The principle objective of this project is to systematically screen agents that might promote oral health using a selective battery of in vitro and animal tests. Secondary objectives include the development of testing procedures. Recent studies indicate that the anticaries benefits of the intraoral fluoride releasing device can be improved if the teeth are pretreated with a calcium phosphate solution developed by Chow and coworkers (1974). We have identified mechanisms that might contribute to therapeutic effects of the antiplaque agents, alexidine and octenidine. We have developed an in vivo method for measuring the pH of rat plaque in situ.