Comparison of fluoride profiles by SIMS with mineral density of subsurface enamel lesions treated intra-orally with a fluoride-releasing device.

A variety of intra-oral model systems has evolved which allows for the study of remineralization of coronal and/or root-surface lesions following application of topical fluoride (F) agents. The problem of interpretation of the results has led to a variety of analytical methods (i.e., microhardness, F biopsy, microradiography, and polarizing light microscopy), each of which provides important but limited information related to the overall understanding of remineralization. Microhardness measures change in mineral content which is more precisely localized by microradiography and polarized light microscopy. F biopsy allows for assessment of the F uptake of lesions, but does not suggest the chemical state of the F. Previous work has demonstrated that patterns of mineral deposition during remineralization do not necessarily parallel the F uptake profiles, and fluoridated apatites cannot be distinguished from non-specifically-adsorbed F (Clark et al., 1988). Because artificial lesions demonstrate variations in depth and mineral content, complementary analytical methods that demonstrate profiles of both F content and mineral density curves on the same section are needed so that the process of remineralization can be more clearly understood. This study used secondary ion mass spectrometry (SIMS) for F profiles and quantitative microradiography for assessment of mineral deposition on the same section. These state-of-the-art methods demonstrate the precision with which information about remineralization can be obtained. Subsurface lesions in human enamel specimens were developed by immersion in 0.1 M lactate buffer with 1% CMC at a pH of 4.5 for 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)