Etching in low concentration H2O2/TiO_N bleaching: a randomized clinical trial

OBJECTIVES: The purpose of this interventional randomized double‐blinded split‐mouth clinical trial was to evaluate, in a period of 12 months, the efficacy, tooth sensitivity and pulp blood flow alterations after the use of prior acid etching on enamel and in‐office HP10% and HP15% bleaching agents containing nanoparticles of TiO_N photocatalyzed with LED/laser light source, comparing to a control of HP35% without hybrid light (HL) source activation. METHODS: Thirty‐six healthy volunteers, both genders, aged 18 to 35 years, were randomly divided in 3 groups (n=12): HP10% (experimental gel) photocatalyzed with HL‐based violet LED/laser (experimental), HP15% photocatalyzed with HL‐based blue LED/laser light, both treated in 1 session of 37min30sec, and HP35%, treated in 1 session of 45min each. Within each group, one of the mouth sides was randomly selected for the execution of acid etching prior to the gel application. Efficacy was evaluated by ΔE values measured via spectrophotometer. Tooth sensitivity was analyzed by differences of visual analog scale (VAS). Pulp blood flow was evaluated by Laser Doppler system. Data were analyzed by repeated measures analysis of variance with Bonferroni's correction to post hoc analysis in parametric cases, and Friedman's test in non‐parametric analysis. RESULTS: Protocols and acid effects had different behaviors throughout the time regarding ΔE, being HP35% the protocol which promoted the highest increase in ΔE after 1 year. Protocols had different sensitivity behaviors throughout time. Regarding tooth pulp flowmetry, HP35% showed the lowest medians for the percentile variations. CONCLUSIONS: Etching was not able to favor the effectiveness of whitening after 1 year, however, it didn’t increase sensitivity or pulp blood flow. The bleaching protocols were determinant on the degree of color change and evidenced influence on tooth sensitivity and dental pulp blood flow.