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

Abstract

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.