The use of dental amalgam for the reconstruction of teeth is controversial due to its release of mercury during in-service use. Thus, amalgam alternatives are frequently placed by dental practitioners. The most commonly used alternatives, ceramic reinforced polymer-matrix composites, have a survival rate that is approximately half that of amalgam. The purpose of this submission is to develop an alternative class of materials that can serve as a substitute for mercury-containing dental amalgam. Its successful development will lead to a cost-effective method of reconstructing diseased tooth tissue for the long-term using a mercury-free material. The specific aims of this research are to (1) synthesize polymerizable alkylthiols that can mediate strong bonds between metal fillers and polymers, (2) identify the optimal method of surface preparation of candidate substrates for the deposition of the alkylthiol, and (3) formulate prototype metal-polymer composites. The research design involves a synthesis phase where candidate compounds will be assessed for their ability to mediate strong bonds on models systems, the use of surface science techniques (spectroscopies, microscopies) to verify success of the synthesis as well as deposition of the compounds on candidate substrates, and the final phase where prototype materials will be mechanically characterized and assessed for their feasibility to be used as restorative materials for load-bearing surfaces of teeth. The potential for technological innovation is very positive. A core base of knowledge involving thiol chemistry and the ability of thiols to form dense, ordered monolayers on metals is used here. When functionalized with polymerizable vinyl groups, these compounds can strongly bind metal fillers to a polymer matrix and form an advanced material for dental use. PROPOSED COMMERCIAL APPLICATIONS: This research has several potential commercial applications. The first is in the field of oral health, where the successful development of a cost- effective, more durable alternative to dental amalgam is being sought. A second application involves the use of the adhesion promoters developed. These can act as couplers between metals and polymers for any biomedical application. They could be used for indirect restorative procedures in dentistry where metal appliances or single tooth restorations are bonded to enamel/dentin, or as bone cements in orthopedics when metal implants are used.
