In vivo remineralization by a monofluorophosphate dentifrice as determined with a thin-section sandwich method.

Artificial caries lesions were formed in thin sections of subsurface enamel sandwiched between protective sheets of plastic. Six lesions were placed into the buccal surfaces of lower partial dentures of seven subjects, covered with a stainless steel mesh to provide a plaque cover, and brushed with either a sodium monofluorophosphate or placebo dentifrice for four weeks, by means of a double-blind random cross-over design. Analysis of the lesions by quantitative microradiography revealed that significant remineralization (21%) occurred in the monofluorophosphate group and significant further demineralization (27%) in the placebo group. The difference between the active and placebo treatments was significant (p = 0.02), showing that the monofluorophosphate was effective not only in preventing lesion progression but also in promoting mineral deposition. The simultaneous presence of remineralized lesions and lesions with increased demineralization showed the non-uniformity of conditions within a mouth.