Enamel caries formation and lesion progression with a fluoride dentifrice and a calcium-phosphate containing fluoride dentifrice: a polarized light microscopic study.

The effects of a fluoride dentifrice (Colgate Total) and a calcium-phosphate containing fluoride dentifrice (Enamelon) on caries-like enamel lesion formation and progression were evaluated in vitro. One quarter from each tooth (n = 12) was assigned to one of the study groups: 1) control group [artificial saliva only]; 2) Colgate Total; and 3) Enamelon. The dentifrices were applied to the enamel windows (3 minutes, 3 time per day for 14 days). Following treatment, enamel lesions were created with an acidified gel. After lesion initiation, sections were obtained for polarized light microscopy. To evaluate lesion progression, enamel windows with caries-like lesions in each test group were treated again for 14 days, returned to acidified gels for lesion progression, and then sections were obtained for polarized light microscopy. Mean lesion depths (polarized light, water imbibition) were as follows: 1) Lesion Initiation: Control 109 +/- 19 microns, Colgate Total 76 +/- 14 microns, Enamelon 63 +/- 17 microns; 2) First Lesion Progression: Control 164; +/- 24 microns, Colgate Total 124 +/- 22 microns, Enamelon 110 +/- 19 microns; 3) Second Lesion Progression: Control 235 +/- 23 microns; Colgate Total 172 +/- 27 microns, Enamelon 153 +/- 18 microns. Both Colgate Total and Enamelon enhanced the resistance of sound enamel and caries-like enamel lesions to a continuous in vitro cariogenic challenge when compared with matched controls (P < .05, ANOVA, DMR). Enamelon provided a further reduction in lesion depth for all periods when compared with Colgate Total (P > .05, ANOVA, DMR). Addition of bioavailable calcium and phosphate ions to a fluoride dentifrice may improve the ability of enamel to resist caries initiation and subsequent lesion progression.