Project Summary/Abstract Because of the formation and subsequent sloughing off of microbial biofilms from the inner surfaces of plastic tubing, dental unit water is heavily contaminated with microorganisms. These microorganisms pose a potentially significant threat to both dental health care workers and dental patients, particularly those who are medically compromised or immunocompromised. The long-range goal of this project is to use N-halamine- based rechargeable antimicrobial tubing to control the formation of dental unit waterline biofilms. The specific aims of the proposed research are to: (1) covalently bind self-recharging N-halamines onto plastic tubing; (2) characterize the mechanical properties, antimicrobial activity, anti-adherent function, and rechargeability of the new tubes; (3) evaluate the biofilm-controlling function and safety of the new tubes in model dental water delivery systems, and (4) provide preliminary data on the cost of the new approach. To achieve these goals, the first part of the proposed research will optimize the grafting reactions to covalently bind both amide and amine N-halamine precursors into plastic tubing currently used in outpatient dental clinic waterlines, so as to introduce self-recharging antimicrobial effects into the tubing and achieve long-lasting biofilm-control (e.g., longer than 1 month). This will be followed by a series of studies to provide detailed information on the mechanical properties, antimicrobial/anti-adherent activity, rechargeability, and effects of recharging on the mechanical properties of the new tubes. Then the new tubes will be evaluated with mixed species of water bacteria in model dental water delivery systems to determine the efficacy and safety of the new approach in controlling DUWL biofilms. Finally, the cost of the tubes will be estimated, as a first step in evaluating the cost-effectiveness of the new approach. If successful, the rechargeable antimicrobial tubing approach will provide an innovative solution to the biofilm problem in dental unit water delivery systems. Further, the antimicrobial plastic tube materials to be developed in this study may find applications in other clinically important surfaces. All these will make significant contributions to a better and safer healthcare environment.