Effect of calcium and phosphate in an artificial chemical model of root caries formation.

PURPOSE: To investigate the mineral density of artificial root caries lesions formed under varying concentrations of calcium phosphate, with or without the presence of fluoride. METHODS: Sixty-four human tooth root blocks were exposed to various lactic acid solutions for 96 h. These included a low concentration (0.16 mM) of calcium chloride and potassium dihydrogen phosphate (Group L), a low concentration (0.16 mM) of calcium chloride and potassium dihydrogen phosphate with 0.5 ppm fluoride (with sodium fluoride) (Group LF), a high concentration (2.2 mM) of calcium chloride and potassium dihydrogen phosphate (Group H), and a high concentration (2.2 mM) of calcium chloride and potassium dihydrogen phosphate with 0.5 ppm fluoride (Group HF). The mineral loss in the artificial lesions formed was measured using micro-computed tomography. RESULTS: The mineral loss in groups L, LF, H and HF was 35.38 +/- 2.15%, 31.96 +/- 2.1%, 32.58 +/- 1.15%, and 27.78 +/- 2.3%, respectively. A significant difference (P < 0.001) was observed between groups L and LF, groups LF and HF, groups H and HF, and groups L and HF. Calcium phosphate and fluoride exposure both had significant effects (P < 0.001) on mineral loss. CONCLUSION: Artificial root caries lesions were associated with decreased mineral loss in solutions containing higher concentrations of calcium phosphate or in the presence of fluoride, compared with those formed in solutions with lower calcium phosphate concentrations or without fluoride.