The candidate?s long-term objective is to become a respected research scientist in the field of biomaterials, with more immediate goals of contributing to a theoretical understanding and practical development of dental materials. This proposal will enable her to apply her training and experience to build a knowledge base in dental material failure analysis and fractography. The work will be conducted at the Paffenbarger Research Center, which has nurtured many successful independent researchers by providing an environment of motivated, encouraging professionals, state-of-the art experimental facilities, individual and formal educational instruction, and personal mentoring. The proposed project is in response to a need for a science-based analysis of the failure of dental restorations. This study will utilize material properties, novel testing techniques and fractography in an interdisciplinary approach to determine failure causes in commercial and model dental materials. In Aim 1, strength and toughness parameters are obtained with newly developed standardized tests. Clinical relevancy is attained through strength distributions and fractographic correlations between test samples and failed restorations. In Aim 2, the new edge toughness test quantitatively ranks materials according to chipping susceptibility, and enables back-calculation of force values that cause chipping by edge-chip dimensional measurements. Aim 3 evaluates techniques, such as dyes, oblique lighting and computerized data collection, for identifying fractographic features in dental ceramics. There are currently no guidelines for fractographic analysis specific to this class of materials. The restoration fractographic analysis in Aim 4 enables controversies on the location of fracture initiation to be resolved, and failure causes and progression to be determined. Aim 5 sets up an accessible database of critically evaluated dental material properties. Currently, it is not possible to compare property values among dental materials because of the different test parameters used by investigators in this field. The achievement of the stated aims will constitute the establishment of a failure analysis technology that will benefit every aspect of the restoration industry, including design, processing, clinical procedures and placement, and mechanical testing and standards development.