The purpose of this study was to evaluate the physical properties of dental sealant resins under aging conditions to determine the critical factors controlling functional property loss with time. The effect of processing on the chemical and thermal properties of several different sealant formulations was evaluated. These processing parameters included the blue light exposure time for each light-curing system and time after illumination. The results indicate that the level of cure for each system was incomplete at the end of all processing procedures. Heating as well as further aging of the cured resin advanced the cure. Additionally, one of our goal was to model the curing characteristics of the sealant as a function of depth in the fissure to evaluate the thickness influence on the sealant mechanical properties. The strength and stiffness of the light-cured sealant varied as a function of depth in the fissure. This results in a gradient of deformation which could cause early fracture of the resin upon chewing. Incomplete resin conversion is important since dental adhesives have been shown to be leached by saliva and the elution products have been recently shown to be potentially estrogenic. Samples of differently processed commercial sealants were immersed in an ethanol/water solution and extractions were analyzed by HPLC. An inverse correlation between the degree of cure and the % of elution as well as high level of extraction was found. An <i>in vivo</i> study has been performed on fifteen pigs. The purpose of the experiment is to obtain data on <i>in vivo</i> sealing ability of the sealant. Low sealant retention rates have been found but interesting observations of sealed fissures were made and the pig can be considered like an acceptable model. / Master of Science