title: Evaluation of TMJ sound on the subject with TMJ disorder by Joint Vibration Analysis.
abstract: BACKGROUND
  Qualitative and semi-quantitative methods have been developed for TMJ sound classification, but the criteria presented are completely inhomogeneous. Thus, to develop more objective criteria for defining TMJ sounds, electroacoustical systems have been developed. We used Joint vibration analysis in the BioPAK system (Bioresearch Inc., Milwaukee, USA) as the electrovibratography.
  
  
  OBJECTIVE
  The aim of this study was to examine the TMJ sounds with repect to frequency spectra patterns and the integral > 300 Hz /< 300 Hz ratios via six-months follow-up.
  
  
  METHODS
  This study was done before and after the six-months recordings with 20 dental school students showed anterior disk displacement with reduction. Joint vibrations were analyzed using a mathematical technique known as the Fast Fourier Transform.
  
  
  RESULTS
  In this study Group I and Group II showed varied integral > 300 /< 300 ratios before and after the six-months recordings. Also, by the comparative study between the integral > 300 /< 300 ratios and the frequency spectrums, it was conceivable that the frequency spectrums showed similar patterns at the same location that the joint sound occurred before and after the six-months recordings. while the frequency spectrums showed varied patterns at the different locations that the joint sound occurred before and after six-month recordings, it would possibly be due to the differences in the degree of internal derangement and/or in the shape of the disc.
  
  
  CONCLUSIONS
  It is suggested that clinicians consider the integral > 300 /< 300 ratios as well as the frequency spectrums to decide the starting-point of the treatment for TMJ sounds.
authors.affiliation: Graduate Student, Department of Prosthodontics, College of Dentistry, Chosun University, Kwang-ju, Korea.
authors.forename: In-Taek
authors.initials: IT
authors.lastname: Hwang
authors.forename: Da-Un
authors.initials: DU
authors.lastname: Jung
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Dong-Wan
authors.initials: DW
authors.lastname: Kang