Page 154 - Demo

Chapter 5152in human TMJ TJR. Keeping the higher mastication rate and laterotrusive movement in mind, the force the fossa is subjected to is higher compared to that in humans. This might have led to excessive stress in the bone surrounding the screws, resulting in bone resorption and micromovements between the fossa and the underlying bone, causing aseptic loosening of the implant component (30–32). In order to ascertain the effect of the altered wear patterns and volumes, the results of either only sheep # 7998 or all 3 sheep were removed from the results and a renewed statistical evaluation was made. However the difference in linear and volumetric wear between both groups remained non-significant, and in both cases the human equivalent for the measured linear and volumetric wear remained well within the acceptable range. Despite the deviant wear pattern for the fourth fossa, we kept these results included, as there was no displacement that occurred.Condylar wear analysisIn knee and hip arthroplasty, there is an industry standard for surface smoothness (American Society for Testing and Materials F 2083-12, American Society for Testing and Materials F 2033-12), which does not exist for TMJ replacements. This is of importance because earlier studies have proven that a high surface roughness (Ra 0.2–0.63 µm) will also increase the amount of wear that can occur in the opposing articular surface (33–35) and can lead to the formation of larger wear particles, which can cause third body wear. (14,36).In this study, the industry standard for total knee prostheses was applied to the TMJ implant surfaces. These surfaces were polished to obtain a Rabelow 0.1 µm, which was confirmed by the surface roughness parameters determined here for DLC-coated condyle prior to implantation (Ra =0.09). The non-coated implants exhibited a significant increase in wear after implantation, resulting in an Ra (0.28 ± 0.17) well above the orthopedic industry standard. The Ra of the DLC-coated condyles (0.12 ± 0.04) however, remained well within the industry standard (Tables 1 and 4). Furthermore, the difference in both Sa and Ra was found to be significant by means of Mann-Whitney U test, as a non-Gaussian distribution was found for the non-coated condyles. Nikolas de Meurechy NW.indd 152 05-06-2024 10:14