title: No effect of conscious clenching on simple arithmetic task in healthy participants.
abstract: OBJECTIVE
  This study aimed to investigate whether clenching aids performance in a task requiring mental concentration in healthy participants.
  
  
  METHODS
  Twenty healthy participants (an average of 26.8 ± 2.0 years, nine females and 11 males) were recruited from our department. Participants performed four sets of hundred-square calculations as a mental arithmetic task. Among these sets, the third and the fourth sets were randomly divided into two conditions: one condition where participants made an effort to not allow their teeth to touch ('no tooth-contact' condition), and another where they made a conscious effort to rhythmically clench their teeth ('clenching' condition) during the task. Surface EMG was recorded from the left masseter muscle. Arithmetic performance was compared between the tooth-contact and clenching conditions using paired t-tests. In addition, we computed Pearson product-moment coefficients of the correlations between the difference in EMG activity and arithmetic performance in the two conditions.
  
  
  RESULTS
  No significant change in arithmetic score was found between the no tooth-contact (68.8 ± 12.2) and clenching conditions (66.5 ± 12.7; P=0.27). No significant correlation was found between the difference in EMG activity and changes in arithmetic performance (r=0.32, P=0.17).
  
  
  CONCLUSIONS
  In healthy participants, conscious clenching was not associated with any benefit in arithmetic performance. Although our study was limited by only measuring the short-term effects of clenching on a simple arithmetic task, the results indicate that it may not be harmful for clinicians to encourage their patients to refrain from clenching their teeth.
authors.affiliation: Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan. tmizumor@dent.osaka-u.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mizumori
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Shinji
authors.initials: S
authors.lastname: Inano
authors.forename: Masakazu
authors.initials: M
authors.lastname: Sumiya
authors.forename: Fumiko
authors.initials: F
authors.lastname: Murashima
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yatani
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D003766:Dental Occlusion; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000502:physiology; D055641:Mathematical Concepts; D011597:Psychomotor Performance / Q000502:physiology*; D014070:Tooth / Q000502:physiology*