"Edge toughness" and material properties related to the machining of dental ceramics

Seven dental ceramic compositions, including zirconia, glass-infused alumin a, polycrystalline alumina, porcelain and three different machinable glass ceramics (MGC's) were tested for edge flaking. The chosen load range encomp assed the forces typically associated with machining operations for these m aterials. The results were examined with regard to material properties and the applicability of a parameter defined as "edge toughness" to machinabili ty. It was determined that a non-linear low-load chipping relationship may be more relevant to machinability than the ''edge toughness'' parameter cal culated from the high-load linear region.