title: Influence of chewing and clenching on salivary cortisol levels as an indicator of stress.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effects of chewing and clenching on salivary cortisol levels as an indicator of stress.
  
  
  METHODS
  Seventeen healthy dentulous subjects were given arithmetic exercises to perform within a 20-minute time limit in order to elicit stress (stress loading). In the first experiment (chewing), after stress loading, the subjects were asked to chew a paraffin wax while reading printed material (books, magazines, etc.) in silence for 10 minutes. The same procedure was then carried out again for control purposes, but this time the subjects were not required to chew wax. In the second experiment (light clenching), after stress loading, the subjects were required to carry out 5 seconds of light clenching followed by 5 seconds of rest repeatedly over a 3-minute period. The whole 3-minute process was repeated a total of three times. The control data for this second experiment consisted of measurements taken during the rest periods. Saliva specimens were collected in both experiments both before stress loading and after each procedure during 1-minute intervals to measure cortisol levels.
  
  
  RESULTS
  In the chewing experiment, salivary cortisol levels were significantly reduced by chewing, compared with those in the controls (p < 0.05). This reduction in salivary cortisol was observed during chewing over a 10-minute period following stress loading. In the clenching experiment, salivary cortisol levels also showed a significant reduction during clenching, compared with those in the controls (p < 0.05).
  
  
  CONCLUSIONS
  These results suggest that chewing and clenching promote relaxation in subjects under stress.
authors.affiliation: Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College, Japan. taharay@tdc.ac.jp
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tahara
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakurai
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Ando
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000032:analysis; D002012:Bruxism / Q000378:metabolism / Q000523:psychology*; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D008297:Male; D008409:Mastication; D012463:Saliva / Q000737:chemistry* / Q000378:metabolism; D013315:Stress, Psychological / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D006854:Hydrocortisone