title: Functional changes of temporomandibular joint mechanoreceptors induced by reduced masseter muscle activity in growing rats.
abstract: OBJECTIVE
  To determine the influence of masseter muscle activity during growth on the functional characteristics of temporomandibular joint (TMJ) mechanoreceptors.
  
  
  METHODS
  Sixty-six 3-week-old male Wistar rats were divided into an experimental group, in which the masseter muscles were bilaterally resected at 3 weeks of age, and a control group. Single-unit activities of the TMJ mechanoreceptors were evoked by indirect stimulation of passive jaw movement. Electrophysiologic recordings of TMJ units were made at 5, 7, and 9 weeks of age.
  
  
  RESULTS
  During this period, the firing threshold of the TMJ units was significantly lower and the maximum instantaneous frequency of the TMJ units was significantly higher in the experimental group than in the control group.
  
  
  CONCLUSIONS
  Reduced masseter activity during the growth period alters the response properties of TMJ mechanoreceptors.
authors.affiliation: Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. takaorts@tmd.ac.jp
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ishida
authors.forename: Tadachika
authors.initials: T
authors.lastname: Yabushita
authors.forename: Kunimichi
authors.initials: K
authors.lastname: Soma
mesh_terms: D000818:Animals; D008297:Male; D008406:Masseter Muscle / Q000502:physiology* / Q000601:surgery; D008445:Maxillofacial Development; D008465:Mechanoreceptors / Q000502:physiology*; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D012684:Sensory Thresholds; D013704:Temporomandibular Joint / Q000294:innervation*