Antimicrobial properties and bioactivity of zirconia-based biocomposites.

Zirconia-based composites are promising materials for medical and dental applications. They are widely used due to their osteoconductivity and chemical stability. Moreover, when modified with beneficial fillers, they combine mechanical strength with bioactivity. This study addresses the interplay between bioactive fillers, cytotoxicity, antibacterial activity, and reactive oxygen species (ROS) levels in ZrO₂ composites. The composites were tested for their biological properties. Thanks to hydrothermally obtained zirconia used in ZrO₂/HAp composites the sintering temperature was reduced, which limited hydroxyapatite decomposition. However, ZrO₂/HAp composites revealed higher cytotoxicity and ROS levels, linked to calcium ion release resulting from the partial HAp decomposition. Composites with BGCu exhibited strong antibacterial activity and acceptable cytotoxicity due to copper ions disrupting microbial structures and inducing oxidative stress. hBN-containing composites displayed moderate bacteriostatic activity but higher cytotoxicity than BGCu composites. These findings highlight the potential of ZrO₂/BGCu composites as bioactive materials for bone regeneration and antimicrobial applications. While composites with hydroxyapatite demonstrate a balance between bioactivity and cytotoxicity, BGCu emerge as a promising modification to enhance antibacterial properties with controlled cytotoxicity. Further research is needed to optimise filler compositions to balance ion release, biological stability, and functionality.