High‐Concentration Hydrogen Peroxide Gels Containing Calcium Polyphosphate Associated With Violet Led Light: Bleaching Efficacy and Effects on Enamel Properties

Objectives: To evaluate the effect of violet LED light (VL) and hydrogen peroxide (HP) in-office bleaching gels supplemented with calcium polyphosphate (CaPP) or calcium gluconate (GU): Materials and Methods: Bovine enamel blocks (n = 10) were randomly assigned: commercial HP gel, commercial HP gel with GU, or experimental 35% HP with or without CaPP (0.5 or 1.5 wt%), and their VL-irradiated versions. Bleaching efficacy was assessed by color analyses (CIE L*a*b*, ΔEab, ΔE00, ΔWID) at baseline (T0) and after treatment (T1). Knoop microhardness (KHN), percentage surface microhardness loss (%SHL), and roughness variation (ΔRa) were measured at T0, T1, and 14 days post-treatment (T2). Surface morphology was assessed by scanning electron microscopy (SEM). Data were analyzed using generalized linear models, Kruskal–Wallis and Dunn tests (α = 0.05). Results: The group irradiated only with VL exhibited lower color change (p < 0.0001). CaPP addition significantly increased ΔE00 in VL-irradiated groups (p < 0.05). For roughness and SEM, no significant differences were observed among groups. Only CaPP- and GU-containing gels restored initial KHN values at T2 (p < 0.05). CaPP groups showed lower %SHL than control groups (p < 0.05). Conclusions: Bleaching gels containing CaPP maintained bleaching efficacy and mediated enamel microhardness recovery. VL further enhanced the bleaching effect in CaPP gels. Clinical Significance: CaPP represents a promising alternative for bleaching gel formulations, promoting enamel remineralization and enhancing bleaching efficacy when combined with VL.