Avaliação da eficácia e dos potenciais efeitos adversos de diferentes técnicas clareadoras através de ensaios In vivo, In situ e In vitro

Abstract

The aim of the study was to evaluate the efficacy and potential adverse effects of different bleaching techniques through In vivo, In situ and In vitro studies. The randomized clinical trial aimed to evaluate the effectiveness and sensitivity of the inoffice and at-home bleaching treatment. For this, 130 patients were selected and divided into two groups and subjected to two treatments, being one placebo. The evaluation was performed with digital color spectrophotometer, before, after and one week after the completion of treatment. The parameters L, a* and b* were subjected to statistical analysis by Friedman and Tukey test. The variables ?L, ?a, ?b and ?E were submitted to Mann Whitney test (a = 0.05). For sensitivity evaluation, a visual analogue scale with scores ranging from 1 (no sensitivity) to 5 (severe sensitivity) was daily recorded by patients. Data were statistically analyzed by Mann Whitney and Friedman tests. Both treatments showed significant whitening effect for the L * and b * parameters. For color variations, was no statistically significant difference in parameters ?a, ?b and ?E. The bleaching treatment clinic generated greater sensitivity in the first two weeks of treatment and home in the first week. When comparing the two treatments, only in the first day, the in office treatment showed greater sensitivity than the at-home treatment. The evaluation of genotoxicity aimed to investigate the micronucleus formation generated by the treatments. Prior treatment, 15, and 45 days after bleaching, the oral mucosa samples from 10 patients from each group were collected with a citobrush. Samples were prepared and fixed on slides. A blind examiner performed the manual counting of micronuclei in 1,000 cells per individual and time. Data were tabulated and submitted to the Mann-Whitney and Kruskal-Wallis test. The in-office bleaching treatment produced a higher formation of micronuclei in both 15 and 45 days. The In situ and In vitro testing aimed to evaluate the adverse effect generated by 10% hydrogen peroxide and whitening strips on microhardness of human dental enamel. For In situ assay, six volunteers used a removable appliance with fixed specimens. The bleaching treatment was applied for 1 h / day, remaining in mouth for 23h. For the In vitro assay, the specimens received the same treatments, remaining in water for 23h to 36.5oC. Microhardness readings were performed before and after treatment bleaching protocols. Statistical analysis was performed using ANOVA and Tukey’s test. None significant decrease in microhardness was observed In situ; however, a significant reduction of hardness values were observed for In vitro condition, where the whitening strips statistically decreased the values compared to the whitening gel. In conclusion, the at home or in office bleaching protocols were effective in improving color, with a low level of sensitivity response, and the at home treatment produced a slightly better performed and produced lower genotoxicity effect. In addition the type of study was important to evaluate the mineral loss after bleaching treatment, where those specimens treated in situ have not exhibited microhardness decrease, which was only observed In vitro.