Mechanical properties and cytotoxicity of 3Y-TZP bioceramics reinforced with Al2O3 particles

Abstract The influence of Al 2 O 3 addition and sintering parameters on the mechanical properties and cytotoxicity of tetragonal ZrO 2 –3 mol% Y 2 O 3 ceramics was evaluated. Samples containing 0, 10, 20 and 30 wt.% of Al 2 O 3 particles were prepared by cold uniaxial pressing (80 MPa) and sintered in air at 1500, 1550 and 1600 °C for 120 min. The effects of the sintering conditions on the microstructure were analyzed by X-ray diffraction analysis and scanning electron microscopy. Hardness and fracture toughness were determined by the Vickers indentation method and the mechanical resistance by four-point bending tests. As a preliminary biological evaluation, “in vitro” cytotoxicity tests were realized to determine the cytotoxic level of the ZrO 2 –Al 2 O 3 composites, using the neutral red uptake method with NCTC clones L929 from the American Type Culture Collection (ATCC) bank. Fully dense ceramic materials were obtained with a hardness ranging between 1340 HV and 1585 HV, depending on the amount of Al 2 O 3 in the ZrO 2 matrix. On the other hand, no significant influence of the Al 2 O 3 addition on fracture toughness was observed, exhibiting values near 8 MPa m 1/2 for all compositions and sintering conditions studied. The non-cytotoxic behavior, the elevated fracture toughness, the good bending strength ( σ f = 690 MPa) and the elevated Weibull's modulus ( m = 11) exhibited by the material, show that these ceramic composites are highly suitable biomaterials for dental implant applications.