Nano‐hydroxyapatite‐induced remineralization of artificial white spot lesions after bleaching treatment with 10% carbamide peroxide.

Objective: To assessed in vitro the effect of nanohydroxyapatite (n‐HA) to improve the aesthetic appearance and microhardness of white spot lesions (WSL) when associated with a low‐concentration bleaching agent (carbamide peroxide—CP10%). Material and methods: Enamel/dentin specimens (n = 60) of 5 × 5 × 2.2 mm were prepared, of these, 48 were submitted to pH‐cycling to create artificial WSL. Subsequently, these were allocated into five groups (n = 12): n‐HA; n‐HA + CP10%; CP10%; WSL control (WSLC); sound control (Sound). The color was assessed at baseline, pre‐treatment, and post‐treatment using a spectrophotometer, and the color (ΔE/ΔE00) and whiteness index (ΔWID) alterations were determined. The enamel cross‐sectional microhardness (CSMH) was evaluated (post‐treatment) with a Knoop indenter, 25gf/5 s, 20–200 μm. The data was analyzed through generalized linear models (α = 5%). Results: ΔE and ΔE00 were significantly higher for the bleached groups (n‐HA + CP10% and CP10%), and the n‐HA was higher than the WSLC group (p < 0.05). ΔWID was significantly higher for the bleached groups (p < 0.05). The CSMH values were significantly higher in the sound group than in the n‐HA, CP10%, and WSLC groups (p < 0.05). The WSLC had lower microhardness than the n‐HA + CP10% and sound groups (p < 0.05). Conclusion: n‐HA is suitable to remineralize and recover the color of the WSL. However, its association with CP10% maintains the esthetical outcome while increasing its in‐depth remineralizing effect. Clinical significance: Considering the aesthetic and functional repercussions of the WSL persistence, treatments that tend to improve its physical appearance and reinforce its weakened substructure in a non‐invasive way are ideal. For this associating low‐concentration, bleaching agents to the remineralizing treatments is promising to treat this type of lesions. [ABSTRACT FROM AUTHOR]