Currently, none of the commercially available glass-ionomer cements (GICs) are being used for Class I and II restorations due to their poor wear-resistance and low mechanical strengths, although these cements have numerous advantages over composite resins. We have demonstrated that novel star-shape polyacid-constructed hybrid glass-ionomer cement exhibits outstanding and comparable wear resistance as well as mechanical strengths to current composite resins. Further, nanofiller-strengthened GIC showed significantly improved hardness and wear-resistance. Combined with surface-modified nanofillers, the above star-shape polymer-constructed GIC may be developed into a novel dental restorative for sites requiring wear-resistance and high-strength restorations. The objective of this research is to develop a novel biocompatible nanostructured light-cured glass-ionomer system with comparable wear-resistance and mechanical strengths to current dental composite resins, in response to NIDCR's FOA for Nanostructured Dental Composite Restorative Materials. In this research, a series of starshape poly (acrylic acid)s and nanoparticles with polymer surface modification will be synthesized using advanced aqueous ATRP technology. Both nanosized functional polymers and fillers will be characterized and used to construct a novel biocompatible high-strength light-cured GIC. The system will be optimized based upon molecular weight, length of the polymer on nanofiller surface, tethering ratio of methacrylate on the polymer, nanofiller loading ratio, total filler powder/polymer liquid ratio, working viscosity, and efficiency of the initiator system. Flexural strength, hardness and viscosity will be used as primary screening tools for evaluation. Wear resistance and fracture toughness will be used as secondary screening tools. Other important mechanical and physical properties will also be evaluated. In vitro biocompatibility of the new system will be evaluated using MTT assay. This project will build on an ongoing collaboration between a dental materials scientist with strong polymer synthesis experience and a clinical dentist with strong dental materials research background. Successful achievement of the goals of this project will positively impact the fields of Restorative Dentistry and early caries intervention by providing a new attractive adhesive dental restorative. This project will also provide an ideal training environment for biomedical engineering students and dental materials students because it will allow them, through close interactions with the collaborators from different disciplines, to develop a broad perspective on dental materials research. ? ? ?
