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 dental health care in general.Some of the research in dental composites is directed toward developing generic polymer science potentially useful for composite applications, e.g., durable resin matrices and stronger more durable coupling between fillers and resins.Improved reinforcement is sought by defining the type, and percentages of fillers which will result in improved performance of composites.Methods for reducing polymerization shrinkage and attendant stress and marginal leakage are also explored.Cements are investigated and basic formulations developed for lower solubility, higher biocompatibility, higher strength, greater toughness and adhesion to various substrates including enamel and dentin.Analysis techniques include IR spectroscopy, chromatography, x-ray analysis, mechanical testing, and dilatometry.Another major effort is directed at elucidating the fundamentals involved in wear and degradation of dental composites and restoratives.Wear and hardness measurement techniques are used as well as identification of the origins and sources of flaws leading to failure.Weibull statistical analysis is expected to provide useful information for this task.In this regard an objective is to investigate improved correlations between clinical results of wear and failure with laboratory test data.Metrology and analysis constitutes the underlying theme of investigations into porcelain-metal systems, casting of dental alloys and the expansion of dental casting investments."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)."

Issued May 1 984 Interagency Agreement Y01-DE-30001 (formerly Y01-DE-4001 5) Certain commercial materials and equipment are identified in this report to specify the experimental procedure. In no instance does such identification imply recommendation or endorsement by the National Bureau of Standards or that the materials and equipment identified are necessarily the best available for the purpose.