Influence of a Combination of Catalysts to Improve the Outcomes of In-office Bleaching

The aims of this study were to investigate (1) whether the addition of catalytic enzymes and violet LED light to the conventional in-office hydrogen peroxide (H2O2) bleaching protocol could improve esthetic results in a shorter time and (2) whether these strategies could minimize adverse effects on the enamel surface and the diffusion of H2O2 through the tooth structure.

120 bovine dental discs were divided into two study phases. In phase I, 60 sectioned specimens were pigmented with black tea for analysis of chromatic change, bleaching index, and trans-amelodentinal diffusion. In phase II, 60 unpigmented specimens were evaluated for enamel roughness and microhardness. In both phases, the specimens were divided into four groups (n=15): NC (negative control): no treatment; G45: 35% H2O2 bleaching gel for 45 minutes; GT: 35% H2O2 bleaching gel with peroxidase enzyme for 15 minutes on enamel previously covered with a polycaprolactone nanofiber mesh scaffold; GTL: Same procedure as GT, irradiated with violet LED light for 15 minutes. Esthetic efficacy (ΔE00 and WID) was analyzed in three sessions (T1, T2, T3) and 7 days (T4) after treatment, and H2O2 diffusion was evaluated at T1 (phase I). In phase II, the specimens were evaluated for microhardness and surface roughness at T0 and T4. For the analysis of microhardness, roughness and chromatic alteration, a Two-Factor ANOVA with Repeated Measures was used to evaluate the groups over time, while H2O2 diffusion was analyzed by One-Way ANOVA.

GTL promoted the greatest change in ΔE00 in all sessions; however, ΔWID in GTL did not differ from G45 at T3 and T4. The diffusion of H2O2 in GT was 69% lower than G45. The enamel microhardness and roughness of the GT and NC groups were not altered by treatments, but were significantly worse in G45.

When compared with conventional in-office whitening alone, the strategies tested achieved the same esthetic results in two-thirds less time, reduced alterations to the enamel surface, and reduced the trans-amelodentinal diffusion of H2O2.