Natural dental tissues possess hierarchical microstructures that impart remarkable mechanical properties and damage tolerance, inspiring the development of biomimetic restorative materials. However, conventional dental composites lack such sophisticated architectures and face challenges in achieving reliable bonding, particularly when microstructural anisotropy is involved. This study systematically investigated the bonding performance of biomimetic ceramic fiber-resin composites featuring orthogonal plywood (OP) and double-Bouligand (DB) microstructures, addressing the critical question of how directional microarchitectures influence adhesion quality and durability. Biocompatibility was evaluated using CCK-8 assay and Calcein-AM/PI staining, and cytotoxicity was quantified by relative growth rate (RGR) and cytotoxicity grade (CTG) according to ISO 10993-5 criteria. Four surface treatment protocols—combining universal adhesive or silane coupling agent with hydrofluoric acid etching or sandblasting—were comprehensively evaluated to identify optimal bonding strategies. The superior sandblasting-silane protocol was further validated through 5,000 thermocycling cycles (5–55 °C), with detailed analysis of loading directional effects on bond strength. The OP and DB composites exhibited excellent cytocompatibility, with RGR values exceeding 90% at all time points, corresponding to cytotoxicity grades 0–1. Surface treatment significantly affected shear bond strength (SBS) (P 0.05), indicating orientation-independent bonding performance. These findings demonstrate that appropriate combined mechanical and chemical surface treatments can achieve high and directionally stable bond strength in biomimetic ceramic fiber–resin composites. Clinically, this suggests promising potential for these materials as restorative substrates requiring reliable adhesive performance. Nevertheless, the present study is limited by its in vitro design, the use of a single aging protocol, and a single resin cement system, and further in vivo and long-term studies are required to confirm clinical durability.
Yang et al. (Thu,) studied this question.