The goal of this research is the development of improved polymer composites for use as dental restorative materials. Specifically, we aim to synthesize highly functional "molecular filler" species, which, when combined with monomer resins yield composites that possess lower shrinkage and improved mechanical properties relative to current formulations. Series of fillers with differing sizes, morphologies, and functionalities will be synthesized and characterized. These fillers will be compounded with methacrylate and thiol-ene monomer resins and photopolymerized. Properties of the resulting composites, including glass transition temperature, modulus, shrinkage, and mechanical strength will be measured in order to determine their ability to serve as dental restorative materials. Collaboration with clinicians and dental researchers at the University of Colorado Health Sciences Center will be heavily emphasized in both the development and testing of the materials to ensure that the formulations created are suitable for clinical use. The research portion of this proposal is particularly relevant to NIDCR's mission to pursue and improve treatment strategies for dental diseases and disorders. Additionally, the proposal's training aspect will provide the applicant's first experience in the dental research field, thus supporting the Center's strategic initiative goal to train investigators from the field of chemistry with requisite experience to make meaningful career contributions in dental research. Relevance: Dental caries, commonly referred to as tooth decay, remains a significant public health issue, due in part to its status as the most frequently occurring chronic disease affecting children. The goal of this project is the development of improved filling materials for repairing tooth damage caused by tooth decay. The materials being developed in this study are expected to possess longer service lifetimes and lower filling failure rates than those currently available.