title: A new method for evaluating the threshold of periodontal ligament mechanoreceptor by slow speed mechanical stimulation.
abstract: OBJECTIVE
  This study aimed to establish a reliable method for detecting the threshold for perception of force applied to tooth and to report the basic properties of force threshold in the normal dentition subjects.
  
  
  BACKGROUND
  The perception of mechanical stimulation exerted to tooth is formed by input from periodontal ligament mechanoreceptors and intradental mechanoreceptors. Periodontal ligament mechanoreceptors respond to a wide range speed of stimulus, whereas intradental mechanoreceptors are activated only by a rapid stimulation. Reliable properties of perception have not been reported because of the difficulties to regulate velocity and degree of the stimulus.
  
  
  METHODS
  Eighteen healthy subjects were observed in this study (mean age: 27.2 +/- 5.7 years). A loading device to generate slow speed loading was fabricated and measured as follows: (i) the fluctuation of the force threshold within a day, (ii) day-to-day fluctuation, (iii) changes in the force threshold by a transient mechanical loading.
  
  
  RESULTS
  In the normal dentition, it was observed that the fluctuation within a day and day to day of the pressure sense showed no significant differences; however, a transient mechanical loading caused the sensitivity of the periodontal ligament to decrease significantly.
  
  
  CONCLUSIONS
  The device examining the force threshold resulted from periodontal ligament mechanoreceptors was useful in evaluating the sensitivity of the periodontal ligament.
authors.affiliation: Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan. kazu_z@md.okayama-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oki
authors.forename: Mai
authors.initials: M
authors.lastname: Hamanaka
authors.forename: Taro
authors.initials: T
authors.lastname: Arima
authors.forename: Shuhei
authors.initials: S
authors.lastname: Takahashi
authors.forename: Kouichi
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Shogo
authors.initials: S
authors.lastname: Minagi
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003799:Dental Stress Analysis / Q000379:methods*; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D010513:Periodontal Ligament / Q000294:innervation* / Q000502:physiology*; D010812:Physical Stimulation / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012684:Sensory Thresholds; D013314:Stress, Mechanical