title: Measuring tooth mobility with a no-contact vibration device.
abstract: OBJECTIVE
  Mechanical parameters obtained from the frequency response at tooth vibration informs of various periodontal tissue conditions. An electromagnetic vibration device was investigated for measuring tooth mobility using mechanical parameters obtained from the frequency response characteristics of an experimental tooth model. This electromagnetic vibration device was able to assess the overall condition of periodontal tissue associated with the alteration of each parameter. In this study, reliability and effects of bottom thicknesses of simulated periodontal ligament relative to mechanical parameters were analysed.
  
  
  METHODS
  Measurement of tooth vibration was performed by an electromagnetic vibration device on experimental tooth models with different bottom thicknesses of simulated periodontal ligament. Using an electromagnetic vibration device, the mechanical parameters resonant frequency, elastic modulus and coefficient of viscosity were calculated from the frequency response characteristics derived from tooth vibration by an electromagnetic force. Variation of those parameters was investigated under four different experimental conditions and the implications of the results were discussed.
  
  
  RESULTS
  An electromagnetic vibration device clearly detected three mechanical parameters in all experimental conditions. The resonant frequency and the elastic modulus decreased with increasing bottom thickness. However, no significant difference in the coefficient of viscosity was observed among the experimental conditions.
  
  
  CONCLUSIONS
  Assessment of tooth mobility using mechanical parameters of an electromagnetic vibration device reproduced fine details of various simulated periodontal ligament conditions. Variation in the parameters resonant frequency, elastic modulus and coefficient of viscosity might be useful in evaluating changes of components in periodontal tissues.
authors.affiliation: Department of Endodontics, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamane
authors.forename: M
authors.initials: M
authors.lastname: Yamaoka
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
authors.forename: I
authors.initials: I
authors.lastname: Furutoyo
authors.forename: N
authors.initials: N
authors.lastname: Komori
authors.forename: B
authors.initials: B
authors.lastname: Ogiso
mesh_terms: D000465:Algorithms; D003762:Dental Instruments; D004548:Elasticity; D055590:Electromagnetic Phenomena / Q000295:instrumentation*; D003765:Models, Dental; D008962:Models, Theoretical; D010513:Periodontal Ligament / Q000503:physiopathology; D014086:Tooth Mobility / Q000175:diagnosis*; D014732:Vibration; D014783:Viscosity