Effect of Nano-sized Hydroxyapatite Filler on Remineralization Efficacy of an Adhesive Resin: an in vitro study

Abstract

Aim The aim of this study was to evaluate the remineralization efficacy of an adhesive resin containing nano-sized hydroxyapatite filler. Methodology The study consisted of four groups: control (without filler), 2% hydroxyapatite (HA), 5% HA, and 7% HA. Nano-hydroxyapatite powder was mixed with Scotchbond Multi-Purpose®. The teeth were sectioned to expose the midcoronal dentine. Bonding agents and resin composite restorations were applied. Teeth were incubated in simulated body fluid for 24-h, 30-day, and 90-day intervals. After incubation, the teeth were sliced. Hardness and elasticity modules were obtained for the three different time periods (for a total of n = 360 samples). The detection and measurement of mineral deposition areas were obtained by confocal laser scanning microscopy (CLSM) (for 120 samples). Elemental analysis was performed with energy-dispersive X-ray spectroscopy (EDS) (n = 360 samples). The statistical analysis of each parameter was performed using two-way ANOVA and group comparisons by post hoc tests. Results Study groups and storage periods affected the hardness (p = 0.00) and elasticity scores (p = 0.00). The CLSM results showed that increasing the storage periods and amount of HA resulted in mineral deposition areas (p = 0.02). The calcium and phosphor ion values of dentine that were obtained using EDS were increased (p = 0.00). Conclusion Hydroxyapatite fillers positively affect the remineralization activity of adhesive resins. In terms of remineralization efficacy, the best results were obtained in the 7% HA group.