Additive manufacturing of reconstruction devices for maxillofacial surgery: design and accuracy assessment of a mandibular plate prototype

Abstract

Additive manufacturing (AM) presents unique opportunities for medical applications and in particular in maxillofacial surgery for developing patient specific implants. The quality assessment of additive manufactured products is an essential aspect for the real introduction in health services. In this framework, the purpose of the present study is to investigate the possibility of developing prototypes of mandibular plates as preoperative surgical planning models, by verification of design, analysis of internal structure integrity and evaluation of the effects of variables involved in AM processes. A PolyJet threedimensional (3D) printing system is used in the study due to its very fine resolution. The computer aided design (CAD) models of the implants were converted to stereolithography (STL) file formats in different STL conversion resolutions and then printed using commercial prototyping polymers to observe the effect of model resolution. Finite element analysis (FEA) was conducted to study the capability of the designed mandibular plate to support the involved biomechanical loads. Micro-computed tomography (micro-CT) analysis was performed to verify the dimensions and the internal defects of the printed objects, considering that the presence of defects can affect the quality and compromise the final performance. Results were analyzed to understand the effect of the 3D printing process flow conditions on the obtained prototypes. Relative error in reference to the CAD models mainly evidenced the difference in resolution due to STL files and the effect of the design. No anomalies and defects were detected inside the evaluated samples.