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High-concentration carbamide peroxide containing home bleaching may cause a varying influence on the microhardness of esthetic restorative materials. SUMMARYThis study evaluated the effect of a highconcentration carbamide peroxide-containing home bleaching system (Opalescence PF) and a hydrogen peroxide-containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucitereinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 lm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n¼10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test.Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p¼0.005), Empress Esthetic (p¼0.003), Empress 2 layering (p¼0.005), and Matchmaker-MC (p¼0.003), whereas a statistically significant

SUMMARYThis study evaluated the effects of fiber nets and application techniques and flowable composites as a liner on microleakage and the effects of fiber nets on polymerization shrinkage in Class II MOD cavities. Standard MOD cavities were performed in 80 extracted third molars. The teeth were randomly divided into eight groups (n=10 +FSI. All the teeth were then immersed in 0.5% basic fuchsin solution for 24 hours after thermocycling for 1000 cycles (5°C and 55°C). The teeth were sectioned longitudinally and observed under a stereomicroscope. In order to determine the polymerization shrinkage, another study was designed. In Group A, composite was applied as a bulk. In Group B, the resin composite was divided into two parts and Ribbond fiber was placed in the middle of the mass. In Group C, everStick NET fiber was placed inside the composite, as in Group B. Statistical analysis were performed by using one-way ANOVA and Tukey HSD tests for both microleakage and polymerization shrinkage (p<0.05). Less microleakage was observed in groups where composites were applied by the incremental technique compared with those E Ozel • M Soyman Clinical RelevanceFiber nets applied to Class II composite restorations resulted in a significant reduction in microleakage. Fiber nets also decreased polymerization shrinkage. Therefore, these materials may be acceptable for clinical applications. Incremental placement remains the preferred restorative technique for posterior composite restorations.

Objective:To investigate the effect of a prophylaxis paste on surface roughness of different composites, enamel, dentin and porcelain surfaces.Methods:Three different composites (FiltekZ250/Group1, Filtek Supreme XT/Group2, Premise/Group3), enamel/Group4, dentin/Group5 and porcelain/Group6 samples were used in this study. All specimens were prepared flat by SiC discs and polished with a diamond polishing paste. The surface roughness measurements were determined with a profilometer after polishing (initial surface roughness). Prophylaxis paste was applied to the samples for 12 seconds, renewing every 6 seconds. After cleaning the samples, roughness values were measured again. Data were analyzed by Kruskal Wallis and Dunn’s multiple comparison test. Wilcoxon test was performed for the comparison of the initial and final surface roughness values (P<.05). The results were evaluated within the P<.05 confidence level.Results:The initial and final surface roughness values (μm) were determined as follows: Group1: 0.039±0.009 and 0.157±0.018, Group2: 0.023±0.005 and 0.145±0.027, Group3: 0.028±0.008 and 0.109±0.012, Group4: 0.024±0.006 and 0.071±0.015, Group5: 0.030±0.007 and 0.143±0.029, Group6: 0.024±0.006 and 0.064±0.014. Significant difference was determined between the initial and final values for all groups.Conclusions:Composite and dentin surfaces were more affected by the application of prophylaxis paste than enamel and porcelain surfaces. The prophylaxis paste increased the surface roughness of all groups, but did not reach the bacterial retention roughness rate of 0.2μm.

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