Evaluation of Fluoride-Releasing Dental Materials by Means of in Vitro and in Vivo Demineralization Models: Reaction Paper

It is essential that we understand the dose-response mechanisms of fluoride delivered intra-orally at sites in intimate contact with dental tissues. Many studies show that extremely low levels of fluoride can inhibit caries. However, few of these studies provide a direct comparison between fluoride release and the inhibition of secondary caries. For this, laboratory, animal, and in situ caries models are required which can predict clinical efficacy. This paper supplements Dr. Erickson's presentation (Erickson and Glasspoole, 1995) by illustrating the adaptation of currently used demineralization and caries models to the development and evaluation of fluoride-containing resin materials. As representative of this class of material, those which release by ion-exchange are reviewed. It is concluded that model systems designed for topical fluorides and non-fluoride dental materials can be adapted for use with fluoride-releasing materials. Further, the use of materials with a long history of clinical efficacy as inhibitors of marginal caries, such as the silicates, is a useful means of determining target values for developing new fluoride-releasing materials. The minimum concentration of F- that must be maintained in the immediate vicinity of a material to provide caries protection at localized sites is not yet known. Nor is it known what combination of release rate, pattern of release, and duration of release is needed to optimize either localized or full-mouth protection. These issues deserve closer examination to aid our understanding of F^- action when delivered from dental materials, so that improved caries model systems can be designed for use with dental materials.