Fluoride uptake, retention, and remineralization efficacy of a highly concentrated fluoride solution on enamel lesions in situ.

Repeated topical application of concentrated fluorides is known to reduce caries. Little is known about fluoride retention and remineralization in incipient caries lesions following a single application. We investigated fluoride and the remineralization kinetics of a single application of elmex fluid (GABA International AG, Münchenstein, Switzerland; 10,000 ppm F) in initial enamel lesions. In this double-blind, placebo-controlled, randomized, crossover in situ study that conformed to good clinical practice, volunteers received intra-oral removable appliances carrying demineralized enamel samples after application of elmex fluid or placebo. After 5 min, 1, 2, 3, and 4 weeks in situ, KOH-soluble fluoride (KOHF), structurally bound fluoride (SBF), mineral gain, and lesion depth reduction were measured. Elmex fluid promoted higher KOHF and SBF at all times, decreased KOHF with time, increased SBF up to 3 weeks, and registered a higher mineral gain than placebo. Volunteers with higher stimulated salivary flow rates had lower fluoride uptake, but higher mineral gain. In conclusion, a single application of highly concentrated fluoride solution increases remineralization.