title: Assessment of masticatory muscle activity and occlusion time in patients with advanced tooth wear.
abstract: OBJECTIVE
  Tooth wear is a basic physiological adjustment mechanism in the masticatory system. Unfortunately, it is not clear what the relationship is between the activity of the masticatory muscles and the tooth hard tissue loss (mainly enamel) in patients with advanced tooth wear. The aims of this study were (1) to compare the occlusion times and (2) to compare the EMG activity in maximal voluntary clench of the masseter and anterior temporalis muscles of patients with advanced tooth wear to the same activity of healthy volunteers.
  
  
  METHODS
  50 (16F, 34M) patients and 30 (12F, 18M) age matched controls were clinically examined to assess the degree of wear (TWI). Each subject underwent electromyographic analysis (bilateral anterior temporalis, superficial masseter, anterior digastric and sternocleidomastoid muscles) and digital occlusal analysis.
  
  
  RESULTS
  Mean values of the electrical potentials of the mandible elevating muscles during clench were higher in the study group compared to the controls. A negative correlation was found between the temporalis and masseter muscle activities during clench and the mean value of TWI (r=-0.383, p=0.009; r=-0.447, p=0.002). Occlusion time was longer in the study group compared to controls (p<0.05).
  
  
  CONCLUSIONS
  Mandibular adductors demonstrated lower muscular activities during clenching in the tooth wear patients; however, the cause of this finding is not certain. Prolongation of occlusion time may exacerbate occlusal surfaces wear or excessive wear may prolong occlusion time.
authors.affiliation: Department of Prosthetic Dentistry, Medical University of Bialystok, Poland. Electronic address: teresasierpinska@net.bialystok.pl.
authors.forename: Teresa
authors.initials: T
authors.lastname: Sierpinska
authors.affiliation: Department of Prosthetic Dentistry, Medical University of Bialystok, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kuc
authors.affiliation: Department of Prosthetic Dentistry, Medical University of Bialystok, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Golebiewska
mesh_terms: D016022:Case-Control Studies; D003766:Dental Occlusion; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000502:physiology*; D008875:Middle Aged; D013997:Time Factors; D057085:Tooth Wear / Q000503:physiopathology*
keywords: Muscular activity; Occlusion time; Tooth wear