A longitudinal microhardness analysis of fluoride dentifrice effects on lesion progression in vitro.

The longitudinal microhardness technique has been used to determine the effect of a sodium fluoride dentifrice on the progression of artificial carious lesions in a pH cycling model in vitro. The NaF dentifrice was found to be extremely effective in reducing the progression of caries in enamel, limiting both the depth of acid damage and the degree of mineral loss measured at discrete intervals within specimens. Lesion progression areas, estimated using Simpson’s rule to integrate hardness data, indicated that the NaF dentifrice effected a 73 and 82% overall reduction in lesion advancement, relative to placebo and untreated controls. This area analysis appeared to represent a useful means for simplifying comparisons of treatment effects in remineralization studies using cross-sectional microhardness as the measurement tool. In terms of comparative accuracy to microradiography, analysis of published data indicated that the longitudinal microhardness technique, while limited in some respects, can provide useful estimates of remineralization/lesion-progression areas.