study the direct inlay technique gave no clinical advantage over conventional, incremental placement.

Compend Contin Educ Dent 1999 Dec;20(12):1138-44, 1146, 1148

Resin composites in the post-amalgam age.

Lutz F, Krejci I   Department of Preventive Dentistry, Periodontology and Cariology School of Dentistry, University of Zurich, Switzerland.  Resin-based composites are now being used as either amalgam substitutes or amalgam alternatives for the direct placement of box-shaped, stress-bearing restorations in posterior teeth. The expected longevity of these restorations is 8 years. With amalgam substitutes, preservation of enamel and dentin and restoration of tooth form and function must be warranted for the full length of the envisaged service life. In addition, with amalgam alternatives, the restoration must be, and must remain, imperceptible at a normal talking distance. The limiting factor with amalgam substitutes is the elevated risk of secondary caries, which is a result of the marginal openings that are unavoidably associated with the nature of the operative technique. Restorations in permanent teeth using amalgam substitutes most likely fail in some critical aspect of the Swiss Dental Society quality guidelines. With amalgam alternatives, the high cost and the demanding operative technique remain the main criticisms. However, amalgam alternatives, if they are placed using a sophisticated operative technique resulting in perfectly adapted restorations, meet the high expectations outlined in the Swiss Dental Society quality guidelines and fit the clinical concept of the post-amalgam age.

J Esthet Dent 1999;11(5):234-49

Packable composites: overview and technical considerations.
Leinfelder KF, Bayne SC, Swift EJ Jr   Department of Operative Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, USA.  OBJECTIVE: New composites, called packable or condensable composites, are being promoted as amalgam alternatives. The purposes of this review article are to identify these products, define new terminology associated with them, summarize the advertised properties for the materials, discuss the ideal properties for packable composites, review the properties of the major products, and critically evaluate the proposed handling procedures for these materials. REVIEW: The term packable is preferable to condensable for describing this new class of materials. All materials should be considered amalgam alternatives, not amalgam substitutes. The compositions and physical properties reported by manufacturers reveal that none of the materials represents a remarkable improvement over the properties of more traditional universal composites. The designs of Solitaire (Heraeus Kulzer), ALERT (Jeneric-Pentron), and SureFil (Dentsply/Caulk) are discussed in detail. The distinguishing characteristics of all packable compositions are less stickiness or stiffer viscosity than conventional composites, which allow them to be placed in a manner that somewhat resembles amalgam placement. CONCLUSIONS: Packable composites may allow more convenient placement in posterior sites and may offer some technique advantages over conventional composites. However, there is no evidence that their clinical properties are consistently better than those of conventional universal composites. CLINICAL SIGNIFICANCE: Packable composites may be selected as alternatives to amalgam or conventional universal composites, but they are not equal to or better than dental amalgam in all respects. Also, in most cases, mechanical properties of packable composites are not substantially better than those of most conventional universal composites.

J Esthet Dent 1999;11(3):135-42
Seventeen-year clinical study of ultraviolet-cured posterior composite Class I and II restorations.
Wilder AD Jr, May KN Jr, Bayne SC, Taylor DF, Leinfelder KF   Department of Operative Dentistry, School of Dentistry, University of North Carolina at Chapel Hill, USA.
OBJECTIVES:
To compare the clinical performance of four commercial ultraviolet light-cured composite materials, and to evaluate curing-system effects on long-term wear resistance of Class I and II restorations. MATERIALS AND METHODS: Approximately 32 samples of each of four different ultraviolet light-cured composites (n = 130) were inserted into conventional Class I and II cavity preparations by two clinicians. Cavosurface margins of the preparations were not beveled. Enamel walls of the preparation were etched, and the respective bonding agent was applied. Each restoration was evaluated by two clinicians at 5, 10, and 17 years. Direct evaluations were performed using modified United States Public Health Service (USPHS) criteria. Indirect evaluations were performed using the Leinfelder cast evaluation method. RESULTS: After 17 years, 65% of the restorations were recalled and pooled direct evaluations were conducted for color matching (94% alfa), marginal discoloration (100% alfa), marginal integrity (100% alfa), secondary caries (92% alfa), surface texture (72% alfa), and anatomic form (22% alfa). Mean occlusal wear from indirect evaluations at 5, 10, and 17 years was 197 +/- 85 microns, 235 +/- 72 microns, and 264 +/- 80 microns, respectively. For direct and indirect evaluations there were significant differences (p < or = .05) between the baseline and 5-year recall evaluations. CLINICAL SIGNIFICANCE: This study demonstrated that the mean pooled occlusal wear of four ultraviolet light-cured posterior composites at 17 years was 264 microns (approximately 0.25 mm), and that most wear (75%) occurred in the first 5 years. Of all recalled restorations, 76% were judged clinically acceptable at 17 years, and 22% of those exhibited no clinically detectable wear.

Clin Oral Investig 1999 Dec;3(4):208-15
Related Articles,
Internal adaptation and overhang formation of direct Class II resin composite restorations.
Frankenberger R, Kramer N, Pelka M, Petschelt A   University of Erlangen-Nuremberg, Policlinic for Operative Dentistry and Periodontology, Germany. frankbg@dent.uni-erlangen.de  The aim of the present in vitro study was to evaluate different restorative concepts for posterior resin composite fillings in terms of internal adaptation and overhang formation. Eighty standard occluso-distal cavities with and without a 1.5-mm bevel were restored in a phantom head using Syntac Classic and Tetric Ceram with and without Tetric Flow as thin lining or Solid Bond and Solitaire with and without FlowLine. The restorations were finished intraorally and afterwards subjected to thermal loading (1150 x +5 degrees C/+55 degrees C) for 24 h. The proximal margins of the original specimens were analyzed for overhangs under a stereo light microscope (100-fold magnification) before and after intraoral control with loupes, including additional polish. Afterwards the teeth were cut longitudinally, replicated, and their internal integrity analyzed under a SEM (200-fold magnification). The combination of flowable and viscous composites resulted in enhanced internal adaptation for both adhesive systems. However, Syntac Classic exhibited superior adaptation characteristics compared with Solid Bond. In terms of overhang formation, the use of flowable materials always led to higher percentages of marginal overhangs in beveled cavities. Higher viscous materials alone resulted in higher percentages of underfilled margins of beveled than box-shaped cavities. It was clear that the use of magnifying glasses during finishing was beneficial for reducing marginal overhangs up to 40%.

J Prosthet Dent 1999 Oct;82(4):391-7 Related Articles,
Two-year clinical evaluation of direct and indirect composite restorations in posterior teeth.
Scheibenbogen-Fuchsbrunner A, Manhart J, Kremers L, Kunzelmann KH, Hickel R   School of Dentistry, Ludwig-Maximilians-University, Munich, Germany.
STATEMENT OF PROBLEM: Few long-term clinical studies have reported data of modern posterior composites as direct and indirect restorations. PURPOSE: This prospective, long-term clinical trial (1) evaluated direct and indirect composite restorations for clinical acceptability as posterior restoratives in single or multisurface carious teeth and (2) provided a survey on the 2-year results. MATERIAL AND METHODS: Nine dental students placed 88 composite restorations (Tetric, blend-a-lux, Pertac-Hybrid Unifil), 43 direct composite restorations and 45 indirect inlays, under the supervision of an experienced dentist. The first clinical evaluation was performed 11 to 13 months after placement by 2 other experienced dentists, using modified USPHS criteria. A second follow-up of 60 restorations took place within 20 to 26 months after placement. RESULTS: A total of 93% of indirect and 90% of direct composite restorations were assessed to be clinically excellent or acceptable. Two restorations (1 indirect composite inlay and 1 margin of a direct composite restoration) failed during the second year because of fracture. Indirect inlays demonstrated a significantly better “anatomic form of the surface” than direct composite restorations. Premolars revealed a significantly better margin integrity and postoperative symptoms than molars. CONCLUSION: Posterior composite restorations provided a satisfactory clinical performance over a 2-year period when placed by relatively inexperienced but supervised students.

J Prosthet Dent 1999 Aug;82(2):167-71,

Fracture resistance of teeth restored with onlays of three contemporary tooth-colored resin-bonded restorative materials.

Brunton PA, Cattell P, Trevor Burke FJ, Wilson NH   Turner Dental School, The University of Manchester, Manchester, England. paul.brunton@man.ac.uk  STATEMENT OF PROBLEM: There are uncertainties regarding the use of large indirect composites and ceramics in the restoration of posterior teeth. PURPOSE: This study investigated the fracture resistance of teeth restored with restorations of 3 contemporary resin-bonded tooth-colored materials placed in a standardized onlay preparation. MATERIAL AND METHODS: A random sample of preparations for tooth-colored onlays was obtained from a full service dental laboratory. A preparation was then duplicated in 30 natural teeth by copy milling. An additional 10 teeth were not prepared, and acted as a control. Ten onlays of each of the 3 materials (Belle Glass, SR Isosit, and Empress) were produced and resin bonded into place according to the manufacturers’ instructions. The restorations were compressively loaded to fracture and the mode of failure recorded. RESULTS: The fracture resistances obtained for the teeth restored with the composite material (mean 1.56 kN; SD 0.54) were greater than those obtained for the teeth restored with the ceramic material (mean 0.99 kN; SD 0.49) and the fiber-reinforced composite material (mean 0.99 kN; SD 0.56). CONCLUSION: Teeth restored with composite onlay restorations demonstrated a higher fracture resistance than equivalent sized onlay restorations produced from fiber-reinforced composite or a ceramic material. Failure under compressive loading may be found to be less catastrophic when a fiber-reinforced composite rather than a composite or ceramic material is used.

Community Dent Oral Epidemiol 1999 Apr;27(2):137-43

Cost-effectiveness of composite resins and amalgam in the replacement of amalgam Class II restorations.
Tobi H, Kreulen CM, Vondeling H, van Amerongen WE   Department of Cariology Endodontology Pedodontology, Academic Centre for Dentistry Amsterdam, The Netherlands. h.tobi@acta.nl  OBJECTIVES: The replacement of an old amalgam Class II restoration is a common treatment and will remain so for decades. In addition to effectiveness, possible adverse health effects and esthetics, the costs of the treatment options will play a role in the choice of material. The aim of this study was to yield information on the relative cost-effectiveness of the use of composite resins and amalgam for the rerestoration of amalgam Class II restorations. METHODS: As part of a larger randomized clinical trial, treatment effectiveness and treatment costs were estimated in 73 composite and amalgam Class II posterior re-restorations. The main treatment outcome was longevity. Secondary outcomes included need of repair and quality of the margin while in situ. Costs were analyzed from the perspective of dentistry, assuming a treatment strategy aimed at offering ‘value for money’. From this perspective, differential costs were based on personnel costs as approximated by treatment time. RESULTS: Replacing an amalgam Class II restoration with amalgam is associated with lower costs than replacing with a composite resin. A sensitivity analysis, considering type of composite, increasing proficiency with the material, and time needed for future removal of material, demonstrated that these differences are fairly robust. The materials performed equally well for the first 5 years after placement with respect to longevity. Differences in secondary outcomes were minor and not all in favor of the same material. CONCLUSIONS: It is tentatively concluded that amalgams are more cost-effective than composites for replacing existing Class II amalgam restorations.

J Dent Res 1999 Feb;78(2):706-12

Ceramic whisker reinforcement of dental resin composites.

Xu HH, Martin TA, Antonucci JM, Eichmiller FC   Paffenbarger Research Center, American Dental Association Health Foundation, Gaithersburg, Maryland 20899, USA.

Resin composites currently available are not suitable for use as large stress-bearing posterior restorations involving cusps due to their tendencies toward excessive fracture and wear. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to reinforce dental resins with ceramic single-crystalline whiskers of elongated shapes that possess extremely high strength. A novel method was developed that consisted of fusing silicate glass particles onto the surfaces of individual whiskers for a two-fold benefit: (1) to facilitate silanization regardless of whisker composition; and (2) to enhance whisker retention in the matrix by providing rougher whisker surfaces. Silicon nitride whiskers, with an average diameter of 0.4 microm and length of 5 microm, were coated by the fusion of silica particles 0.04 microm in size to the whisker surface at temperatures ranging from 650 degrees C to 1000 degrees C. The coated whiskers were silanized and manually blended with resins by spatulation. Flexural, fracture toughness, and indentation tests were carried out for evaluation of the properties of the whisker-reinforced composites in comparison with conventional composites. A two-fold increase in strength and toughness was achieved in the whisker-reinforced composite, together with a substantially enhanced resistance to contact damage and microcracking. The highest flexural strength (195+/-8 MPa) and fracture toughness (2.1+/-0.3 MPa x m(1/2)) occurred in a composite reinforced with a whisker-silica mixture at whisker:silica mass ratio of 2:1 fused at 800 degrees C. To conclude, the strength, toughness, and contact damage resistance of dental resin composites can be substantially improved by reinforcement with fillers of ceramic whiskers fused with silica glass particles.

Oper Dent 1998 Nov-Dec;23(6):282-9

An in vitro study of the effect of restorative technique on marginal leakage in posterior composites.

Neiva IF, de Andrada MA, Baratieri LN, Monteiro Junior S, Ritter AV   Federal University of Santa Catarina, School of Dentistry, Florianopolis, Brazil.

The purpose of this in vitro study was to compare marginal leakage of class 2 light-cured composite resin restorations, with different insertion and polymerization techniques. Fifty sound premolars extracted for prosthetic purposes were used in the study. Conservative class 2 (MOD) preparations were made in all teeth, with one proximogingival margin on enamel and the other on cementum. All the preparations and restorations were performed by the same operator utilizing the same restorative materials. After restoration the teeth were thermocycled and their gingival margins exposed to a dye. Results showed that the kind of matrix system had no significant influence upon the degree of marginal leakage on enamel. On cementum, oblique and horizontal incremental insertion and polymerization techniques using the collimator cone exhibited the least leakage, while the clear matrix band/reflective wedge technique presented the greatest leakage.

Gen Dent 1998 May-Jun;46(3):256-63; quiz 264-5

Wear resistance of composites: a solved problem?

Soderholm KJ, Richards ND   University of Florida College of Dentistry, Department of Dental Biomaterials, Gainesville 32610-0446, USA.

During the past few years, the use of posterior composites has increased, due to an increased demand from patients to have their metallic restorations replaced with tooth colored restorations. However, until recently, posterior composites were not considered suitable alternatives to metallic restorations mainly because of their tendency to contract during polymerization and wear more than traditional metallic materials. Improvements in bonding agents and composite materials have now made it possible to produce posterior composites that may not produce excessive long-term wear. Despite these improvements, clinicians may find that some composites wear more than expected in certain patients. By developing a good understanding of the different wear mechanisms, the clinician can become familiar with clinical wear variations and select clinical cases where composites may work well without excessive wear.

Odontoclinica

Publicaciones recientes

Últimos comentarios

Categorias

Archivos

Composites Posteriores Bibliografía.

Leave a Reply

Traductor

Odontoclínica

Sitios de interés

Odontoclinica

Publicaciones recientes

Últimos comentarios

Categorias

Archivos

Composites Posteriores Bibliografía.

Leave a Reply

Traductor

Odontoclínica

Temas publicados

Mas leidos

Sitios de interés