Straight, semi-anatomic and anatomic TMJ implants: The influence of condylar geometry and bone fixation screws

• Published in: Journal of cranio-maxillo-facial surgery Vol. 39; no. 5; pp. 343 - 350
• Main Authors: Ramos, A, Completo, A, Relvas, C, Mesnard, M, Simões, J.A
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.07.2011; Elsevier
• Subjects: Arthroplasty, Replacement; Biological and medical sciences; Biomechanical Phenomena; Bone Screws; Computer-Aided Design; Condyle fractures; Dental Alloys; Dental Stress Analysis - methods; Dentistry; Finite Element Analysis; Humans; Injuries of the limb. Injuries of the spine; Joint Prosthesis; Mandible; Mandibular Condyle - injuries; Mandibular Fractures - physiopathology; Medical sciences; Models, Anatomic; Otorhinolaryngology. Stomatology; Prosthesis Design; Stress and strain; Surgery; Temporomandibular Joint - surgery; Tensile Strength; TMJ implant; Traumas. Diseases due to physical agents; TMJ implant; Mandible; Finite element analysis; Stress and strain; Condyle fractures; Implant; Stomatology; Diseases of the osteoarticular system; Temporomandibular joint; Fracture; Anatomy; Trauma; Stress strain; Condyle of mandible; Geometry; Fixation; Screw; Bone; Finite element
• ISSN: 1010-5182; 1878-4119
• DOI: 10.1016/j.jcms.2010.07.006

Abstract A 3D finite element model of in vitro intact and implanted mandibles with different temporomandibular joints (TMJ) was analyzed. Three TMJ implant geometries were assessed. The displacements, stress and strain fields on the condyle were obtained for both simulated cases. Strains were also assessed near the screws that fixate the implant to the mandible. The geometry of the mandible was obtained through 3D digitalization of a synthetic model. The TMJ implants studied were modelled considering a commercial implant which was also used to create semi-anatomic and anatomic implants that were analyzed and to assess the influence of the geometry. Numerical finite element models were built and the implants were positioned by an experienced orofacial surgeon. All implants were fixed by four screws which were placed in the same position on the mandible. The boundary conditions were simulated considering the support on the incisive tooth, the loads of the five most important muscular forces and a 5 mm mouth aperture. This study indicates that the deformation on the intact mandible was similar when an anatomic implant was considered in the implanted mandible. However, the anatomic geometry presented some problems concerning the implant integrity due to geometric variations. The geometry of TMJ implant also played a role relatively to the screws structural integration and bone fixation. The geometry of TMJ implant defines the necessary number of screws and position in the mandible fixation.