To determine the influence of the fracture toughness (KIC) methods [single-edge-V-notch-beam (SEVNB) and chevron-notch-beam (CNB)] as well as an optional heat treatment on the KIC of three different zirconia generations (1st: ZI, 3rd: FX, 4th: HT). One hundred and twenty specimens each (3×4×45 mm) were fabricated, sintered, notched (n=360) and half of them heat treated before KIC measurements with 4-point-flexural-strength test. SEM images of the notches were recorded. Highest KIC was found for ZI followed by HT and FX. SEVNB resulted in significantly higher KIC than CNB. Heat treatment resulted in decrease for SEVNB and increase for CNB of KIC (except for FX). Groups tested using CNB showed higher reliability of values (Weibull modulus) than tested using SEVNB. SEM images present crack path and fracture surface. Different zirconia materials lead to different KIC values. The test method and a prior heat treatment showed an influence on the KIC values and their reliability.
Keywords: Chevron-notch-beam; Single-edge-V-notch-beam; Zirconia.