Silorane. Bibliografía.

La búsqueda de un material restaurador del sector posterior se ha centrado en los composites cuyo monómero se ha modificado en base a Silorane.
Parece ser un esfuerzo válido para disminuir la contracción de polimerización de este tipo de materiales, se habla de una contracción de menos del 1%, lo cual, sería un importante avance. De acuerdo a la bibliografía este tipo de materiales se viene investigando (o al menos publicando los avances) desde hace al sólo 8 años a la fecha.
La Bibliografía es por tanto escasa.
Dr. Jorge Garat.

Braz Oral Res. 2011 Feb;25(1):5-12.

Low shrinkage composite resins: influence on sealing ability in unfavorable C-factor cavities.

Klautau EB, Carneiro KK, Lobato MF, Machado SM, Souza Junior MH.

Department of Dental Materials, School of Dentistry, Federal University of Pará, Belém, PA, Brazil.

Abstract

The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep) surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA) and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA) (G1); Filtek Z-350 (3M/ESPE,St Paul, MN, USA) (G2); Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA) (G3); Premisa (KERR Corporation, Orange, CA, USA) (G4). Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA) + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA). After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54) or depth (p = 0.8364) of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.

J Mech Behav Biomed Mater. 2011 Apr;4(3):237-44. Epub 2010 Jun 15.

Two-body wear of dental restorative materials.

Hahnel S, Schultz S, Trempler C, Ach B, Handel G, Rosentritt M.

Abstract

Aim: The aim of this in vitro study was to determine the two-body wear resistance of modern direct dental restorative materials. Methods: Eight standardized specimens were prepared from 14 dental restorative materials (nano-, micro-, hybrid-, macrofilled composites; compomer, silorane, ormocer); a veneering composite (Sinfony) and enamel were used for reference. Vickers hardness (HV) and inorganic filler weight were determined. Specimens were subjected to mastication simulation using a mastication simulator (50 N, 1.2×10(5) cycles, 1.2 Hz) in a pin-on-block design and simultaneous thermal cycling (600 cycles, 5/55 °C, 2 min/cycle). Steatite balls were used as antagonists. Vertical substance and volume loss were determined using cast replicas and a 3D laser scanning device. Means and standard deviations were calculated, and statistical analysis was performed using one-way ANOVA and the Games-Howell test for post hoc analysis (α=.05). Results: HV ranged between 19 and 76; inorganic filler weight ranged between 44% and 88%. Significantly lowest vertical substance and volume loss were detected for the microfilled composite Heliomolar; enamel yielded similar vertical substance and volume loss. Intermediate wear was found for the other microfilled and hybrid composites as well as the silorane and the ormocers. Significantly highest wear was found for the macrofilled composite Quixfil and the compomer Compoglass F. Discussion: Within the limitations of an in vitro study, the findings indicate similar wear behaviour for silorane- and ormocer-based dental restorative materials. However, correlations between HV, filler content, and wear resistance were poor.

Dent Mater. 2010 Dec;26(12):1144-50. Epub 2010 Sep 15.

Polymerization stress, shrinkage and elastic modulus of current low-shrinkage restorative composites.

Boaro LC, Gonçalves F, Guimarães TC, Ferracane JL, Versluis A, Braga RR.

Department of Dental Materials, University of São Paulo, São Paulo, SP, Brazil.

Abstract

OBJECTIVE: To compare currently available low-shrinkage composites with others regarding polymerization stress, volumetric shrinkage (total and post-gel), shrinkage rate and elastic modulus.

METHODS: Seven BisGMA-based composites (Durafill/DU, Filtek Z250/FZ, Heliomolar/HM, Aelite LS Posterior/AP, Point 4/P4, Filtek Supreme/SU, ELS/EL), a silorane-based (Filtek LS, LS), a urethane-based (Venus Diamond, VD) and one based on a dimethacrylate-derivative of dimer acid (N’Durance, ND) were tested. Polymerization stress was determined in 1-mm high specimens inserted between two PMMA rods attached to a universal testing machine. Total volumetric shrinkage was measured using a mercury dilatometer. Maximum shrinkage rate was used as a parameter of the reaction speed. Post-gel shrinkage was measured using strain-gages. Elastic modulus was obtained by three-point bending. Data were submitted to one-way ANOVA/Tukey test (p=0.05), except for elastic modulus (Kruskal-Wallis).

RESULTS: Composites ranked differently for total and post-gel shrinkage. Among the materials considered as “low-shrinkage” by the respective manufacturers, LS, EL and VD presented low post-gel shrinkage, while AP and ND presented relatively high values. Polymerization stress showed a strong correlation with post-gel shrinkage except for LS, which presented high stress. Elastic modulus and shrinkage rate showed weak relationships with polymerization stress.

SIGNIFICANCE: Not all low-shrinkage composites demonstrated reduced polymerization shrinkage. Also, in order to effectively reduce polymerization stress, a low post-gel shrinkage must be associated to a relatively low elastic modulus.

Braz Dent J. 2010;21(6):538-42.

Comparison of silorane and methacrylate-based composite resins on the curing light transmission.

Guiraldo RD, Consani S, Consani RL, Berger SB, Mendes WB, Sinhoreti MA, Correr-Sobrinho L.

Department of Restorative Dentistry, School of Dentistry, University of North Paraná, Londrina, PR, Brazil. rdguiraldo@gmail.com

Abstract

The aim of this study was to investigate the influence of different composite resins – Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) – on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25%) was significantly higher than that of Heliomolar (12%). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.

Clin Oral Investig. 2011 Jan 18. [Epub ahead of print]

Oxidative stress and cytotoxicity generated by dental composites in human pulp cells.

Krifka S, Seidenader C, Hiller KA, Schmalz G, Schweikl H.

Department of Operative Dentistry and Periodontology, University of Regensburg Medical Centre, Franz Josef Strauβ Allee 11, 93042, Regensburg, Germany.

Abstract

Dental composites are a source of residual monomers that are released into the oral environment. Since monomers act on cultured cells through reactive oxygen species (ROS), we hypothesized that composites generate ROS associated with cytotoxicity. Human pulp-derived cells were exposed to extracts of methacrylate-based materials including triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate-free composites (Tetric Ceram, Tetric EvoCeram, els, els flow, Solitaire 2) and a silorane-based composite (Hermes III). The materials were polymerized in the presence and absence of a polyester film and then extracted in culture medium. The generation of ROS was measured by flow cytometry, and cytotoxicity was determined as well. Methacrylate-based composites reduced cell survival but varied in efficiency. Undiluted extracts of Solitaire 2 specimens prepared in the absence of a polyester film reduced cell survival to 26% compared with untreated cultures. Cytotoxicity was reduced when specimens were covered with a polyester film during preparation. Cytotoxicity of the composites was ranked as follows: Solitaire 2 >> els flow > Tetric Ceram = Tetric EvoCeram = els > Hermes III. The generation of ROS followed the same pattern as detected with cytotoxic effects. A positive correlation was found between ROS production and cell survival caused by extracts made from materials not covered with a polyester film. These findings suggest that components released from composites affect cellular signaling networks through ROS formation. Regenerative and reparative capacities of the dentine-pulp complex may be impaired by biologically active resin monomers released from composite restorations.

Dent Mater. 2011 Apr;27(4):348-55. Epub 2010 Dec 30.

Investigations on a methacrylate-based flowable composite based on the SDR™ technology.

Ilie N, Hickel R.

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

Abstract

OBJECTIVE: Monomer development for a reduced shrinkage of composite materials still challenges the modern research. The purpose of this study was to analyse the shrinkage behavior of an innovative composite material for dental restorations based on a resin system that is claimed to control polymerization kinetics having incorporated a photoactive group within the resin.

METHODS: Shrinkage stress development within the first 300s after photoinitiation, gel point as well as micro-mechanical properties (Vickers hardness HV, modulus of elasticity E, creep Cr and elastic-plastic indentation work W(e)/W(tot)) were evaluated (n=10). The experimental flowable resin-based composite (RBC) was measured in comparison to regular methacrylate-based micro- (Esthet X Flow) and nano-hybrid flowable RBCs (Filtek Supreme Plus Flow). Additionally, the high viscosity counterparts of the two regular flowable methacryate-based composites (Esthet X Plus and Filtek Supreme Plus) as well as a low shrinkage silorane-based micro-hybrid composite (Filtek Silorane) were considered. The curing time was 20s (LED unit Freelight2, 3M-ESPE, 1226mW/cm(2)).

RESULTS: The experimental material achieved the significantly lowest contraction stress (1.1±.01MPa) followed by the silorane-based composite (3.6±.03MPa), whereas the highest stress values were induced in the regular methacrylate-based flowable composites EsthetX Flow (5.3±.3MPa) and Filtek Supreme Flow (6.5±.3MPa). In view of gel point, the best values were obtained for the experimental flowable composite (3.1±.1s) and Filtek Silorane (3.2±.3s), which did not differ significant from each others, whereas EsthetX Plus and Filtek Supreme Plus did also not differ significantly, inducing the shortest gel point. The experimental flowable material achieved also the lowest shrinkage-rate (maximum at 0.1MPa/s). For all analysed materials, no significant difference in the micro-mechanical properties between top and bottom were found when measured on 2mm thick increments 24h after polymerization. The categories of flowable materials performed in the measured micro-mechanical properties significantly inferior when compared to the hybrid-composites, showing lower HV and E and predominantly higher creep and plastic deformation. Within the flowable RBCs, the experimental material achieved the lowest Vickers hardness, the highest modulus of elasticity, the highest creep and showed the significantly lowest elastic deformation.

SIGNIFICANCE: The experimental flowable composite revealed the lowest shrinkage stress and shrinkage-rate values in comparison to regular methacrylate composites but intermediate micro-mechanical properties. Being at the same time more rigid (higher modulus of elasticity) and more plastic (low W(e)/W(tot) and high creep values) as the regular flowable materials, its effect on interfacial stress build-up cannot be easily predicted.

J Esthet Restor Dent. 2010 Apr;22(2):127-38.

Effect of finishing/polishing systems on the surface roughness of novel posterior composites.

Marghalani HY.

Conservative Dental Science Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia. hymarghalani@hotmail.com

Abstract

PURPOSE: The aim of this in vitro study was to evaluate and compare the surface finish of some direct posterior resin composites with new novel ones, which are based on a resin matrix other than the ordinary dimethacrylate, after fine finishing and polishing with eight different systems. MATERIALS AND METHODS: Forty-eight disk-shaped specimens of the posterior composites were prepared in a split Teflon mold and irradiated by an Astralis 10 light cure (560 mW/cm(2) for 10 seconds) at four quadrants on each sample’s side. The specimens were divided into eight groups according to the designed finishing and/or polishing protocols. The surface roughness in the form of surface finish (Ra) was recorded using a contact profilometer. The surface of the specimens was observed under the scanning electron microscope. RESULTS: Analysis of variance revealed highly significant differences between the materials for the Ra roughness parameter at each finishing and polishing system used (p < 0.05). On the one hand, Filtek P90 (3M ESPE Dental Products, Seefeld, Germany) and Definite (Degussa, Dental Centrum, Hanau, Germany) provided the smoothest surface finish (Ra) when they were finished and polished with a series of Sof-Lex pop-on disks (3M ESPE Dental Products) and Astropol (Ivoclar Vivadent, Schaan, Liechtenstein), respectively. On the other hand, Filtek P60 (3M ESPE Dental Products) presented the roughest surface when it was finished with Fini disks (Jeneric/Pentron Clinical Technologies, Wallingford, CT, USA). Scanning electron microscope images indicated a uniform surface topography for Filtek P90 with most finishing/polishing systems. Contrary to CompoSite polishers (Shofu Inc., Kyoto, Japan), Astropol showed the smoothest surface finish with most of the investigated composites. CLINICAL SIGNIFICANCE The smoothest surface finish was achieved by most of the finishing/polishing systems investigated specifically on cationic (Filtek P90) and organically modified ceramics (Definite) composites compared with dimethacrylate-based composites, suggesting their successful clinical use.

Oper Dent. 2010 Jul-Aug;35(4):412-9.

Investigation of mechanical properties of modern dental composites after artificial aging for one year.

Hahnel S, Henrich A, Bürgers R, Handel G, Rosentritt M.

Department of Prosthetic Dentistry, University Medical Center Regensburg, Regensburg, Germany. Sebastian.Hahnel@klinik.uni-regensburg.de

Abstract

This in vitro study investigated the aging behavior of dental composites with regard to surface roughness (SR), Vickers hardness (VH) and flexural strength (FS), and the study elucidated the impact of artificial aging parameters. One hundred and sixty-five rectangular specimens were prepared from five composites (Filtek Supreme XT, Filtek Silorane, CeramX, Quixfil, experimental ormocer) and subjected to various artificial aging protocols (storage in distilled water/ethanol/artificial saliva for 7, 90 and 365 days; thermal cycling, 2 x 3000 cycles 5/55 degrees C). SR, VH and FS were determined at baseline and after each aging treatment. Means and standard deviations were calculated; statistical analysis was performed using three-way ANOVA and the Tukey-Kramer multiple comparison test (alpha=.05). The results showed a significant influence in the composite and aging duration on mechanical parameters; the aging medium did not have a significant influence on VH and FS, but there was a significant influence on SR. The highest overall VH was found for theexperimental ormocer; Filtek Silorane yielded the lowest values. For FS, the significantly highest values were found for Filtek Silorane, and the lowest values were found for the experimental ormocer. Prolonged aging periods (90 or 365 days) or thermal cycling led to significant decreases in both VH and FS and significant increases in SR. The findings of the current study indicate that composites differ significantly for SR and its mechanical properties with regard to FS and VH, as well as in aging behavior. Generally, artificial aging leads to a significant decrease in mechanical properties, which underlines the relevance of continuous improvement of dental composites.

Clin Oral Investig. 2010 Jul 20. [Epub ahead of print]

Marginal adaptation of a low-shrinkage silorane-based composite: 1-year randomized clinical trial.

Schmidt M, Kirkevang LL, Hørsted-Bindslev P, Poulsen S.

Department of Pediatric Dentistry, School of Dentistry, Faculty of Health Sciences, Arhus University, Vennelyst Boulevard 9, 8000, Arhus, Denmark, malene.schmidt@odontologi.au.dk.

Abstract

The aim of the present study was to examine the marginal adaptation of a new low-shrinkage silorane-based composite material (Filtek Silorane, 3M-Espe) by comparing it with a methacrylate-based composite material (CeramX, Dentsply DeTrey). In particular, we wanted to test the hypothesis that reduced polymerization shrinkage would improve the marginal adaptation. Seventy-two patients participated in the study. A total of 158 restorations were placed in 80 premolars and 78 molars. Only Class II restorations were included, and each patient could contribute with more than one tooth. The restorations were scored at baseline and after one year. While statistical comparison of marginal adaptation at follow-up indicated better performance of CeramX both occlusally and approximally (p = 0.01 and p < 0.01), the low kappa value (32%) reflects the difficulty to assess marginal adaptation clinically. The reduction in polymerization shrinkage demonstrated in the laboratory was not clinically significant in the present study.

J Dent. 2010 Jun 18. [Epub ahead of print]

Colour and translucency in silorane-based resin composite compared to universal and nanofilled composites.

Pérez MM, Ghinea R, Ugarte-Alván LI, Pulgar R, Paravina RD.

Department of Optics, Faculty of Science, University of Granada, Campus Fuentenueva s/n 18071, Granada, Spain.

Abstract

OBJECTIVES: The purpose of this study was to determine the optical properties, colour and translucency, of the new silorane-based resin composite and to compare it to universal dimethacrylate-based composites. METHODS: Six dimethacrylate-based resin composites and one silorane-based resin composite (all A2 shade) were studied. Colour of non-polymerized and polymerized composites was measured against white and black backgrounds using a spectroradiometer. Changes in colour (DeltaE*(ab)), translucency (DeltaTP) and colour coordinates (DeltaL*, Deltaa* and Deltab*) were calculated for each resin composite. Results were evaluated using a one-way ANOVA, a Tukey’s test and a t-test. RESULTS: The polymerization-dependent DeltaE*(ab) ranged from 4.7 to 9.1, with the smallest difference for the silorane-based resin composite. The colour changes of silorane-based composite were due to the changes of coordinates Deltaa* and Deltab*. However, for the dimethacrylate-based composites, the colour changes mainly originated by DeltaL*and Deltab*. The silorane composite exhibited the smallest TP values. Tukey’s test confirmed significant statistical differences (p<0.05) between mean TP values of Filtek Silorane and each brand of dimethacrylate-based composites before and after polymerization. CONCLUSIONS: The new silorane-based restorative system showed different optical properties compared to clinically successful dimethacrylate composites. The silorane composite exhibited better polymerization-dependent chromatic stability, and a lower translucency compared to other tested products. Copyright © 2010 Elsevier Ltd. All rights reserved.

Dent Mater. 2010 Jun 19. [Epub ahead of print]

Contraction stress of low-shrinkage composite materials assessed with different testing systems.

Marchesi G, Breschi L, Antoniolli F, Di Lenarda R, Ferracane J, Cadenaro M.

Department of Biomedicine, Unit of Dental Sciences and Biomaterials, University of Trieste, Trieste, Italy.

Abstract

OBJECTIVES: The contraction stress of a silorane-based material and a new low-shrinkage nanohybrid composite were compared to three conventional dimethacrylate-based resin composites using two different measuring systems. It was hypothesized that the silorane-based material and the low-shrinkage nanohybrid composite would exhibit lower contraction stress than dimethacrylate-based composites irrespective of measuring system. METHODS: The materials tested were Filtek Silorane LS (3M ESPE), Venus Diamond (Heraeus Kulzer), Tetric EvoCeram (Ivoclar Vivadent), Quixfil (Dentsply DeTrey), and Filtek Z250 (3M ESPE). Shrinkage stress was assessed using a stress-strain analyzer consisting of two opposing attachments, one connected to a load sensor and the other fixed to the device, or a system fixed to a universal testing machine with an extensometer as a feedback system. All specimens were light-cured with 20J/cm(2); the contraction force (N) generated during polymerization was continuously recorded for 300s. Contraction stress (MPa) was calculated at both 40s and 300s. Data were statistically analyzed by three-way ANOVA and Tukey’s post hoc test (alpha=0.05). RESULTS: Venus Diamond exhibited the lowest stress under both experimental conditions. Stress values scored as follows: Venus Diamond<Tetric EvoCeram<Filtek Silorane LS<Quixfil<Filtek Z250 (p<0.05). Stress values measured with the stress-strain analyzer were significantly lower than those measured with the universal testing machine with feedback. SIGNIFICANCE: The hypothesis was partially rejected because only Venus Diamond exhibited the lowest stress values among the tested materials. Contraction stress was higher for all composites when measured in a test system with a feedback. This study confirms that simply reducing the shrinkage does not ensure reduced stress development in composites. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Dent Mater. 2010 Apr;26(4):337-44. Epub 2010 Jan 6.

Physical properties of a new silorane-based restorative system.

Lien W, Vandewalle KS.

Advanced Education in General Dentistry Residency, Wilford Hall Medical Center, Lackland AFB, TX 78236, USA.

Abstract

OBJECTIVES: To distinguish the physical properties of a new silorane-based restorative material in comparison to five methacrylate-based restorative materials–a compomer, giomer, nanocomposite, hybrid and micro-hybrid. METHODS: The following properties were examined per restorative material: compressive strength, diametral tensile strength, flexural strength/modulus, fracture toughness, microhardness, and polymerization shrinkage. The mean and standard deviation were determined per group. A one-way ANOVA/Tukey was performed per property (alpha=0.05). RESULTS: Significant differences were found between groups per property (p<0.001). CONCLUSIONS: Compared to the methacrylate-based restorative materials, the new silorane-based material had the lowest polymerization shrinkage, but an overall mixed mechanical performance. The silorane-based material had relatively higher flexural strength/modulus, fracture toughness, but relatively lower compressive strength and microhardness than the methacrylate-based restorative materials. Published by Elsevier Ltd.

J Dent. 2010 Mar 9. [Epub ahead of print]

An in vitro evaluation of microtensile bond strengths of two adhesive bonding agents to residual dentine after caries removal using three excavation techniques.

Banerjee A, Kellow S, Mannocci F, Cook RJ, Watson TF.

King’s College London Dental Institute, KCL, United Kingdom.

Abstract

OBJECTIVES: To assess amounts of residual dentine retained after using three excavation techniques; the microtensile bond strengths (muTBS) to residual dentine, comparing etch-rinse vs. self-etching adhesives. METHODS: 42 carious molars were subdivided (N=21) dependent upon adhesive/composite system (Adper Scotchbond 1XT and Filtek Supreme vs. Filtek Silorane adhesive and composite). Dividing into three (N=7), dependent upon caries excavation technique employed (hand vs. chemo-mechanical: Carisolv gel vs. experimental enzymatic gel (SFC-V)), caries removal was assessed using visual/tactile criteria and in situ autofluorescence (AF) confocal fibre-optic micro-endoscopy (CFOME). Post-restoration/four-week hydrated storage, four 0.9mm(2) beams per tooth underwent muTBS testing/microscopic analysis of fractured surfaces. Three cavities from each excavation group were analysed using SEM. RESULTS: SEM revealed surface roughness with smear layer occluding tubule orifices in hand-excavated samples and a reduced, variable smear layer for both chemo-mechanical systems. CFOME AF assessment indicated hand excavation left sound dentine, Carisolv left affected dentine and SFC-V slightly under-prepared clinically. Mean muTBS values from etch-rinse samples (27MPa (SD 3.9), hand; 22MPa (SD 5.1), Carisolv; 26MPa (SD 4.4), SFC-V) showed statistical differences between hand and Carisolv groups. Mean muTBS data for self-etch samples (22MPa (SD 3.3), hand; 27MPa (SD 6.1), Carisolv; 25MPa (SD 4.7), SFC-V) showed significant differences between hand and Carisolv, and hand vs. SFC-V. Failure loci distribution in etch-rinse samples was between dentine-adhesive, within adhesive and within composite whereas self-etch samples exhibited failure predominantly between adhesive and composite. CONCLUSIONS: Data indicated that all null hypotheses were disproved. Copyright © 2010 Elsevier Ltd. All rights reserved.

Dent Mater. 2009 Dec;25(12):1509-16. Epub 2009 Aug 20.

Setting characteristics and cavity adaptation of low-shrinking resin composites.

Papadogiannis D, Kakaboura A, Palaghias G, Eliades G.

Department of Biomaterials, School of Dentistry, University of Athens, Greece. deminho@gmail.com

OBJECTIVES: The aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities. METHODS: The materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S(r)) and time at maximum strain rate (t(max)) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD(max)) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni’s post hoc test and Pearson’s correlation coefficient. RESULTS: The %S values ranged from 1.34% (FS) to 2.29% (CX), while %S(r) ranged from 0.06%s(-1) (FS) to 0.15%s(-1) (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S(r) and t(max) with %VVF (r(2)=0.884 and r(2)=0.927) and also for %S(r) and t(max) with %LD (r(2)=0.823 and r(2)=0.869). SIGNIFICANCE: %S(r) and t(max) are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.

Eur J Oral Sci. 2010 Feb;118(1):100-2.

Elution of substances from a silorane-based dental composite.

Kopperud HM, Schmidt M, Kleven IS.

Nordic Institute of Dental Materials (NIOM), Haslum, Norway. hilde.kopperud@niom.no

Previous studies have shown that residual monomers, initiators, and additives are eluted from methacrylate-based dental composite materials. Recently, a composite material (Filtek Silorane), based on a new resin chemistry, was introduced. The purpose of this study was to investigate substances eluted from Filtek Silorane in water and ethanol. Polymerized specimen discs of the material were immersed in either distilled water or 75 vol% ethanol at 37 degrees C, and the solutions were analyzed using liquid chromatography-mass spectrometry after 1, 4, 24, and 72 h eluting time. No substances were found to leach from Filtek Silorane in water, whereas silorane monomers and an initiator component were eluted from the material into the ethanol solution.

J Adhes Dent. 2010 Feb 12. doi: 10.3290/j.jad.a18395. [Epub ahead of print]

Microtensile Bond Strength Distributions of Three Composite Materials with Different Polymerization Shrinkages Bonded to Dentin.

Cabrera E, Macorra JC.

Purpose: To assess the detrimental effects that polymerization contraction causes on the interfacial microtensile bond strength (muTBS) to dentin of three light-curing resin composites: two conventional bis-GMA-based composite resins (Filtek Z250, TPH Spectrum) and a low shrinkage material (Filtek Silorane [SIL]). Materials and Methods: Flat surfaces of labial dentin were made in 46 bovine teeth and restored in single (group A) or in three separate (group B) one-increment visible-light cured resin composite blocks, with similar locations among teeth. After 24 h, restored teeth were sectioned perpendicular to interfaces, producing rectangular compound specimens (385 specimens were produced in group A, and 132 in group B), and submitted to tension (crosshead speed 1mm/min) until failure. muTBS results were adjusted to bonded area and transformed to percentages of maximum values within each tooth (PTens). In A groups, distances of specimens to the gingival ends of each restoration were transformed to PDistances: the percentage of that distance within its specimen. Results: Spearman’s nonparametric correlation test showed that for Z250, TPH and SIL, in A groups, a material’s correlation coefficient was positive for the first half of restorations (0% to 50% PDistances) and negative for the second (50% to 100%). For all materials, PTens values in extremes of restorations (pooled 0 and 100% PDistances) in A groups were smaller than corresponding values in B groups. These differences were statistically significantly (Student’s t-test) only for Z250 and TPH. Conclusion: Even in cases of favorable configuration factor, polymerization shrinkage in large restorations can reduce interface mechanical characteristics. The relevance of this decrease has still to be established.

J Oral Rehabil. 2010 Feb 19. [Epub ahead of print]

Investigating filler morphology and mechanical properties of new low-shrinkage resin composite types.

Leprince J, Palin WM, Mullier T, Devaux J, Vreven J, Leloup G.

School of Dentistry and Stomatology, Université catholique de Louvain, Brussels.

Summary Three types of low-shrinkage composites are today commercially available: Ormocers, cationic ring-opening curing systems and highly filled methacrylate-based materials, which cure via free-radical polymerization mechanisms. The aim of this study was to characterize the inorganic fraction of materials belonging to each type and to compare their mechanical properties. Two Ormocers (Admira and an experimental Ormocer V35694), one ring-opening composite (Filtek Silorane) and five methacrylate-based composites [Filtek Supreme XT, Tetric EvoCeram, Grandio, Synergy D6 (Coltène-Whaledent, Langenau, Germany) and an experimental material, V34930] were tested. Inorganic fillers were quantified by thermogravimetric analysis and morphologically characterized by scanning electron microscopy. Dynamic modulus was determined by an impulse excitation technique, static elastic moduli and flexural strength by a three-point bending method. The results were analyzed using anova tests (P < 0.05) and linear correlations. Grandio, V34930 and V35694 exhibited significantly higher filler mass fractions. Both dynamic and static moduli of Grandio and V34930 were significantly higher than the other materials (P < 0.05), although no significant difference in flexural strength was observed between material type (P > 0.05). From the present findings, it was suggested that V35694 and Filtek Silorane exhibit comparable properties to conventional methacrylate-based composites, although clinically the cavity type and location must guide material choice. Under high occlusal load, the use of Grandio and V34930 might be favoured. For small cavities, alternative technologies could be preferred as the need for mechanical resistance is lower and the potential for stress generation is greater.

Dent Mater. 2010 Mar 2. [Epub ahead of print]

TEM characterization of a silorane composite bonded to enamel/dentin.

Mine A, De Munck J, Van Ende A, Cardoso MV, Kuboki T, Yoshida Y, Van Meerbeek B.

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

OBJECTIVES: The low-shrinking composite composed of combined siloxane-oxirane technology (Filtek Silorane, 3M ESPE, Seefeld, Germany) required the development of a specific adhesive (Silorane System Adhesive, 3M ESPE), in particular because of the high hydrophobicity of the silorane composite. The purpose of this study was to characterize the interfacial ultra-structure at enamel and dentin using transmission electron microscopy (TEM). METHODS: Non-demineralized/demineralized 70-90nm sections were prepared following common TEM specimen processing procedures. RESULTS: TEM revealed a typical twofold build-up of the adhesive resin, resulting in a total adhesive layer thickness of 10-20mum. At bur-cut enamel, a tight interface without distinct dissolution of hydroxyapatite was observed. At bur-cut dentin, a relatively thin hybrid layer of maximum a few hundreds of nanometer was formed without clear surface demineralization. No clear resin tags were formed. At fractured dentin, the interaction appeared very superficial (100-200nm). Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a varying pattern of both spot- and cluster-like appearance of nano-leakage. Traces of Ag were typically detected along some part of the enamel-adhesive interface and/or between the two adhesive resin layers. Substantially more Ag-infiltration was observed along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. CONCLUSIONS: The nano-interaction of Silorane System Adhesive should be attributed to its relatively high pH of 2.7. The obtained tight interface at both enamel and dentin indicates that the two-step self-etch adhesive effectively bridged the hydrophilic tooth substrate with the hydrophobic silorane composite. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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.

Dent Mater. 2009 Nov 9. [Epub ahead of print]

Does a low-shrinking composite induce less stress at the adhesive interface?

Van Ende A, De Munck J, Mine A, Lambrechts P, Van Meerbeek B.

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.

Int J Artif Organs. 2009 Oct 31;32(9):671-677.

Adhesion of Streptococcus mutans to different restorative materials.

Poggio C, Arciola CR, Rosti F, Scribante A, Saino E, Visai L.

Department of Operative Dentistry, University of Pavia – Italy.

Adherence of oral bacteria to the surface of dental restorative materials is considered an important step in the development of secondary caries and periodontal disease. The aim of this study was to investigate and compare the adherence of different restorative materials to Streptococcus mutans strain (CCUG35176) in order to ascertain possible differences. The materials tested ranged across different classes including: flowable composites (Gradia Direct LoFlo; Filtek Supreme XT Flowable), anterior composites (Gradia Direct Anterior), universal composites (Filtek Supreme XT), packable composites (Filtek Silorane; Filtek P60), glass-ionomers (Fuji IX Gp Extra; Equia) and a control reference material (Thermanox plastic coverlips). Bacterial suspension was deposited onto each material and the adhesion was evaluated trough the colony forming units (CFUs) determination. Packable silorane-based composite was found to be less adhesive than posterior packable composite P60, flowable composites and glass ionomers. The fluoride of glass ionomers did not prevent the attachment of S. mutans; furthermore, after roughness analysis and SEM investigations, the hypothesis that the difference in bacterial adhesion can be determined by the particular surface chemistry of the material itself as well as by different electrostatic forces between bacteria and restorative surfaces must be given serious consideration.

Oper Dent. 2009 Sep-Oct;34(5):578-85.

Comparing microleakage and the layering methods of silorane-based resin composite in wide Class II MOD cavities.

Bagis YH, Baltacioglu IH, Kahyaogullari S.

Ankara University, Operative Dentistry, Besevler, Ankara, Turkey. bagis@dentistry.ankara.edu.tr

OBJECTIVE: This in vitro study compared the effects of different layering techniques and different monomer-based composites on microleakage. METHOD AND MATERIALS: Thirty-two freshly extracted caries-free human third molars were used. A wide mesio-occlusal-distal (MOD) cavity was prepared in each third molar, with the occlusal dimension being approximately two-thirds of the intercuspal dimension, and the cervical limit of one proximal box was stopped 1 mm below and the other 1 mm above the cementoenamel junction. The cavities were filled with a methacrylate-based nanohybrid composite (Grandio, VoCo) and a silorane-based microhybrid composite (Filtek Silorane, 3M ESPE). All samples were subjected to 1000 thermal cycles of 5 degrees C/55 degrees C in water with a 30-second dwell time and, after the procedure, the teeth were immersed in a 0.5% basic fuchsin dye at 23 degrees C for 24 hours. Sectioned samples were examined under a stereomicroscope (Leica MZ12, Leica Microsystems), and microleakage scores were statistically analyzed using the Kruskal-Wallis and the Mann-Whitney U tests. RESULTS: No microleakage was observed for silorane-based resin composite restorations. The nanohybrid-based resin composite restorations showed different levels of leakage. Statistical analysis of microleakage scores showed differences only at the enamel margins for nanohybrid material for both layering techniques (p < 0.05). The nanohybrid-based resin composite restorations showed better results with the vertical layering technique for enamel margins.

J Esthet Restor Dent. 2009;21(2):122-31.

Comment in:

J Esthet Restor Dent. 2009;21(2):132.

Temperature changes in silorane-, ormocer-, and dimethacrylate-based composites and pulp chamber roof during light-curing.

Miletic V, Ivanovic V, Dzeletovic B, Lezaja M.

Edinburgh Postgraduate Dental Institute, The University of Edinburgh, Lauriston Place, Edinburgh, UK. vesna.miletic@gmail.com

STATEMENT OF THE PROBLEM: Light-curing of resin-based composites (RBCs) is associated with temperature increase in the pulp chamber, which may have a detrimental effect on the vital pulp. PURPOSE: The purpose of the study was to evaluate temperature changes of silorane-, ormocer-, and dimethacrylate-based RBCs at the bottom surface of the RBC and in the pulp chamber roof dentin (PCRD) during curing. MATERIALS AND METHODS: In part A, temperatures were measured for Filtek LS (3M ESPE, St. Paul, MN, USA), Admira (Voco GmbH, Cuxhaven, Germany), and Herculite XRV (Kerr Corp., Orange, CA, USA) with a high-power light-emitting diode (LED) unit by placing thermocouples in contact with the bottom surface of the material in standardized acrylic molds. In part B, temperature changes in PCRD were measured in extracted molars during light-curing of adhesives and RBCs in 2-mm-deep cavities with a remaining dentin thickness (RDT) of 1 mm. RESULTS: Filtek LS showed a different temperature curve compared with Admira and Herculite XRV. Significantly higher temperatures were recorded for Filtek LS (p < 0.001) than for Admira and Herculite XRV in acrylic molds. Temperature rises recorded in PCRD for adhesives and RBCs were between 4.1 and 6.4 degrees C. No significant differences in PCRD temperatures were found between the three groups during adhesive curing and RBC curing (p > 0.05). CONCLUSIONS: Filtek LS showed a different heat-generation pattern from and significantly higher temperatures than Admira and Herculite XRV when the materials were tested in acrylic molds. Similar temperatures were recorded in the PCRD during curing of adhesives and RBCs. CLINICAL SIGNIFICANCE: Although a substantial temperature rise in the bulk material occurred during light-curing of the three resin-based composites, a remaining dentin thickness of 1 mm caused a significant reduction in pulp chamber roof dentin temperatures. Temperatures measured in the pulp chamber roof dentin corresponding to the zone occupied by the postmitotic odontoblast layer were not statistically different for the three types of resin-based composites.

J Dent. 2009 Jul 24.

Erosion and abrasion of tooth-colored restorative materials and human enamel.

Yu H, Wegehaupt FJ, Wiegand A, Roos M, Attin T, Buchalla W.

Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zurich, Plattenstrasse 11, Zurich 8032, Switzerland.

OBJECTIVES: The aim of this study was to investigate the effects of erosion and toothbrush abrasion on different restorative materials and human enamel. METHODS: Human enamel and 5 kinds of tooth-colored restorative materials were used. The restorative materials included three composite resins (Filtek Silorane, Tetric EvoCeram, and Tetric EvoFlow), a polyacid-modified composite (Dyract Extra), and a conventional glass-ionomer cement (Ketac Fil Plus). For each type of the material, 40 specimens were prepared and embedded in ceramic moulds and divided into four groups (n=10): control group (C), erosion group (E), abrasion group (A), and erosion-abrasion group (EA). The specimens were subjected to six daily erosive attacks (groups E and EA; citric acid, pH 2.3, 1min) and/or six abrasive attacks (groups A and EA; toothbrush abrasion, 100 strokes, 1min), while the control specimens (group C) were maintained in artificial saliva. After 10-day treatment, the substance loss and surface changes were determined by surface profilometry and scanning electron microscopy. RESULTS: Human enamel presented higher substance loss when compared to restorative materials. Generally, combined erosion-abrasion (EA) caused the highest substance loss, followed by erosion, abrasion, and storage in artificial saliva. Composite resin presented highest durability under erosive and/or abrasive attacks. Enamel and restorative materials showed degradation in groups E and EA through SEM observation. CONCLUSIONS: Toothbrush abrasion has a synergistic effect with erosion on substance loss of human enamel, polyacid-modified composite and glass-ionomer cement. The acid- and abrasive-resistance of human enamel was lower compared to restorative materials.

Dent Mater J. 2009 May;28(3):362-7.

Effects of food-simulating liquids on the mechanical properties of a silorane-based dental composite.

Yesilyurt C, Yoldas O, Altintas SH, Kusgoz A.

Department of Operative Dentistry, Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey. cyesilyurt@ktu.edu.tr

The purpose of this study was to investigate the effects of food-simulating liquids (FSL) on the hardness and flexural strength (FS) of a new silorane-based composite and to compare it with methacrylate-based composites (MBCs). Four restorative materials (Filtek Silorane, P60, Z250, and Supreme XT) were used. Specimens for the FS and hardness measurements were fabricated in customized molds. Immediately after polymerization, the materials were stored in the following dietary simulating solvents at 37 degrees C for 1 week: distilled water, 0.02 N citric acid, heptane, and 75% aqueous ethanol solution. After conditioning, the FS and hardness values were measured. Data were subjected to ANOVA/Scheffé’s test at a significance level of 0.05. The hardness and FS of Filtek Silorane were not significantly affected by FSL (p>0.05). Conversely, the hardness of MBCs significantly decreased after conditioning in water and ethanol (p<0.05). Similarly, the FS values of MBCs were significantly affected after conditioning in ethanol.

Dent Mater. 2009 May;25(5):589-600. Epub 2008 Dec 20.

Nanoleakage, ultramorphological characteristics, and microtensile bond strengths of a new low-shrinkage composite to dentin after artificial aging.

Duarte S Jr, Phark JH, Varjão FM, Sadan A.

Department of Comprehensive Care, Case Western Reserve University, School of Dental Medicine, 10900 Euclid Avenue, Cleveland, OH 44106-4905, USA. sillas.duarte@case.edu

OBJECTIVES: To study the microtensile bond strengths and nanoleakage of low-shrinkage composite to dentin. The null hypotheses tested were (1) aging does not affect the bonding of low-shrinkage composite; (2) there is no difference in microtensile bond strengths and nanoleakage using different bonding strategies. METHODS: 32 extracted molars were assigned to one of four groups: LS System Adhesive (LS, 3M ESPE); dentin etched for 15s with phosphoric acid+LS System Adhesive (LSpa); Adper Single Bond Plus (SB, 3M ESPE); SB+LS Bond (SBLS). Occlusal dentin was exposed and restored with Filtek LS (3M ESPE). The samples were tested after 24h or after 20,000 thermocycles and 6 months of aging. Teeth were sectioned with a cross-section of 0.8+/-0.2mm(2) and fractured at a crosshead speed of 1mm/min. The data were submitted to ANOVA/Duncan’s post hoc test, at p<0.05. Five slabs from each group were selected and immersed in 50wt% ammoniacal silver nitrate. Then, specimens were processed for SEM, the silver penetration was measured and data analyzed with Kruskal-Wallis at p<0.05. RESULTS: No statistically significant difference was found among the experimental groups for the factor dentin treatment (p=0.165) and aging (p=0.091). All experimental groups exhibit some degree of nanoleakage. There was no adhesion of Filtek LS applied directly over dentin surfaces treated with SB. SIGNIFICANCE: The new low-shrinkage resin composite showed compatibility only with its dedicated adhesive. Pre-etching did not improve the bond strengths to low-shrinkage resin composite. Some degree of nanoleakage was evident in all groups.

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.

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.

Dent Mater. 2009 Jul 10.

Oxygen inhibition and incremental layer bond strengths of resin composites.

Shawkat ES, Shortall AC, Addison O, Palin WM.

Biomaterials Unit, School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, St Chads Queensway, Birmingham B4 6NN, UK.

OBJECTIVES: When dentists light cure resin composite restorations in increments or after contouring the surface layer to shape with a hand instrument the surface layer is exposed to air during polymerization. The presence of an oxygen inhibited resin surface layer may impact on clinical performance. Conflicting data has been produced in vitro regarding this topic. METHODS: To shed further light on this subject the current investigation assessed the thickness of the oxygen inhibited layer (OIL) and subsequent interfacial bond strength at various times post-cure of an “initial increment” for a range of experimental and commercial resin composites. The latter included conventional methacrylate-based composites and a novel low shrink Silorane resin chemistry product. RESULTS: A decrease in composite viscosity brought about by an increase in diluent monomer content in the matrix for the experimental composite formulations led to increase in OIL thickness. The OIL surface layer thickness for the commercial methacrylate-based RBC specimens cured in air were 19.2+/-6.3 and 13.8+/-5.3mum, respectively and 9.0+/-6.6mum for Silorane. No test material exhibited a measurable OIL thickness polymerized in the nitrogen atmosphere. SIGNIFICANCE: From the current findings it may be concluded that incremental bond strength is not wholly reliant on surface inhibition since no differences in bond strength following immediate placement were observed between air and nitrogen atmosphere for any experimental or commercial material. For large restorations requiring multiple increments which are placed on fresh material, the bond strength between successive layers of Silorane should be no different to conventional methacrylate materials. Repair and bonding to aged Silorane restorations may be more problematic as inferior incremental bond strengths ensued when addition was delayed.

Temperature changes in silorane-, ormocer-, and dimethacrylate-based composites and pulp chamber roof during light-curing.

Miletic V, Ivanovic V, Dzeletovic B, Lezaja M.

Edinburgh Postgraduate Dental Institute, The University of Edinburgh, Lauriston Place, Edinburgh, UK. vesna.miletic@gmail.com

STATEMENT OF THE PROBLEM: Light-curing of resin-based composites (RBCs) is associated with temperature increase in the pulp chamber, which may have a detrimental effect on the vital pulp. PURPOSE: The purpose of the study was to evaluate temperature changes of silorane-, ormocer-, and dimethacrylate-based RBCs at the bottom surface of the RBC and in the pulp chamber roof dentin (PCRD) during curing. MATERIALS AND METHODS: In part A, temperatures were measured for Filtek LS (3M ESPE, St. Paul, MN, USA), Admira (Voco GmbH, Cuxhaven, Germany), and Herculite XRV (Kerr Corp., Orange, CA, USA) with a high-power light-emitting diode (LED) unit by placing thermocouples in contact with the bottom surface of the material in standardized acrylic molds. In part B, temperature changes in PCRD were measured in extracted molars during light-curing of adhesives and RBCs in 2-mm-deep cavities with a remaining dentin thickness (RDT) of 1 mm. RESULTS: Filtek LS showed a different temperature curve compared with Admira and Herculite XRV. Significantly higher temperatures were recorded for Filtek LS (p < 0.001) than for Admira and Herculite XRV in acrylic molds. Temperature rises recorded in PCRD for adhesives and RBCs were between 4.1 and 6.4 degrees C. No significant differences in PCRD temperatures were found between the three groups during adhesive curing and RBC curing (p > 0.05). CONCLUSIONS: Filtek LS showed a different heat-generation pattern from and significantly higher temperatures than Admira and Herculite XRV when the materials were tested in acrylic molds. Similar temperatures were recorded in the PCRD during curing of adhesives and RBCs. CLINICAL SIGNIFICANCE: Although a substantial temperature rise in the bulk material occurred during light-curing of the three resin-based composites, a remaining dentin thickness of 1 mm caused a significant reduction in pulp chamber roof dentin temperatures. Temperatures measured in the pulp chamber roof dentin corresponding to the zone occupied by the postmitotic odontoblast layer were not statistically different for the three types of resin-based composites.

Comparison of the hybrid layer formed by Silorane adhesive, one-step self-etch and etch and rinse systems using confocal micro-Raman spectroscopy and SEM.

Santini A, Miletic V.

The University of Edinburgh, Postgraduate Dental Institute, Lauriston Building (4th floor), Lauriston Place, Edinburgh EH3 9HA, United Kingdom. ariosantini@hotmail.com

OBJECTIVES: To determine the extent of the hybrid layer (HL) of the novel adhesive system (Silorane, 3M ESPE) compared to one-step and etch and rinse adhesive systems, using 2D confocal micro-Raman spectroscopy and SEM. METHODS: Silorane adhesive system was compared to two one-step self-etch (G Bond, GC; AdheSE One, Ivoclar Vivadent) and etch and rinse (Excite, Ivoclar Vivadent) as controls. Adhesives were applied to human dentine, cured and sections prepared perpendicular to the flat adhesive-dentine surface. Two-dimensional micro-Raman mapping was performed over 20mumx20mum areas across the adhesive-dentine interface. SEM micrographs of the same specimens were obtained. One-way ANOVA (Tukey’s post-test) was used to analyse the differences in HL thickness among the four adhesive systems and the paired t-test to compare the results obtained by micro-Raman and SEM for each adhesive. RESULTS: Silorane adhesive system formed a HL of comparable thickness to methacrylate-based but thicker than the acrylamide-based one-step self-etch adhesives from SEM analysis. A gradual decrease in adhesive penetration was observed in all systems. A 1-mum zone, between the cured primer and bond was identified by Raman but not visualised on SEM. Compared to SEM, HL calculated from Raman data were always greater. CONCLUSIONS: Micro-Raman spectroscopy gives a more precise indication of dentine demineralisation and monomer infiltration and highlights the intermediate zone of approximately 1mum between Silorane primer and bond, not visible with SEM at x10,000 magnification. Giving as it does, a compilation of many linear scans it allows HL mean values to be calculated.Clin Oral Investig. 2008 Sep 23. [Epub ahead of print]

Candida albicans adhesion to composite resin materials.

Bürgers R, Schneider-Brachert W, Rosentritt M, Handel G, Hahnel S.

Department of Prosthetic Dentistry, Regensburg University Medical Centre, Franz-Josef-Strauss-Allee, 93042, Regensburg, Germany, ralf.buergers@klinik.uni-regensburg.de.

The adhesion of Candida albicans to dental restorative materials in the human oral cavity may promote the occurrence of oral candidosis. This study aimed to compare the susceptibility of 14 commonly used composite resin materials (two compomers, one ormocer, one novel silorane, and ten conventional hybrid composites) to adhere Candida albicans. Differences in the amount of adhering fungi should be related to surface roughness, hydrophobicity, and the type of matrix. Cylindrical specimens of each material were made according to the manufacturers’ instructions. Surface roughness R (a) was assessed by perthometer measurements and the degree of hydrophobicity by computerized contact angle analysis. Specimens were incubated with a reference strain of C. albicans (DMSZ 1386), and adhering fungi were quantified by using a bioluminometric assay in combination with an automated plate reader. Statistical differences were analyzed by the Kruskal-Wallis test and Mann-Whitney U test. Spearman’s rank correlation coefficients were calculated to assess correlations. Median R (a) of the tested composite resin materials ranged between 0.04 and 0.23 mum, median contact angles between 69.2 degrees and 86.9 degrees . The two compomers and the ormocer showed lower luminescence intensities indicating less adhesion of fungi than all tested conventional hybrid composites. No conclusive correlation was found between surface roughness, hydrophobicity, and the amount of adhering C. albicans.

J Dent. 2008 Sep 6.

Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging.
Furuse AY, Gordon K, Rodrigues FP, Silikas N, Watts DC.

Biomaterials Science Research Group, School of Dentistry, The University of Manchester, Manchester, United Kingdom; Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.

OBJECTIVES: To evaluate the colour-stability and gloss-retention of silorane versus dimethacrylate composites exposed to accelerated aging from daylight radiation. METHODS: Five disc-shaped specimens of photo-cured resin-composites were prepared and manually polished for each material (Filtek Silorane, Herculite XRV, Tetric Evoceram and QuiXfil). Colour and gloss were evaluated before and after periods (baseline, 24, 72, 120 and 192h) of accelerated photo-aging in xenon light following ISO 7491:2000. Colour measurements were performed with a colourimeter according to the CIE-Lab colour-space. The colour change (DeltaE) for each time was calculated. The surface gloss was measured using a glossmeter. Results were evaluated using one-way ANOVA and Tukey tests (alpha=0.05). Correlations between logtime, DeltaE and gloss were evaluated using Pearson’s correlation (alpha=0.05). RESULTS: Materials generally decreased in L* and a* and increased in b*. The strong exception was Filtek Silorane which maintained a* and b*. DeltaE was found to be a positive linear function of logtime for all materials. Materials varied in the magnitude and rate of increase of DeltaE with logtime: QuiXfil>Tetric EvoCeram>(Filtek Silorane>/=Herculite XRV). DeltaE remained<3.3 for Filtek Silorane and Herculite XRV. Gloss was found to be a negative linear function of logtime. Gloss was maximal in the sequence: Filtek Silorane approximately Tetric EvoCeram>Herculite XRV>QuiXfil. CONCLUSIONS: Silorane gave the best overall performance in stability over time, compared to a set of representative dimethacrylate composites.

Dent Mater. 2008 Sep 1.

J Dent. 2008 Jul;36(7):560-3. Epub 2008 May 7.

Incremental layers bonding of silorane composite: The initial bonding properties.
Tezvergil-Mutluay A, Lassila LV, Vallittu PK.
Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku, LemminkŠisenkatu 2, FIN-20520 Turku, Finland.

OBJECTIVES: Lack of oxygen inhibition layer of silorane composite with cationic polymerization raises the question of the bonding of incremental layers of the composite. This study aimed to evaluate the bond strength of the silorane composite layers. METHODS: Fresh, 20s, 5min aged silorane composite (Silorane, -ESPE) used as substrate to adhere new silorane composite. For a comparison, dimethacrylate-based composite resin (Z250, 3M-ESPE) was adhered to the silorane composite with or without intermediate adhesive resin. As a control, dimethacrylate composite with oxygen inhibition layer was attached to fresh dimethacrylate composite. The bonded specimens (n=12/group) were water stored for 24h. The shear bond strengths (SBS) were measured with a crosshead speed of 1.0mm/min. Failure modes were assessed. Data were analysed by ANOVA, Tukey’s post hoc tests and Chi-square tests (p=0.05). RESULTS: Dimethacrylate-dimethacrylate composite resin combination showed the highest mean SBS (33.0MPa) values with no adhesive failures. Fresh silorane-silorane SBS was slightly lower (26.7MPa) and was further decreased by aging the substrate for 20s (25.4MPa) and 5min (22.4MPa). The percent of adhesive failures increased from 25% to 75%, respectively. The failure modes were significantly different (Chi-square, p<0.001). Silorane-dimethacrylate composite showed the lowest (4.0MPa) SBS among the groups, which was increased significantly by use of phosphate-methacrylate-based intermediate resin (p<0.05). CONCLUSION: In order to bond dimethacrylate composite to silorane composite, a phosphate-methacrylate-based intermediate resin is required. The silorane composite showed slightly lower incremental bonding properties than conventional dimethacrylate composites.

J Dent. 2008 Jun 10.

Comparison of the hybrid layer formed by Silorane adhesive, one-step self-etch and etch and rinse systems using confocal micro-Raman spectroscopy and SEM.

Santini A, Miletic V.
The University of Edinburgh, Postgraduate Dental Institute, Lauriston Building (4th floor), Lauriston Place, Edinburgh EH3 9HA, United Kingdom.

OBJECTIVES: To determine the extent of the hybrid layer (HL) of the novel adhesive system (Silorane, 3M ESPE) compared to one-step and etch and rinse adhesive systems, using 2D confocal micro-Raman spectroscopy and SEM. METHODS: Silorane adhesive system was compared to two one-step self-etch (G Bond, GC; AdheSE One, Ivoclar Vivadent) and etch and rinse (Excite, Ivoclar Vivadent) as controls. Adhesives were applied to human dentine, cured and sections prepared perpendicular to the flat adhesive-dentine surface. Two-dimensional micro-Raman mapping was performed over 20mumx20mum areas across the adhesive-dentine interface. SEM micrographs of the same specimens were obtained. One-way ANOVA (Tukey’s post-test) was used to analyse the differences in HL thickness among the four adhesive systems and the paired t-test to compare the results obtained by micro-Raman and SEM for each adhesive. RESULTS: Silorane adhesive system formed a HL of comparable thickness to methacrylate-based but thicker than the acrylamide-based one-step self-etch adhesives from SEM analysis. A gradual decrease in adhesive penetration was observed in all systems. A 1-mum zone, between the cured primer and bond was identified by Raman but not visualised on SEM. Compared to SEM, HL calculated from Raman data were always greater. CONCLUSIONS: Micro-Raman spectroscopy gives a more precise indication of dentine demineralisation and monomer infiltration and highlights the intermediate zone of approximately 1mum between Silorane primer and bond, not visible with SEM at x10,000 magnification. Giving as it does, a compilation of many linear scans it allows HL mean values to be calculated.

Dent Mater J. 2007 Mar;26(2):149-55.

Low-shrinkage composite for dental application.

Ilie N, Jelen E, Clementino-Luedemann T, Hickel R.
Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Munich, Germany. nicoleta.ilie@dent.med.uni-muenchen.de

In modern research, development of monomers that reduce shrinkage of composite materials remains an ongoing quest and perennial challenge. The purpose of this study, therefore, was to analyze the shrinkage behaviour of an innovative composite material for dental restorations based on a monomer with a new chemical formulation, known as silorane. To this end, shrinkage stress development during curing, gel point, and coefficient of near linear fit of contraction stress/time were evaluated after polymerizing the material with 10 different curing regimes. Shrinkage stress varied between 1.4 MPa after a 10-second curing in a pulsed regime to 4.4 MPa after curing for 40 seconds with a high energy curing unit, Bluephase. Pearson correlation analysis showed that with respect to the tested curing units, shrinkage stress correlated significantly with energy density (0.89), irradiance (0.70), curing time (0.51), coefficient of near linear fit of contraction (0.70), and gel point (-0.60). Silorane exhibited low shrinkage stress values in comparison to regular methacrylate composites. Nevertheless, stress due to thermal contraction when the light exposure ended was not negligible-but could be reduced by applying the appropriate curing strategy.

Dent Mater. 2007 Aug;23(8):1011-7. Epub 2006 Nov 9.

Properties of silorane-based dental resins and composites containing a stress-reducing monomer.

Eick JD, Kotha SP, Chappelow CC, Kilway KV, Giese GJ, Glaros AG, Pinzino CS.
Department of Oral Biology, University of Missouri-Kansas City, Kansas City, MO, USA. eickj@umkc.edu

OBJECTIVE: To evaluate properties of silorane-based resins and composites containing a stress reducing monomer. METHODS: Resin mixtures and composites were formulated containing (a) a developmental stress reducing monomer [TOSU; Midwest Research Institute]; (b) Sil-Mix (3M-ESPE); (c) photo cationic initiator system. Standard BISGMA/TEGDMA resin (B/T) and composite (Filtek Z250) were used as controls. Polymerization volume change was measured using a NIST mercury dilatometer and polymerization stress using an Enduratec mechanical testing machine. Three point bend tests determined flexural elastic modulus, work of fracture, and ultimate strength (ADA 27; ISO 4049). Fracture toughness was measured using ASTM E399-90. Four groups of resins and composites were tested: Sil-Mix, methacrylate standard, and Sil-Mix with two addition levels of TOSU. An ANOVA was used and significant differences ranked using Student-Newman-Keuls test (alpha=0.05). RESULTS: Polymerization stress values for resins containing TOSU were significantly less than the other materials. Polymerization shrinkage values for Sil-Mix formulations were significantly less than for B/T, but were not different from each other. TOSU-containing formulations generally had somewhat lower mechanical properties values than Sil-Mix or B/T. Polymerization stress values for Sil-Mix-based composites were significantly less as compared to Z250. The 1wt.% TOSU composite had the lowest stress. No difference between composite groups was noted for fracture toughness or work of fracture. For ultimate strength, the 5wt.% TOSU formulation differed significantly from Z250. All Sil-Mix formulations had elastic modulus values significantly different from Z250. SIGNIFICANCE: The ability of TOSU to reduce polymerization stress without a proportional reduction in mechanical properties provides a basis for improvement of silorane-based composites.

Dent Mater J. 2006 Sep;25(3):445-54.

Silorane-based dental composite: behavior and abilities.

Ilie N, Hickel R.
Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Munich, Germany. nicoleta.ilie@dent.med.uni-muenchen.de

The purpose of this study was to examine the characteristics of an innovative composite material for dental restorations based on silorane–a monomer with a new chemical composition, and thereby compare the examined characteristics against those of well-known methacrylate-based composites. Degree of conversion at 2-mm and 6-mm depths as well as hardness, modulus of elasticity, and creep resistance through the middle of 6-mm high samples were measured. It was observed that up to 20 minutes after curing, curing time–and not irradiance–played the determinant role for a high degree of cure. No differences were registered between the two categories of material in terms of hardness. However, modulus of elasticity of the silorane-based material was slightly lower and the creep resistance higher than a methacrylate composite (Tetric EvoCeram). In conclusion, siloranes exhibited good mechanical properties comparable to those of clinically successful methacrylate-based composite materials.

J Dent. 2006 Jul;34(6):405-10. Epub 2005 Nov 9.

Stability of silorane dental monomers in aqueous systems.

Eick JD, Smith RE, Pinzino CS, Kostoryz EL.
University of Missouri-Kansas City, School of Dentistry, Kansas City, MO 64108, USA.

Siloranes (silicon-based monomers with oxirane functionality) are investigated as matrix resins for new low shrinkage/stress dental composites. Compounds containing oxirane groups are known to be reactive with water, which could impart instability to the composite. OBJECTIVE: To test the stability of siloranes by measuring changes in the chemical structure of the oxirane group in aqueous environments. METHODS: Two siloranes (PH-SIL and TET-SIL) and their 1:1 mixture (SIL-MIX) were evaluated (n=2-3). Siloranes were mixed in aqueous solutions with and without 1% tetrahydrofuran (THF) containing either liver esterase or epoxide hydrolase at pH 7.4, or dilute HCl at pH 1.4. The stability of conventional dioxiranes 3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexane carboxylate (ECHM-ECHC), and bisphenol A diglycidyl ether (BADGE) were also monitored under similar conditions. NMR was used to estimate the extent of reaction and give structural information about reaction products. RESULTS: Siloranes were found to be stable for 24h in all aqueous environments tested. In contrast, ECHM-ECHC reacted at pH 1.4 to form species containing oxirane, ester, hydroxyl and carboxylic acid groups. Water hydrolyzed the ester group of ECHM-ECHC in the presence of liver esterase. In the presence of epoxide hydrolase, BADGE oxirane groups were hydrolyzed to diols, hydrolysis ranged from 0 to 34% depending on the aqueous environment. CONCLUSION: The stability and insolubility of siloranes in biological fluid simulants suggests that these may be more suitable for use in the oral environment than conventional oxirane-functional monomers.

Dent Mater. 2005 Sep;21(9):852-63.

The influence of short and medium-term water immersion on the hydrolytic stability of novel low-shrink dental composites.

Palin WM, Fleming GJ, Burke FJ, Marquis PM, Randall RC.
Biomaterials Unit, School of Dentistry, University of Birmingham, St Chad’s Queensway, Birmingham B4 6NN, UK. w.m.palin@bham.ac.uk

OBJECTIVES: Differences in mechanical and physical properties exhibited by novel low-shrink resin-based composite (RBC) formulations compared with conventional methacrylate RBCs may contribute to the clinical success of the candidate material. The aim of the current study was to investigate the effect of water uptake characteristics and water solubility on the mechanical properties of two methacrylate (Z100 and Filtek Z250), an experimental oxirane (OXI) and silorane (SIL) RBC following short- and medium-term immersion. METHODS: The water sorption/solubility and associated diffusion coefficients of each material (n=5) were measured using gravimetric analysis following short- (0.1, 0.5, 1, 4, 24 and 48 h) and medium-term (1, 4, 12 and 26w) immersion. The bi-axial flexure strength, associated Weibull moduli (n=20) and fracture analysis using scanning electron microscopy (SEM) of each material for similar immersion periods was also investigated. RESULTS: Following 0.5h and each subsequent short- and medium-term immersion period the water sorption of Z100 and Filtek Z250 was decreased compared with OXI. A significant decrease in bi-axial flexure strength and associated increase in filler particle exfoliation identified through SEM was identified for OXI compared with Z100, Filtek Z250 and SIL following 26w immersion. SIL exhibited the significantly lowest water sorption, solubility and associated diffusion coefficient following each immersion period. SIGNIFICANCE: The increase in water sorption, solubility and the associated diffusion coefficient of the experimental oxirane RBC, OXI was manifested as a significant decrease in bi-axial flexure strength and attributed to the decrease in synergy between the filler particles and resin matrix. The decreased water sorption, solubility and associated diffusion coefficient of the experimental silorane RBC, SIL may potentially improve hydrolytic stability of RBC restorations demonstrated by the non-significant decrease in bi-axial flexure strength following medium-term immersion.

Dent Mater. 2005 Jan;21(1):68-74.

Siloranes in dental composites.

Weinmann W, Thalacker C, Guggenberger R.
3M ESPE, Seefeld, Germany.

OBJECTIVE: The purpose of this study was to compare the product profile of a Silorane based composite which polymerizes by a cationic ring opening process with the product profile of different methacrylate based restoratives. METHODS: Four methacrylate based materials Filtek Z250, Filtek P60,Tetric ceram, Spectrum TPH and a Silorane based material were investigated with regard to their compressive strength, flexural strength, E-Modulus and ambient light stability. The data were analyzed by 1-way ANOVA and 2 sample t test (p<0.05). Shrinkage data were determined by the Archimedes method and the bonded disk method. The reactivity of the Silorane and Tetric ceram were derived from the time resolved shrinkage behaviour and the development of the E-Modulus over time. RESULTS: The Silorane Composite revealed with 0.94 vol% (bonded disk method) and 0.99 vol% (Archimedes method) the lowest polymerization shrinkage among all tested composites. Its reactivity was comparable to the reactivity of Tetric Ceram. However, the ambient light stability of >10 min for Silorane was higher than the ambient light reactivity of the other tested methacrylates (55-90 s). SIGNIFICANCE: The ring opening chemistry of the Siloranes enables at the first time shrinkage values lower than 1 vol% and mechanical parameters as E-Modulus and flexural strength comparable to those of clinically well accepted methacrylate based composites.

Am J Dent. 2000 Nov;13(Spec No):82D-84D.

Exploring beyond methacrylates.

Guggenberger R, Weinmann W.
ESPE Dental AG, Seefeld, Germany. Rainer.Guggenberger@ESPE.de

PURPOSE: This article focuses on the polymerization shrinkage of current dental composites as their major disadvantage and to find new routes for a solution. MATERIALS AND METHODS: A brief introduction describes selected methods for the shrinkage determination as well as some principal solutions to overcome the shrinkage problem. RESULTS: Siloranes, a new class of ring opening monomers, are presented as a promising resin matrix for dental composites. The synthesis of these monomers, and further consequences of the new chemistry for the formulation are discussed. Two selected silorane composites are presented with their mechanical data and their volume shrinkage.