Development of a hydroxyapatite nanoparticle-based gel for enamel remineralization —A physicochemical properties and cell viability assay analysis

Nano-hydroxyapatite (nHA) was synthesized from abalone mussel shells (Haliotis asinina) using a precipitation method, and gel HA-Abalone was developed using the carbomer materials with concentrations of 0, 10, 20, 30, and 40 wt%. The specimens used were 25 freshly extracted caries-free premolar teeth, and the treatment was done twice a day for 14 days. Gel HA-Abalone 20 wt%, with a crystallite size of 14.70±1.21 nm, was the best concentration to achieve the best remineralization (~863 VHN) of the superficial layer. Based on the results of cell viability assay on gel HA-Abalone 20 wt%, the growth of NIH/3T3 cells was inhibited beginning at a gel concentration of 1,000 µg/mL, and the half maximal inhibitory concentration (IC50) value was 1,497 µg/mL. Based on to the one-way analysis of variance (ANOVA), the result reflected statistically significant differences in the average of the cell viability and enamel surface microhardness values (p