Efficacy of Fluoride Toothpaste Fortified With Micro- and Nano-Hydroxyapatite on Remineralization and Surface Roughness of Synthetic Enamel

Objectives

To evaluate the remineralization efficacy and surface effects of 1450 ppm fluoride toothpaste fortified with synthetic hydroxyapatite (Syn-HAP) of varying particle sizes and concentrations on synthetic enamel. Material and methods: Nano-sized Syn-HAP (nanoSyn-HAP) was synthesized via a mechanochemical process and characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sixty disc-shaped synthetic pellets underwent artificial caries induction and were randomly divided into five groups: Untreated (negative control), commercial 1450 ppm fluoride toothpaste (FT), FT plus 5% micrometer-sized Syn-HAP (FT+5mHAP), FT plus 5% nanoSyn-HAP (FT+5nHAP), and FT plus 10% nanoSyn-HAP (FT+10nHAP). Specimens then underwent a 15-day pH cycling regimen with twice-daily treatments. Knoop microhardness was evaluated at baseline, post-caries induction, and post-treatment; surface roughness and scanning electron microscopy (SEM) were assessed at baseline and post-treatment. Data were analyzed using ANOVA and Bonferroni post-hoc tests (p < 0.05).