The Application of in Situ Models for Evaluation of New Fluoride-Containing Systems

Many in situ models have assessed the anticaries potential of fluoride-containing systems (Stookey et al., 1985; Mellberg et al., 1986, 1992a,b; Corpron et al., 1986; Featherstone and Zero, 1992; Ogaard and Rolla, 1992; Stephen et al., 1992). Several models have reportedly been validated according to guidelines proposed by Proskin et al. (1992). The proposed guidelines cover only dentifrices containing sodium fluoride (NaF) or sodium monofluorophosphate (SMFP) as active ingredients. These compounds are the most widely used sources of fluoride in dentifrices, and dose-response clinical standards are available for both. Other fluoride compounds, such as amine fluoride (AmF) and stannous fluoride (SnF2), have also been proven effective in reducing caries (Muehler et al., 1957, 1958; Marthaler, 1968; Lu et al., 1980; Cahen et al., 1982). Profile standards for these fluorides were not included in the proposed guidelines, primarily due to the lack of clinical data necessary to establish a dose response for these ingredients. Criteria for demonstrating the efficacy of these ingredients, along with methods to assess new fluoride compounds, need to be established. In situ models are used to evaluate the anticaries potential of new compounds added to mouthrinses, gums, slow-release devices, etc. (Creanor et al., 1992; Manning and Edgar, 1992; Lamb et al., 1993; Toumba and Curzon, 1993; Wang et al., 1993). Ingredients are often added to dentifrices previously proven effective against caries in order to provide additional benefits of gum health, tartar control, cleaning, etc. Proposals are made regarding the in situ testing of new dentifrices containing clinically proven fluoride compounds other than NaF and SMFP, as well as alternative delivery systems, in order to assist in their evaluation.