title: Influence of layer and stain firing on the fracture strength of heat-pressed ceramics.
abstract: Fracture strength (T = torque to initiate fracture; K(IC) = fracture toughness) and the fractography of heat-pressed leucite reinforced ceramic (IPS Empress, Ivoclar AG-Schaan, Liechtenstein) were analysed by the notched disc test technique and scanning electron microscopy methodologies. To determine the effects of additional firing schedules on the heat-pressed core ceramic, three groups of specimens were prepared. These groups were heat-pressed core, heat-pressed core and simulated stain firing, and heat-pressed core and simulated layer firing. Statistical analysis of both T and K(IC) values showed that there was no statistically significant difference between these three groups (P > 0.05). Scanning electron microscopy analysis of the fractured surfaces revealed that crack propagation occurred around some of the leucite particles and also partly and directly through other leucite particles.
authors.affiliation: Ankara University Faculty of Dentistry, Turkey.
authors.forename: S
authors.initials: S
authors.lastname: Uçtaşli
authors.forename: H J
authors.initials: HJ
authors.lastname: Wilson
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003735:Dental Casting Technique; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D003776:Dental Porcelain; C078519:leucite