Prevention of caries progress in xerostomic patients by topical fluoride applications: a study in vivo and in vitro

Fluoride uptake by the surface enamel of teeth was studied in vivo and in vitro in xerostomic patients and in extracted human teeth respectively, following various topical fluoride applications (Duraphat varnish, 2·26 per cent F; APF gel, 1·23 per cent F; Elmex gélee, 0·4 per cent F). Fluoride increments known to be effective for inhibition of caries in xerostomic patients were achieved in vivo and in vitro from all preparations. Arrest of caries was observed only in patients who were cooperative in the preventive fluoride programme. It was concluded, on the basis that the fluoride incorporation found in the experiments in vitro was not stable, that topical fluoride applications in xerostomic patients had to be used frequently to ensure a prophylactic success.