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

OBJECTIVES: The aim of this study was to evaluate the clinical performance of silorane-based composite restorations applied after different surface treatments. MATERIALS AND METHODS: 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 1 year. RESULTS: 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 1 year (p > 0.05). After 1 year, only the group with 37% phosphoric acid + silorane specific self-etching adhesive (G2) showed a significant reduction in marginal adaptation (p < 0.05). CONCLUSION: 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 1 year was found when additional phosphoric acid etching was used prior to silorane specific self-etching adhesive. CLINICAL RELEVANCE: The use of phosphoric acid etching prior to specific self-etching adhesive can adversely affect the marginal adaptation of silorane-based restorations.

Marginal integrity of low-shrinking versus methacrylate-based composite: effect of different one-step self-etch adhesives.

The aim of the study was to evaluate the influence of composite type and adhesive system on the quality of marginal adaptation in standardized Class V cavities before and after thermo-mechanical loading (TML). The cavities were restored using different combinations of three adhesive systems [(Silorane System Adhesive (SSA), Clearfil S3 Bond (S3), G-Bond (G-B)] and two resin composite materials (Filtek Silorane, Clearfil AP-X). Six groups (n = 10): Group A (SSA-Primer + SSA-Bond, Filtek Silorane), Group B (SSA-Primer + SSA-Bond, Clearfil AP-X), Group C (S3 + SSA-Bond, Filtek Silorane), Group D (S3 + SSA-Bond, Clearfil AP-X), Group E (G-B + SSA-Bond, Filtek Silorane) and Group F (G-B + SSA-Bond, Clearfil AP-X) were defined. Marginal adaptation was assessed on replicas in the SEM at 200 × magnification before and after TML (3000 × 5-55 °C, 1.2 106 × 49 N; 1.7 Hz) under simulated dentinal fluid. The highest scores of continuous margins (%CM) were observed in the group F (G-B + SSA-Bond, Clearfil AP-X: before loading 96.4 (±3.2)/after loading 90.8 (±7.0)). A significant effect of adhesive system, composite type and loading interval was observed on the results (p < 0.05). Significantly lower scores of %CM were observed for silorane-based composite (Filtek Silorane) after TML in comparison with methacrylate-based composite (Clearfil AP-X) considering total marginal length (p < 0.05). For both Filtek Silorane and Clearfil AP-X, G-Bond performed significantly better than SSA-Primer and Clearfil S3 Bond (p < 0.05). For all combinations of one-step self-etch adhesives and SSA-Bond resin coating, silorane-based low-shrinking composite exhibited inferior marginal adaptation than did the methacrylate-based composite.

Effect of timing of repair on repair bond strength of methacrylate- and silorane-based composite resins.

Successful repair of defective composite resin restorations is considered a conservative treatment. The aim of this study was to compare the repair bond strengths of a methacrylate composite (MC) and a silorane composite (SC) repaired after 5 different intervals. Seventy-two test specimens of each material (MC and SC) were prepared. The specimens of each material were divided into 6 groups (n = 12): 1, control (additional composite bonded immediately after polymerization of the substrate composite resin); 2, repaired after 20 minutes; 3, repaired after 24 hours; 4, repaired after 1 week; 5, repaired after 1 month; and 6, repaired after 6 months. Repair consisted of placement of a layer of adhesive bonding agent and then new composite using a plastic mold. Each repair was made with the same material as the original specimen but in a different shade to facilitate fracture assessment. The repaired specimens were stored in distilled water at 37°C for 24 hours before they were submitted to a shear test. There was no statistically significant difference between group MC1 and the other MC groups, except for group MC4, which had lower shear bond strength (SBS) values than groups MC1, MC2, and MC3. Among the SC specimens, all the groups had significantly lower SBS values than group SC1. The mean SBS values of groups SC4, SC5, and SC6 were significantly lower than the SBS of group SC2. All the SC repair time groups presented significantly lower SBS values compared to their corresponding MC groups (P ≤ 0.004). The results showed that the repair bond strength of SC was adversely affected at all time periods, while this effect was not detected for MC groups except for group MC4. The SC material exhibited less repairability than the MC material.

Low Shrinkage Silorane Composites.

Polymerization shrinkage of methacrylate composites utilizing bisphenol-A glycidal methacylate or urethane dimethacrylate has typically been about 3-3.5% by volume. Though adjustments have been made to filler loading, filler size, filler particle distribution, and improved silanization, the polymerization contraction still creates some significant clinical problems. A new composite utilizing a completely different chemistry has been released, with polymerization shrinkage of less than one percent. This article will review the clinical effects of polymerization contraction of composite resins, the nature and properties of this chemical form of composite, and potential clinical applications.

Influence of Cavity Margin Design and Restorative Material on Marginal Quality and Seal of Extended Class II Resin Composite Restorations In Vitro.

PURPOSE: To investigate the influence of three cavity designs on the marginal seal of large Class II cavities restored with low-shrinkage resin composite limited to the enamel. MATERIALS AND METHODS: One hundred twenty (120) intact human molars were randomly divided into 12 groups, with three different cavity designs: 1. undermined enamel, 2. box-shaped, and 3. proximal bevel. The teeth were restored with 1. an extra-low shrinkage (ELS) composite free of diluent monomers, 2. microhybrid composite (Herculite XRV), 3. nanohybrid composite (Filtek Supreme XTE), and 4. silorane-based composite (Filtek Silorane). After artificial aging by thermocycling and storage in physiological saline, epoxy resin replicas were prepared. To determine the integrity of the restorations' approximal margins, two methods were sequentially employed: 1. replicas were made of the 120 specimens and examined using SEM, and 2. the same 120 specimens were immersed in AgNO3 solution, and the dye penetration depth was observed with a light microscope. Statistical analysis was performed using the Kruskal-Wallis and the Dunn-Bonferroni tests. RESULTS: After bevel preparation, SEM observations showed that restorations did not exhibit a higher percentage of continuous margin (SEM-analysis; p>0.05), but more leakage was found than with the other cavity designs (p<0.05). The lowest percentage of continuous margin was observed in ELS restorations (p<0.05). More fractured margins were observed in the undermined enamel cavity design groups (p<0.05). CONCLUSION: Bevel preparation failed to improve margin quality in large Class II composite restorations and is no longer recommended. However, undermined enamel should be removed to prevent enamel fractures.

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites.

OBJECTIVES: The aim of this study is to evaluate the distribution of the filler size along with the zeta potential, and the integrity of silane-bonded filler surface in different types of restorative dental composites as a function of the material age condition. MATERIALS AND METHODS: Filtek P60 (hybrid composite), Filtek Z250 (small-particle filled composite), Filtek Z350XT (nanofilled composite), and Filtek Silorane (silorane composite) (3M ESPE) were tested at different stage condition (i.e., fresh/new, aged, and expired). Composites were submitted to an accelerated aging protocol (Arrhenius model). Specimens were obtained by first diluting each composite specimen in ethanol and then dispersed in potassium chloride solution (0.001 mol%). Composite fillers were characterized for their zeta potential, mean particle size, size distribution, via poly-dispersion dynamic light scattering. The integrity of the silane-bonded surface of the fillers was characterized by FTIR. RESULTS: The material age influenced significantly the outcomes; Zeta potential, filler characteristics, and silane integrity varied both after aging and expiration. Silorane presented the broadest filler distribution and lowest zeta potential. Nanofilled and silorane composites exhibited decreased peak intensities in the FTIR analysis, indicating a deficiency of the silane integrity after aging or expiry time. CONCLUSION: Regardless to the material condition, the hybrid and the small-particle-filled composites were more stable overtime as no significant alteration in filler size distribution, diameter, and zeta potential occurred. A deficiency in the silane integrity in the nanofilled and silorane composites seems to be affected by the material stage condition. CLINICAL SIGNIFICANCE: The materials conditions tested in this study influenced the filler size distribution, the zeta potential, and integrity of the silane adsorbed on fillers in the nanofilled and silorane composites. Thus, this may result in a decrease of the clinical performance of aforementioned composites, in particular, if these are used after inappropriate storage conditions.

Five-year clinical performance of a silorane- vs a methacrylate-based composite combined with two different adhesive approaches.

OBJECTIVES: The objective of this study was to compare the 5-year clinical performance in posterior restorations of three restorative systems including a low-shrinkage system and a methacrylate-based composite combined either with an etch-and-rinse or a self-etch adhesive. MATERIALS AND METHODS: Each of 25 patients received three class I (occlusal) or class II restorations performed with each one of the three restorative systems: Filtek Silorane Restorative System including a two-step self-etch adhesive, Adper Scotchbond 1 XT (two-step etch-and-rinse adhesive) + Filtek Z250, and Adper Scotchbond SE (two-step self-etch adhesive) + Filtek Z250. All materials were applied as per manufacturer's instructions. Two blind observers evaluated the restorations at four different moments (baseline, after 1, 2, and 5 years) according to the USPHS-modified criteria. Kruskal-Wallis and Mann-Whitney U tests were conducted to compare the behavior of the restorative systems, while Friedman and Wilcoxon tests were applied to analyze the intrasystem data (p < 0.05). RESULTS: After 5 years, marginal staining around the restorations with Adper Scotchbond SE + Filtek Z250 was statistically more frequent and severe than that of the restorations performed with the other two systems. Intrasystem comparisons revealed a deterioration of the marginal adaptation after 5 years for all systems. A significant number of restorations bonded with self-etch adhesives showed marginal staining after 5 years of clinical service. A deterioration of the color appearance and an increase of the surface roughness were also detected in the restorations performed with Adper Scotchbond SE + Filtek Z250. CONCLUSIONS: A deterioration of the marginal adaptation was evidenced for all restorative systems, while marginal staining was more frequently seen only around the restorations performed with self-etch adhesives. CLINICAL RELEVANCE: No advantage was found of the silorane- over the methacrylate-based composite when combined with an etch-and-rinse adhesive.

Silorane, ormocer, methacrylate and compomer long-term staining susceptibility using ΔE and ΔE 00 colour-difference formulas.

The aim of this study was to evaluate the staining susceptibility of a silorane (Filtek Silorane), an ormocer (Ceram X Duo), a methacrylate (Tetric EvoCeram) and a compomer (Dyract) exposed on the long term to various staining agents by using ΔE and ΔE 00 colour-difference formulas. Thirty-six disc-shaped specimens were made of each of the four chemically different materials, randomly divided in six groups (n = 6) and immersed in five staining solutions (red wine, juice, coke, tea and coffee) or stored dry (control) in an incubator at 37 °C for 99 days. Spectrophotometric measurements by means of a spectrophotometer (Spectroshade Handy Dental, MHT) were repeated over a white (L* = 92.6, a* = -1.2, b* = 2.9) and black (L* = 1.6, a* = 1.2, b* = -1.0) background made of plasticized paper, in order to determine the colour changes according to ΔE, ΔE 00 and translucency formulas. Statistical analysis was performed by means of factorial Anova, Fisher's LSD test (post hoc) and a Spearman rank correlation between ΔE and ΔE 00. When analysed over a white background, mean ΔE 00 values were highly significantly different and varied from 0.8 (Ceram X Duo/air) to 20.9 (Ceram X Duo/red wine). When analysed over a black background, mean ΔE 00 values were highly significantly different and varied from 1.0 (Ceram X Duo and Tetric/air) to 25.2 (Ceram X Duo/red wine). Differences in translucency varied from 0.3 (Ceram X Duo/air) to 21.1 (Ceram X Duo/juice). The correlation between ΔE and ΔE 00 over a white background was 0.9928, while over a black background, it was 0.9886.

Mechanical properties of silorane-based and methacrylate-based composite resins after artificial aging.

The aim of this study was to compare the compressive strength of a silorane-based composite resin (Filtek P90) to that of conventional composite resins (Charisma, Filtek Z250, Fill Magic, and NT Premium) before and after accelerated artificial aging (AAA). For each composite resin, 16 cylindrical specimens were prepared and divided into 2 groups. One group underwent analysis of compressive strength in a universal testing machine 24 hours after preparation, and the other was subjected first to 192 hours of AAA and then the compressive strength test. Data were analyzed by analysis of variance, followed by the Tukey HSD post hoc test (α = 0.05). Some statistically significant differences in compressive strength were found among the commercial brands (P < 0.001). The conventional composite resin Fill Magic presented the best performance before (P < 0.05) and after AAA (P < 0.05). Values for compressive strength of the silorane-based composite were among the lowest obtained, both before and after aging. Comparison of each material before and after AAA revealed that the aging process did not influence the compressive strength of the tested resins (P = 0.785).

Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 µm) for water-sprayed Silorane and greatest (22.9 µm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected.

Bonding strength of silorane-based composite to Er-YAG laser prepared dentin.

The aim of this study was to investigate the shear bond strength of two adhesive systems to laser-irradiated dentin compared with their shear bond strength to bur-cut dentin as well as to evaluate the influence of composition and type of dental materials on shear bond strength. Thirty-two dentin specimens prepared from human third molars were divided into two groups and conditioned either with an Er:YAG laser machine or with a carbide bur. Two different adhesive systems (Silorane System Adhesive and Single Bond) were evaluated in the present study. After light curing of the adhesives, a Teflon mold was placed over the ring with the dentin sample and filled with the composite resins Filtek Silorane and Filtek Z250 combined with the appropriate adhesive systems. This procedure resulted in 32 cylindrical specimens (3 mm in diameter, 4 mm in height) being bonded to the dentin. The specimens were stored for 24 h at 37 °C in water and then were thermocycled. Shear bond strength testing was conducted by means of a universal testing machine and failure patterns were analyzed under a stereomicroscope. Two specimens of each fracture failure mode were randomly selected for SEM evaluation. Filtek Silorane present no statistically significant difference in shear bond strength compared with Filtek Z250, regardless of dentin treatment (p > 0.05). Additionally, the self-etching Silorane Adhesive System exhibited as good adhesive values as etch-and-rinse Single Bond, independently on dentinal substrate (p > 0.05). Specimens prepared by Er:YAG laser appear as receptive to adhesive procedures as conventional carbide bur-cut specimens (p > 0.05).

Influence of laser etching on enamel and dentin bond strength of Silorane System Adhesive.

The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p < 0.05). The highest SBS was found after additional phosphoric acid treatment in dentin groups (p < 0.05). There were no statistically significant differences between the laser-etched and non-etched groups in enamel and dentin (p > 0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p > 0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive.

Repair Bond Strength of Aged Silorane-based Composite Using Intermediate Adhesive Systems Based on Different Monomers.

PURPOSE: To investigate the effect of pre-repair aging periods and intermediate adhesive systems based on different monomers on the repair bond strength of silorane-based resin composite. MATERIALS AND METHODS: A total of 32 Filtek P90 (3M ESPE) substrate specimens (4 mm diameter and 4 mm height) were made. Substrate specimens were grouped according to the pre-repair time periods into four groups (n = 8/group): 15 to 30 min, 24 h, 1 month, and 3 months. All substrate specimens were ground flat using a diamond stone and were etched using Scotchbond phosphoric acid etchant (3M ESPE). The specimens of each pre-repair time period were equally distributed among the two repair groups, using either silorane-based (P90 System Adhesive) or acrylamide-based (AdheSE One F, Ivoclar Vivadent) intermediate adhesive systems. Specimens of P90 System adhesive received Filtek P90 as the repair resin composite, and Tetric N-Ceram (Ivoclar Vivadent) was used with AdheSE One F specimens. Additional specimens were made from the repair resin composite materials to study the cohesive strength. Specimens were sliced into sticks (0.6 ± 0.01 mm2) for microtensile bond strength testing (µTBS). Modes of failure were determined. RESULTS: Two-way ANOVA with repeated measures revealed no significant effect for the pre-repair aging periods, intermediate adhesive systems based on different monomers, or their interaction on repair bond strength of silorane-based resin composite. CONCLUSION: Up to 3 months of pre-aging the repaired silorane-based resin composite had no negative effect on its repair bond strength, even when an intermediate adhesive system based on a different monomer (acrylamide) was used.

Silanising agents promote resin-composite repair.

OBJECTIVE: The aim of this study was to investigate the effect of silane in the repair of old and new resin-composite restorations. METHOD: Part 1: repair of old composite was performed on 60 resin-composite substrates that were 6 years old and were made of six different brands of composite. Three experiments were performed. In the first experiment, the substrates were ground flat and composite was fixed to the surface with bonding agent without silane (i.e. Clearfil Bond SE only, the control). Shear bond strength (SBS) was tested according to ISO/TS 11405 after thermocycling. In the second experiment, the same 60 substrates were ground again and treated with bis-silane a 2-part silane mixed shortly before application before applying bonding agent (Clearfil Bond SE plus silane) and repair composite before SBS testing. In the third experiment, the same substrates were ground again and a one-step bonding product containing silane (Scotchbond Universal bond containing silane) was used for the repair procedure before SBS testing. Part 2: to evaluate the repair of newly made composite restorations, 66 composite substrates were made and stored in water for 2 months. The specimens were divided into three groups and were tested using the same protocols as used to evaluate repair of old composite. RESULTS: Mean SBS (± standard deviation), in MPa, for repair of old composite was 6.2 ± 4.0 (Clearfil Bond SE only, control), 14.8 ± 7.8 (Clearfil Bond SE plus silane) and 15.3 ± 5.6 (Scotchbond Universal bond with silane), whereas for new composite mean SBS was 15.4 ± 8.6 (Clearfil Bond SE only, control), 23.4 ± 8.3 (Clearfil Bond SE with silane) and 23.7 ± 5.8 (Scotchbond Universal containing silane). A significant difference was observed between the control and the test groups with silanising agents, both in Part 1 (P < 0.001) and in Part 2 (P < 0.005). CONCLUSION: Silanising agents increase the bond strength of the resin composite repair.

Influence of organic acids present in oral biofilm on the durability of the repair bond strength, sorption and solubility of resin composites.

PURPOSE: To evaluate the repair bond strength after storage in water, lactic and propionic acid after 7 days and 6 months and the sorption and solubility of resin composites used. METHODS: Five cylinders of each resin composite (microhybrid, nanofilled and silorane-based composite) were prepared. Specimens were aged with thermocycling (5 and 55°C) 5,000 times. A repair procedure was performed using intraoral sandblasting with 50-µm aluminum oxide, application of an adhesive system and cylinder of composite was fabricated. Specimens were sectioned into beams and stored in three immersion media: water, propionic acid and lactic acid. The microtensile bond strength was measured after periods of 7 days and 6 months. Sorption and solubility were evaluated using 15 specimens (0 = 6 mm; h = 1 mm) of each resin composite, which were prepared and assigned into three groups (n = 5) according to the immersion media (water, propionic acid and lactic acid). Data were analyzed using one-way/two-way/three-way ANOVA and Tukey's test (α = 0.05). RESULTS: The resin composites, immersion media and time of immersion did not affect the repair bond strength (microhybrid 38.3 to 40.9 MPa; nanofilled 38.7 to 42.2 MPa; silorane 41.2 to 51.1 MPa). Additionally, the immersion media did not affect the sorption and solubility. The silorane-based composite presented the lowest sorption (10.5 to 12.1 µg/mm3) and solubility (-2.4 to -2.7 µg/mm3), while the nanofilled methacrylate-based composite showed the highest sorption (32.1 to 33.6 µg/mm3). Regarding solubility, the nanofilled and microhybrid methacrylate-based composites did not present statistically significant differences.

Evaluation of the influence of three different temperatures on microleakage of two self-etch and one total-etch adhesives.

AIM: To evaluate the bonding temperature effect on dentin-restoration microleakage. The null hypothesis of the study is that the score of microleakage is identical among different adhesive bondings at different temperatures. MATERIALS AND METHODS: Ninety caries free maxillary premolars were selected. Class V cavities were prepared on the cemento enamel junction (CEJ) of the buccal sides with enamel margins on occlusal sides and cementum margins on gingival sides. The specimens were divided into 3 groups: G1, single bond adhesive + Z250 composite; G2, P90 adhesive + Filtek Silorane composite; and G3, Clearfil SE bond + Clearfil APX. All groups were divided into three subgroups based on the adhesive temperature: A-4°C; B-25°C; and C-40°C. After coating the specimens with nail polish 1 mm beyond the margin of the restorations, they were stored in 0.5% basic Fuchsin dye solution for 24 hours. The teeth then were buccolingually sectioned and observed under a stereomicroscope. RESULTS: There was no significant difference between microleakage of occlusal and gingival margins in each group. Clearfil SE bond and Adper single bond displayed lower microleakage than P90 adhesive at 4°C and 25°C. The most and least microleakage score for Adper single bond was at 40°C and 25°C respectively. Clearfil SE bond showed less microleakage at 25°C than 4°C and 40°C. CONCLUSION: Clearfil SE bond and Adper single bond displayed less microleakage at 25°C while there was no significant difference among for P90 adhesive microleakage at three temperatures.

Bond strength of different restorative materials to light-curable mineral trioxide aggregate.

UNLABELLED: The aim of the present study was to evaluate the bond strength of methacrylate-based (MB) composites, silorane-based (SB) composites, and glass-ionomer cement (GIC) in comparison to TheraCal and to compare those findings with the reference pulp capping material (MTA). STUDY DESIGN: A total of 90 acrylic blocks were prepared. Each of the blocks were prepared as 15 mm high and 10 mm diameter and the blocks had a 2 mm high and a 5 mm diameter central hole. In 45 of the samples, the holes were fully filled with TheraCal and in the other 45 samples, the holes were fully filled with MTA. The TheraCal and the MTA samples were randomly divided into 3 subgroups of 15 specimens each: Group-1: Methacrylate-based (MB) composite; Group-2: Silorane-based (SB) composite; and Group-3: Glass-ionomer cement (GIC). For the shear bond strength (SBS) test, each block was secured in a universal testing machine. After the SBS test, the fractured surfaces were examined under a stereomicroscope at ×25 magnification. RESULTS: The analysis of variance that compared the experimental groups revealed the presence of significant differences among the groups (P < 0.001). The highest (19.3 MPa) and the lowest (3.4 MPa) bond strength value were recorded for the MB composite-TheraCal and the GIC-TheraCal, respectively.There were significant differences in bond strength between the TheraCal and the MTA groups for the MB composite subgroup (P < 0.001) and the SB composite subgroup (P < 0.05); however, there was no significant difference in bond strength for the GIC subgroup (P ≯ 0.05). Conlusions: The results from this in vitro study suggest that the new pulp capping material, known as light-curable MTA, showed clinically acceptable and higher shear bond scores compared to MTA when used with the MB composite.

Using Multiple Bonding Strategies.

There are many ways to bond to tooth structure, some micro-mechanical some chemical, some a combination. Different dentin bonding materials have different bonding strengths to differently prepared surfaces, and because of differences in their nature, different areas of tooth structure present peculiar bonding challenges. This paper will review a variety of material types, elucidating their particular bonding strengths and commenting on improved bonding strategies to increase durability, strength, and favorable pulpal response. In this discussion, resin dentin bonding systems, glass ionomers, Gluma, resin cements, and newer combined products will br reviewed.

Sorption and solubility of self-etching adhesives immersed in organic acids present in oral biofilm.

PURPOSE: This study evaluated the sorption and solubility of self-etching adhesive systems after immersion in distilled water, lactic acid, and propionic acid. MATERIALS AND METHODS: Specimens of 2 two-step (P90 System Adhesive [P90], Clearfil SE Bond [CSE]) and 1 single-step (Adper Easy One [AEO]) adhesive systems were prepared and divided into 4 groups: P90 primer ( P90-P), P90 bond (P90-B), AEO, and CSE bond (CSE-B). Specimens were placed in a desiccator and weighed daily until achieving a constant mass (m1). The specimens (n = 5) were then immersed in the respective media and weighed until a achieving a constant mass (m2). The specimens were again desiccated (m3). Sorption and solubility data were analyzed with two-way ANOVA and Turkey's test. Specimens were also observed using SEM without immersion, after 24 h, and at the end of the respective total time of immersion. RESULTS: For all immersion media, the highest sorption values were obtained for AEO and P90-P, followed by CSE-B and P90-B, which presented the lowest sorption. The time required for adhesives to absorb the solutions was: 11 to 19 days for P90-P, 12 to 13 days for P90-B, 15 to 19 days for AEO, and 14 to 18 days for CSE-B. The highest values of solubility were shown for AEO and P90-P in all immersion media. In water and propionic acid, the adhesives with the lowest solubility values were CSE-B and P90-B. CSE-B had the lowest solubility in lactic acid. CONCLUSION: The greatest surface degradation was observed after each respective total time of immersion. AEO specimens presented more evident surface degradation and the highest sorption and solubility.

Two-year clinical performance of dimethacrylatebased composite restorations repaired with a silorane-based composite.

PURPOSE: To investigate the clinical performance of a silorane-based composite resin used for repairing dimethacrylate- based composite restorations. MATERIALS AND METHODS: One operator repaired defective dimethacrylate-based resin restorations that were randomly assigned to one of two treatment groups: control (n=50), repaired with Adper SE Plus and Filtek P60 Posterior Restorative (3M ESPE); or test (n=50), repaired with P90 System Adhesive Self-Etch Primer and Bond and Filtek P90 Low Shrink Posterior Restorative (3M ESPE). After 1 week, restorations were finished and polished. Two calibrated examiners (weighted Kappa≥0.78) evaluated the repaired restorations, blindly and independently, at baseline, after 6 months, 1 and 2 years. The parameters examined were marginal adaptation, anatomic form, surface roughness, marginal discoloration, postoperative sensitivity, and secondary caries. The restorations were classified as Alfa, Bravo, or Charlie, according to modified US Public Health Service criteria. Variation in the levels of clinical parameters over time was evaluated by Friedman's ANOVA (α=0.05). The Mann-Whitney test assessed the differences between the materials for all clinical criteria at baseline, 6-month, 1- and 2-year recalls (α=0.05). The Wilcoxon test compared each composite resin for all clinical criteria at the same recalls (α=0.05). RESULTS: After two years, 79 repaired restorations were re-examined. No statistically significant differences were found between the materials at baseline or at the 2-year recall (p>0.05). Comparing baseline and 2-year recall, there was a statistically significant difference for marginal discoloration (p=0.029) in silorane-based composite restorations. CONCLUSION: After two years, the clinical performance of the silorane-based composite was similar to that of the dimethacrylate-based composite when used to make repairs.