For at least two decades it has been recognized that more efficient models are needed for the conduct of clinical caries trials and this was emphasized at the NIDCR workshop held on May 6-7, 2004. Although there has been a significant amount of research focused on the development of more efficient models for these investigations there has been no agreement on acceptability of these clinical models for evaluating new caries-preventive measures. Thus, the overall goal of this conference is to develop a general consensus among the scientific community regarding the acceptability of new, more efficient models for clinical trials designed to assess the impact of caries-preventive measures on remineralization or demineralization, precavitation and caries. The Specific Aims of this workshop-conference will be to reach a consensus in the scientific community with respect to: (1) the identification of new, more efficient clinical models for use in conducting clinical evaluations of new caries preventive agents or measures; (2) the delineation of any special experimental conditions related to these models required for their scientific acceptance (test duration, treatment compliance, etc); and, (3) the initiation of the process for these clinical models to be accepted by various review agencies such as the ADA and the FDA. In essence, this proposed workshop-conference is designed to utilize scientific information generated in the past three years to build upon the progress made at the International Consensus Workshop on Caries Clinical Trials held in Loch Lomond, Scotland in January 2002. The conference will begin with a series of state-of-the-art presentations on different clinical methodologies to assess remin/demin, precavitation or cavitation stages of the disease. Then about 40 invited experts in cariology will work in small groups to address defined issues related to these methodologies. The meeting will be held on July 3-5, 2005 in the Downtown Marriott Hotel in Indianapolis, Indiana, immediately prior to the annual ORCA (European Organization for Caries Research) meeting.