Fused deposition modeling of defect-specific conformable bone grafts from 13-93B3 polymer-bio-glass composites

Abstract

Large bone defects are usually treated with autografts, allografts, synthetic materials, or bioactive ceramics. Each of these options has limitations, including donor site issues, limited availability, and poor fit for individual patient needs. Bioactive glasses have the potential to promote bone growth but often lack sufficient strength for clinical use. This study investigated the possibility of using 3D-printed bone grafts made from polylactic acid (PLA), polycaprolactone (PCL), and borate bioactive glass (BBG, 13-93B3) to create customized and strong grafts. We created composite filaments (PLA/BBg and PCL/BBg; 50 wt% polymer and 50 wt% BBg) as well as pure PLA and PCL filaments. We then tested for the compatibility of these materials with cells and living tissue, their mechanical properties, and the ease of printing. Tests with mesenchymal stem cells revealed increased metabolic activity of approximately 15.4% for PCL/BBg and 20.7% for PLA/BBg and higher alkaline phosphatase activity of approximately 20.8% and 35.4%, respectively, on day 7, which indicates better early bone formation. The constructs made from PCL/BBg had mineral contents similar to those of natural bone and were easy to print via fused deposition modeling. They produced porous structures with a compressive strength of approximately 9 MPa and a modulus of 168 MPa that matched human mandibular trabecular bone. In vivo tests on a rabbit model with premaxillary defects over 14 weeks revealed better bone healing in the PCL/BBg-treated areas, with no signs of inflammation or toxicity. These results indicate that PCL/BBg composite filaments could be effective for making patient-specific, biodegradable bone grafts that have precise structures and strong mechanical properties. More studies involving larger animals are needed to push this research toward clinical use.