Muscle organization in individuals with and without pain and joint dysfunction

J Dent Res. 2012 Jun;91(6):568-73. doi: 10.1177/0022034512445909. Epub 2012 Apr 20.

Abstract

Central nervous system organization of masticatory muscles determines the magnitude of joint and muscle forces. Validated computer-assisted models of neuromuscular organization during biting were used to determine organization in individuals with and without temporomandibular disorders (TMD). Ninety-one individuals (47 women, 44 men) were assigned to one of four diagnostic groups based on the presence (+) or absence (-) of pain (P) and bilateral temporomandibular joint disc displacement (DD). Electromyography and bite-forces were measured during right and left incisor and molar biting. Two three-dimensional models employing neuromuscular objectives of minimization of joint loads (MJL) or muscle effort (MME) simulated biting tasks. Evaluations of diagnostic group and gender effects on choice of best-fit model were by analysis of variance (ANOVA) and Tukey-Kramer post hoc tests, evaluations of right-left symmetry were by Chi-square and Fisher's exact statistics, and evaluations of model accuracy were by within-subject linear regressions. MME was the best-fit during left molar biting in +DD individuals and incisor biting in men (all p < 0.03). Incisor biting symmetry in muscle organization was significantly higher (p < 0.03) in healthy individuals compared with those with TMD. Within-subject regressions showed that best-fit model errors were similar among groups: 8 to 15% (0.68 ≤ R(2) ≤ 0.74). These computer-assisted models predicted muscle organization during static biting in humans with and without TMDs.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Biomechanical Phenomena
  • Bite Force*
  • Case-Control Studies
  • Chi-Square Distribution
  • Computer Simulation*
  • Dental Stress Analysis
  • Electromyography
  • Facial Pain / physiopathology*
  • Female
  • Humans
  • Joint Dislocations
  • Linear Models
  • Male
  • Masticatory Muscles / physiology
  • Masticatory Muscles / physiopathology*
  • Middle Aged
  • Models, Biological
  • Temporomandibular Joint Disorders / physiopathology*
  • Young Adult