Can the efficacy of in-office tooth bleaching change in the presence of orthodontic brackets? An in vitro study

Objective: To assess the color change of bovine enamel after tooth bleaching while using orthodontic brackets. Methodology: This in vitro study selected 48 bovine incisors without visible fractures or cracks (cut in blocks of 8x12x3 mm). They were distributed in four groups: no staining and with brackets (NSWB), no staining and no brackets (NSNB), with staining and brackets (WSWB), and with staining and no brackets (WSNB) (n=12). The color was initially assessed with a spectrophotometer for NS (no staining). The teeth in WS (with staining) groups were immersed in an instant coffee solution for 15 days and the initial color was also assessed. After prophylaxis and adhesive treatment, the brackets were bonded to the teeth. The teeth were bleached with 35% hydrogen peroxide and the color was analyzed 30 days after bleaching. A two-way Analysis of Variance was applied as well as a subsequent multiple comparison analysis (p>0.05). Results: According to the data obtained, the factor of the presence of brackets (p=0.569) had no significant influence. This differed from the factor of tooth staining (p<0.001). Moreover, there was no interaction between them (p=0.863). Conclusion: The presence of brackets in non-stained teeth did not affect bleaching effectiveness. The ΔE of stained teeth was always lower than non-stained teeth, especially for the NB (no brackets) group.