Paper published in Journal of the Mechanical Behavior of Biomedical Materials

Jelena Macan, Maja Dutour Sikirić, Marco Deluca, Raul Bermejo, Carmen Baudin, Milivoj Plodinec, Krešimir Salamon, Miran Čeh and Andreja Gajović have published a paper titled ” Mechanical properties of zirconia ceramics biomimetically coated with calcium deficient hydroxyapatite” in
Journal of the Mechanical Behavior of Biomedical Materials, Volume 111, 2020, 104006, ISSN 1751-6161, https://doi.org/10.1016/j.jmbbm.2020.104006.

Abstract: Mechanical properties and stability of porous tetragonal yttria-stabilised zirconia (Y-TZ) ceramics, biomimetically coated with calcium deficient hydroxyapatite (CaDHA) to obtain a bioactive material, were investigated. The 5.7 mol% yttria-stabilised tetragonal zirconia was obtained by sol-gel process and sintered at different temperatures to obtain a homogeneous and porous structure whose strength would match that of human bone. Sufficient strength was achieved by sintering at 1400 °C. The CaDHA coating was obtained at room temperature by a simplified preparation method consisting of immersion of the Y-TZ ceramics into a calcifying solution, after a short surface pretreatment in HCl. Although HAP or β-TCP are more frequently used, CaDHA was chosen due to its structural similarity to the bone mineral and ability to support bone ingrowth to a greater extent than biphasic calcium phosphates. To verify the applicability CaDHA coatings, we tested their adherence to Y-TZ ceramics for the first time to the best of our knowledge. Vickers hardness (3.8 ± 0.2 GPa) reflected the hardness of underlying ceramic. The tensile strength (269 ± 52 MPa) and Weibull modulus (5) of the obtained biomaterials matched or exceeded those of bone. There was no statistical difference in the tensile strength between the coated (269 ± 52 MPa) and the uncoated (239 ± 46 MPa) ceramics. The Y-TZ-CaDHA coating system presented adequate structural integrity under scratch test with critical load for coating cracking of 18 ± 2 N. These results indicate the potential of the prepared bioceramic to be used as bone implants.
Keywords: Yttria stabilised zirconia; Sol-gel process; Calcium phosphates; Metastable calcifying solution; Mechanical properties

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