Microstructure-based multiphysics study of hydroxyapatite-mullite composite as a potential bioceramic

Hydroxyapatite (HAp) is widely used in biomedical applications due to its exceptional biocompatibility. However, the inherent brittleness and low fracture toughness of HAp limit its utility in high-load-bearing applications, such as dentistry and bone tissue engineering. To overcome these mechanical shortcomings, HAp is frequently reinforced with stronger, secondary inclusions to form durable bio-composites. Evaluating the long-term viability of these composites in vivo is challenging due to their complex, multi-inclusion microstructures and simultaneous chemophysical degradation processes. This study presents a microstructure-based 3D model designed to evaluate the long-term mechanical performance of HAp-based composites in simulated bodily environments. Key biomaterial degradation processes are coupled throughout the 3D composite microstructure, which was reconstructed using X-ray computed tomography. These processes are solved concurrently using finite element analysis based on diffusion-reaction and continuous damage theories. Results demonstrate that incorporating an inert reinforcing phase, such as mullite particles, successfully grants the HAp matrix a mechanical strength comparable to that of natural teeth.