Improving the Fracture Resistance of Dental Ceramic

Abstract

A time-temperature sequence for optimally strengthening dental ceramic by ion exchange was investigated. Stress relaxation occurs at higher temperatures and/or longer times. Im-proved strengths are obtained in a reasonable period of time that could be used for clinical application. J Dent Res 56(10):1209-1213 October 1977. The fracture of glass and ceramic materials may often be traced to the propagation of sur-face flaws through the bulk material. The pres-ence of these defects is inevitable since they are caused by ordinary handling and accentuated by slight chemical attack from moisture. Ten-sile rather than compressive forces are generally responsible for crack extension and ultimate failure. A practical method of increasing the tensile strength of ceramics is to create a com-pressive skin on the surface of the ceramic; the applied tensile forces must then overcome th