title: How should the articular disk position be analyzed?
abstract: OBJECTIVE
  To compare 2 methods used to determine the disk position based on sagittal magnetic resonance images.
  
  
  METHODS
  A cross-sectional study of patients with the signs and symptoms of temporomandibular disorders was conducted. The patients' ages and gender distributions were collected. The disk position diagnosis from the clinical examination was considered the primary outcome. Three observers evaluated the presence of anterior displacement on magnetic resonance images according to 2 criteria: method 1 (12-o'clock position) and method 2 (location of the intermediate zone). To assess the intraobserver variability of the 2 methods, the examiners evaluated the same magnetic resonance images at the beginning of the study (time 1) and 40 days later (time 2). The intraobserver agreement was assessed using the observed agreement and the kappa statistic. McNemar's test was used to assess the differences between each method and the clinical examination findings (P < .05). The accuracy, sensitivity, specificity, and positive and negative predictive values were calculated by comparing the diagnosis from each method with that from the clinical examination (considered the reference standard).
  
  
  RESULTS
  The final sample was composed of 20 subjects with a mean age of 33.0 ± 33.7 years; 3 were men (15%) and 17 were women (85%). A statistically significant difference between the 2 methods was found. Method 1 yielded a greater percentage of anterior displaced disks (52.5%). The agreement between the clinical diagnosis and method 1 was lower (70.0%) than that between the clinical diagnosis and method 2 (87.5%). No statistically significant difference was found between the clinical diagnosis and method 2.
  
  
  CONCLUSIONS
  The disk position should be judged according to the intermediate zone criterion.
authors.affiliation: Department of Stomatology, School of Dentistry, University of São Paulo, Brazil. marciaproven@gmail.com
authors.forename: Marcia de Mello
authors.initials: Mde M
authors.lastname: Provenzano
authors.forename: Israel
authors.initials: I
authors.lastname: Chilvarquer
authors.forename: Marlene
authors.initials: M
authors.lastname: Fenyo-Pereira
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000473:pathology; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D004204:Joint Dislocations / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008335:Mandibular Condyle / Q000473:pathology; D015588:Observer Variation; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular / Q000502:physiology; D012680:Sensitivity and Specificity; D013016:Sound; D013704:Temporomandibular Joint / Q000473:pathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology*; D013705:Temporomandibular Joint Disorders / Q000473:pathology*