Polymeric biomaterials maintained the esthetic efficacy and reduced the cytotoxicity of in-office dental bleaching

Evaluate the kinetics of hydrogen peroxide (H2O2) degradation, esthetic efficacy and cytotoxicity of a bleaching gel with 35%H2O2 applied on enamel previously covered or not with polymeric nanofibrillar scaffold (SNan), polymeric primer catalyst (PPol), and both. Standardized enamel/dentin discs (n = 128) obtained from bovine teeth were adapted to pulp chambers. After covering enamel with the polymeric products, the bleaching gel was applied for 45 min, establishing the following groups: G1: no treatment (negative control); G2: 35%H2O2 (positive control); G3: SNan; G4: PPol; G5: SNan + PPol; G6: SNan + 35%H2O2; G7: PPol + 35%H2O2; G8: SNan + PPol + 35%H2O2. The kinetics of H2O2 degradation (n = 8), bleaching efficacy (ΔE/ΔWI; n = 8), trans-amelodentinal cytotoxicity (n = 8), and cell morphology (n = 4) were assessed (ANOVA/Tukey test; p < 0.05). Greater H2O2 degradation occurred in G7 and G8. Bleaching efficacy (ΔE) was higher in G6, G7, and G8 in comparison with G2 (p < 0.05). However, no difference was observed for ΔWI (p > 0.05). G8 presented the lower level of trans-amelodentinal diffusion of H2O2, oxidative stress, and toxicity to the MDPC-23 cells (p < 0.05). Polymeric biomaterials increased the kinetics of H2O2 decomposition, as well as maintained the esthetic efficacy and minimized the cytotoxicity caused by a bleaching gel with 35%H2O2. Clinical Significance: Application of a bleaching gel with 35%H2O2 on enamel previously covered by polymeric biomaterials maintains the esthetic efficacy and reduces the cytotoxicity caused by a single session of in-office dental bleaching.