Muscle organization in individuals with and without pain and joint dysfunction

Jeffrey Nickel, Y. M. Gonzalez, W. D. McCall, R. Ohrba, D. B. Marx, H. Liu, Laura Iwasaki

Research output: Contribution to journalArticle

13 Scopus citations


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 ≤ R2 ≤ 0.74). These computer-assisted models predicted muscle organization during static biting in humans with and without TMDs.

Original languageEnglish (US)
Pages (from-to)568-573
Number of pages6
JournalJournal of dental research
Issue number6
Publication statusPublished - Jun 1 2012
Externally publishedYes



  • biting
  • human
  • masticatory muscles
  • modeling
  • neuromuscular
  • temporomandibular disorders

ASJC Scopus subject areas

  • Dentistry(all)

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