Randomized clinical trial of 2 nonvital tooth bleaching techniques: A 1-year follow-up

Statement of problem. Controlled clinical trials comparing the effectiveness of the walking bleaching (WB) technique and the inside-outside (I-O) technique used in a short daily regimen are lacking. Purpose. The purpose of this randomized clinical trial was to investigate the effectiveness of WB with that of the I-O technique conducted over 4 weeks and to compare color changes after 1 year. Material and methods. Discolored and endodontically treated anterior teeth received a cervical seal and were randomly divided into groups according to the technique. In the WB group (n=9), a mixture of sodium perborate and 20% hydrogen peroxide was applied in the pulp chambers and replaced weekly up to 4 weeks. For the I-O group (n=8), participants applied 10% carbamide peroxide in the pulp chambers and wore custom-fitted trays for 1 hour per day over 4 weeks. CIELab parameters were obtained using a spectrophotometer at baseline, during bleaching (1, 2, 3, and 4 weeks) and after 1 year. Changes in color (Delta E), lightness (Delta L*), green-red axis (Delta a*), blue-yellow axis (Delta b*), and absolute color parameters (L*, b*, and a*) for each evaluation time were calculated and analyzed by repeated measures analysis of variance (ANOVA) and post hoc Bonferroni test (alpha=.05). Results. No significant differences between WB and 1-0 techniques were observed for Delta E, Delta L*, Delta a*, Delta b*, L*, a*, or b* values (P>.05); however, significant differences were observed among the evaluation times (P<.05). Color changes observed after 2 weeks were stable after 1 year; Delta L* and Delta a* values after 1 year were not significantly different from the 1-week evaluation, and significant changes in Delta b* after 3 weeks were maintained at the 1-year follow-up. The same trend was observed for the absolute CIELab color parameters. Conclusions. Both WB and I-O regimens were similarly effective as shown by significant Delta E after 2 weeks and no color regression after 1 year.