title: A pilot study of ambulatory masticatory muscle activities in temporomandibular joint disorders diagnostic groups.
abstract: OBJECTIVE
  To determine differences in masticatory muscle usage between temporomandibular joint disorders diagnostic groups.
  
  
  METHODS
  Seventy-one informed and consented subjects (27 men; 44 women) participated at the University at Buffalo.
  
  
  METHODS
  Research diagnostic criteria and imaging data were used to categorize subjects according to the presence/absence +/- of TMJ disc placement (DD) and chronic pain (P) (+DD+P, n=18; +DD-P, n=14; -DD-P, n=39). Electromyographic (EMG)/bite-force calibrations determined subject-specific masseter and temporalis muscle activities per 20 N bite-force (T20N , μV). Over 3 days and nights, subjects collected EMG recordings. Duty factors (DFs, % of recording time) were determined based on threshold intervals (5-9, 10-24, 25-49, 50-79, ≥80% T20N ). anova and Tukey-Kramer post hoc tests identified 1) diagnostic group differences in T20N and 2) the effects of diagnostic group, gender, time and interval on muscle DFs.
  
  
  RESULTS
  Mean (±SE) temporalis T20N in +DD+P subjects was significantly higher (71.4±8.8 μV) than masseter T20N in these subjects (19.6±8.8 μV; p=0.001) and in -DD-P subjects (25.3±6.0 μV, p=0.0007). Masseter DFs at 5-9% T20N were significantly higher in +DD-P women (3.48%) than +DD-P men (0.85%) and women and men in both other diagnostic groups (all p<0.03), and in +DD+P women (2.00%) compared to -DD-P men (0.83%; p=0.029). Night-time DFs at 5-9% T20N in +DD-P women (1.97%) were significantly higher than in -DD-P men (0.47%) and women (0.24%; all p<0.01).
  
  
  CONCLUSIONS
  Between-group differences were found in masticatory muscle activities in both laboratory and natural environmental settings.
authors: Departments of Orthodontics & Dentofacial Orthopedics and Oral & Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.
authors: L R
authors: LR
authors: Iwasaki
authors: Y M
authors: YM
authors: Gonzalez
authors: H
authors: H
authors: Liu
authors: D B
authors: DB
authors: Marx
authors: L M
authors: LM
authors: Gallo
authors: J C
authors: JC
authors: Nickel
mesh_terms: D000328:Adult; D001732:Bite Force; D059350:Chronic Pain / Q000503:physiopathology; D004576:Electromyography / Q000379:methods*; D005157:Facial Pain / Q000503:physiopathology; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000503:physiopathology; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology*; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000379:methods*; D009129:Muscle Tonus / Q000502:physiology; D010865:Pilot Projects; D012737:Sex Factors; D012890:Sleep / Q000502:physiology; D013703:Temporal Muscle / Q000503:physiopathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology; D013705:Temporomandibular Joint Disorders / Q000145:classification / Q000503:physiopathology*; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000503:physiopathology; D055815:Young Adult
keywords: ambulatory; duty factor; electromyographic; masticatory muscle; temporomandibular joint disorder