Properties and interactions of oral structures and restorative materials

Abstract

The research program described herein is designed to achieve a number of objectives leading to improved dental restorative materials, techniques and applications of dental materials science for improved delivery of health care. The bulk of the research is related in one manner or another to dental composites, cements, adhesives, and sealants. Composite research focuses on improvements through the development of more durable resin matrices, stronger and more durable coupling between fillers and resins, and defining the best overall combination of components, including curing systems, for improved performance of composites. This work has moved swiftly toward a major emphasis on the synthesis and applications of monomers which reduce polymerization shrinkage through the use of expanding monomers (or monomers which undergo much less shrinkage than conventional resin-matrix monomers). Research on cements, adhesives and sealants employs many of the same methods as for composites but with further attention to adhesion to dentin and enamel. Analytical techniques include infrared (IR) spectroscopy, chromatography, x-ray analysis, nuclear magnetic resonance, hardness and tensile testing, and shrinkage dilatometry. A new effort involves a pilot study aimed at the use and further development of fluorescent dye spectroscopy for analysis of processes such as curing, applying coupling agents and monitoring the degradation of bonding between fillers and resin matrices; this application holds promise for far-reaching results. Studies on the wear and durability of dental materials are conducted to complement the generic developmental work on composites, cements, adhesives and sealants. The wear work is to help guide further improvements in materials. A second distinct area of effort focuses on dental alloy and ceramic systems. Weibull statistics and finite element stress analysis are employed for the determination of the strengths of ceramic and ceramic-metal systems as affected by processing parameters and thermo-mechanical properties. This program is divided in Three Basic Parts for FY 1991; In FY ' s 92 and 93, Part II on Wear Resistance will be subsumed into Part I, Improvement of Dental Composites, Sealants, Cements and Adhesive Materials. v "The activity covered by this agreement consists of work which requires the definition of measurement methods, materials property data, and standards of basic scientific and engineering units, and the application of primary standards to insure equity and comparability in U.S. commerce, international trade, and technical activities. As such it complies with OMB Circular A-76, Revised under paragraph 5f ("Activities classified as Government responsibilities or are intimately related to the public interest")." NO HUMAN SUBJECTS ARE INVOLVED IN THIS RESEARCH vi a variety of food simulating liquids (including water) with the capability for providing constant exposure to the specimen. Various ancillary methods of degradative analyses will be employed.