title: The stock alloplastic temporomandibular joint implant can influence the behavior of the opposite native joint: A numerical study.
abstract: OBJECTIVE
  The objective of the study was to investigate the effect of total stock temporomandibular implants on load mechanisms in both condyles in a specific patient. The patient presented with a disc with wear, and the introduction of a total temporomandibular prosthesis was simulated to compare the articular behavior.
  
  
  METHODS
  Based on specific patient computed tomographic images, two finite element models were created: one model with two intact temporomandibular joints (one joint with pathology), and other model with one implanted joint. The simulations considered the five most important muscles acting in the mandible, and it was possible to evaluate the biomechanical changes in the structures (skull, mandible, and articular disc).
  
  
  RESULTS
  The results revealed more load transfer in the opposite condyle than in the damaged one; the insertion of a total temporomandibular implant changed the load transfer to the opposite condyle. There was decreased stress in the disc by about 50% and increased strain distribution. In the mandibular condyle with implant, the screw fixation is critical, with minimum strain around -9430 με for first screw position. In the cranium, the implant changed the bone strains with a minimum principal strain observed around -2500 με in six screw positions.
  
  
  CONCLUSIONS
  This study indicates that replacing the damaged joint by an implant in an ideal position will improve joint position and consequently redistribute the loads. The study findings provide strong evidence that placing an implant on one side of the mandible will affect the load distribution on that structure and particularly on the opposite side. The temporomandibular joint changes condyle movement; with an implanted condyle, the movement is almost blocked.
authors.affiliation: TEMA, Department of Mechanical Engineering, University of Aveiro, Portugal. Electronic address: a.ramos@ua.pt.
authors.forename: António M
authors.initials: AM
authors.lastname: Ramos
authors.affiliation: Université de Bordeaux, Institut de Mécanique et d'Ingénierie, CNRS UMR 5295, Talence, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Mesnard
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002358:Cartilage, Articular / Q000502:physiology; D003198:Computer Simulation; D017076:Computer-Aided Design; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007595:Joint Prosthesis; D008334:Mandible / Q000502:physiology; D008335:Mandibular Condyle / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology; D008875:Middle Aged; D008954:Models, Biological; D016059:Range of Motion, Articular / Q000502:physiology*; D013314:Stress, Mechanical; D013701:Temporal Bone / Q000502:physiology; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging / Q000502:physiology; D019224:Temporomandibular Joint Disc / Q000502:physiology; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Articular disc; Bone strain; Cranium; Mandible; TMJ implant