Polycaprolactone-Based Composite for Bone Tissue Engineering in the Temporomandibular Joint Mandibular Condyle

Abstract

The temporomandibular joint (TMJ) is a bilateral-complex articulation that connects the mandible to the skull, enabling essential functions such as chewing, speaking, and swallowing. TMJ disorders (TMDs) affect millions worldwide, leading to pain, dysfunction, and reduced quality of life. In severe cases involving advanced internal derangement, trauma, or osteoarthritis, surgical interventions, such as condylectomy, costochondral grafts, or total joint reconstruction may be required. These current solutions for chronic TMD management and etiology often lack patient specificity, exhibit poor long-term outcomes, and fail to adequately restore native joint function, leaving out growing patients or those with metal hypersensitivity, among others. To address these challenges, bioengineered mandibular condyle prostheses have emerged as a promising alternative, offering personalized solutions with bioresorbable materials to support tissue regeneration of the TMJ. This project aimed to develop a combinatory prosthesis composed of polycaprolactone (PCL), hydroxyapatite (HAp), and demineralized bone matrix (DBM), leveraging three-dimensional-fused deposition modeling (3D-FDM) techniques to optimize mechanical performance and degradation kinetics. Anatomical biomimicry and mechanical robustness were further enhanced using computer-aided design (CAD) and computed tomography (CT) data. Uniaxial mechanical testing demonstrated that increased bioactive material weight percentages and ball milling improved compressive properties. Under accelerated degradation conditions, PCL/DBM composites were more prone to bulk degradation compared to PCL/HAp composites, suggesting that HAp may be necessary for structural integrity. This indicates that a 50 wt% HAp composite may enhance mechanical performance and biological outcomes in vivo by increasing bioactive content, addressing the osteogenic limitations in our pilot study. For our future ovine animal model study, we incorporated a slurry of ground bone, bone marrow, and recombinant human bone morphogenetic protein-2 to promote controlled osteogenesis at the condyle-ramus interface. A novel 50 wt% HAp composite biomaterial, homogenized with ball milling and combined with an osteogenic cellular slurry, may further combat the limitations of existing end-stage devices by offering a patient-tailorable solution that integrates with the mandibular condyle, providing biomechanical stability and promoting bone regeneration. These advancements offer a significant step toward clinically translatable TMJ mandibular condyle replacements.