Integrated design to manufacturing process of customised maxillofacial prostheses

Abstract

The results of the CORD feasibility study carried out at the beginning of the present research showed that little research has been done regarding the design and manufacturing processes of large customised titanium implants used for maxillofacial reconstruction. The large titanium implants, as a facsimile of the resected bone, used by the surgeon Mr. Ninian Peckitt, have used many techniques of Computer Assisted Surgery (CAS) to address “functional” surgical reconstruction. This project was about taking the existing, successful implant further along the road of CAS and improving the design and manufacturing processes. The research study consisted in an integrated approach from design process and manufacture to dimensional quality assurance for the developed customised maxillofacial implant. As the research has been completed successfully, a method has been devised to optimise the design process of a customised implant by using solid modelling techniques. Software used to do this was MIMICS from Materialise, Pro/ENGINEER from PTC and 3DataDesign from DeskArtes. The procedure initiated with the CT scans, which were converted and transferred to CAE software. The implant was designed virtually with respect to the patient anatomy and was thus accurate and patient specific. The result was an assembly of the CAD model representation of the patient anatomy and the implant, which fitted perfectly to the anatomical geometry. The implant was brought into Finite Element Analysis (FEA) environment, meshing of the component parts of the implant was investigated in HyperMesh from Altair Eng. and statically analysed for the stress distribution within ANSYS software when loaded with the average bite force identified in specialised publications. The final tasks of the research included: titanium casting manufacturing process of the implant, dimensional/tolerance checking to verify the dimensional accuracy of the cast implant and performance testing to verify the reliability of the material used. Mechanical tests were performed to identify the properties of the materials and implants produced using the mentioned manufacturing process, for comparison with standard values of these materials. The dimensional checks of the actual maxillofacial implant assessed it as feasible engineering and suitable for insertion. The study completed successfully and the carried out research wanted to prove the viability of an idea that by using CT scans, Finite Element Analysis, Computer Aided Analysis and Rapid Prototyping through an integrated approach, realistic modelling, simulation of the body structures and design of implants could be easily performed.