390 Assessing Biocompatibility & Mechanical Testing of 3D-Printed PEEK Versus Milled PEEK in Maxillofacial Surgical Applications

Abstract Aim PEEK (poly-ether-ether-ketone) is an innovative thermoplastic polymeric biomaterial used in Maxillofacial Surgery. As opposed to metallic implants, PEEK implants can be 3D-printed specifically for patients and do not suffer stress shielding effects- a major cause of implant failure. This investigation aimed to compare mechanical integrity and biocompatibility of modern 3D-printed PEEK implants against traditionally produced Milled-PEEK implants and metallic biomaterials e.g., Titanium. Method Fused-deposition-modelling and non-CNC Milling were used to produce ASTM/ISO-designed PEEK samples. Samples were designed and produced using the Apium P155 FDM-3D-printer, Fusion 360 and Simplify3D software. Fracture Toughness KIc, Tensile Strength, Vickers micro-hardness and 3-point flexural strength tests were performed. Cell adhesion on sandblasted 3D-printed PEEK was evaluated by culturing primary human endothelial cells and osteoblasts (HUVEC, HOBS) and evaluating cell growth. Results Milled PEEK had higher tensile strength (p=0.022), higher flexural strength (p<0.0001) and higher fracture toughness (p=0.003) than FDM-printed PEEK. However, FDM-printed PEEK demonstrated higher microhardness than Milled PEEK (p=0.014). Both FDM and Milled PEEK showed mechanical strength values in normal ranges of cortical bone, and close to ranges of alternative bone-replacement biomaterials. Both HOBS and HUVEC demonstrated strong adhesion to PEEK with >95% viability. Conclusions 3D-printing of PEEK is an emerging technology with advantages over milling and metallic biomaterials in implant production. Nonetheless, this manufacturing modality may produce 3D-printed PEEK devices with lower mechanical resistance parameters compared to milled PEEK, but with values compatible with natural bone. Sandblasting is a modality to create uniform micro-rough surfaces potentially enhancing osseointegration of PEEK implants with host tissue.