title: Lifetime of alumina- and zirconia ceramics used for crown and bridge restorations.
abstract: The lifetime of a ceramic is dependent on the presence of incidental cracks and their gradual propagation under the conditions of the oral cavity. The objective of this study was to examine the long-term strength of glass-infiltrated alumina- and various zirconia ceramics currently used in CAD/CAM systems to manufacture crown and bridge frameworks. Fracture mechanics were applied to determine characteristic strength (sigma(omicron)), Weibull modulus (m), fracture toughness (K(Ic)), and the subcritical crack growth parameters n and B. Based on these parameters, lifetime diagrams were generated which allowed the evaluation of the long-term behavior. The results showed that in a moist environment, the glass-infiltrated alumina- and some zirconia ceramics have a high susceptibility to subcritical crack growth. Zirconia ceramics with an alumina oxide content of 0.25 wt %, however, exhibited the highest initial and most favorable long-term strength, and should therefore be suitable for crown and bridge restorations.
authors.affiliation: Department of Prosthodontics, RWTH Aachen University, 52074 Aachen, Germany. jtinschert@online.de
authors.forename: Joachim
authors.initials: J
authors.lastname: Tinschert
authors.forename: Gerd
authors.initials: G
authors.lastname: Natt
authors.forename: Nina
authors.initials: N
authors.lastname: Mohrbotter
authors.forename: Hubertus
authors.initials: H
authors.lastname: Spiekermann
authors.forename: Karen A
authors.initials: KA
authors.lastname: Schulze
mesh_terms: D000537:Aluminum Oxide; D001696:Biomechanical Phenomena; D017076:Computer-Aided Design; D003442:Crowns; D003829:Denture, Partial; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013718:Tensile Strength; D013997:Time Factors; D015040:Zirconium
chemical_list: D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide