Page 138 - Demo

Chapter 5136Implant manufacturingSix weeks before surgery, each sheep was subjected to a computed tomography (CT) scan of the head. This data was provided to the engineers of CADskills BV (Ghent, Belgium) in DICOM format. Using the derived standard template library (STL) files, a virtual condylectomy was performed on the left side, from which a total joint prosthesis was designed using Geomagic Freeform Plus (3D Systems, Rock Hill, SC, USA). The overall design of the prosthesis was slightly enhanced for animal use after examining a 3D-printed plastic model of the first sheep’s skull (Makerbot, MakerBot Industries, Brooklyn, NY, USA and Formlabs II, Formlabs, Somerville, MA, USA). However, the actual prosthetic design, including the number of screws and screw diameters, was devised to be similar to those used in humans. The specific course of the inferior alveolar nerve in the sheep was taken into account for screw length and position in the mandibular stump.The ramal component was produced in a medical-grade Ti alloy (Ti6Al4V ELI grade 23) by AM, more specifically selective laser melting (SLM 125 HL, SLM Solutions Group AG, Lübeck, Germany). A scaffold structure (500 mm interconnected pores with a diamond unit cell structure) was provided both at the boney interface with the mandible as well as at the condylar neck to provide optimal conditions for boney union and enthesis reconstruction of LPM respectively. A narrow tunnel with a diameter of 2.4-2.5 mm, to accommodate a size 0 suture, was designed in the neck of the condyle (Fig.1). After printing, all condylar heads were first milled to achieve a 0.02mm accuracy to the ‘design-STL’, after which they are polished using a chalk-based polishing paste. Six of the 13 condylar heads were further treated with a H-DLC coating using the non-disclosed HadSat protocol, whereas the other seven condylar heads were left untreated after polishing. The identity of the supplier, as well as the means for applying the H-DLC-coating onto the condylar head surface are proprietary information. The surface roughness of one, non-implanted, coated condyle was determined using a confocal laser microscope (Ra = 0.09 µm , Rt = 0.53 µm) to serve as a comparison for the explanted condyles. Ti alloy screws (Ti6Al4V grade 5, 2.3 mm diameter; Surgi-Tec NV, Ghent, Belgium) were used for fixation of the ramal component. Nikolas de Meurechy NW.indd 136 05-06-2024 10:14