Effect of fluoride and of calcium sodium phosphosilicate toothpastes on pre-softened dentin demineralization and remineralization in vitro

Abstract

Objectives The purpose of this in vitro study was to evaluate the effect of toothpastes containing sodium fluoride in different concentrations or a calcium sodium phosphosilicate system on pre-softened dentin demineralization and remineralization. Methods During a ten day pH-cycling protocol, pre-softened bovine root dentin slabs were immersed twice daily, after the demineralization periods, for 2 min, in the following toothpaste slurries: (a) non-fluoridated (control), (b) 7.5% calcium sodium phosphosilicate, (c) 1450 ppm F, (d) 2800 ppm F and (e) 5000 ppm F. Subsequently, the specimens were subjected to a 15-h acid resistance test. Surface microhardness was assessed initially and during the pH-cycling and the acid resistance test period. Repeated measurements in each group were analyzed through appropriate regression models for longitudinal data. Results All fluoride groups, during pH cycling, showed significantly less microhardness loss ( p ≤ 0.010, p ≤ 0.002, p ≤ 0.002) and subsequently exhibited increased acid resistance ( p ≤ 0.010, p ≤ 0.001, p ≤ 0.001) compared to the control. The 5000 ppm and 2800 ppm F toothpastes, inhibited demineralization significantly more effectively than the 1450 ppm F ( p ≤ 0.001, p ≤ 0.030) and the calcium sodium phosphosilicate toothpaste ( p ≤ 0.001), while no significant differences were found between the two high fluoride groups ( p = 0.130). The calcium sodium phosphosilicate toothpaste, during pH cycling showed a difference that approached statistical significance compared to control ( p = 0.079), but its acid resistance behavior was similar to control ( p = 0.610). Conclusions Under these experimental conditions, the high fluoride toothpastes promoted remineralization and inhibited demineralization more effectively, than the 1450 ppm F, the non-fluoridated (control) and the calcium sodium phosphosilicate toothpastes.