Study On In Vitro High Efficient Removal Mechanism Of Ceramic Prostheses In Dental Surgery

In dental surgery processes, ceramics generate an intense grinding force and are prone to engender mechanical damages because of its high hardness and brittleness as well as difficulties resulting from complex and specific intra-oral environments. Removal mechanism on high efficiency dental surgery of a feldspar porcelain and its effect on surface quality under different finishing Parameters including high depth of cut, removal rate and diamond girt sizes were investigated using a novel computer controlled in-vitro apparatus. The main conclusions and work are as follow:1 Both the tangential and normal forces under given conditions were measured to increase with increasing either the depth of cut or the removal rate of dental handpiece. When the porcelain was removed at the higher removal rate, both the tangential and normal forces were markedly higher using the fine bur than those using the medium and coarse burs, which indicates that we should avoid using fine diamond girt bur and make use of coarse bur if just with the consideration of enhancing finishing efficiency.2 Surface roughness appeared to be independent of the increase in either depth of cut or specific removal rate, but decreased significantly with a decrease in diamond girt size.3 Microfracture and ductile maching were found to occur simultaneously in high efficiency dental surgery from analysis of experimental data and characteristic observation to finished surface. The difference in influence of finishing Parameters on removal mechanism is that proportion between microfracture and ductile maching was not same in different conditions. Furthermore, we find that the modified feldspar porcelain was removed mainly due to brittle fracture, although most of grinding energy was expended by ductile flow.The work accomplished in this dissertation is significative to guide clinical operation in dental surgery for dentists.