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

Abstract 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. Resumo Este estudo in vitro teve como objetivo quantificar a penetração de peróxido de hidrogênio (PH), eficácia clareadora (EC) e toxicidade em larvas em diferentes técnicas de clareamento utilizando 6% de PH. Sessenta pré-molares superiores foram divididos em seis grupos (n = 10): Pola Luminate (PL), VivaStyle Paint On PIus (VS), PolaDay (PD), White Class (WC) e Whiteness HP Automixx (AM). Um grupo não exposto aos agentes clareadores foi avaliado como grupo controle negativo (GC). A concentração inicial de PH nos agentes clareadores foi determinada por meio de titulação e o pH medido com um pHmetro digital. A concentração (µg/mL) de PH no interior da cavidade pulpar foi avaliada por espectrofotometria UV-Vis. A EC (ΔEab * e ΔE00) foi avaliada com um espectrofotômetro digital. A toxicidade foi avaliada em modelo larval. Os dados de penetração de PH e mudança de cor foram avaliados por uma ANOVA de uma via e o teste de Tukey, bem como a curva de morte de Kaplan-Meier para toxicidade (α = 0,05). VS, PD e AM