Influence of enamel acid etching prior to in office bleaching

Objectives: This in vivo study evaluated the efficiency of enamel acid etching prior to in office bleaching with and without the employment of hybrid light (HL), as it relates to color change (DE), sensitivity (VAS questionnaire) and treatment stability (6 months). Methods: 24 volunteers were selected according to pre-established criteria and randomly divided into two groups. The baseline color was evaluated using a spectrophotometer VITA Easyshade (VITA). For both groups, the maxillary and mandibular right hemiarcs received enamel acid etching with a 37% phosphoric acid for 15” prior to the application of bleaching gel. G1: a 35% hydrogen peroxide (HP) (Lase Peroxide, DMC Equipments) was applied to the dental arcs. After 1' of gel application, the gel was activated with HL (LED/Diode laser, Whitening Lase II, DMC Equipments) for two 3' activations, with 1 minute between each. Three or five gel applications were performed in the same session. G2: a 35% HP was applied for 3 consecutive 15' applications. Patients returned after 24 hours, 7 days, 1 and 6 months for new evaluations. The results were submitted to 3-way ANOVA (time, acid, light) and Tukey tests (p<0.05). Results: No significant statistical differences were observed between the etched and non-etched groups regarding color change (DE) and sensitivity. The color stability presented significant differences between 24h and 6 months for both groups. G1 required less time for the etched hemiarcs (32') in comparison to the other hemiarcs (36'), and to G2 (45'). Conclusions: These results reveal the advantages of employing light sources (HL) associated with acid etching in in office bleaching. Financial support provided by CNPq and CAPES agencies.