Enhanced enamel remineralization by a nanohydroxyapatite-fluoride biomimetic formulation: a comparative in vitro study

Abstract

This study compared the remineralization efficacy of three commercially available biomimetic and bioactive formulations, including nHAP + NaF, CPP-ACP, and a biocalcium lactate-peroxidase (BioC), using surface microhardness (SMH) and scanning electron microscopy (SEM). Artificial enamel lesions were created on sixty-four human enamel specimens using a validated pH-cycling model. Fifty-two specimens were randomly assigned to four groups ( n = 13): nHAP + NaF, BioC, CPP-ACP, and untreated control for surface microhardness (SMH) analysis, while twelve additional specimens were used for scanning electron microscopy (SEM). SMH was measured at baseline, post-demineralization, and post-treatment using a Vickers microhardness tester. Surface microhardness recovery percentage (SMHR%) was calculated to quantify remineralization efficacy, and surface morphology was qualitatively analyzed using SEM. Statistical analysis was performed using two-way repeated-measures ANOVA, two-way ANOVA, and Tukey’s post hoc tests (α = 0.05). Baseline ( p = 0.107) and post-demineralization ( p = 0.272) SMH values did not differ significantly among groups. Following treatment, significant intergroup differences were observed ( p < 0.001). The nHAP + NaF group demonstrated the highest SMHR% (62.76 ± 4.48%), followed by CPP-ACP (52.21 ± 2.54%) and BioC (42.17 ± 5.00%), whereas the control group showed the lowest recovery (14.11 ± 5.09%) ( p < 0.001). SEM observations supported these findings, with the nHAP + NaF group exhibiting the greatest reduction in surface porosity and the most homogeneous surface morphology after treatment. All investigated bioactive formulations promoted remineralization of artificially induced enamel lesions. Among the tested materials, the nano-hydroxyapatite-sodium fluoride formulation demonstrated the greatest improvement in surface microhardness and the most favorable SEM findings under the experimental conditions of this study. Further in situ and clinical investigations are required to determine whether these findings translate to clinical performance.