Stability of silorane dental monomers in aqueous systems

Evaluation of Color Stability and Translucency of Different Composite Resins Exposed to Alcohol

BACKGROUND

As there is evidence showing the effects of alcohol on the surface properties of composite resins, it is of great importance to understand the effects of commonly consumed beverages on the discoloration of composite restorations in people who consume alcohol.

AIM

The aim of this study was to investigate the changes in the color and translucency of composite resins immersed in different beverages after exposure to alcohol.

METHODS

Disk-shaped samples from each composite resin (Filtek Z250 (Z250), Clearfil Majesty Esthetic (CME), and Esthelite Bulk Fill Flow (EBF), were prepared (n = 60) and randomly divided into two groups (exposed or unexposed to alcohol). The samples were immersed in distilled water, black tea, and coffee. The color parameter (∆E00) and translucency parameter (∆TP) were calculated after 24 h, 1 week, and 3 weeks. Four-way ANOVA and Tukey's post-hoc analysis were used for the statistical analysis (α = 0.05).

RESULTS

Alcohol significantly increased the discoloration of Z250 and EBF in black tea. The discoloration of CME was not affected by alcohol exposure. Z250 and EBF showed clinically unacceptable discoloration (ΔE00 > 2.25) after immersion in black tea and coffee, whereas CME showed clinically unacceptable discoloration after immersion in black tea. Black tea caused the greatest color change in all composite materials regardless of alcohol exposure. EBF showed the lowest ΔTP values (∆TP = -1.82) at 3 weeks of immersion in black tea.

CONCLUSIONS

The effect of alcohol on discoloration depended on the composite type used. The translucency of bulk-fill flowable composite decreased with alcohol exposure.

Effects of Water Sorption and Solubility on Degradation of Silorane and Methacrylate-Based Dental Composites

INTRODUCTION

Wet oral environment may have deleterious effects on performance of the composites due to influences of water sorption and solubility. The study evaluated the hydrolytic degradation caused because of water sorption and solubility of silorane and methacrylate-based dental composites.

METHODS

Ten disc samples (2 mm × 10 mm) were prepared. Samples were analyzed for water solubility and sorption according to ISO 4049:2000 regulations and tested for mass gain or loss following immersion in water or in artificial saliva at 1 day, 15 days, and 30 days period. Student's 't' test, repeated measures analysis of variance (ANOVA), and Tukey's post-hoc tests determined statistical significance of the experimental results with global significance set at P = 0.05.

RESULTS

Considerable sorption and solubility was observed with time in both materials on immersion. Silorane composites showed lower water sorption and solubility than methacrylate-based composite (MBC). Artificial saliva demonstrated higher sorption and solubility compared to distilled water.

CONCLUSION

Silorane composites display enhanced hydrolytic stability even after a month of immersion in contrast to conventional methacrylate-based composites (MBCs), making it a better alternative to MBC resins clinically.

Color stability of resin-based composites exposed to smoke. A systematic review

OBJECTIVE

To conduct a systematic review on color stability of dental resin-based composites (RBC) exposed to conventional and electronic cigarettes.

MATERIALS AND METHODS

In vitro studies reporting on the color stability of RBC exposed to conventional cigarettes or to e-cigarettes: both Tobacco Heating Systems (THS) and Electronic Nicotine Delivery Systems (ENDS). The quality of the included studies was assessed with the QUIN tool (risk-of-bias tool for assessing in vitro studies conducted in dentistry). A systematic search, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was performed on four (n = 4) databases (Embase, Medline, Scopus, Web of Science) for articles published until March 28th, 2022.

RESULTS

Of the 365 screened articles, 13 were included in this review. All the included articles analyzed conventional cigarette smoke (CS), four analyzed Electronic Nicotine Delivery Systems (ENDS) and two Tobacco Heating Systems (THS). In terms of study design, smoke exposure time, smoke flow, type and number of cigarettes a high variability was reported.

CONCLUSIONS

The available evidence suggests that CS smoke significantly affects color stability. Electronic cigarettes show less color change that seems to be easily recovered under clinical acceptability thresholds, although evidence is scarce.

CLINICAL SIGNIFICANCE

Clinicians should be aware, and should therefore warn their patients, that RBCs are subjected to irreversible color change if exposed to smoke. Electronic cigarettes (both ENDS and THS) induce less color change that can be recovered with repolishing or whitening procedures.

Siloranes-Suitability of a Novel Adhesive for Orthodontic Bracket Bonding

Recently, an epoxy-based resin-Filtek Silorane-has been proposed for restorative fillings. It was the aim of the investigation to evaluate the suitability of this novel resin for orthodontic bracket bonding on unground enamel. Shear bond strength was measured for two adhesives-Filtek Silorane, Transbond XT-in combination with steel, ceramic and polymer brackets. For Filtek Silorane etching was performed with the Silorane self-etching primer, as well as phosphoric acid. The Transbond XT samples were etched with phosphoric acid only and served as the control group. All samples were thermo-cycled (1000×, 5-55 °C). Shear testing was carried out with an Instron 3344. In addition, ARI scores were evaluated. The Shear bond strength showed a weak adhesion of Filtek Silorane to unprepared enamel, either with the self-etching primer or the conventional etching (0.87-4.28 MPa). The Shear bond strength of the control group was significantly higher (7.6-16.5 MPa). The ARI scores showed a clear failure at the enamel-adhesive interface for all Filtek Silorane samples. For the combination of Transbond XT and different brackets the failure was found at the adhesive-bracket interface. The novel epoxy-based resin Filtek Silorane is not appropriate for bracket bonding to unprepared enamel.

Effect of Aging on Surface Roughness and Color Stability of a Novel Alkasite in Comparison with Current Direct Restorative Materials

AIM

To compare the surface roughness and color stability of a novel alkasite with current direct restorative materials with and without an aging step.

METHODS AND MATERIALS

Twenty-six specimens of each of the following materials were prepared: alkasite, ormocer, giomer, high-viscosity glass ionomer, glass carbomer, and nanohybrid composite (control). Half of the specimens in each group were stained, the other half of the specimens were aged and then stained. Color and surface roughness evaluations were conducted at baseline, after aging and after staining, using a dental spectrophotometer, and a three-dimentional (3D) noncontact optical profilometer, respectively. Statistical analyses were completed using one-way analysis of variance, post hoc Tukey test, and paired samples t-test.

RESULTS

At baseline and after aging, the surface of alkasite was found to be rougher than nanohybrid composite and ormocer surfaces (p<0.05). However, in terms of roughness increase caused by aging, ormocer, nanohybrid composite, and alkasite were affected in a similar way (p>0.05). In terms of color stability, alkasite was more colored than nanohybrid composite and ormocer (p<0.05), and performed similar to giomer (p>0.05).

CONCLUSIONS

The surface roughness and color stability characteristics of alkasite material was between composite resins and glass ionomer-based materials after aging.

Effect of over the counter mouthwashes with and without alcohol on sorption and solubility of bulk fill resins

Background

Composites sorption and solubility can be precursors of several chemical and physical processes, which lead to deleterious effects on the polymer structure. This study evaluated the effect of mouthwashes with and without alcohol on the sorption and solubility of conventional and low viscosity bulk fill resins.

Material and Methods

Four types of Bulk Fill resins (Filtek™ Bulk Fill, X-tra Fil, Filtek™ Bulk Fill Flow and X-tra Base) were submitted to the following mouthwashes: Listerine Cool Mint and Periogard (containing alcohol) and Listerine Zero and Periogard (alcohol-free). The specimens were stored in the mouthwashes for seven days. Solubility and sorption tests were performed according to ISO 4049. Data were analyzed using two-way-ANOVA, followed by Tukey Test. The data were grouped, and a paired t-test was performed to evaluate the effect of alcohol on the properties studied. The p was fixed at 5%.

Results

Resins immersed in alcohol-containing mouthwashes had higher values of sorption and solubility, with the highest sorption rate for X-Tra Base in Listerine Cool Mint treatment (p<0.05). Flow type resins showed higher sorption than conventional viscosity resins, irrespective of the mouthwash used (p<0.05).

Conclusions

Alcohol-containing mouthwashes affected sorption and solubility of bulk fill resins and the composites that presented worse and better performance regarding the studied properties were X-Tra Base and Filtek™ Bulk Fill, respectively.

Key words:Solubility, Sorption, Mouthwashes, Bulk-fill composites.

Study of POSS on the Properties of Novel Inorganic Dental Composite Resin

: Various amounts of methacryl polyhedral oligomeric silsesquioxane (POSS) were explored to be incorporated into novel nano SiO₂ dental resin composites using light curing method. The scanning electron microscopy (SEM), optical microscopy, fourier transform infrared spectroscopy (FTIR), nanoindentation, nanoscratch and three-point flexure tests were performed. The volumetric shrinkage and mechanical properties such as hardness, elastic modulus, resistance, flexural strength and fracture energy were analyzed. With the additions of POSS, the volume shrinkage decreased and the mechanical properties initially increased. The effects of POSS on these properties were studied to provide a reference for clinically selecting a composite resin with excellent properties.

Influence of water aging on surface hardness of low-shrinkage light-cured composite resins

This study evaluated the microhardness of four types of low-shrinkage composite resins and two types of universal composite resins with either 12 or 16 J/cm² light power energy. Three disks were made for each group (n = 3) for a total of 36 specimens. The specimens were prepared by condensing the composite resin into a circular copper mold (diameter: 6 mm; height: 2 mm) and polymerizing with 700 mW/cm² light power density. The microhardness values of the resin specimens were measured using a Vickers hardness tester after different storage durations. Z250 and Clearfil Majesty Posterior composites showed softer subsurfaces when comparing the 24 h samples for all six types. Conversely, Kalore GC and Admira (AD) composites showed harder subsurfaces during the 24 h samples. All the composite resins showed significant differences (P < 0.05) in microhardness values at one of the aging times when they were polymerized with either 12 or 16 J/cm² light power energy. Composite resin AD had a higher microhardness value after polymerization with 12 J/cm² than with 16 J/cm². The results indicated that low-shrinkage composite resins have better subsurface characteristics, and the light power energy of 16 J/cm² is better for the polymerization of most composites.

The Silorane-based Resin Composites: A Review

This article aims to review the research done on the silorane-based resin composites (SBRC) regarding polymerization shrinkage and contraction stresses and their ability to improve the shortcomings of the methacrylate-based resin composites (MRBC). Special attention is given to their physical and mechanical properties, bond strength, marginal adaptation, and cusp deflection. The clinical significance of this material is critically appraised with a focus on the ability of SBRC to strengthen the tooth structure as a direct restorative material. A search of English peer-reviewed dental literature (2003-2015) from PubMed and MEDLINE databases was conducted with the terms "low shrinkage" and "silorane composites." The list was screened, and 70 articles that were relevant to the objectives of this work were included.

Influence of material and surface treatment on composite repair shear bond strength

OBJECTIVES

The aim of this study is to investigate the influence of the composite material and surface treatment to the bond strength when repairing an aged composite surface with new composite.

MATERIALS AND METHODS

One hundred and sixty resin blocks of methacrylate composite and silorane composite prepared and aged in artificial saliva for 6 months. Specimens treated either with a diamond bur (DB) or air abrasion (AA), conditioned with orthophosphoric acid (OA) or sodium hypochloride (SH) and repaired with methacrylate or silorane composite using the corresponding adhesive system. Repaired composites underwent thermocycling fatigue (×5000), and bond strength was measured at shear.

RESULTS

Methacrylate achieved the highest bond strengths as repair material, in all combinations (26.54-55.56 MPa). Silorane only reached 8.12 MPa when repairing silorane treated with DB and OA. For all other treatment combinations repairing with silorane led to pretest failures. The most susceptible to repair composites/surface treatment combination is when repairing methacrylate treated with AA and SH and methacrylate composite (55.56 MPa).

CONCLUSIONS

Silorane composites are not suitable to be used when repairing an old composite restoration. The repair material is the most critical factor, while aged surface treatment has only a minor influence to the shear bond strength.

POSS Dental Nanocomposite Resin: Synthesis, Shrinkage, Double Bond Conversion, Hardness, and Resistance Properties

Nanocomposite dental resins with 0, 2, 5, and 10 wt % methacryl polyhedral oligomeric silsesquioxane (POSS) as filler in the resin matrix were prepared by a light curing method.The atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), nanoindentation, and nanoscratch tests were carried out to study the effect of POSS contents on the compatibility, double bond conversion, volumetric shrinkage, hardness, modulus, and resistance of the dental resins. POSS was very uniformly dispersed and showed a good compatibility with the matrix. The double bond conversion increased and the volume reduced with the addition of POSS. As the POSS addition increased, the mechanical properties increased initially. Small addition of POSS remarkably enhanced the hardness and scratch resistance of the resin matrix.

Effect of food simulating liquids on the flexural strength of a methacrylate and silorane-based composite

OBJECTIVE

The purpose of this study was to assess the effect of food-simulating liquids on the flexural strength of a methacrylate-based and a silorane-based resin composite.

MATERIALS AND METHODS

In this in vitro study, sixty specimens of Filtek P90 and Filtek Z350 composite were prepared in a customized mold (2 × 2 × 25 mm). The specimens of each composite were divided into five subgroups as follows: one as a control group and the other four groups included distilled water, heptane, 2% citric acid, and 50% aqueous ethanol. The specimens were stored in the solutions for one week at 37°C, and the control group was stored at room temperature for the same period of time. Then, flexural strength values were measured. The statistical analysis was performed by One-Way ANOVA, Paired T test and post hoc LSD at a significance level of 0.05.

RESULTS

In the control group, the mean flexural strength of Filtek P90 and Filtek Z350 were 155.1 MPa and 147.3 MPa, respectively, and there was no significant difference (P-value>0.05). The mean flexural strength of Filtek P90 and Filtek Z350 significantly decreased in ethanol (P-value <0.05). Immersion in 0.02 N citric acid and heptane had no significant effect on the flexural strength of Filtek P90 and Filtek Z350. The maximum flexural strength of Filtek P90 was in the heptane group (192.6 MPa) and minimum flexural strength was in ethanol group (92.7 MPa) the maximum flexural strength of Filtek Z350 was in the heptane group (163.2 MPa) and minimum flexural strength was in the ethanol group (104.7 MPa).

CONCLUSION

The flexural strength of tested resin composites significantly affected by ethanol solution. The flexural strength of resin composites was not affected by other food simulating liquids.

Effect of water storage on flexural strength of silorane and methacrylate-based composite resins

Objectives

This study assessed the effect of water storage on the flexural strength (FS) of low shrinkage composites.

Materials and Methods

A total of 165 bar-shaped specimens (2 × 2 × 25 mm) were fabricated of 2 low shrinkage composites (Filtek P90 [3M ESPE], GC Kalore [GC International]) and a conventional methacrylate-based composite (Filtek Z250 [3M ESPE]). The specimens were subjected to 3-point bending test at 6 time intervals, namely: immediately after curing, at 24 hours, 1 week, 1 month, 6 months, and 1 year following storage in wet and dry conditions. The FS of the specimens were measured by applying compressive load at a crosshead speed of 1.0 mm/min. Data was analyzed using 3-way analysis of variance (ANOVA) and Tukey's test.

Results

Three-way ANOVA revealed significant interactions between time, type of composite, and storage condition (p = 0.001). Tukey's multiple comparison test revealed significant reductions in FS of all composites after 6 months and 1 year of storage in distilled water compared to dry condition.

Conclusions

Filtek P90 showed the highest and GC Kalore showed the lowest FS after 1 year storage in distilled water. The immediate high strength of Filtek Z250 significantly decreased at 1 year and its final value was lower than that of Filtek P90.

In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials

OBJECTIVE

To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites.

METHODS

Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05).

RESULTS

Bleaching resulted in significant differences in ΔE values for all materials (P < .001). Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials.

CONCLUSIONS

Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability.

CLINICAL SIGNIFICANCE

Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary.

The combined effect of food-simulating solutions, brushing and staining on color stability of composite resins

Objective: This study evaluated the effect of food-simulating media associated with brushing and coffee staining on color stability of different composite resins.

Materials and methods: Eighty specimens were prepared for each composite: Grandio SO (Voco), Amaris (Voco), Filtek Z350XT (3M/ESPE), Filtek P90 (3M/ESPE). They were divided into four groups according to food-simulating media for 7 days: artificial saliva (control), heptane, citric acid and ethanol. The composite surface was submitted to 10,950 brushing cycles (200 g load) in an automatic toothbrushing machine. The specimens were darkened with coffee solution at 37 °C for 24 h. After each treatment, color measurements were assessed by spectrophotometry, using CIE L*a*b* system. The overall color change (ΔE) was determined for each specimen at baseline (C1) and after the treatments (food-simulating media immersion/C2, brushing/C3 and dye solution/C4). Data were analyzed by two-way repeated measures ANOVA and Tukey’s tests (p < .05).

Results: The results of RM-ANOVA showed significant differences for composites (p = .001), time (p = .001) and chemical degradation (p = .002). The mean of ΔE for composites were: Z350XT (5.39)^a, Amaris (3.89)^b, Grandio (3.75)^bc, P90 (3.36)^c. According to food-simulating media: heptane (4.41)^a, citric acid (4.24)^a, ethanol (4.02)^ab, artificial saliva (3.76)^b. For the treatments: dye solution (4.53)^a, brushing (4.26)^a, after food-simulating media (3.52)^b.

Conclusions: The composite resin Filtek Z350XT showed significantly higher staining than all other composite resin tested. The immersion in heptane and citric acid produced the highest color alteration than other food-simulating media. The exposure of samples to brushing protocols and darkening in coffee solution resulted in significant color alteration of the composite resins.

Clinical Evaluation of Silorane and Nano-hybrid Resin Composite Restorations in Class II Cavities up to 3 Years

In this study, the clinical performance of a silorane-based resin composite (SC) vs a nano-hybrid resin composite (NHC) was evaluated in Class II cavities. From January 2012 to February 2013, a total of 29 patients (eight men, 21 women; mean age, 24 ± 5 years) received 29 pairs of restorations using both SC (Filtek Silorane, 3M ESPE) and NHC (Filtek Z550, 3M ESPE) materials. Patients were followed until February 2015. One operator performed all restorations using the corresponding adhesive resins according to the manufacturers' instructions. Two calibrated independent examiners evaluated the restorations at one week, six months, and then annually using the modified United States Public Health Service (USPHS) criteria for anatomic form, marginal adaptation, color match, surface roughness, marginal discoloration, secondary caries, and postoperative sensitivity. Changes in the USPHS parameters were analyzed with the McNemar test (α=0.05). The mean observation period was 31.2 months. Marginal adaptation was the only parameter that showed a significant difference and was worse for SC than NHC (p=0.012). At the final recall, 17 restorations from the SC group and five from the NHC group received a score of 1 (explorer catches). These scores were significantly different between baseline and final recall for SC (p&lt;0.001) but not for NHC (p&gt;0.05). Both NHC and SC performed similarly in Class II restorations up to three years except for marginal adaptation, for which the latter demonstrated significant deterioration at the final recall compared with baseline.

Nanoleakage Evaluation of Posterior Teeth Restored with Low Shrinkable Resin Composite- An invitro Study

INTRODUCTION

The effect of nanoleakage on the integrity of resin-dentin bond has been in interest for long-term adhesion.

AIM

This study evaluated the nanoleakage in premolar teeth restored with low shrinkable resin composite.

MATERIALS AND METHODS

A total of 40 human premolars were used for nanoleakage evaluation in this study. Each group was divided into four equal groups; Group A: using silorane with its adhesive system. Group B: using silorane with G-bond. Group C: using Filtek supreme composite with G-bond. Group D: using Filtek supreme composite with AdheSE adhesive. Nanoleakage analysed using Scaning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectrometery (EDX).

RESULTS

The amount of silver present in hybrid layer depend on the adhesive used; this indicated different nanoleakage expressions in different adhesive systems. Filtek Z350 composite with G-bond showed clear silver uptake in both the adhesive and hybrid layer. Low shrinkable resin composite (silorane) with its adhesive system showed less silver penetration and slight silver peak on the elemental energy spectroscopy of energy dispersive X-Ray spectrometry (EDS) as compared to other samples.

CONCLUSION

Adhesives used between different groups, influence the location and degree of nanoleakage. There is difference in nanoleakage patterns between two-step and one-step adhesives and also among the one-step adhesives themselves.

Effect of Er,Cr:YSGG laser on the surface of composite restoratives during in-office tooth bleaching

The aim of this in vitro study was to investigate the effect of Er,Cr:YSGG laser on the surface roughness and microhardness of various composite restoratives during in-office tooth bleaching. Five highly viscous composite restoratives and three flowable composite restoratives were investigated. Thirty cylindrical specimens of each material were made using Teflon molds. The specimens of each composite were randomly divided into three groups (n = 10). Group 1 specimens did not receive bleaching treatment, group 2 received a conventional in-office bleaching treatment, and group 3 received a laser-assisted in-office bleaching treatment using an Er,Cr:YSGG laser. Two-way ANOVA was used to determine significant interactions between materials and bleaching methods. One-way ANOVA and Tukey's post hoc test were used to compare the mean surface microhardness and roughness between materials for each treatment group (a = 0.05). Τhere were no significant differences in surface microhardness between the two bleached experimental groups for all the tested composites (p > 0.05). The reduction of surface microhardness after bleaching procedures ranged from 0.72 to 16.93 % for the specimens received conventional treatment and from 1.30 to 11.51 % for those received laser-assisted treatment. Moreover, there were no significant differences in Ra values between the experimental groups (p > 0.05) in all cases. The increase of surface roughness after the bleaching treatments was negligible and was between 0.43 and 4.78 %. The use of Er,Cr:YSGG laser during in-office tooth bleaching treatment did not affect the surface microhardness and roughness of the tested composite restorative materials.

Role of TiF4 in Microleakage of Silorane and Methacrylate-based Composite Resins in Class V Cavities

AIM

This study investigated the effect of TiF4 solution pretreat-ment on microleakage of silorane and nanofilled methacrylate-based composites in class V cavities.

MATERIALS AND METHODS

Forty-eight intact premolar teeth were randomly allocated to four groups of 12 teeth. Restorative techniques after standard class V tooth preparations were as follows: Group 1, Filtek P90 composite; group 2, Filtek Z350 XT; group 3, TiF4 solution pretreatment and Filtek P90 composite; group 4, TiF4 solution pretreatment and Filtek Z350 XT. After storing the specimens in distilled water at 37°C for 24 hours and followed by immersion of the specimens in a 0.5% basic-fuchsin solution for 24 hours, they were sectioned buccolingually to obtain four surfaces for each specimen for analysis of microleakage using a stereomicroscope. Data analysis was performed using Kruskal-Wallis test to compare the four groups and the Mann-Whitney test for paired comparisons with Statistical Package for the Social Sciences (SPSS) version 17 software.

RESULTS

At the enamel margins, microleakage score of the Filtek Z350 XT group was lower than those of the Filtek P90 with and without the application of the TiF4 (p = 0.009 and p = 0.031 respectively). At the dentin margins, groups 3 and 4 (TiF4+Filtek P90 and TiF4+Filtek z350 XT respectively) showed significantly lower microleakage than group 1 (Filtek P90). However, there was no significant difference between other groups (p > 0.05).

CONCLUSION

At the enamel margins, microleakage score of the silorane-based composite was more than that of the nanofilled composite. No significant differences were observed between the other groups. At the dentin margins, for the silorane-based composite restorations, TiF4 solution pretreatment resulted in significantly lower microleakage. However, the similar result was not observed for Filtek Z350 XT. Also, no significant difference was observed between microleakage scores of Filtek P90 and Filtek Z350 XT with or without TiF4 pretreatment.

CLINICAL SIGNIFICANCE

In spite of better mechanical and physical properties of modern composites than earlier methacrylate-based composites, polymerization shrinkage has been remaining as one of the main shortcomings of them. Different methods, such as using new low shrinkage resin composites and different dentin pretreatments, have been suggested to overcome this problem. This study evaluated the effect of TiF4 as pretreatment on microleakage of class V tooth preparations restored with a nanocomposite and a silorane-based resin composite.

Effect of organic acids in dental biofilm on microhardness of a silorane-based composite

OBJECTIVES

This study evaluated the effect of lactic acid and acetic acid on the microhardness of a silorane-based composite compared to two methacrylate-based composite resins.

MATERIALS AND METHODS

Thirty disc-shaped specimens each were fabricated of Filtek P90, Filtek Z250 and Filtek Z350XT. After measuring of Vickers microhardness, they were randomly divided into 3 subgroups (n = 10) and immersed in lactic acid, acetic acid or distilled water. Microhardness was measured after 48 hr and 7 day of immersion. Data were analyzed using repeated measures ANOVA (p < 0.05). The surfaces of two additional specimens were evaluated using a scanning electron microscope (SEM) before and after immersion.

RESULTS

All groups showed a reduction in microhardness after 7 day of immersion (p < 0.001). At baseline and 7 day, the microhardness of Z250 was the greatest, followed by Z350 and P90 (p < 0.001). At 48 hr, the microhardness values of Z250 and Z350 were greater than P90 (p < 0.001 for both), but those of Z250 and Z350 were not significantly different (p = 0.095). Also, the effect of storage media on microhardness was not significant at baseline, but significant at 48 hr and after 7 day (p = 0.001 and p < 0.001, respectively). Lactic acid had the greatest effect.

CONCLUSIONS

The microhardness of composites decreased after 7 day of immersion. The microhardness of P90 was lower than that of other composites. Lactic acid caused a greater reduction in microhardness compared to other solutions.

The effect of different drinks on the color stability of different restorative materials after one month

Objectives

The aim of this study was to evaluate the effect of three different drinks on the color parameters of four different restorative materials.

Materials and Methods

Three different composites (Filtek Ultimate Universal Restorative, Filtek Ultimate Flowable, and Filtek Silorane, 3M ESPE) and a polyacid-modified composite resin material (Dyract XP, Dentsply DeTrey GmbH) were evaluated. Eighty-four disc-shaped specimens of 8 mm in diameter and 2 mm in thickness were prepared (n = 21 each). Color coordinates (L*a*b*, ΔL*, Δa*, Δb*, and ΔE*) were measured using a VİTA Easyshade Compact (VİTA Zahnfabrik) after 24 hr of storage (baseline) and after 30 day of storage in three different beverages of black tea, Coca cola, or water (control) (n = 7). In each beverage, the specimens were stored three times a day, one hr each, for 30 day. The color changes (ΔE) were calculated and were analyzed by Kruskal-Wallis and Dunn multiple comparison test.

Results

The color difference (ΔE*) of the resin materials ranged between 1.31 and 15.28 after 30 day of immersion in the staining solutions. Dyract XP in Coca cola (15.28 ± 2.61) and black tea (12.22 ± 2.73) showed the highest mean ΔE* value after 30 day, followed by Filtek Ultimate Universal Restorative (5.99 ± 1.25) and Filtek Ultimate Flowable (4.71 ± 1.40) in black tea (p < 0.05).

Conclusions

The compomers displayed unacceptable color changes at the end of 30 day in all beverages. Among resin composites, the silorane based composite exhibited relatively good color stability than the others. Filtek Ultimate Universal Restorative and Filtek Flowable showed similar color changes in all beverages.

Evaluation of Cytotoxicity of Silorane and Methacrylate based Dental Composites using Human Gingival Fibroblasts

AIM

The effects of leached substances from the restorative dental materials may induce local and systemic adverse effects. Thus the biological and toxic properties of the restorative dental materials must be compatible with the oral tissues or with general health. Therefore, the need for biocompatible restorative dental material implies the necessity of toxicity testing. It was the purpose of this investigation to determine and compare the possible toxic effect of silorane based composite (Filtek P90) on human gingival fibroblast (HGF) in vitro using cytotoxicity measuring parameters (MTT assay) in comparison with its methacrylate counterpart (Z100) for their viability, proliferation rate.

MATERIALS AND METHODS

Fresh healthy biopsy specimens of human gingival tissue of patients were obtained. For HGF, cells were cultured in Dulbecco's modified Eagle medium and grown to sub confluent monolayers. After attaining confluence, cells were treated with different doses of the Filtek P90 or Z 100 for different time point. HGF cells were observed for their proliferation, viability by MTT assay.

RESULTS

The results of the cytotoxicity assay showed that, the percentage of viable cells was very good in the first 24h and marginally decreased in the next 48h period in all groups. However, the proliferation rate was never below 84% in all the groups, at any given concentration. Filtek P90 and Z100 treated cells exhibited insignificant decrease in the cell proliferation both in 24h and 48h exposure when compared to significant decrease in the cell survival rate in the positive control (Mitomycin C 250 μg/ml).) Comparison of the toxicity between Filtek P90 and Z100 in 24h & 48h separately showed that there was no significant difference (p<0.05) between these two composites in 24h and 48h' time period at all concentrations of the composites.

CONCLUSION

To conclude, the new silorane based restorative composite showed comparable cytotoxic characteristics to clinically successful dimethacrylate composites suggesting the non-toxic nature in the oral environment and hence contributing to clinical success of these new restorative materials.

Evaluating Resin-Dentin Bond by Microtensile Bond Strength Test: Effects of Various Resin Composites and Placement Techniques

Objectives:

This in vitro study evaluated the microtensile bond strength (MTBS) of a methacrylate-based compared to a silorane-based resin composite in Class I cavity using different placement techniques.

Materials and Methods:

Class I cavities with dimension of (4 mm long, 4 mm wide, 3 mm deep) were prepared in extracted sound human molars. The teeth were randomly divided into six groups. The first three groups were filled with Filtek P90 using three methods of insertion; bulk, incremental and snow-plow, and the remaining three groups were filled with Clearfil AP-X using the same three placement techniques. After 24 hours of storage in water at 37°C, the specimens were thermocycled to 1000 cycles. Specimens were prepared for MTBS testing by creating bonded beams obtained from the pulpal floor. Statistical analysis used: Statistical analyses of data were performed by two-way ANOVA/Tukey (α=.05).

Results:

The experiment showed significant differences between the two resin composites with regard to filling techniques (P<0.05). The MTBS was significantly higher in each of Filtek P90 subgroup compared to Clearfil AP-X ones (P<0.05). With respect to filling technique in both resin composites, bulk insertion showed the significantly lowest MTBS (P<0.05), while no significant difference was found between the outcome of incremental and snow-plow techniques (P>0.05).

Conclusion:

Silorane-based resin composite as opposed to methacrylate based resin composite and layering placements in contrast to bulk filling method had higher microtensile bond strength.

Solubility of two resin composites in different mouthrinses

AIM

This study aimed to compare the solubility of a universal restorative resin composite (Filtek Z250; FZ250) and a silorane-based resin composite (Filtek Silorane; FS) after immersion in alcohol-containing mouthrinse, alcohol-free mouthrinse, and artificial saliva.

METHODS

30 discs (10 mm × 1 mm) were prepared from each material and desiccated until a constant mass was obtained. Specimens were immersed in the test solutions for two days and desiccated again. Solubility was calculated based on the change in weight of each specimen before and after immersion. Data was analyzed using two-way ANOVA and Tukey's Post Hoc test (P < 0.05).

RESULTS

Solubility values for both resin composites were the highest in the alcohol-containing mouthrinse. FZ250 showed greater solubility than FS; the difference was only significant in artificial saliva.

CONCLUSION

Both resin-composite materials tested exhibited some degree of solubility in each of the test solutions. The use of an alcohol-free mouthrinse may be preferable for patients with extensive composite restorations.

Microtensile bond strength of silorane-based composite specific adhesive system using different bonding strategies

OBJECTIVES

The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin.

MATERIALS AND METHODS

Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens (1.0 × 1.0 mm), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing.

RESULTS

Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05). However, it was not significantly different from Preetching/Silorane and Methacrylate groups.

CONCLUSIONS

Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

Effect of 38% carbamide peroxide on the microleakage of silorane-based versus methacrylate-based composite restorations

OBJECTIVES

This study aimed to assess the effect of 38% carbamide peroxide on the microleakage of class V cavities restored with either a silorane-based composite or two methacrylate-based composites.

MATERIALS AND METHODS

A total of 96 class V cavities were prepared on the buccal surface of extracted human teeth with both enamel and dentin margins and were randomly assigned into three groups of Filtek P90 (3M-ESPE) + P90 system adhesive (3M-ESPE)(group A), Filtek Z250 (3M-ESPE) + Adper Prompt L-Pop (3M-ESPE)(group B) and Filtek Z350XT (3M-ESPE) + Adper Prompt L-Pop (group C). Half of the teeth were randomly underwent bleaching (38% carbamide peroxide, Day White, Discus Dental, applying for 15 min, twice a day for 14 day) while the remaining half (control) were not bleached. Dye penetration was measured following immersion in basic fuchsine. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at a level of 0.05.

RESULTS

No significant differences were found between composites in the control groups in enamel (p = 0.171) or dentin (p = 0.094) margins. After bleaching, microleakage of Z250 (in enamel [p = 0.867] or dentin [p = 0.590] margins) and Z350 (in enamel [p = 0.445] or dentin [p = 0.591] margins) did not change significantly, but the microleakage of P90 significantly increased in both enamel (p = 0.042) and dentin (p = 0.002) margins.

CONCLUSIONS

No significant differences were noted between the bleached and control subgroups of two methacrylate-based composites in enamel or dentin margins. Microleakage of silorane-based composite significantly increased after bleaching.

Degree of Conversion and Hardness of a Silorane-Based Composite Resin: Effect of Light-Curing Unit and Depth

Purpose

To investigate the effect of different light-curing units and depths on the degree of conversion (DC) through Fourier transform infrared spectroscopy (FTIR) and Knoop Hardness Number (KHN) of a silorane-based composite resin (Filtek LS, 3M ESPE, St Paul, MN, USA) (LS).

Materials and Methods

LS specimens mounted in a particular designed matrix were photoactivated by three light-cure units (LCUs) at depths of 2, 3, 4, and 5 mm. The DC was determined in a FTIR spectrometer with an attenuated total reflectance accessory. The KHN was measured in an automatic microhardness tester. The results were analyzed using the Friedman and Spearman statistical tests (α=0.05).

Results

There was no effect of LCUs on the DC (p=0.472) or KHN (p=0.174) for all of the studied depths. The highest DC and KHN means were found at 2-mm depth, which were not statistically different from 3-mm depth, but were higher than 4-mm and 5-mm depths (p=0.007). Spearman analysis found a positive linear correlation between the variables KHN and DC (r=0.858, p&lt;0.000).

Conclusions

The LCUs' effect was not verified. Values of DC and KHN for LS decreased with increasing depth. The highest values for both DC and KHN were obtained at depths of 2-3 mm.

Characterization of Water Sorption, Solubility, and Roughness of Silorane- and Methacrylate-based Composite Resins

Objective

The objective of this study was to evaluate the surface roughness (SR), water sorption (WS), and solubility (SO) of four composite resins after finishing/polishing and after one year of water storage.

Materials and Methods

Two low-shrinkage composites (Filtek Silorane [3M ESPE] and Aelite LS [Bisco Inc]) and two composites of conventional formulations (Heliomolar and Tetric N-Ceram [Ivoclar Vivadent]) were tested. Their respective finishing and polishing systems (Sof-Lex Discs, 3M ESPE; Finishing Discs Kit, Bisco Inc; and Astropol F, P, HP, Ivoclar Vivadent) were used according to the manufacturers' instructions. Ten disc-shaped specimens of each composite resin were made for each evaluation. Polished surfaces were analyzed using a profilometer after 24 hours and one year. For the WS and SO, the discs were stored in desiccators until constant mass was achieved. Specimens were then stored in water for seven days or one year, at which time the mass of each specimen was measured. The specimens were dried again and dried specimen mass determined. The WS and SO were calculated from these measurements. Data were analyzed by two-way analysis of variance and Tukey post hoc test (α=0.05).

Results

Filtek Silorane showed the lowest SR, WS, and SO means. Water storage for one year increased the WS means for all composite resins tested.

Conclusions

The silorane-based composite resin results were better than those obtained for methacrylate-based resins. One-year water storage did not change the SR and SO properties in any of the composite resins.

The color stability of silorane- and methacrylate-based resin composites

The purpose of this study were to evaluate the discoloration of a silorane-based resin and two methacrylated-based resin composites upon exposure to different staining solutions coffee, red wine, porcine liver esterase and distilled water for 7 days. The colors of all specimens before and after storage in the solutions were measured by a spectrophotometer based on CIE Lab system, and the color differences thereby calculated. Data were statistically analyzed by ANOVA and Scheffe's test. For coffee and red wine, the mean color change in silorane-based resin was significantly lower than that in methacylate-based resin composites (p<0.05). For porcine liver esterase and distilled water, there was no significant difference in the mean values of color change between silorane- and methacrylate-based resin composites (p>0.05). In conclusion, the silorane-based resin composites exhibited better color stability (less ΔE) after exposure to the colored staining solutions.

Do new matrix formulations improve resin composite resistance to degradation processes?

The aim of this study was to determine the degradation resistance of three new formulations-silorane-, Ormocer- and dimer-acid-based materials-and compare them to the traditional dimethacrylate-based materials. One silorane- (Filtek P90, P90), one Ormocer- (Ceram-X, CX), one dimer-acid- (N'Durance, ND) and two dimethacrylate-based (Filtek P60, P60; Tetric Ceram, TC) materials were investigated. Water sorption (Wsp) and solubility (Wsl) were determined after the materials were immersed in water for 28 days. Knoop hardness (KH) was determined before and after 24 h immersion in pure ethanol. The flexural-strength (FS) was determined by the bending test after one-week storage in a dry environment or after one-week immersion in pure ethanol. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95%). The three new formulations showed lower Wsp than the dimethacrylate-based formulation. CX (0.50 ± 0.17%) and ND (0.72 ± 0.19%) exhibited the lowest Wsp, whereas P90 (0.02 ± 0.03%) and P60 (0.04 ± 0.03%) showed the lowest Wsl. All resins showed reduced Knoop hardness number (KHN) after ethanol immersion. P60 presented the lowest decrease in KH value (19 ± 5%). TC (48 ± 3%) and P90 (39 ± 9%) showed the highest KHN decrease after ethanol storage. The FS of CX, ND and TC were affected by ethanol storage. The new formulations did not improve the degradation resistance, as compared with the traditional methacrylate-based materials.

Effect of cigarette smoke on color stability and surface roughness of dental composites

OBJECTIVE

To evaluate the color stability and surface roughness of 3 dental composites subjected to cigarette smoke and brushing.

METHODS

Twenty specimens were prepared for each type of restorative material used: nanohybrid (Tetric N-Ceram); hybrid (Z250-3M ESPE) and silorane-based microhybrid (Filtek P90-3M ESPE), which were divided into 2 groups (n=10), according to the type of finishing/polishing received: Group 1 - papers with decreasing abrasive grit and Group 2 - polyester matrix (without polishing). After initial readouts of color (Easy Shade-VITA) and surface roughness (SJ-201P Mitutoyo), specimens were subjected to action of smoke from 20 cigarettes, (Marlboro Red-Philip Morris). After each cigarette, the samples were submitted to brushing in a standardised device. After this, final readouts were taken to calculate change in color (ΔE and ΔL) and roughness (ΔRa), which were statistically analysed (2-way ANOVA, Bonferroni, and Student's-t tests respectively, p<0.05).

RESULTS

Tetric N-Ceram presented color change at clinically unacceptable levels (ΔE>3.3) when the polyester strip was used for finishing, a result differing (p<0.05) from those of the other composites, which presented no difference between them (p>0.05). Unpolished composites presented higher Ra values than those that were polished (p<0.05), with exception of the silorane based composite.

CONCLUSION

Absence of polishing increases cigarette capacity to stain composites and surface roughness of composites, with exception of the silorane based type.

Avaliação em curto e médio prazo da sorção e da solubilidade de resinas compostas à base de metacrilato e de silorano em saliva artificial

INTRODUÇÃO: A absorção/adsorção de moléculas de água por monômeros hidrofílicos dentro de materiais resinosos expostos à umidade da boca pode resultar em degradação. OBJETIVO: Este estudo avaliou sorção e solubilidade de resinas compostas à base de metacrilato e silorano em contato com saliva artificial, nos períodos de um dia (curto prazo), e 30 e 90 dias (médio prazo). MATERIAL E MÉTODO: Sessenta corpos de prova foram confeccionados com as resinas Filtek® Z250 e Filtek® P90 Silorano (3M/ESPE), e depois imersos em saliva artificial a 37 ± 1 ºC durante um, 30 e 90 dias. Os dados foram analisados usando-se ANOVA um fator/dois fatores seguido dos testes Tukey ou Tamhane (α = 0,05). RESULTADO: As médias de sorção das duas resinas aumentaram com o tempo (p = 0,001). A sorção de Z250 (1 e 90 d) foi significativamente maior do que de P90 (p = 0,008), com valores semelhantes após 30 dias. A solubilidade das resinas também aumentou com o tempo, com diferença significativa entre todos os períodos (p = 0,001), exceto para a resina P90 (entre 1 e 30 d). Não houve diferença estatística significante entre os grupos Z250 (1 d) e P90 (1 dia), Z250 (1 d) e P90 (30 d), e Z250 (30 d) e P90 (90 d). Para os demais pares, comprovaram-se diferenças significativas (p < 0,001). CONCLUSÃO: As propriedades de sorção e solubilidade das resinas compostas testadas foram influenciadas pelo tempo de exposição à saliva artificial. O silorano teve desempenho ora melhor ora semelhante à resina de metacrilato.

Effect of Surface Treatment with Er;Cr:YSSG, Nd:YAG, and CO2 Lasers on Repair Shear Bond Strength of a Silorane-based Composite Resin

Background and aims. The aim of the present study was to compare the effect ofsurface treatment with Er; Cr:YSSG, Nd:YAG, and CO₂ lasers on repair shear bond strength of a silorane-based composite resin.

Materials and methods. Sixty eight cylindrical samples of a silorane-based composite resin (Filtek Silorane) were pre-pared and randomly divided into 4 groups as follows: group 1: without surface treatment; groups 2, 3 and 4 with surface treatments using Er; Cr:YSSG, Nd:YAG, and CO₂ lasers, respectively. A positive control group (group 5) was assigned in order to measure cohesive strength. Repair shear bond strength values were measured and data was analyzed using one-way ANOVA and a post hoc Tukey test at a significance level of α=0.05.

Results. There were statistically significant differences in repair shear bond strength values between group 2 and other groups (P < 0.05); and between group 1and groups 3and 4 (P < 0.001); however, there were no significant differences be-tween groups 3 and 4 (P = 0.91).

Conclusion. The repair shear bond strength of silorane-based composite resin was acceptable by surface treatment with lasers

Color stability of modern composites subjected to different periods of accelerated artificial aging

The aim of this study was to evaluate the color stability of composites subjected to different periods of accelerated artificial aging (AAA). A polytetrafluorethylene matrix (10 x 2 mm) was used to fabricate 24 test specimens of three different composites (n=8): Tetric Ceram (Ivoclar/Vivadent); Filtek P90 and Z250 (3M ESPE), shade A3. After light activation for 20 s (FlashLite 1401), polishing and initial color readout (Spectrophotometer PCB 687; BYK Gardner), the test specimens were subjected to AAA (C-UV; Comexim), in 8-h cycles: 4 h exposure to UV-B rays at 50°C and 4 h condensation at 50°C. At the end of each cycle, color readouts were taken and the test ended when the mean value of ΔE attained a level ≥3.30. Tetric Ceram presented alteration in ΔE equal to 3.33 in the first aging cycle. For Filtek P90 and Z250, two (ΔE=3.60) and four (ΔE=3.42) AAA cycles were necessary. After each cycle, there was a reduction of luminosity in all the samples (ΔL). It was concluded that a short period of AAA was sufficient to promote clinically unacceptable color alteration in composites, and that this alteration was material-dependent.

Effect of alcoholic and non-alcoholic beverages on color stability and surface roughness of resin composites: An in vitro study

Background:

Consumption of certain beverages may affect the esthetic and physical properties of the resin composite, thereby undermining the quality of restorations.

Aim:

To analyze the effect of three beverages (Whiskey, Coca-Cola, and Nimbooz) on color stability and surface roughness of two different types of resin composites at various time intervals in vitro.

Materials and Methods:

A methacrylate-based nanofilled composite and a silorane-based microhybrid composite were used. Each material was randomly divided into four equal subgroups of 10 samples each according to the beverages used (Whiskey, Coca-Cola, Nimbooz, and Distilled water). The samples were immersed in each beverage for 10 minutes each day for 56 days. Color change and surface roughness measurements were noted at the baseline — the seventh, fourteenth, twenty-eighth, and fifty-sixth day.

Statistical Analysis Used:

RANOVA and Bonferroni tests were used to find the difference in color change and surface roughness in the two resin composites when immersed in different beverages. The Pearson Correlation test was carried out to test if any correlation existed between color change and surface roughness.

Results:

Silorane-based resin composites were more stable in different beverages over time.

Conclusion:

The effect of interaction of different resin composites, various beverages, and time depended on a multitude of factors.

Marginal Microleakage of Low-shrinkage Composite Silorane in Primary Teeth: An In Vitro Study

BACKGROUND AND AIMS

Despite the increasing demand for adhesive restorations in pediatric dentistry, polymerization shrinkage and subsequent marginal microleakage remains a problem. The aim of this study was to evaluate of the sealing ability of novel low-shrinkage composite silorane in class V cavity of primary canines in comparison with three types of composite resin.

MATERIALS AND METHODS

Ninety-one non-carious extracted primary canines were randomly divided in six groups (n=15). Standard class V cavities were prepared on the buccal surface of each tooth that the occlusal margin was in the enamel and the cervical margin extending 1 mm below the cemento-enamel junction. The preparations were restored with the different composite materials in normal consistency with application the bonding in six groups (Filtek silorane; etch + Filtek Silorane; Z250; Filtek supreme; els saremco; Aelite LS). Teeth were then exposed to thermal cycles (1000 cycles, 5°C and 55°C), sealed and immersed in a 0.5% basic fuchsine for 24 hours, and finally sectioned. Buccolingual and mar-ginal leakage was assessed with dye penetration.

RESULTS

The best seal were obtained with etch + Filtek Silorane (P < 0.05) and the weakest seal with Z250 composite res-torations (P > 0.05). Except for etch + silorane, there was no significant differences in sealing ability (P > 0.05), and in the microleakage degree at the cementum and enamel margins (P > 0.05) between the groups.

CONCLUSION

According to the results, low-shrinkage silorane composite restorations with etching the cavity provide the highest seal in primary teeth.

Repair of Dimethacrylate-Based Composite Restorations by a Silorane-Based Composite: A One-Year Randomized Clinical Trial

Purpose

To investigate clinical performance of a low-shrinkage silorane-based composite resin when used for repairing conventional dimethacrylate-based composite restorations.

Background

Despite the continued development of resin-based materials, polymerization shrinkage and shrinkage stress still require improvement. A silorane-based monomer system was recently made available for dental restorations. This report refers to the use of this material for making repairs and evaluates the clinical performance of this alternative treatment.

Materials and Methods

One operator repaired the defective dimethacrylate-based composite resin restorations that were randomly assigned to one of two treatment groups: control (n=50) repair with Adper SE Plus (3M/ESPE) and Filtek P60 Posterior Restorative (3M/ESPE), and test (n=50) repair with P90 System Adhesive Self-Etch Primer and Bond (3M/ESPE) and Filtek P90 Low Shrink Posterior Restorative (3M/ESPE). After one week, restorations were finished and polished. Two calibrated examiners (Kw≥0.78) evaluated all repaired restorations, blindly and independently, at baseline and one year. The parameters examined were marginal adaptation, anatomic form, surface roughness, marginal discoloration, postoperative sensitivity, and secondary caries. The restorations were classified as Alpha, Bravo, or Charlie, according to modified US Public Health Service criteria. Mann-Whitney and Wilcoxon tests were used to compare the groups.

Results

Of the 100 restorations repaired in this study, 93 were reexamined at baseline. Dropout from baseline to one-year recall was 11%. No statistically significant differences were found between the materials for all clinical criteria, at baseline or at one-year recall (p&gt;0.05). No statistically significant differences were registered (p&gt;0.05) for each material when compared for all clinical criteria at baseline and at one-year recall.

Conclusions

The hypothesis tested in this randomized controlled clinical trial was accepted. After the one-year evaluations, the silorane-based composite exhibited a similar performance compared with dimethacrylate-based composite when used to make repairs.

Silorane resin supports proliferation, differentiation, and mineralization of MLO-A5 bone cells in vitro and bone formation in vivo

Methyl methacrylate used in bone cements has drawbacks of toxicity, high exotherm, and considerable shrinkage. A new resin, based on silorane/oxirane chemistry, has been shown to have little toxicity, low exotherm, and low shrinkage. We hypothesized that silorane-based resins may also be useful as components of bone cements as well as other bone applications and began testing on bone cell function in vitro and in vivo. MLO-A5, late osteoblast cells, were exposed to polymerized silorane (SilMix) resin (and a standard polymerized bisGMA/TEGDMA methacrylate (BT) resin and compared to culture wells without resins as control. A significant cytotoxic effect was observed with the BT resin resulting in no cell growth, whereas in contrast, SilMix resin had no toxic effects on MLO-A5 cell proliferation, differentiation, nor mineralization. The cells cultured with SilMix produced increasing amounts of alkaline phosphatase (1.8-fold) compared to control cultures. Compared to control cultures, an actual enhancement of mineralization was observed in the silorane resin-containing cultures at days 10 and 11 as determined by von Kossa (1.8-2.0 fold increase) and Alizarin red staining (1.8-fold increase). A normal bone calcium/phosphate atomic ratio was observed by elemental analysis along with normal collagen formation. When used in vivo to stabilize osteotomies, no inflammatory response was observed, and the bone continued to heal. In conclusion, the silorane resin, SilMix, was shown to not only be non cytototoxic, but actually supported bone cell function. Therefore, this resin has significant potential for the development of a nontoxic bone cement or bone stabilizer.