SPECIALIZED MATERIALS SCIENCE RESEARCH CENTER

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The principal objective of this Center proposal is to employ high technology concepts, instrumentation, and computer support to develop materials and analytical systems for diagnostic, therapeutic, and restorative applications. One of the conceptual areas to be explored is the controlled release of elements or compounds from bonding agents, interfacial films, surface coatings, cavity preparation liners, and root canal sealers to serve as: 1) markers of caries activity below restorations, 2) time-release sources of fluoride, 3) calcifying solutions to remineralize carious tissue, 4) buffers and antibacterial agents to alter bacterial activity in carious environments, and 5) bioactive interfacial material used to enhance closure and healing of osseous defects and exposed pulp tissue. Recent breakthroughs in the technology of polymer microspheres, microencapsulation techniques, and sol-gel processing of bioactive ceramics will be used to develop innovative dental materials containing controlled-release agents. These materials should extend the life expectancy of restorations by minimizing their premature replacement due to the uncertainty in caries diagnosis in sites which lie along the tooth-restoration interface, by reducing the risk for recurrent caries or caries progression associated with existing restorations, and by minimizing the need for endodontic therapy. Another innovative approach will entail the application of stereophotogrammetric technology to develop in automated analytical system for quantifying topographical changes that occur on biological and prosthetic material surfaces. Stereopairs of images derived from a two-camera system or scanning electron microscope will be optically digitized and stored as image files in a computer from topographic maps of surfaces. Automated stereophotogrammetric systems can be used to develop CAD-CAM processed prostheses and to evaluate wear or chemical degradation rates of natural teeth and restorative materials. Another novel concept to be explored involves the development of a castable glass-ceramic with internal coloration controlled through the interactive effect of colorant elements or oxides and thermal processing. Currently available castable ceramics can only be shaded by applying an external layer of shading porcelain and, in some cases, by using pigmented cements. The long-range research goals of this Center program are: 1) to establish optimum formulations and processing techniques for development of polymer microsphere and microcapsule delivery systems for a broad spectrum of diagnostic and therapeutic agents, 2) to develop restorative resins which deliver a controlled dose of fluoride or other therapeutic agents without appreciable structural degradation over the projected lifetime of the restoration or appliance, 3) to establish the efficacy of bioactive glasses processed by sol-gel technology which form direct interfaces with tissue and promote wound healing in pulpal and periapical areas, 4) to develop an automated stereophotogrammetric system for mapping topographical changes on tooth structure and restorations, and 5) to develop and assess the performance of a family of Li2O-CaO-Al2O3-SiO2 glass-ceramics with internal coloration control.