Optimization of Machining Performance of Dental Ceramic Restorative Materials
Le, Dung T.
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Dental ceramics are gaining popularity because of their esthetics, strength, chemical durability, and bio-compatibility. However, the inherent brittleness of ceramics poses a challenge to the manufacturing community as the cracking formed during the material removal leads to premature clinical failures. Consequently, fabrication of excellent-fitting and durable dental prostheses calls for new and innovative processing technologies to minimize the formation of, micro-scale cracking.<P>This thesis presents a combined analytical and experimental study with focus on optimizing the machining performance of a type of newly developed dental material. It is called DICOR/MGC, where MGC stands for machinable glass ceramic. The study starts from analyzing their microstructural characteristics to searching for the machining conditions that provide satisfactory performance in terms of surface finish and acceptable flexural strength. To gain a better understanding of the material removal mechanism(s), a dynamometer is designed to perform an on-line recording of the cutting force generated during machining. Method of using an environmental scanning electron microscope is employed to examine the machined surface texture and identify the machining induced cracking. Two major contributions of this thesis study are (1) the fundamental understanding of the relationships among the material microstructures, the machining parameters, and the material preparation on surface integrity of dental ceramics, and (2) the development of an architecture for searching machining conditions that optimize the machining performance of dental ceramics.