The project objective is to develop new glass-ceramic compositions and casting methods for fabricating dental prostheses. During the grant """"""""megafillers"""""""" for composite restorations were developed. This project will feature developing compositions for precision fabricated restorations having intrinsic tooth colors and requiring no further processing to obtain proper aesthetics. The primary goal is to provide alternative materials for precision-cast and CAD/CAM posterior restorations, and high-performance dental composite fillers. These new glass-ceramics can form tooth colored alternatives to composites, ceramics, and metals for load bearing posterior applications, and they have demonstrated properties of thermal expansion, microstructure homogeneity, strength, hardness, tolerability, and wear superior to existing dental porcelains. A lower melting, stuffed beta-quartz glass- ceramic will be formulated and tested in three lost-wax casting methods. The methods selected, Dicor (Caulk/Dentsply) casting system, pressure- vacuum, and standard centrifugal systems, are readily available low-cst technologies. After determination of casting conditions, investment materials and conditions will be optimized for accuracy and dimension reproduction. The glass-ceramic will be subjected to heat treatments to induce crystal growth and impart inherent color. Heat treatment conditions will be determined for a range of tooth-like colors, and dopant oxides will be added, if necessary, to match dental colors. The resultant glass-ceramic will then be tested for wear against both human enamel and dental materials. The product will be a castable ceramic with inherent tooth color that can be cast with existing lost-wax methods and equipment to form custom prostheses. A second goal is to evaluate a beta-quartz containing glass-ceramic as a prosthesis material in CAD/CAM applications. Existing and experimental glass ceramic compositions will be tested for their machinability with the rotary CAD/CAM diamond instrumentation. Experiments will evaluate the precision and edge detail of restorations thus machined. Positive results will broaden the range of intrinsically tooth colored materials available for CAD/CAM applications. The final goal is to determine if a stuffed beta-quartz glass-ceramic dental composite filler will improve properties such as strength, thermal expansion, surface wear, and wear on opposing enamel compared to existing composites. Superior glass ceramic properties will be performance tested in experimental composites.
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