Flexural resistance of Cerec CAD/CAM system ceramic blocks. Part 2: Outsourcing materials

摘要

Purpose: To test different Cerec CAD/CAM system ceramic blocks, comparing mean flexural strength (σ), Weibull modulus (m), and Weibull characteristic strength (σ0) in an ISO standardized set-up. Methods: Following the recent ISO Standard (ISO 6872:2008), 11 types of ceramic blocks were tested: IPS e.max CAD MO, IPS e.max CAD LT and IPS e.max CAD HT (lithium disilicate glass-ceramic); In-Ceram SPINELL, In-Ceram Alumina and In-Ceram Zirconia (glass-infiltrated materials); inCoris AL and In-Ceram AL (densely sintered alumina); In-Ceram YZ, IPS e.max Zir-CAD and inCoris ZI (densely sintered zirconia). Specimens were cut out from ceramic blocks, finished, crystallized/infiltrated/sintered, polished, and tested in a three-point bending test apparatus. Flexural strength, Weibull characteristic strength, and Weibull modulus were obtained. Results: A statistically significant difference was found (P 0.001) among lithium disilicate glass-ceramic (σ = 272.6±376.8 MPa, m = 6.2±11.3, σ0 = 294.0±394.1 MPa) and densely sintered alumina (σ = 441.8±541.6 MPa, m = 11.9±19.0, σ0 = 454.2±565.2 MPa). No statistically significant difference was found (P= 0.254) in glass infiltrated materials (σ = 376.9±405.5 MPa, m = 7.5±11.5, σ0 = 393.7±427.0 MPa). No statistically significant difference was found (P= 0.160) in densely sintered zirconia (σ = 1,060.8±1,227.8 MPa, m = 5.8±7.4, σ0 = 1,002.4±1,171.0 MPa). Not all the materials tested fulfilled the requirements for the clinical indications recommended by the manufacturer.