The Effect of Different Bleaching Techniques Using 6% Hydrogen Peroxide: Penetration Inside the Pulp Cavity,...

This in vitro study aimed to quantify the penetration of hydrogen peroxide (HP), bleaching efficacy (BE) and toxicity in larvae in different bleaching techniques using 6% HP. Sixty maxillary premolars were divided in six groups (n = 10): Pola Luminate (PL), VivaStyle Paint On PIus (VS), PolaDay (PD), White Class (WC) and Whiteness HP Automixx (AM). A group not exposed to bleaching agents was evaluated as a control group (CG). Previously, the initial HP concentration in the bleaching agents was determined via titration and pH was measured with a digital pH meter. The concentration (µg/mL) of HP inside the pulp cavity was assessed using UV-Vis spectrophotometry. The BE (ΔE* ab and ΔE00) was evaluated with a digital spectrophotometer. The toxicity was evaluated in larvae model. Data from HP penetration and color change were evaluated for a one-way ANOVA and the Tukey's test, as well as Kaplan-Meier death curve for toxicity (α = 0.05). VS, PD and AM had an initial concentration lower than that the manufacturers reported. VS had a more acidic pH. PL and WC showed a significantly lower HP amount inside the pulp cavity when compared to VS (p = 0.001). Regarding BE, no significant difference was observed for ΔE* ab (p = 0.38), and ΔE00 (p = 0.42). No toxicity was observed when all 6% HP was compared to GC (p > 0.05). All 6% HP products tested showed bleaching efficacy, low penetration into the pulp chamber and were non-toxic to Tenebrio molitor larvae.