Aim:The purpose of this study was to evaluate the dental effect and sensitivity of at-home dental bleaching with 10% hydrogen peroxide (H 2 O 2 ). Materials and methods:Twenty volunteers with A2 or darker central incisors were selected for this study. Was used 10% H 2 O 2 for thirty minutes twice a day, for two weeks. Shade evaluation was assessed visually by the value-oriented shade guide Vita Classical shade guide, Vita Bleachedguide 3D-MASTER and by the Easyshade spectrophotometer at baseline, during bleaching (first and second weeks), and post-bleaching (one month). The perceptions of sensitivity were recorded by the patients through the numerical rating scale (0 to 4) and 0 to 10 visual analog scales daily. Data from the shade guide units was subjected to a one way repeated measures (RM) analysis of variance (ANOVA) test (α = 5%). The overall ΔE, absolute risk and intensity of tooth sensitivity were calculated as well as the 95% confidence interval. Results:The absolute risk of tooth sensitivity was 65% and the intensity was mild. Data from ΔSGU and ΔE after 1 month of bleaching for H 2 O 2 10% showed significant whitening, 4 units for Vita Classical, 5 units for Vita Bleachedguide and 9.7 units for spectrophotometer. Conclusion:At-home bleaching using 10% hydrogen peroxide is effective in 14 days of bleaching. The most common adverse events were mild tooth sensitivity, and no subjects discontinued use early because of a treatment-related adverse event.Clinical significance: At-home dental bleaching with 10% hydrogen peroxide gel reduces the time of use of the tray, maintaining the effectiveness with low intensity of dental sensitivity. Brazilian clinical trials registry (REBEC) RBR-45xmzj.

The relationship between the application of die-spacer prior to wax pattern fabrication and metal removal from the inner surface of the casting on marginal and internal discrepancies of complete cast crowns was evaluated. One hundred and twenty complete crowns were cast with palladium-silver alloy melted by gas-oxygen torch or electrical resistance and cast with a centrifuge casting machine. After casting, the crowns were seated on each type of different marginal configuration dies (90-degree shoulder, 20-degree beveled shoulder, and 45-degree chamfered shoulder) with a static load of 90 N during 1 min. Evaluation of the marginal fit of the specimens was made using a digital micrometer. The crowns were embedded in acrylic resin and longitudinally sectioned to verify the internal discrepancy that occurred in lateral and occlusal interfaces with a digital micrometer. The data were submitted to ANOVA and Tukey's test with a significance level of 5%. The best marginal and inner fits were obtained with the gas-oxygen torch source. The 45-degree chamfered shoulder showed the best marginal and inner fit, and better internal relief was obtained in the crowns abraded with 50 microm Al2O3 particles.

The aim of this research was to evaluate the load cycling influence in resin composite restorations through marginal leakage analysis, in enamel and cementum. Forty bovine incisors were allocated in four groups (n=10): I – Z250 resin composite / Single Bond adhesive system; II – Charisma resin composite / Gluma One Bond adhesive system; III - Z250 resin composite / Single Bond adhesive system submitted to 1,000 cycles (10Kgf); group IV - Charisma resin composite / Gluma One Bond adhesive system submitted to 1,000 cycles. The class V restorations were located at cementum-enamel junction and the load was applied on the incisal edge. The samples were immersed in 2% buffered methylene blue solution. The samples were cross-sectioned and the leakage, which received a score, was evaluated through stereomicroscope (45 X ). Data were submitted to Kruskal-Wallis’ test (5%). Analysis showed no statistical differences among margins localized in enamel or in cementum, for loaded and unloaded groups (p>0,05). However, enamel showed better results than cementum in the same sample (p<0,05).Load cycling did not increase the microleakage in enamel or in cement margins. Comparing the infiltration degree in the same sample, the staining solution penetration was higher in cementum margins, for both loaded and unloaded groups.