Zirconia is in well known as a dental biomaterial and has been applied as structural material for implants, dental bridges, crowns or inserts due to its biocompatibility, high fracture toughness, and radiopacity. On the other hand oxide ceramics can undergo subcritical cracking which is crucial parameter in the case of a long-term loading in a humid environment (such as human body). Pure zirconium oxide stabilized with yttrium oxide is considered also as an inert material. To improve bioactive properties, modifying additives are used to induce a specific biological response. One of the most common bioactive filler, which enhances early and late bone-to-implant integration; is represented by hydroxyapatite. Another example of a material that has the effect of enhancing osteointegration is bioglass. Bioactivity can also be understood in the context of providing dental materials with antibacterial function. Among the most commonly used antibacterial materials are silver and copper nanoparticles. In the present work we tried to consider 3 aspects simultaneously. First of all determination of slow crack growth parameters and then lifetime estimation of biocomposites made of ZrO₂ and hydroxyapatite (HAp), where zirconia powder was obtained by hydrothermal method. Secondly, comparison of biological properties such as antibacterial efficacy and biocompatibility of ZrO₂/HAp in respect of ZrO₂ composites modified with hexagonal boron nitride (hBN), bioglass (BG), and bioglass containing copper (BGCu). Thirdly, demonstration of bioactive properties that promote the formation of an apatite layer on the biocomposite surface in contact with SBF.

Our findings indicated that all materials demonstrated a high degree of biocompatibility. However, it is noteworthy that a slight cytotoxicity was observed in the composites modified with HAp and hBN. Furthermore, the same composite materials exhibited notable antibacterial properties against Gram-positive bacteria and some Gram-negative strains. Moreover, the mechanical tests showed that ZrO₂/HAp biocomposites revealed susceptibility to subritical cracking.