Mechanical properties of zirconia ceramics biomimetically coated with calcium deficient hydroxyapatite

• Published in: Journal of the mechanical behavior of biomedical materials Vol. 111; p. 104006
• Main Authors: Macan, Jelena, Sikirić, Maja Dutour, Deluca, Marco, Bermejo, Raul, Baudin, Carmen, Plodinec, Milivoj, Salamon, Krešimir, Čeh, Miran, Gajović, Andreja
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.11.2020
• Subjects: Calcium; Calcium phosphates; Ceramics; Durapatite; Humans; Hydroxyapatites; Materials Testing; Mechanical properties; Metastable calcifying solution; Sol-gel process; Surface Properties; Yttria stabilised zirconia; Zirconium; Mechanical properties; Yttria stabilised zirconia; Metastable calcifying solution; Sol-gel process; Calcium phosphates
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2020.104006

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. [Display omitted] •Porous ZrO2 ceramics were coated with calcium-deficient hydroxyapatite (CaDHA).•Bioactive CaDHA coating was used due to structural similarity to the bone mineral.•CaDHA was obtained by simplified biomimetic procedure.•Mechanical properties of ZrO2-CaDHA match or exceeds those of bone.•The values of scratch test critical load significantly exceed those of HA coatings.