Dentine remineralization by simulated saliva formulations with different Ca and Pi contents

The understanding of the dentine remineralization process and the ability to reproduce it in vitro are essential to the development of preventive and therapeutic measures. This study investigated how simulated saliva formulations with different Ca and P(i) contents and degrees of saturation with respect to biologically relevant calcium phosphates may affect the remineralization of eroded dentine, as a function of time. Slabs of bovine root dentine (n = 8 per group) were flattened, polished, demineralised by 1% citric acid for 30 and 60 min and remineralized for 3, 7 and 14 days, by one of the following buffered (pH 7) solutions [Ca:Pi ratio, Ca/Pi concentrations (mM), ionic strength]: solution A: 1.6, 1.5/0.9, 0.115; solution B: 1.6, 2/1.25, 0.117; solution C: 1.6, 3.2/2, 0.121; solution D: 0.3, 1.11/3.7, 0.118; solution E: 0.3, 1.45/5, 0.122. Integrated mineral loss (30 and 60 min) was quantified by transverse microradiography after each remineralization period. ANOVA and regression analyses (alpha = 0.05) showed, irrespective of the demineralisation time, that the solutions C and E were able to remineralize dentine. This effect increased throughout the remineralization times and was significantly higher for E. Remineralization was successfully shown in vitro, under specific conditions of degree of saturation and Ca and Pi contents of the solutions. Optimum remineralization was observed for the solution E supersaturated with respect to relevant calcium phosphates, with low Ca:Pi ratio and highest Pi concentration.