Page 246 - Demo

Chapter 9244Surface FinishingA sandblasted, large-grit, and acid-etched (SLA) surface at the bony interface of the mandibular component and the skull base of the fossa component of the TMJ Parametro is achieved by both micro-shot peening with alumina grit (ø =550 µm) and etching using 2 wt% oxalic acid at 85°C for 10 min. This enhanced surface roughness allows for bone ingrowth which reduces the stress on the screw-bone interface quite rapidly, allowing a reduction in the number screws required for primary stability from seven to five. (Fig. 1e)Fig 2: Microscopic views (Magnification 500x) of the condylar surfaces of two different TMJ Parametro implants using scanning electron microscopy. (a) A condyle that was coated with HadSat showing few irregularities. (b) An uncoated, polished condyle showing multiple grooves.FunctionalityKinematics of the prosthetic joint. When comparing the load on the contralateral side of a mandible that has undergone total TMJ replacement with the load on the condyle of a healthy mandible, the load increase is approximately 15% when using a stock prosthesis.(8–13) Increases in mechanical loads have been shown to stimulate cartilage production and articular disc damage which can negatively affect the patient (e.g., pain) and should thus be avoided.(14,15)In order to prevent disease development in the unaffected joint, an attempt was made to prevent an increase in load in the untreated joint. Nikolas de Meurechy NW.indd 244 05-06-2024 10:14