Comprehensive Evaluation of Machinabilities of Dental Ceramics

Machinability of ceramics is a comprehensive behavior resulting from the interactions of several factors. In this paper, the fuzzy comprehensive evaluation system was applied to establish a model for machinabilities of several dental ceramics, including zirconia, empress feldspar, empress toughening leucite and lithium disilicate glass. The hardness (HV), fracture toughness (KIC) and elastic modulus (E) of ceramic samples were used in evaluation model with different weighted indexes. The ceramics could be thus divided into 4 groups of “easiest”, “easy”, “difficult” and “most difficult”, based on evaluated results. Lithium disilicate glass belongs to “easiest”, empress feldspar and empress toughening leucite are at the “easy” level, and zirconia is “difficult” to be machined compared with other counterparts. The evaluations by established model are well supported by the practical machining experiments while these dental ceramics being undergone cutting. This implies that the derived evaluation model is an easy and simple way to estimate machinability of dental ceramics.