Mechanical properties of Y:TZP/TiO2 coated with hydroxyapatite for dental implants

Abstract

Purpose/aim: (1) To investigate the effect of titania content in mol% (0, 10 and 30) in the specific surface area (SBET), the size of the agglomerates and the intensity of the peaks corresponding to crystalline phase present in the ceramic powder of Y:TZP/TiO2; (2) to investigate the effect of titania addition (0, 10 and 30 mol%) on the microstructure, relative density (RD), Young’s modulus (E), Poisson’s ratio (PR), flexural strength ( f) andWeibull modulus (m) of a Y:TZP/TiO2 composite; and (3) to investigate the effect of the presence of a biomimetic coating on the microstructure and mechanical properties ( f and m) of Y:TZP/TiO2 composite. Materials and methods: Y:TZP (3mol% of yttria) and Y:TZP/TiO2 composite (10 or 30mol% of titania) were synthesized using a co-precipitation route. The powders were pressed and sintered at 1400 ◦C/2 h. Half of the discs were subjected to biomimetic coating. The powderswere characterized by X-ray diffraction (XRD), laser scattering, gas adsorption and scanning electron microscopy (SEM). The surfaces, with and without biomimetic coating, were characterized by SEM and XRD. The RD was measured by the Archimedes’ principle. E and PRwere measured by ultrasonic pulse-echo method. For the mechanical properties the specimens (n = 30 for each group) were tested in a universal testing machine. Weibull modulus was estimated by the maximum likelihood method and ANOVA with Tukey test (˛ = 5%) was used to evaluate f, E and RD. Results: All powders had a SBET greater than 42m2/g and the titania addition favored the formation of larger agglomerates. Titania addition increased the grain size of the composite and caused a significant decrease in the f in MPa (control: 815.4a; T10: 455.7b and T30: 336.0c), E in GPa (control: 213.4a; T10: 155.8b and T30: 134.0c) and relative density in % (control: 99.0a; T10: 94.4c and T30: 96.3b) of the Y:TZP/TiO2 composite. The presence of 30% titania caused substantial increase in m and PR. Biomimetic coating resulted in the formation of apatite globules heterogeneously distributed on the surface of the material and this treatment did not significantly alter the f and m of the composite (Table 1). Conclusions: The Y:TZP/TiO2 composite coated with a layer of CaP has great potential to be used as implant material. Properties of the powderwere affected by titania addition. Addition of titania toY:TZP caused an increase in grain size, a significant decrease in f, E and RD. The presence of biomimetic coating did not jeopardize the reliability of Y:TZP/TiO2 composite.