title: Studies on contributing factors in temporomandibular disorders.
abstract: OBJECTIVE
  To better understand the pathogenesis of TMD by studying microtrauma of the temporomandibular joint (TMJ), immune responses within TMJ, and psychosocial factors of the past ten years.
  
  
  METHODS
  Condyle and disc movements from 38 patients with temporomandibular disorders (TMD) were observed with the use of videotape recording and soundtape recording techniques after TMJ arthrography. Pathological changes following occlusal trauma were examined using an animal model. Immune complexes in condyle cartilage; antibody to collagen II; and cytokines such as interleukin 1, tumor necrosis factor, and interleukin 6 were detected in synovial fluid of TMD. Psychosocial characteristics were analyzed with the Minnesota Multiphasic Personality Inventory (MMPI) of 80 TMD patients and the Life Events Experience Survey (LEES) of 42 TMD patients.
  
  
  RESULTS
  Persistent and recurrent microtrauma did exist within joints of TMD patients, caused by occlusal trauma and occlusal interference. Occlusal trauma in animals could induce condyle and disc degenerative changes that are similar to the findings in TMJ osteoarthrosis patients. Sequestered antigens within cartilage could be exposed to the immune system after joint degeneration. Humoral and cellular immune responses did exist within TMJ and played an important role in the pathogenesis of TMD. Forty percent of TMD patients suffered from psychosomatic disorders, significantly more than in the healthy control.
  
  
  CONCLUSIONS
  Microtrauma of TMJ, immune responses within TMJ, psychosocial factors, and anatomical structures of the TMJ itself are the four main contributing factors of TMD. Possible mechanisms of the interactions of the four factors are presented, and principles of preventing and treating TMD are also suggested.
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Stomatology, Beijing Medical University (BMU), Haidian District, P. R. China.
authors.forename: Z K
authors.initials: ZK
authors.lastname: Zhang
authors.forename: X C
authors.initials: XC
authors.lastname: Ma
authors.forename: S
authors.initials: S
authors.lastname: Gao
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Gu
authors.forename: K Y
authors.initials: KY
authors.lastname: Fu
mesh_terms: D000328:Adult; D003769:Dental Occlusion, Traumatic / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008335:Mandibular Condyle / Q000473:pathology; D013315:Stress, Psychological / Q000150:complications; D013582:Synovial Fluid / Q000737:chemistry / Q000276:immunology; D013704:Temporomandibular Joint / Q000276:immunology* / Q000293:injuries; D013705:Temporomandibular Joint Disorders / Q000209:etiology* / Q000276:immunology / Q000523:psychology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D014409:Tumor Necrosis Factor-alpha