Avaliação “in vitro” de diferentes técnicas de clareamento de dentes escurecidos por sangue

Abstract

This research will present a study that evaluated the effectiveness of three bleaching techniques on blood stained teeth, simulating a dental discoloration after pulpal hemorrhage. It is an in vitro study, in which human teeth were selected from the Human Bank of teeth of the Dentistry School of the Federal University of Santa Maria, and submitted to a human blood staining protocol. After staining, the teeth were randomized and separated into groups (n=10) according to one of three whitening techniques. The first group was submitted to the Walking Bleach technique, using sodium perborate associated with liquid hydrogen peroxide at 20%, applying the mixture to the pulp chamber. The second group was submitted to the Inside/Outside technique, using hydrogen peroxide at 7.5% internally and externally. The third group was submitted to the In-Office bleaching technique, using hydrogen peroxide at 35% internally and externally. The color measurements were performed at five time points: after the staining protocol (T0 - baseline), after one week of bleaching (T1), after two weeks of bleaching (T2), after completion of treatments (T3) and one-week follow-up (T4), using a clinical spectrophotometer (Easyshade Advance 4.0, VITA), which shows the color measurement in numbers, where the coordinates L * a * b * of the color were annotated. The coordinates were inserted into CIELAB and CIEDE2000 the formulas, to calculate the color difference (ΔE*ab and ΔE00, respectively). The color difference (ΔE) was calculated between T1-T0 (1 week of bleaching), T2-T0 (2 weeks of bleaching), T3-T0 (completion of treatments) and T4-T0 (oneweek follow-up). The normal distribution of the data was verified by the Kolmogorov-Smirnov test, and the mean values of ΔE*ab, ΔE00, ΔL*, Δa* and Δb* were submitted to ANOVA and Tukey’s PostHoc tests. Statistical analysis used α=0.05 as significance. The results demonstrated that all bleaching techniques presented similar effectiveness at 1-week followup. The In-Office bleaching technique, presented expressive color change since the first application, as for Walking bleach and Inside/Outside techniques, demonstrated greater bleaching effectiveness from the second week onwards of treatment.