Wong, Raymond CWTideman, HenkMerkx, Matthias AWJansen, JohnGoh, Suk MingDENTISTRY2023-05-262023-05-262012-12-01Wong, Raymond CW, Tideman, Henk, Merkx, Matthias AW, Jansen, John, Goh, Suk Ming (2012-12-01). The modular endoprosthesis for mandibular body replacement. Part 2: Finite element analysis of endoprosthesis reconstruction of the mandible. JOURNAL OF CRANIO-MAXILLOFACIAL SURGERY 40 (8) : E487-E497. ScholarBank@NUS Repository. https://doi.org/10.1016/j.jcms.2012.03.0101010-51821878-4119https://scholarbank.nus.edu.sg/handle/10635/241074Introduction: Problems with loosening of the modules for the modular endoprosthesis were encountered in animal studies for mandibular body replacement. We performed a finite element analysis to look at the stress distribution and areas of stress concentration in a human sized mandible. Variations were made to the stem and defect length to look at how the forces changed. The hypothesis was: (1) reconstruction with a modular endoprosthesis did not lead to areas of stress concentration beyond the material strength of cortical bone and titanium alloy; (2) changes in dimensions of the endoprosthesis did not cause a corresponding linear increase to the stresses. Materials and methods: The endoprosthesis was modelled to create a male, female part with stems and a connection screw (Case I). The stem length was halved (Case II) and defect length doubled (Case III). Geometric data of a human sized mandible were obtained, a continuity defect created digitally at the right molar area and the models combined. Boundary conditions were set and the model loaded to get a bite force of 300 N at the incisor region. An intact mandible was used as a control. Results: The right side of the reconstructed mandible became less rigid and flexed more. The highest stresses were within the endoprosthesis at two areas of stress concentration: (1) shear stress at the superior surface of the stems close to the junction of the stem and the module body; (2) compressive stresses at the bottom bevel of the dove-tailed connection. The stress distribution for Case I and II did not differ much except for the magnitude which was slightly higher for Case II. There was a tendency for outward bending at the module connection for Case III which potentially might cause loosening of the module connection. Displacements of the mandible were less than 1 mm throughout. Conclusion: The endoprosthesis with its present dimensions would be expected to perform adequately at a bite force of 300 N. An increase in defect length caused a tendency for bending at the stem and the module connection. With a decrease in stem length, there were little differences except a slight increase in magnitude. © 2011 European Association for Cranio-Maxillo- Facial Surgery.enScience & TechnologyLife Sciences & BiomedicineDentistry, Oral Surgery & MedicineSurgeryFinite element analysisModular endoprosthesisMandibular reconstructionArticle2023-05-25