During the past 40 years has been a remarkable decline in the prevalence of dental caries in children and adults due to the widespread use of fluoride in public health programs, such as communal water fluoridation, dental practice and in oral hygiene products. In spite of this dramatic improvement, dental caries continues to be the most prevalent dental disease. It is known that the traditional visual-tactile clinical caries examination procedure cannot detect the lesions until they are well advanced and involve 300-500 microns of enamel. Further, such lesions are difficult to reverse with fluorides and other measures often resulting in the need for restorative treatment. It is reasonable to assume that lesions detected at a much earlier stage of development might be more readily reversed and numerous recent reports support the use of new imaging technologies for t he detection of dental cries much earlier than is possible with current clinical methods. These technologies include quantitative laser fluorescence (QLF), electroconductivity (EC), infra-red fluorescence (IR), direct digital radiography (DDR) and digital imaging fiber-optic transillumination (DIFOTI). These technologies have the potential to offer higher specificity and sensitivity with respect to caries detection and quantification. However, little clinical data are available to validate the use of any of these methodologies to detect early dental caries. In addition, the availability of early caries detection technologies will permit the investigation of novel caries interventions which may further reduce the prevalence of dental caries. The fundamental hypotheses to be tested in this investigation are: (1) Developing technologies such as quantitative light or laser fluorescence will permit the accurate detection of dental cries much earlier than is possible with the conventional visual-tactile method; and, (2) Innovative interventions can be identified that will effectively reverse and control early carious lesions. This project will involve two clinical studies: a validation study and an intervention study. The validation study (years 1-3) will validate the use of QLF, IR, EC, DDR, and DIFOTI for the detection of early primary dental caries on occlusal, buccal-lingual and interproximal surfaces as compared to polarized light microscopy (PLM), an accepted "gold standard", on subsequently exfoliated deciduous teeth. The intervention study will utilize the validated method(s) in a clinical trial to determine the efficacy of the most effective interventions determined from Project 1 for the treatment of early primary dental caries. The specific aims of the proposed studies are to: 1, conduct a clinical trial to validate QLF, IR, EC, DDR and/or DIFOTI as a means to detect early caries and, 2) conduct a clinical trial using the validated early detection method(s) with the most effective interventions identified in Project 1 to determine their efficacy in preventing or reversing early primary caries.