title: Detection of dentinal microcracks using infrared thermography.
abstract: BACKGROUND
  It is difficult to make a definite diagnosis of a cracked tooth solely based on an inspection within the root canal, especially in case of microcracks. At present, there seems to be no established method to detect dentinal microcracks in roots; therefore, the current detection techniques need to be improved. Vibrothermography (VibroIR) helps to detect microcracks by the friction heat generated from ultrasonic vibration. The purpose of this study was to establish a novel method using VibroIR to detect dentinal microcracks.
  
  
  METHODS
  The root canals of 20 roots with cracks and control roots were prepared after removing the tooth crowns. A tapered indenter was inserted into the root canal and pressed until a microcrack was created under an optical microscope. Using VibroIR, the detection trials for dentinal microcracks were performed with an ultrasonic vibration power ranging from 0.43 to 1.48 W at an angle of 0°, 30°, 45°, 60°, and 90° between the ultrasonic vibration point and the microcrack line. After the detection test, the microcrack width was measured with an optical microscope.
  
  
  RESULTS
  Frictional heat was detected in the microcracks with thermography at 0.89 to 1.48 W and at an ultrasonic vibration point angle less than 60° from the crack line for 10 seconds. Microcracks with a width of 4 to 35.5 μm were detected with this method.
  
  
  CONCLUSIONS
  VibroIR may be an effective method for the diagnosis of root dentinal microcracks.
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Matsushita-Tokugawa
authors.forename: Jiro
authors.initials: J
authors.lastname: Miura
authors.forename: Yukiteru
authors.initials: Y
authors.lastname: Iwami
authors.forename: Takahide
authors.initials: T
authors.lastname: Sakagami
authors.forename: Yui
authors.initials: Y
authors.lastname: Izumi
authors.forename: Naoya
authors.initials: N
authors.lastname: Mori
authors.forename: Mikako
authors.initials: M
authors.lastname: Hayashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Imazato
authors.forename: Fumio
authors.initials: F
authors.lastname: Takeshige
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Ebisu
mesh_terms: D003387:Cracked Tooth Syndrome / Q000175:diagnosis*; D003786:Dental Pulp Cavity / Q000293:injuries; D003804:Dentin / Q000293:injuries*; D017276:Friction; D006358:Hot Temperature; D006801:Humans; D007259:Infrared Rays; D008853:Microscopy; D013817:Thermography / Q000379:methods*; D013997:Time Factors; D014082:Tooth Fractures / Q000175:diagnosis*; D014092:Tooth Root / Q000293:injuries; D014465:Ultrasonics; D014732:Vibration