Evaluating the Remineralizing Potential of Carbonated Hydroxyapatite on Enamel After At-Home Bleaching: An In Vitro Study

Background: Tooth bleaching may result in enamel demineralization and increased surface roughness. This study aimed to investigate the effects of at-home bleaching on enamel surface morphology and assess the potential of carbonated hydroxyapatite (CHA) as a remineralizing agent compared to casein-phosphopeptide-amorphous calcium phosphate nanocomplex (CPP-ACP). Methods: Extracted premolars were divided into four groups. Group 1 had no treatment, while group 2 was treated with 22% carbamide peroxide. In addition, group 3 was treated with 22% carbamide peroxide followed by remineralization with CPP-ACP, and group 4 was treated with 22% carbamide peroxide followed by remineralization with CHA. After bleaching with 22% carbamide peroxide, remineralization agents were applied for seven days. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy were used to evaluate surface morphology and elemental composition. Results: There was a statistically significant reduction in calcium and phosphorus levels but an increase in carbon content in Groups 2, 3, and 4 compared to Group 1 (P=0.000). Group 4 (bleached and CHA-treated) had the highest carbon content (40.2±0.9 wt (%)). SEM analysis revealed a smooth enamel surface in group 1, while group 2 (bleached) displayed increased surface irregularities. Groups 3 and 4, treated with CPP-ACP and CHA, respectively, confirmed significant mineral deposition on enamel surfaces. Conclusion: Overall, at-home bleaching with 22% carbamide peroxide caused enamel damage and mineral loss. Both CPP-ACP and CHA demonstrated potential for remineralization following bleaching.