PROJECT SUMMARY Secondary caries is considered the leading cause of dental restorations failure. The economic burden of treating this dental condition is significant at a cost of over $5 billion each year in USA. Improving the seal of dental materials bonded to dental hard tissues is critical for the prevention of secondary caries, progression of dental disease and tooth loss. Removing bacteria at the bonded interface will prevent the (bio)chemical degradation of the bonded materials, and thus, increase the clinical service of restorations. A common limitation of current antibacterial technologies includes the short durability of the effects due to leaching and depletion of ions. Therefore, there is an immense need to develop a new generation of dental antibacterial materials to reduce and eliminate dental diseases at bonded interfaces (e.g. secondary caries). We recently developed a new composite with piezoelectric properties for antibacterial therapies by incorporating charged nano-fillers into dental resins. Our innovative approach significantly improves current technologies by using a single filler with long-lasting antibacterial effects. In this study, we propose to find the optimal amount of piezoelectric nano-filler to enable the antibacterial effect while retaining high mechanical and physical properties of the composite (aim 1). In addition, we will evaluate the oral microbiome-modulating effects of piezoelectric charges to understand the specific changes on the biofilm composition and identify the targeted species by piezoelectric charges (aim 2). We expect the development of the proposed technology to significantly impact the dental field by reducing the failure rate of composite restorations, in turn, reducing the costs associated with those failures, improving the health of patients, and preventing unnecessary loss of additional tooth structure.