It was observed that externally applied bleaching gels may penetrate into the pulp chamber. This study was conducted to evaluate the peroxide diffusion from two whitening strips into the pulp chamber. Twenty-four, human, extracted, maxillary central teeth were separated into three groups (n = 8). All teeth were sectioned 3-mm apical to CEJ, the intracoronal pulp tissue was removed, and the pulp chamber was filled with acetate buffer. Vestibuler crown surfaces of teeth in the experimental groups were subjected to whitening strips; the teeth in the control group were exposed only to distilled water. The acetate buffer solution in each tooth was transferred to the tube. Leuco-crystal violet and enzyme horseradish peroxidase also were added to the tube. The pulpal peroxide was determined spectrophotometrically. The results indicated that the whitening strip containing 14% hydrogen peroxide presented a higher pulpal peroxide penetration than 6.5 % hydrogen peroxide (p < 0.001).

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The peroxides from the whitening strip and paint-on whiteners penetrated into the pulp chamber to varying degrees.

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Objective: The aim of this study was to evaluate the effect of four different mouthrinses on the surface roughness of two nanohybrid resin composites. Material and Methods: Fifty samples were prepared for each of the resin composites (2x8 mm) and a profilometer was used to determine the initial surface roughness (Ra) of each sample. Then, they were divided into 5 subgroups (n= 10), and exposed to the following mouthrinses (12h, 37 ºC): containing alcohol and essential oils; alcohol and chlorhexidine; alcohol-free and essential oils; alcohol free and cetil prydinium chlorite; or distilled water (control). The surface roughness of each sample was measured again. Statistical analyses of the data were performed via two-way ANOVA and Bonferroni tests. Results: Overall, statistically significant differences were not found between the resin composites (p> 0.05), but significant differences were found among the mouthrinses (p< 0.05). Interactions between the mouthrinses and the resin composites was statistically significant (p< 0.05). Both of the resin composites had the highest surface roughness after exposure to mouthrinse with alcohol and essential oils (p< 0.05), followed by mouthrinse with alcohol and chlorhexidine. Both alcohol-free mouthrinses caused surface roughness either similar to distilled water (p> 0.05) or lower than distilled water (p< 0.05) on the nanohybrid resin composites used. Conclusion: The mouthrinses affected the surface roughness of the resin composites in different ways. This was dependent on mouthrinse contents and the chemical structure of the resin composites. Alcohol-containing mouthrinses caused the most changes in the surface roughness of both resin composites. Keywords Alcohol; Chlorhexidine; Composite resin; Essential oil; Roughness.