title: The jaw functional limitation scale: development, reliability, and validity of 8-item and 20-item versions.
abstract: OBJECTIVE
  To develop the Jaw Functional Limitation Scale (JFLS), comprising 3 constructs and a global scale, based on a preliminary instrument, and to investigate content validity of the overall functional limitation construct, reliability, and generalizability. A temporomandibular disorders (TMD) patient group, compared to other diagnostic groups, was hypothesized to report further limitation in each of the 3 new proposed constructs.
  
  
  METHODS
  One hundred thirty-two consecutive patients from 5 diagnostic groups (TMD, primary Sjogren syndrome, burning mouth syndrome, skeletal malocclusion, and healthy controls) participated in a known-groups validity design. Fifty-two jaw functional limitation items were identified by an expert panel for content validity. Rasch methodology was used for item reduction and assessment of model fit. The instrument was retested 1 to 2 weeks later.
  
  
  RESULTS
  Three constructs (mastication, vertical jaw mobility, and emotional and verbal expression) comprising a total of 20 items were identified along with a global scale (the JFLS-20), and each exhibited excellent psychometric properties with respect to modeled variance, item fit, reliability, and internal consistency. The psychometric properties of each construct remained satisfactory when analyzed separately among the 5 diagnostic groups. Temporal stability was satisfactory. A shorter 8-item form (JFLS-8) also proved useful for assessing global functional jaw limitation.
  
  
  CONCLUSIONS
  The JFLS-20 is an organ-specific instrument comprising 3 constructs for assessing functional status of the masticatory system; the 3 scales exhibit properties that are ideal for both research and patient evaluation in patient groups with a range of functional limitations of the jaw. The JFLS-8 emerged as a short form for measuring global functional limitation of the jaw.
authors.affiliation: Department of Oral Diagnostic Sciences, University at Buffalo, Buffalo, NY 14214, USA. ohrbach@buffalo.edu
authors.forename: Richard
authors.initials: R
authors.lastname: Ohrbach
authors.forename: Pernilla
authors.initials: P
authors.lastname: Larsson
authors.forename: Thomas
authors.initials: T
authors.lastname: List
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002054:Burning Mouth Syndrome / Q000503:physiopathology; D016002:Discriminant Analysis; D004326:Drinking / Q000502:physiology; D005149:Facial Expression; D005157:Facial Pain / Q000145:classification / Q000503:physiopathology; D005260:Female; D006801:Humans; D007568:Jaw / Q000503:physiopathology*; D008297:Male; D008310:Malocclusion / Q000503:physiopathology; D008409:Mastication / Q000502:physiology; D008875:Middle Aged; D011594:Psychometrics; D016059:Range of Motion, Articular / Q000502:physiology; D012720:Severity of Illness Index; D012859:Sjogren's Syndrome / Q000503:physiopathology; D013060:Speech / Q000502:physiology; D013705:Temporomandibular Joint Disorders / Q000145:classification / Q000503:physiopathology*; D013997:Time Factors