The Intraoral Fluoride Releasing Device is a new intraoral therapeutic system being developed by the National Institute of Dental Research. The IFRD is designed to provide continual topical fluoride for periods of up to six months for the prevention of dental caries. The IFRD reduced the incidence of experimental dental caries in rats by more than 50% and has been used in humans for periods of up to six months without producing adverse effects. The objectives of this project are to refine the shape and method of attachment of the IFRD in order to make it more durable and easier to use in humans and to investigate various treatment regimens in animals in an attempt to optimize the cariostatic benefits from the topical fluoride provided by the IFRD. Findings from recent animal studies indicate that the marked caries reductions produced by the IFRD were due to topical effects of fluoride and the results also suggest that the cariostatic effects may persist for a significant time period after an IFRD is removed from the mouth. An improved manufacturing process for the IFRD is being developed and new methods for retaining and protecting the IFRD in the mouth are being reviewed.