3D-printed bioresorbable polycaprolactone-tricalcium phosphate implant for mandible reconstruction: A biomechanical in-vivo evaluation.

Abstract

Large mandibular critical-sized defects commonly require free vascularized bone flaps. However, this procedure is associated with donor site morbidities and complex microsurgical procedures. An implant-based technique that can achieve similar reconstructive outcomes would be a valuable addition in a reconstructive surgeon's armamentarium. This preliminary study evaluated 3D-printed polycaprolactone-tricalcium phosphate implant for reconstructing mandibular critical-sized defects using a porcine model. Seven mandibular body critical-sized defects were created in 5 male Yorkshire-Landrace pigs (3 unilateral and 2 bilateral defects). These defects were reconstructed using polycaprolactone-tricalcium phosphate implants. The study endpoint was at 3 months. The reconstructed mandibular specimens were resected for evaluation. Ossification was evaluated using computed tomography scans and histology. Biomechanical strength was evaluated using the three-point bend test. The contralateral unoperated sides served as the controls. The animals retained normal mastication. All implants demonstrated ossification on computed tomography scans with a median of 24.1% (range 13.6-27.2%). Histological examination (using hematoxylin and eosin and Masson's Trichrome stains) demonstrated new bone formation. The three-point bend test demonstrated a borderline significant difference in the maximum flexural force between the reconstructed mandibles and controls (p = 0.059), with a mean difference of 426.62 N (95% CI -16.57 to 869.81). Using polycaprolactone-tricalcium phosphate implants in reconstructing mandibular critical-sized defects is safe and reliable. Polycaprolactone-tricalcium phosphate is bioresorbable, osteo-conductive, and osteo-inductive. It provides immediate functional restoration and mechanical strength under load-bearing situations.