Clinical evaluation of in-office bleaching gel application times

Objectives: The purpose of this randomized clinical trial was to evaluate the tooth-whitening efficacy of 30 minutes versus 45 minutes in-office vital bleaching with a hydrogen peroxide gel. Methods: Twelve patients were treated with three separate (7-days interval) 30- and 45-min chairside exposures of 35% hydrogen peroxide (White Gold Office, Dentsply), using a split mouth design. Instrumental color measurements from teeth were obtained at baseline and at seven, fourteen, twenty-one and thirty days after first whitening section using an intraoral spectrophotometer (EasyShade, Vita) according to the CIELab color scale. The mean changes of the L*a*b* values between different measurements in each group were expressed as delta E and were analyzed with ANOVA and the Tukey's post-hoc test, with significance level of 5%. Results: Results showed that for both analyzed groups delta E mean was significantly lower after one week than at other evaluation times. Independently of the analyzed period, average for delta E was significantly higher for 45-min than for 30-min treatment group. Conclusion: It was concluded that both in-office treatment times were effective for teeth whitening. Forty-five minutes bleaching with 35% hydrogen peroxide produced significantly lighter teeth than 30 minutes chairside exposure, during all active-treatment periods and follow-up visits.