The effects of hybrid light activation and enamel acid etching on the effectiveness, stability and sensitivity after a single session in-office bleaching: A 12-month clinical trial

Background: The use of hybrid-light (HL) during in-office teeth bleaching can provide faster and reliable results after a single bleaching session, especially if associated with previous acid etching. The present in vivo, interventional, split-mouth, triple-blinded and randomized study evaluated the efficiency of a HL, with and without prior enamel acid etching, assessing the gel application time, degree of color change, sensitivity and treatment stability up to 12 months. Methods: Thirty-four patients were selected and randomly divided into four groups. The color was evaluated using a spectrophotometer with the CIELab color system, and a VAS questionnaire was used to evaluate the sensitivity. Both upper and lower hemiarches (GI and III) received enamel acid etching with 37% phosphoric acid for 15 s prior to the application of 35% hydrogen peroxide gel (HP). For GI and II, HP was applied on both dental arches for 3-4 consecutive applications and activated by HL (2 x 3' activations with 1' interval); and 3 x 15' (HP) for GIII and IV without HL. Patients returned in 24 h, 1 week, 1-, 6- and 12-months intervals. The clinical operator was different from the clinical measurements operator. Results: After 3-way ANOVA, Tukey's, Wilcoxon and Mann-Whitney tests, all with p < 0.05, no statistical differences were observed between the groups regarding color change (Delta E) and sensitivity in all evaluations. The lowest gel application time was observed for GII (acid etch + HL), followed by GI (HL). Conclusions: The present study's results reveal the advantages of HL associated with acid etching prior to in office bleaching.