Silorane-based Composite Resin Research Articles

Pre-Heating of Low-Shrinkage Composite Resins: Effects on Color Stability and Surface Roughness.

Objectives: The present study aimed to investigate the effect of preheating on the color stability and surface roughness of a silorane-based composite resin. Materials and Methods: A total of 44 Filtek P90 composite resin disks, (10mm×1mm), were fabricated using plastic molds and were divided into two groups. In group 2, the composite resin syringes were placed in a thermostatically controlled water bath at 55‒60°C before preparing the disks. After polishing the samples with silicon carbide papers, they were stored in distilled water for 48 hours. Roughness and color parameters were then measured in two stages: immediately after retrieval from distilled water and after 40 days of storage in tea solution. Finally, the differences in roughness and color parameters were recorded. Independent samplet-test and regression analysis were used at a significance level of P<0.05. Results: Based on the findings of the present study, there was no significant difference among the mean ∆E values (P=0.4); however, a significant difference in mean surface roughness (P=0.01) was found between the two groups. Regression analysis showed a significant relationship between the study groups in terms of surface roughness and ΔE values​ (preheated: r2 = 0.73; non-preheated: r2= 0.76). Conclusion: Filtek P90 silorane-base composite showed ΔE>3.3 and surface roughness above 0.2µ under preheated and non-preheated conditions and discoloration increased following preheating.

Can the type of preheated resin composite influence the microtensile bond strength of ceramic restoration to human dentin?

The aim of this study was to evaluate the effect of the type of preheated resin composite on the microtensile bond strength (µTBS) between dentin and feldspathic ceramic inlays. Thirty healthy human premolars received inlay preparations for feldspathic ceramic restorations and were then divided into three treatment groups according to the luting agent (n = 10): Conventional Resin Cement (RC), Preheated Nanofilled Methacrylate-Based Resin composite (MB), and Preheated Microhybrid Silorane-Based Resin composite (SB). The composite resin was preheated to 55 °C, considering the cementation group. After cementation, the sets were cut into slabs with a bonding area of 1 mm2 to be further submitted to the µTBS test (0.5 mm/min, and10 Kgf load cell). One-way ANOVA and Tukey test (p < .5) were performed to analyze the bond strength data (MPa). Failures were observed under a stereomicroscope and representative specimens were evaluated using a Scanning Electron Microscopy (SEM). ANOVA revealed that the type of luting agent utilized was significant (p = .001). Bond strength values for the RC (7.37 ± 1.27 MPa)A and MB (6.98 ± 1.96 MPa)A treatment groups were similar and greater than the SB (4.74 ± 1.65 MPa)B. Adhesive failures between the cementing agent and ceramic were prevalent for the treatment groups. The preheated nanofilled methacrylate resin-based composite technique can promote bond strength similar to resin cement, whereas preheated silorane-based resin composite as a luting agent should be seen with caution. Thus, we concluded that the type of luting agent has influenced the µTBS of feldspathic restoration to dentin.

Effect of degree of conversion of different resin composite monomers (methacrylate and silorane) on two caries-associated bacteria: “An in Vitro study”

Background and Objectives: The biological response of oral bacteria to dental restorative polymer composites is mediated by the release of unpolymerized residual monomers. The aims of the present study were first, evaluating the effect of composite elutes from methacrylate composite resins and silorane-based composites on two cariogenic bacterial pathogens: Streptococcus mutans and Lactobacillus acidophilus and second, determination of degree of conversion (DC) of standardized discs made from the low-shrinkage silorane-based composite (FiltekTM P90) resin and methacrylate-based composite resin (FiltekTM Z350XT nanocomposite, FiltekTM Z350 Flow) using Fourier transform infrared spectroscopy (FTIR). Materials and Methods: Thirty-six composite specimens were prepared for the agar diffusion test and dissolved in a solvent (dimethyl sulfoxide) to attain a suspension, which was used to assess the effect of the residual monomers from methacrylate composite resins and silorane-based composites on the growth of S. mutans and L. acidophilus. To avoid more dilutions of the specimens, the colonies of bacteria were counted by the naked eye. Thirty composite specimens of 2 mm × 6 mm were polymerized for DC test, and the DC was measured using FTIR, also for unpolymerized composite resin. Results: The growth of S. mutans bacteria was inhibited when cultured with Filtek Z350 Flow composite resin, while the growth of L. acidophilus bacteria was stimulated by the Filtek Silorane p90 and Filtek Z350 Flow composite resin. The DC test with the Filtek Silorane composite resin showed highest DC (58%), then the Filtek Z350XT (Nanocomposite) (42%) followed by the Filtek Z350 Flow (Flowable) showed lowest (35%). Conclusions: Our results demonstrate that composite filling materials have a versatile nature of effect on oral pathogenic bacteria, which could modulate their pathogenesis. Dentists may thus select the appropriate type of composite filling according to the caries susceptibility of patients.

THERMAL CONDUCTIVITY OF DIFFERENT COMPOSITE REZIN MATERIALS IN DIFFERENT POLYMERIZATION TIMES AND MODES

Objective: The current study investigated the thermal conductivity of dimethacrylate- and silorane-based composite resins at different polymerization times and modes.

Composite resin for restoration of a posterior tooth and polishing: clinical case report

The aim of the present report was to describe a case of direct composite resin restoration in tooth 46, with emphasis on the importance of polishing. A 21-year-old female patient dissatisfied with the aesthetic amalgam restoration of her tooth 46 came to the our institution for correction of the situation. The procedure performed consisted of registration of occlusal contacts, selection of resin color, removal of amalgam restoration, coronal reconstruction with composite resin, occlusal adjustment, finishing and polishing, with the use of atomic force microscopy of the resin before and after polishing. A correct clinical protocol for the posterior composite resins is fundamental for the optimization of aesthetic results, for clinical performance and for consequent restorative longevity. The atomic force microscopy images of the resin used before and after polishing emphasize the necessity and clinical importance of this operative step.Descriptors: Dental Materials; Dental Restoration, Permanent; Dental Polishing; Microscopy.ReferencesFrese C, Staehle HJ, Wolff D. The assessment of dentofacial esthetics in restorative dentistry: a review of the literature. J Am Dent Assoc. 2012;143(5):461-66.Moraschini V, Fai CK, Alto RM, dos Santos GO. Amalgam and resin composite longevity of posterior restorations: A systematic review and meta-analysis. J Dent. 2015;43(9):1043-50.Kovarik RE. Restoration of posterior teeth in clinical practice: evidence base for choosing amalgam versus composite. Dent Clin North Am. 2009;53(1):71-6.Kanzow P, Wiegand A, Schwendicke F. Cost-effectiveness of repairing versus replacing composite or amalgam restorations. J Dent. 2016;54:41-7.Lynch CD, Opdam NJ, Hickel R, Brunton PA, Gurgan S, Kakaboura A, et al. Guidance on posterior resin composites: Academy of Operative Dentistry - European Section. J Dent. 2014;42(4):377-83.Fernández E, Martín J, Vildósola P, Oliveira Junior OB, Gordan V, Mjor I et al. Can repair increase the longevity of composite resins? Results of a 10-year clinical trial. J Dent. 2015;43(2):279-86.Sabbagh J, McConnell RJ, McConnell MC. Posterior composites: Update on cavities and filling techniques. J Dent. 2017;57:86-90.Constantinescu DM, Apostol DA, Picu CR, Krawczyk K, Sieberer M. Mechanical properties of epoxy nanocomposites reinforced with functionalized silica nanoparticles. Proc Struct Integ. 2017;5:647-52.Yadav RD, Raisingani D, Jindal D, Mathur R. A comparative analysis of different finishing and polishing devices on nanofilled, microfilled, and hybrid composite: a scanning electron microscopy and profilometric study. Int J Clin Pediatr Dent. 2016;9(3):201-8.Fernandes ACBCJ, Assunção IV, Borges BCD, Costa GFA. Impact of additional polishing on the roughness and surface morphology of dental composite resins. Rev Port Estomatol Med Dent Cirur Maxilofac. 2016;57(2):74-81.Antonson SA, Yazici AR, Kilinc E, Antonson DE, Hardigan PC. Comparison of different finishing/polishing systems on surface roughness and gloss of resin composites. J Dent. 2011;39(Suppl 1):e9-17.Kumari CM, Bhat KM, Bansal R. Evaluation of surface roughness of different restorative composites after polishing using atomic force microscopy. J Conserv Dent. 2016;19(1):56-62.Pimentel PEZ, Goyatá FR, Cunha LG. Influência da técnica de polimento na lisura superficial de resinas compostas. Clin int j braz dent. 2012;8(2):226-34.Chour RG, Moda A, Arora A, Arafath MY, Shetty VK, Rishal Y. Comparative evaluation of effect of different polishing systems on surface roughness of composite resin: An in vitro study. J Int Soc Prev Community Dent. 2016;6(Suppl 2):166-70.Lins FC, Ferreira RC, Silveira RR, Pereira CN, Moreira AN, Magalhaes CS. Surface roughness, microhardness, and microleakage of a silorane-based composite resin after immediate or delayed finishing/polishing. Int J Dent. 2016;2016:8346782.

Mechanical Degradation of Different Classes of Composite Resins Aged in Water, Air, and Oil.

A significant deterioration of the properties can drastically compromise the survival rate of restorative materials. The aim of this study was to assess flexural strength and hardness of three composite classes: hybrid composite resin (HCR), nanoparticulate composite resin (NCR), and silorane-based composite resin (SBCR). One hundred specimens were prepared for hardness testing by using a split metallic mold measuring 10 mm in diameter and 2 mm deep. Twenty specimens were prepared for each restorative material, randomly assigned for storage in air, distilled water, or mineral oil. After intervals of 24 hours, 30, 60, 90, and 120 days, hardness and flexural strength tests were initially compared in two levels: “storage medium” and “time” within each material group. A two-way analysis of variance was performed (p<0.05) on the variables “material” and “storage time” (p<0.05). The HCR showed to be stable with regard to the evaluation of flexural strength and hardness (p<0.05). A significant reduction occurs for the NCR in comparison to the other groups (p<0.05). The NCR presented the lowest values of hardness and flexural strength kept on water over time. The characteristics of material showed a strong influence on the decrease of the mechanical properties analyzed.

Effect of bleaching protocols on surface roughness and biofilm formation on silorane-based composite resin

Knowledge about the effect of bleaching on behavior of composite resins is important to find a suitable composite resin for restoration of teeth undergoing bleaching. This study aimed to assess the effect of different bleaching protocols on surface roughness and biofilm formation on a silorane-based composite resin. In this in vitro experimental study, 60 silorane-based composite resin samples measuring 3 mm in thickness and 6 mm in diameter were fabricated and polished. They were then randomly divided into four groups (n = 15). In Group 1, samples were stored in distilled water as control. Samples in Groups 2, 3, and 4 were subjected to bleaching with 15% carbamide peroxide, 35% hydrogen peroxide, and 35% hydrogen peroxide activated by light, respectively. Surface roughness was measured using a profilometer. Streptococcus mutans cultured in brain-heart infusion broth was used for the assessment of biofilm formation on the samples. The bacterial colonies were counted using the pure-plate technique. Data were analyzed using one-way ANOVA and post hoc Tukey's tests. Regression model was used to assess the association between surface roughness and biofilm formation (P < 0.05). The mean surface roughness of the four groups was not significantly different (P = 0.11); however, a significant difference was noted in the mean biofilm formation among the groups (P = 0.00). Bleaching decreased biofilm formation. The lowest biofilm formation was noted in the group subjected to light-activated 35% hydrogen peroxide. Increased surface roughness enhanced biofilm formation to a certain level; excessive roughness did not increase biofilm formation.

Effect of Green Tea (Camellia sinensis) Solution on Color Change of Silorane- and Methacrylate-Based Composite Resins

Color change is an undesirable but avoidable effect in composite resin. Limited research has been conducted on the effect of green tea solution on silorane- and methacrylate-based composite resins. In this study, we used 30 silorane- and methacrylate-based composite resin disks (shade A3) (6 mm in diameter and 2 mm in thickness) prepared from Filtek P90 and Filtek Z250. Specimens were divided into six groups (n = 5), and each group was immersed in three green tea solutions at different concentrations (1%, 2%, and 3%) for 6 hours. Color assessment was performed with a spectrophotometer based on CIE*Lab theory, and results were subjected to statistical analysis using one-way ANOVA and independent t-test. Significant differences were observed in Δi* between the two composite disks after immersion in tea solutions (p < 0.05). Color change in silorane-based composite resin was higher than that in methacrylate-based resin; this color change was the highest when silorane-based composite resin was immersed in 3% green tea solution (ΔE = 3.85).

Silorane Based Resin Composite Versus Nanohybrid Resin Composite: Effect of pH of Storage Media on Volumetric Changes and Adaptability at Tooth/Restoration Interface

This study compared dimensional stability and adaptability of two resin composites [Filtek P90 and Filtek Supreme XT] after storage in different pH media. Methods: For dimensional stability, cylindrical specimens were prepared either from Filtek P90 or Filtek Supreme XT. Specimens’ dimensions were measured before and after storage in neutral [pH7] or acidic saliva [pH 3.6] for 1 week, 1month or 3 months. Volumetric changes were calculated. For adaptability, 80 class V cavities were made in sound human teeth. The cavities were restored with Filtek P90 or Filtek supreme XT. The adaptation was evaluated using stereomicroscope; before and after storage in acidic or neutral saliva for 1 week,1 or 3 months. Results: Filtek P90 showed significantly higher contraction compared to Filtek Supreme XT only after 3 months storage. After 1 week or 1 month, the difference in volumetric changes between two material was statistically non-significant. The pH of storage media showed non-significant effect on volumetric changes of both composites. For adaptability to cavity walls in acidic saliva, no statistically significant difference was found between gap dimensions at tooth restoration interface for both Filtek P90 and Filtek Supreme XT. However, in neutral saliva, Filtek P90 showed statistically significantly higher mean gap dimensions than Filtek Supreme XT through all time storage. Conclusions: Silorane-based resin composite undergoes volumetric changes comparable to nanohybrid resin composite except on long term storage where it revealed contraction. The adaptation of silorane based composite was worse compared to that of nanohybrid composite in neutral pH media.

Influence of surface treatment on the performance of silorane-based composite resin in class I restorations: a randomized clinical trial.

The aim of this study was to evaluate the clinical performance of silorane-based composite restorations applied after different surface treatments. This controlled and randomized clinical trial included 26 patients with class I restoration indications. The teeth were randomly assigned to the following treatments: control 1/G1, silorane specific self-etching adhesive (P90 self-etch primer and bond) + silorane-based composite resin (Filtek™ P90 low shrink posterior restorative); G2, 37% phosphoric acid + silorane specific self-etching adhesive + silorane-based composite resin; G3, blasting with aluminum oxide + silorane specific self-etching adhesive + silorane-based composite resin; and control 2/G4, self-etching adhesive (Adper™ SE Plus self-etch adhesive) + dimethacrylate-based composite resin (Filtek™ P60 posterior restorative). The clinical performance was evaluated at baseline and after 1year. A total of 141 restorations were made and evaluated. For all clinical criteria evaluated, no significant difference was found between the surface treatments at baseline and after 1year (p > 0.05). After 1year, only the group with 37% phosphoric acid + silorane specific self-etching adhesive (G2) showed a significant reduction in marginal adaptation (p < 0.05). In general, all surface treatments showed an adequate clinical performance for silorane-based composite resin in class I restorations. However, a reduction in the marginal adaptation after 1year was found when additional phosphoric acid etching was used prior to silorane specific self-etching adhesive. The use of phosphoric acid etching prior to specific self-etching adhesive can adversely affect the marginal adaptation of silorane-based restorations.

Silorane versus methacrylate composites: A comparative study of the micro-leakage

This in vitro study aimed to evaluate the micro-leakage at the occlusal and cervical margins in class II cavities in permanent molars restored with a low shrink silorane resin composite (Filtek P90) applied with or without etching and two methacrylate-based composite resins (valux plus and Amelogen® plus). Two standardised class II box cavities were prepared in proximal surfaces of 60 sound non-fluorotic permanent molars which were divided into three groups of 20 each according to the type of composite. Group I: silorane-based composite (Filtek P90) in the mesial cavity and methacrylate-based microhybrid composite (Adper single bond 2/valux plus) in the distal cavity, Group II: silorane-based composite in the mesial cavity and silorane-based composite with previous etching in the distal cavity, and Group III: silorane-based composite in the mesial cavity and methacrylate-based micro-hybrid composite (PQ1 /Amelogen plus) in the distal cavity. The samples underwent an artificial aging with thermocycling. Root apices were sealed with transparent orthodontic resin and coated with transparent varnish except 1 mm around the restoration. The specimens were immersed in 1% methylene blue solution at room temperature for 48 hour. The samples were sectioned longitudinally in the mesiodistal direction and evaluated under a stereomicroscope at 20X. Scoring was done according to the depth of methylene blue penetration into the cavities. Statistical analysis of the data was performed using SPSS 17.0 software. Silorane-based composite resin showed less micro-leakage than the methacrylate-based composites. Etching improved the sealing ability of silorane restorations. Silorane-based composite preceded by etching had less micro-leakage among the other materials used in this in vitro study. Keywords: Silorane, methacrylate based composite, sealing, micro-leakage, class II cavity

Effect of surface preparation with Nd:YAG and Er,Cr:YSGG lasers on the repair bond strength of lithium disilicate glass ceramic to a silorane-based composite resin.

Background. This study was undertaken to evaluate the repair bond strength of lithium disilicate glass ceramic to a silorane-based composite resin after surface preparation with Nd:YAG and Er,Cr:YSGG lasers. Methods. A total of 102 lithium disilicate glass ceramic samples (IPS e.max Press), measuring 5 mm in diameter and 4 mm in thickness, were randomly assigned to 6 groups (n=17): group 1, no surface preparation (control); group 2, acid etching with 9.5% hydrofluoric acid (HF); group 3, surface preparation with 4.5-W Nd:YAG laser; group 4, surface preparation with 6-W Nd:YAG laser; group 5, surface preparation with 1.5-W Er,Cr:YSGG laser; and group 6, surface preparation with 6-W Er,Cr:YSGG laser. After preparation of surfaces and application of silane, all the samples were repaired with the use of a silorane-based composite resin, followed by storage in distilled water at a temperature of 37°C for 24 hours and thermocycling. Finally, the samples were subjected to a shearing bond strength test; the fracture modes were determined under a stereomi-croscope. Results. There were significant differences between the HF group and the other groups (P=0.000). Two-by-two comparisons of the other groups revealed no significant differences (P>0.05). Conclusion. Use of HF proved the most effective surface preparation technique to increase the repair bond strength between lithium disilicate glass ceramic and silorane-based composite resin; compared to the control group.

Comparison of the Shear Bond Strength of Silorane-Based Composite Resin and Methacrylate Based Composite Resin to MTA.

Background. Mineral trioxide aggregate (MTA) is a material that has recently gained popularity in the application of the vital pulp therapy. Along with the increasing use of MTA to this end, the permanent restoration material to be placed on MTA has become a significant issue. The aim of this in vitro study was to investigate the bond strength of the novel low-shrinkage silorane-based composite resin (SBC) to MTA. Methods. Twenty acrylic blocks filled with MTA were prepared for this study. SBC was the test group and methacrylate-based composite resin (MBC) was used as the control group. Shear bond strength test was performed to determine the bond strength. The surfaces of broken samples were evaluated under a stereomicroscope and grouped as adhesive, cohesive and mixed. Data were examined by statistical analysis. Results. Statistical analysis revealed that SBC exhibited higher shear bond strength than the control group. It was observed that most of the failures in the test group were of cohesive type within MTA. Conclusion. Based on the results, SBC showed higher shear bond strength than the control group; however, clinical follow-up is needed to evaluate the clinical success.

Effect of Various Laser Surface Treatments on Repair Shear Bond Strength of Aged Silorane-Based Composite.

Introduction: Successful repair of composite restorations depends on a strong bond between the old composite and the repair composite. This study sought to assess the repair shear bond strength of aged silorane-based composite following surface treatment with Nd:YAG, Er,Cr:YSGG and CO2 lasers. Methods: Seventy-six Filtek silorane composite cylinders were fabricated and aged by 2 months of water storage at 37°C. The samples were randomly divided into 4 groups (n=19) of no surface treatment (group 1) and surface treatment with Er,Cr:YSGG (group 2), Nd:YAG (group 3) and CO2 (group 4) lasers. The repair composite was applied and the shear bond strength was measured. The data were analyzed using one-way analysis of variance (ANOVA) and Tukey posthoc test. Prior to the application of the repair composite, 2 samples were randomly selected from each group and topographic changes on their surfaces following laser irradiation were studied using a scanning electron microscope (SEM). Seventeen other samples were also fabricated for assessment of cohesive strength of composite. Results: The highest and the lowest mean bond strength values were 8.99 MPa and 6.69 MPa for Er,Cr:YSGG and control groups, respectively. The difference in the repair bond strength was statistically significant between the Er,Cr:YSGG and other groups. Bond strength of the control, Nd:YAG and CO2 groups was not significantly different. The SEM micrographs revealed variable degrees of ablation and surface roughness in laser-treated groups. Conclusion: Surface treatment with Er,Cr:YSGG laser significantly increase the repair bond strength of aged silorane-based composite resin.

Acoustic emission characteristics of methacrylate-based composite and silorane-based composite during dental restoration according to a variety of C-factor

Acoustic emission (AE) characteristics according to a variety of Configuration factor (C-factor) of methacrylate-based composite resin (Clearfil AP-X, Kuraray) and silorane-based composite resin (Filtek P90, 3M ESPE) during dental restoration were investigated in combination with the Finite element stress analysis (FESA). AE measurement results showed that most micro-cracks occurred within 1 min after the light irradiation started. As the C-factor increased, average cumulative AE hits and average cumulative AE energy increased. Those AE parameters for AP-X with high shrinkage strain were higher than P90 with low shrinkage strain. FESA results showed that the maximum shrinkage stress appeared at the resin/tooth interface on the specimen surface. The stress of AP-X was bigger than that of P90, which coincided with the AE behaviors with increasing C-factor.

Comparison of Shear Bond Strength of Silorane and Methacrylate-Based Composites to IPS Empress 2 Ceramic with Various Surface Treatments

Objectives Treatment of chipped or fractured porcelain with composite resin is considered as an economic treatment for minor fractures in ceramics. The aim of this study was to evaluate the effect of different ceramic surface treatments on bond strength of methacrylate-based and silorane-based composite resin to IPS Empress 2.Methods Sixty IPS Empress 2 ceramic discs were fabricated and after etching with 9.6% hydrofluoric acid, they were divided into six groups:(1) P90 primer and bonding agent + Filtek P90 composite resin; (2) Single Bond + Filtek Z250 composite resin; (3) similar to the first group+ silane pretreatment; (4) similar to the second group + silane pretreatment; (5) silane pretreatment + Filtek P90 composite resin; (6) silane pretreatment + Filtek Z250 composite resin. Each specimen was subjected to shear load until fracture occurred. Statistical analysis was performed using one-way ANOVA, Tukey’s test and t-test.Results Regardless of the type of surface treatment, Z250 composite demonstrated significantly higher shear bond strength than P90 composite (P < 0.05). Group 4 showed the highest shear bond strength values with statistically significant difference with other groups while the fifth group showed the least values (P < 0.05).Conclusion Silane coating along with the application of adhesive system and etching in methacrylate-based composite was the most efficient surface treatment in terms of bond strength.

Effect of preheat repetition on color stability of methacrylate- and silorane-based composite resins.

Background. The aim of this study was to investigate the effect of preheating methacrylate- and silorane-based composite resins on their color stability up to 40 times at 55‒60°C. Methods. Seventy-six methacrylate and silorane-based composite resin samples, with a diameter of 10 mm and a height of 2 mm, were divided into 4 groups (n=19). After the samples were prepared, their color parameters were determined using a reflective spectrophotometer. The composite resin samples were separately stored in a solution of tea for 40 consecutive days. Then the samples underwent a color determination procedure again using a spectrophotometer and color changes were recorded. Finally two-way ANOVA was used to study the effect of composite temperature on its staining (P<0.05). Independent-samples t-test was used to evaluate changes in conversion rates of preheated composite resin samples compared to non-heated samples at P=0.005 and P=0.029 for silorane-based and Z250 composite resin samples, respectively. Results. Both composite resin type (P=0.014) and preheating (P<0.001) had significant effects on ΔE. Conclusion. Repeated preheating of methacrylate- and silorane-based composite resin samples, up to 55‒60°C for 40 rounds, resulted in more color changes compared with unheated composite resin samples. After storage in a solution of tea the color change rate in the composite resin samples of silorane-based was higher than the Z250 composite resin samples.

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.

Effects of different kinds of beers on the surface roughness of glazed and polished methacrylate and Silorane-based composites: a 1-month study.

The aim of this in vitro study was to evaluate the effect of different kind of beers on the surface roughness of glazed and polished methacrylate- and Silorane-based resin composites after different immersion periods. Methacrylate-based resin composites (Tetric N-Ceram, Ceram-X) and a Silorane-based resin composite (Filtek Silorane) were tested in the study. A total of 126 specimens (n=42 for each composite) were fabricated using a cylindrical custom metal mould. Surface roughness measurement was performed using a profilometer at baseline and after a 1-week and 1-month immersion in different kind of beers or distilled water. The results were analysed using repeated measure ANOVA and Tukey's HSD test (α=0.05). Repeated measure ANOVA results revealed that immersion period was a significant factor in the surface roughness of the tested specimens (p<0.001). The lowest surface roughness values were obtained with the specimens' polished Optidisc+BisCover LV. Regardless of the polishing systems used, Tetric N-Ceram showed the statistically lowest surface roughness values (p<0.05), whereas Filtek Silorane showed the highest surface roughness (p<0.001). The surface roughness values of the tested resin composites were affected by the polishing procedure used, the exposure time in the solutions and the type of composite resin.

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations.Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05.Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001). Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001). In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001).Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.