The impact of an alkasite restorative material on the ph of a streptococcus mutans biofilm and dentin remineralization: an in vitro study

Abstract

This study investigated the effect of an alkasite material on the pH of Streptococcus mutans biofilm and dentin hardness. S. mutans biofilms were formed on a resin composite (FZ) and an alkasite (CN) materials and their pH determined after 24 h. Hydroxide, fluoride and calcium ions released from the materials were determined at 6 h, 1, 3, 7, 14, and 28 d. Fourteen human molar teeth were cut horizontally across the middle third of the crown, bisected mesio-distally into two sections and each section divided into two, yielding four quadrants. Quadrant 1 was a sound dentin control, quadrants 2-4 were chemically demineralized, a cylinder of FZ and CN placed on the surfaces of quadrants 2 and 4, respectively. The microhardness of quadrants 1 and 3 were measured at depths of 20, 40, and 60 µm from the occlusal surface, and similarly of quadrants 2 and 4 after 30 days. Independent t-tests, Mann-Whitney-U, and repeated-measure-ANOVA tests were used for data analysis.The pH of the biofilm on CN (4.45) was significantly higher(p<0.05) than that on FZ (4.06).The quantity of all ions released from CN was significantly higher than from FZ. The hardness of demineralized dentin under CN was significantly higher than that of demineralized dentin at all depths, and higher than that of demineralized dentin under FZ at 20 and 40 µm. In conclusion, CN released hydroxide, fluoride, and calcium ions, which was associated with raising the biofilm pH and the hardness of demineralized dentin.