In vitro remineralization of human and bovine white-spot enamel lesions by NaF dentifrices: A pilot study

The aim of this feasibility study was to evaluate the in vitro remineralization effects of four dentifrice systems using microhardness and fluoride uptake analyses. In vitro testing for the potential remineralization of the white-spot lesions in bovine and human enamel was performed using a 10-day pH cycling model. The study involved the following NaF silica-based dentifrices: 1) placebo (0 ppm F), 2) 500 ppm F, 3) 1150 ppm F, and 4) 500 ppm F plus functionalized tricalcium phosphate (fTCP). Each day consisted of four two-minute treatments, one four-hour acid challenge (pH = 5.0), and immersion in artificial saliva (pH = 7.0) between these events. After cycling, specimens were analyzed for surface microhardness (SMH), enamel fluoride uptake (EFU), and cross-sectional microhardness (CSM). Statistical analyses revealed significant differences (ANOVA, LSD, p<0.05) among the four groups, with the placebo and 500 ppm F dentifrices providing significantly less remineralization relative to the 1150 ppm F and 500 ppm F plus fTCP dentifrices. Notably, while CSM measurements for both enamel types generated similar profiles for the four groups, SMH and EFU revealed human enamel was more sensitive to the 500 ppm F dentifrice groups compared to bovine enamel. This apparent sensitivity may be due to the inherent structural differences between the two substrates.