Silorane Resin Research Articles

Экзогенные причины изменения цвета прямых композитных реставраций зубов

INTRODUCTION: Technological processes of manufacture of dental materials with different manipulation qualities and physicochemical properties, are being constantly improved. Nowadays, a doctor can select the optimal material for each specific clinical case and to achieve the maximal functional and esthetic result. Thus, the most common method of restoration of the tooth crown is direct restoration using composite materials. In the last decade, the demand for conservative restorative dentistry has sharply increased. In turn, esthetic characteristics of composite materials are of key importance both in filling of teeth of the anterior group, and in restoration of the lateral teeth. Discoloration of the dental filling material is a common cause of its replacement. Therefore, to achieve a positive long-term result, it is important to prevent the change of composite color over time. This requires a clear understanding of the causes and conditions of discolorations. AIM: To systematize the scientific data accumulated in recent years concerning the study of the effect of coloring substances of human diet on the aesthetic characteristics of composite materials for direct dental restoration. CONCLUSION: Various pigments present in food and beverages have an effect on composite materials, reducing their microhardness, increasing the rate of wear and changing the color. It depends on the composition of the composite matrix and its chemical structure. Many studies prove that BIS-GMA based composite materials are most susceptible to staining, while UDMA and BIS-EMA matrices, as well as silorane resins, are stained to a lesser extent.

Release of Organic Compounds by Composites Depending on the Source of Curing Light, Immersion Solution and PH

Objectives: This in vitro study evaluated the release of organic compounds by composite KaloreTM (GC FUJI) and FiltekTM Silorane (3M ESPE) by means of fluorescence spectrometry, varying the source of curing light, the immersion solution and the pH of these immersions. Methods: 56 specimens were made for each composite, 28 polymerized with halogen light and 28 with LED light. Samples of each composite were stored in water with neutral or acidic pH and in saliva with acidic or neutral pH (n=7 specimens for each condition examined). The reading was performed between 1 and 672 hours (28 days).The results were statistically analyzed using the Tukey and ANOVA tests, adopting the significance level of 5%. Results: The KaloreTM resin released more organic compounds than FiltekTMSilorane in the aqueous environment, either in the polymerization by the halogen light as by the LED light in both pHs (p<0.05). There was no significant difference in aqueous environment, only when polymerized by halogen light and acid pH (p>0.05). When immersed in artificial saliva, the KaloreTM resin also released more organic compounds than FiltekTMSilorane, but there was only statistically significant difference when polymerized by LED light, both in neutral pH and at acid pH. Both resins released greater amount of organic compounds in aqueous solution, compared to saliva, regardless of the light source and pH (p<0.05). Conclusion: Even the most modern resins such as KaloreTM and FiltekTM Silorane release organic compounds and the polymerization by LED light decreases the liberation of organic compounds by FiltekTM Silorane resin.

Cytotoxicity and degree of conversion of methacrylate and silorane

Composites have been proven to have a cytotoxiceffect on a variety of tissues and cells. Aim: The aim of thisstudy was to analyse the degree of conversion of resinsand its correlation with the cell viability in primary gingivalfibroblasts. Methods: Resin-based silorane (Filtek P90)and conventional methacrylate resins (Filtek Z100, FiltekZ250 and Filtek Z350XT) were used to evaluate cell viabilityand the degree of conversion. The resins were light-cured bya LED for 20 and 40 seconds. The degree of conversion wasanalysed by Fourier transform infrared spectroscopy. Cellularmetabolism was evaluated after 24 hours by the MTT assay(n = 6) using the storage solution of composite resin foreither 24 hours or 12 days. Variance analysis (ANOVA) witha Bonferroni correction (p < 0.05) was performed to comparethe groups. Results: The composite Filtek P90 showed ahigher degree of conversion when polymerised for 40 or20 seconds, while the composites Filtek Z100, Filtek Z250 andFiltek Z350XT showed similar degree of conversion. Only theFiltek Z100 resin was cytotoxic. Conclusion: We found nostatistically significant correlation between cell viability andthe degree of conversion.

Effect of Insertion Techniques on the Shear Bond of Low Shrinkage Composite Restorative Materials

ABSTRACTBackground: Dental composite has been used in dentistry offering a significant number of benefits andadvantages. However, the polymerization shrinkage remains a major drawback of these materials whicheffect on their bond strength. Objectives: this study aimed to evaluate the shear bond strength (SBS) of
 low shrinkage composite with different insertion techniques (layering and bulk) using two storage condi-tions (wet and dry) then compare them with conventional methacrylate composites. Methods: one handed
 and eight cylindrical shaped specimens were fabricated from three different types of dental composite di-vided into 12 groups according to insertion technique and the storage condition (n=9/groups). Shear test
 were carried out using universal testing machine with speed of 0.5mm/min. Data were analyzed using one-way ANOVA and the Tukey test. The fractured surfaces of the test samples were visually evaluated using
 light microscope at 20 and 40 magnifications and classified their fracture into adhesive, cohesive or mixed.Results: Filtek Supreme composite inserted in bulk technique and stored dry showed the highest values(36.45 MPa). Silorane and Tetric Ceram composites were lower in their all groups except for specimensinserted in layers was further decreased by wet storage (21.90, 21.35 MPa).Conclusion: It can be concluded that insertion technique and storage condition type didn’t significantlyaffect SBS of Silorane resin in comparison with other methacrylate resins, except for the specimens insertedin layers and wet condition, there was a significant decrease in SBS values.

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 conditioning methods, adhesive systems and resin composite on repair strength of dimethacrylate and silorane resin composites

This study evaluated the effect of surface conditioning methods and adhesive systems on the repair bond strength of resin composites. Specimens (FLS: Filtek LS) (N = 144) were prepared using a silicone matrix. The specimens were stored in distilled water and then were randomly divided into the twelve groups (n = 12) according to the surface conditioning method (unground or diamond bur) and adhesive system (no adhesive, LS: Filtek LS, AS: Adper Scotchbond SE Plus) and resin composite (FLS: Filtek LS; FS: Filtek Supreme). The specimens were fixed in an hourglass-shaped silicone matrix and the other half of the specimen was restored. Hourglass-shaped specimens (n = 12) were used as positive control to measure the cohesive strength of the resin composite (Filtek LS). Microtensile bond test was performed (0.5 mm/min) and failure types were analyzed. Data were analyzed using two-way analysis of variance, Tukey’s and Dunnett’s tests (α = 0.05). Adhesive protocol and resin composite significantly affected the results (p < 0.05). For the FS composite, the highest results were obtained using LS adhesive with (18.4 ± 7.7) and without (18.8 ± 4.8) bur roughening. For FLS composite, the highest results were obtained using AS adhesive with (33.2 ± 7.1) and without (25.7 ± 3.6) bur roughening. Without the use of adhesive resin, significantly lower bond strength results were observed with both LS (5 ± 2.1, 4.5 ± 1.5) and FLS (2.2 ± 1.2, 4.4 ± 1.1) for unground and diamond bur roughened groups, respectively (p < 0.0001). Cohesive strength of the FLS (52.3 ± 7.6) was significantly higher than any of the repaired groups (p < 0.0001). FS–LS combination and the groups repaired without adhesive presented more adhesive (Type I) failures.

Influence of filling technique and bevel preparation on marginal sealing of conventional and low shrinkage composite restorations

AIM: The aim of this study was to evaluate two composite restorations (conventional methacrylate-based and low shrinkage-based silorane), associated or not to beveling and incremental technique, in relation to the microleakage and marginal gap formation tests. MATERIAL AND METHODS: 30 sound human molars had their mesial and distal surfaces prepared with and without bevel. The teeth were divided into six groups according to the type of resin (conventional nanofilled or silorane resin), and restorative filling technique (incremental technique or builk). Microleakage and marginal gap formation data were statistically analyzed by Kruskal-Wallis and Chi-Square tests, with a significance level set at 5%. RESULTS: Group 1 (Z350 XT, without bevel, incremental technique) presented highest rate of microleakage and marginal gap in most of the restorations, with statistically significant differences. Groups 4 and 6 (P90, beveled, builk and P90, beveled and incremental technique) had lower rates of microleakage and absence of marginal gaps in most of the restorations. CONCLUSION: It’s concluded that the silorane showed lower rates of marginal gaps and microleakage, when compared to the conventional methacrylate-based resin. Bevel preparation was effective in reducing microleakage and marginal gaps for both resins used. Incremental technique was not necessary when associated with low shrinkage composite resin.

Impact of monomer functional groups of resin-based materials on the interaction with water

Objective: The objective of this in vitro study was to compare dentin bonding systems and composite resins based on their functional groups in terms of water sorption (WS) and water solubility (WSB). Material and Methods: Three dentin bonding systems (Adper Single Bond 2 – 3M ESPE, Clearfil SE Bond – Kuraray, P90 Adhesive System – 3M ESPE) and three commercial composite resins (Filtek Z350 – 3M ESPE, Filtek Z250 – 3M ESPE, Filtek P90 – 3M ESPE) were tested. Eight specimens of each material were prepared to evaluate the WS and WSA. The discs were individually stored in a desiccator until constant mass was achieved. Specimens were then individually stored in distilled water until the mass was stabilized again. Finally, the specimens were dried again in the desiccator until constant mass was obtained. WS and WSA were calculated from these measurements. Data were analyzed by one-way ANOVA and Tukey post hoc test (p &lt; 0.05). Results: Filtek Silorane-Bond presented the lowest values of WS, and Clearfil SE Bond presented the lowest WSB. Filtek Silorane resin showed the lowest WS and WSA results. Conclusion: Based on the results, it can be concluded that the WS and WSB were influenced by the composition of the materials. The main functional group of the materials determines their susceptibility to water and influences their performance.

Development of methacrylate/silorane hybrid monomer system: Relationship between photopolymerization behavior and dynamic mechanical properties.

Resin chemistries for dental composite are evolving as noted by the introduction of silorane-based composites in 2007. This shift in the landscape from methacrylate-based composites has fueled the quest for versatile methacrylate-silorane adhesives. The objective of this study was to evaluate the polymerization behavior and structure/property relationships of methacrylate-silorane hybrid systems. Amine compound ethyl-4-(dimethylamino) benzoate (EDMAB) or silane compound tris(trimethylsilyl) silane (TTMSS) was selected as coinitiators. The mechanical properties of the copolymer were improved significantly at low concentrations (15, 25, or 35 wt %) of silorane when EDMAB was used as coinitiator. The rubbery moduli of these experimental copolymers were increased by up to 260%, compared with that of the control (30.8 ± 1.9 MPa). Visible phase separation appeared in these formulations if the silorane concentrations in the formulations were 50-75 wt %. The use of TTMSS as coinitiator decreased the phase separation, but there was a concomitant decrease in mechanical properties. In the neat methacrylate formulations, the maximum rates of free-radical polymerization with EDMAB or TTMSS were 0.28 or 0.06 s(-1) , respectively. In the neat silorane resin, the maximum rates of cationic ring-opening polymerization with EDMAB or TTMSS were 0.056 or 0.087 s(-1) , respectively. The phase separation phenomenon may be attributed to differences in the rates of free-radical polymerization of methacrylates and cationic ring-opening polymerization of silorane. In the hybrid systems, free-radical polymerization initiated with EDMAB led to higher crosslink density and better mechanical properties under dry/wet conditions. These beneficial effects were, however, associated with an increase in heterogeneity in the network structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 841-852, 2016.

Effect of Bleaching and Thermocycling on Resin-Enamel Bond Strength.

The aim of this study was to evaluate the effect of bleaching and thermocycling on microshear bond strength of bonded resin composites to enamel. Enamel slices were prepared from ninety-six intact human premolars and resin composite cylinders were bonded by using Adper Single Bond 2 + Filtek Z350 or Filtek silorane adhesive and resin composite. Each essential group was randomly subdivided to two subgroups: control and bleaching. In bleaching group, 35% hydrogen peroxide was applied on samples. Thermocycling procedure was conducted between 5°C and 55°C, for 3.000 cycles on the half of each subgroup specimen. Then microshear bond strength was tested. Methacrylate-based resin composite had higher bond strength than silorane-based one. The meyhacrylate-based group without bleaching along with thermocycling showed the most bond strength, while bleaching with 35% carbamide peroxide on silorane-based group without thermocycling showed the least microshear bond strength. Bleaching caused a significant degradation on shear bond strength of silorane-based resin composites that bonded using self-etch adhesive resin systems.

Durability of silorane repair with silorane and methacrylate resin.

Objective: The durability of bonded interface between silorane (SIL) and methacrylate-based (MET) composite resins wasn’t investigated yet. The purpose was to evaluate the repair strength (RS) and nanoleakage of the SIL repair using silorane- or methacrylate-based materials immediately [IM] or after 6 months of water storage [6M]. Materials and Methods: fifteen resin blocks (Filtek P90, 3MESPE) were polished, sandblasted with 50-µm aluminum oxide sandblasting and cleaned with 37% phosphoric acid. Then the specimens were divided into three groups: SIL-SIL (adhesive and composite resin); SIL-MET (silorane adhesive and methacrylate based composite) and MET-MET (methacrylate-based adhesive and composite resin) were used for the repair. Composite-composite bonded sticks (0.9 mm2) were sectioned and divided to be tested in tension (1.0 mm/min) IM or 6M. Two sticks from each tooth, at each time, were immersed in a 50% silver nitrate solution and evaluated by SEM. Data were analyzed by two-way repeated measures ANOVA and Tukey´s tests. Results: The RS of the SIL was not dependent upon the adhesive and composite used for the repair. A significant reduction of the RS was observed for all groups after 6M. Conclusions: Both materials can be used for the repair of the silorane composite, despite degradation occur after 6M.

Five-year evaluation of a low-shrinkage Silorane resin composite material: A randomized clinical trial

The aim of the present study was to investigate the clinical performance of a low-shrinkage silorane-based composite material (Filtek™ Silorane, 3 M-Espe) by comparing it with a methacrylate-based composite material (Ceram•X™, Dentsply DeTrey). A number of 72 patients (158 restorations) participated in the study. After 5 years, a total of 107 restorations (52 Filtek™ Silorane, 55 Ceram•X™) in 48 patients were evaluated. Only class II restorations were included. All the restorations were placed by the same dentist, and the restorations were scored by one experienced dentist/evaluator. Materials were applied following the manufacturer's instructions. The primary outcome was marginal adaptation. Secondary outcomes were: marginal discoloration, approximal contact, anatomic form, fracture, secondary caries, and hypersensitivity. After 5 years, no statistically significant differences between the two materials were found in marginal adaptation either occlusally (p = 0.96) or approximally (p = 0.62). No statistically significant differences were found between the two materials in terms of approximal contact, anatomic form, fractures, or discoloration. Secondary caries was found in two teeth (Filtek™ Silorane). One tooth showed hypersensitivity (Ceram•X™). Restorations of both materials were clinically acceptable after 5 years. This study did not find any advantage of the silorane-based composite over the methacrylate-based composite, which indicates that the low-shrinkage of Filtek™ Silorane may not be a determinant factor for clinical success in class II cavities. This paper is the first to evaluate the 5-year clinical performance of a low-shrinkage composite material.

Effect of pre-treatment with chlorhexidine on the retention of restorations: a randomized controlled trial.

This study aimed to evaluate the effect of chlorhexidine (CHX) application on etched dentin on the 6-month retention of restorations placed on non-carious cervical lesions (NCCLs). A randomized controlled split-mouth and triple blind trial was carried out. Patients (n=42) with at least two non-carious cervical lesions were included. NCCLs were randomly assigned to two groups: control (placebo solution) or test group (2% CHX solution for 60 s after acid etching and before the adhesive application). Class V restorations (n=169) were performed with an etch-and-rinse adhesive system and composite resin by 10 trained operators. A calibrated examiner evaluated the restorations at 1 week (baseline) and at 6 months using the FDI criteria. The primary outcome was retention of the restorations. The analysis of factors associated to failure of restorations was carried out by Fisher's exact test (α=0.05). After 6 months of follow-up, 3.4% (CI 95% 1.3-7.3) of the restorations failed. There was no statistically significant difference between control and CHX (p=0.920). Regarding the cavity variables, deeper (p=0.04), wider (p=0.004) and wedge-shaped (p=0.033) cavities failed more. Both treatments provided acceptable clinical performance of the restorations. The use of CHX as a adjuvant in dentin adhesion did not influence the retention of Class V restorations after 6 months of follow-up.

Evaluation of shear bond strength of silorane resin to conventional, resin-modified glass ionomers and nano-ionomer cements

To evaluate the shear bond strength of silorane composite resin to conventional and resin-modified glass ionomer cements. Shear bond strengths of Vitrebond (Group I), Ketac N100 (Group II) and Ketac Bond (Group III) glass ionomer cements to the composite Filtek P90 were evaluated. The bond strength was tested using a universal testing machine at a cross-head speed of 0.5mm/min. Comparison between the groups was carried out using an analysis of variance test and pairwise comparison using Tukey's post-hoc test with a significance level of P≤0.05. The measured bond strengths were 17.14±3.39MPA for Group I (Vitrebond), 15.34±3.39MPa for Group II (Ketac N100) and 14.12± 2.79MPa for Group III (Ketac Bond). Group I achieved higher bond strength than Groups II and III. Resin-modified glass ionomer cement (i.e. Vitrebond) appears to be preferable to nano-ionomer glass ionomer cement (i.e. Ketac N100) and conventional glass ionomer cement (i.e. Ketac Bond) as a base under low-shrink posterior composite (i.e. Filtek P90).

A comparison of the mechanical properties of a modified silorane based dental composite with those of commercially available composite material

ObjectivesThe aim of this study was to compare the mechanical properties of the nano-hydroxyapatite incorporated silorane composite material with the commercially available dental composites. MethodsFiltek Silorane resin composite was incorporated with 5% and 10% nano-hydroxyapatite crystals and then mechanically tested in comparison along with the commercially available Filtek Silorane and Filtek Supreme XT after 1, 14, 30 and 90 days period. ResultsThe mechanical tests revealed that the modified silorane based dental composite had a significant increase in the mechanical properties than the commercially available Filtek Silorane and Filtek Supreme XT. SignificanceThe collected data suggests that nano-hydroxyapatite crystals modified silorane may provide the clinicians with a better composite materials having a longer life especially in the posterior restorations where the masticatory forces are very much high.

Marginal leakage of class V cavities restored with silorane-based and methacrylate-based resin systems

The aim of this study was to compare the microleakage of class V cavities restored by silorane resin with those restored by the methacrylate resin system. Sixty standardized class V cavities were prepared on premolars. The teeth were restored with Filtek(TM) Silorane and Silorane(TM) System Adhesive, Filtek(TM) Silorane and Adper(TM) Easy One and Filtek(TM) Supreme XT and Adper(TM) Easy One. The area and the depth of dye leakage were measured. Considering dye leakage area, the best results were achieved in group I (mean-M=0.114±0.083 mm(2)), then in group III (M=0.384±0.480 mm(2)) and finally in group II (M=5.389±6.587 mm(2)). Considering the depth of dye leakage, there was a significant difference between group I (mean rank-m.r.=1.23±0.44 mm) and II (1.98±0.83 mm), group II and III (1.23±0.40 mm). In this study silorane composite and its adhesive showed less microleakage than the methacrylate composite, and it showed compatibility only with its assigned adhesive. Less microleakage of silorane restorations could provide better and long lasting composite fillings.

Marginal sealing ability of silorane and methacrylate resin composites in class II cavities: A scanning electron microscopic study

Aim and Objectives:To comparatively evaluate the microleakage and microgap formation along the gingival margin in class II cavities restored with silorane resin composite and methacrylate resin composite with and without flowable resin liner.Materials and Methods:Sixty human mandibular premolars were distributed into three groups, each group containing 20 teeth (n = 20). Mesial (subgroup A) and distal (subgroup B) box cavities were prepared with gingival margin above and below cemento enamel junction (CEJ), respectively, in each tooth and restored as follows — Group I — Silorane resin composite with self-etch primer and bond (Filtek P90, 3M ESPE MN, USA). Group II — Methacrylate resin composite (Filtek P60, 3M ESPE MN, USA) and self-etch adhesive (Adper Easy one, 3M ESPE MN, USA). Group III — Methacrylate resin composite with self-etch adhesive and a flowable resin liner (Filtek Z350 XT, 3M ESPE MN, USA). The teeth were thermocycled and immersed in 50% silver nitrate solution before sectioning. The specimens were observed under scanning electron microscope for dye penetration and microgap formation. The data was subjected to statistical analysis using Kruskal-Wallis test and Mann-Whitney U test using SPSS version 18.Results:Subgroup A in all the three groups showed significantly less microleakage and microgap formation compared to subgroup B with P < 0.05.Intergroup comparison of subgroup A did not show statistically significant difference, whereas subgroup B showed statistically significant difference for microleakage between group I and group II (P = 0.003), group III and group II (P = 0.002).Conclusion:Silorane resin composite and methacrylate resin with liner showed significantly less microleakage in class II cavities along the gingival margin placed below CEJ compared to methacrylate resin without liner. All the study groups showed less microleakage and microgap formation along the gingival margin placed above CEJ.

Effect of Surface Treatments on Microtensile Bond Strength of Repaired Aged Silorane Resin Composite

This laboratory study compared the repaired microtensile bond strengths of aged silorane resin composite using different surface treatments and either silorane or methacrylate resin composite. One hundred eight silorane resin composite blocks (Filtek LS) were fabricated and aged by thermocycling between 8°C and 48°C (5000 cycles). A control (solid resin composite) and four surface treatment groups (no treatment, acid treatment, aluminum oxide sandblasting, and diamond bur abrasion) were tested (N=12 blocks, 108 beams/group). Each treatment group was randomly divided in half and repaired with either silorane resin composite (LS adhesive) or methacrylate resin composite (Filtek Z250/Single Bond Plus). After 24 hours in 37°C distilled water, microtensile bond strength testing was performed using a non-trimming technique. Surface topography after surface treatment was analyzed using scanning electron microscopy (SEM). Failure mode was examined using optical microscopy (50×). Weibull-distribution survival analysis revealed that aluminum oxide sandblasting followed by silorane or methacrylate resin composite and acid treatment with methacrylate resin composite provided insignificant differences from the control (p>0.05). All other groups were significantly lower than the control. Failure was primarily adhesive in all groups. Aluminum oxide sandblasting produced microtensile bond strength not different from the cohesive strength of silorane resin composite. After aluminum oxide sandblasting, aged silorane resin composite can be repaired with either silorane resin composite with LS system adhesive or methacrylate resin composite with methacrylate dental adhesive.

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.

An in vitro evaluation of shear bond strength of silorane and bis-GMA resin-based composite using different curing units

Aim:To evaluate shear bond strength of silorane and bis-GMA based composite resins using self-etch and total-etch adhesive systems, and compare the effect of Quartz-tungten-halogen (QTH) and Light emitting diode (LED) on the shear bond strength of the experimental materials.Materials and Methods:Flat dentin surfaces were exposed on intact extracted molars and composite resin was built 2 mm in diameter. Teeth were divided randomly into four groups. Groups 1 and 2 were restored with P90 system adhesive and Filtek P90 and cured with QTH and LED units respectively. Groups 3 and 4 were restored with total etch adhesive and Filtek Z100 and cured with QTH and LED units respectively. Specimens were subjected to shear bond strength testing using Instrom Universal testing machine.Results:Data was subjected to one-way analysis of variance. Total-etch groups gave significantly higher shear bond strength values than the self-etch groups. No significant difference in shear bond strength was found between Groups 3 and 4, while Group 1 showed significantly higher values than Group 2.Conclusion:Type of light curing unit is not a significant factor affecting shear bond strength for bis-GMA RBCs using total-etch technique; while for curing silorane resin based composite (RBCs), conventional halogen curing units showed better results.