title: Automatic detection of tooth cracks in optical coherence tomography images.
abstract: OBJECTIVE
  The aims of the present study were to compare the image quality and visibility of tooth cracks between conventional methods and swept-source optical coherence tomography (SS-OCT) and to develop an automatic detection technique for tooth cracks by SS-OCT imaging.
  
  
  METHODS
  We evaluated SS-OCT with a near-infrared wavelength centered at 1,310 nm over a spectral bandwidth of 100 nm at a rate of 50 kHz as a new diagnostic tool for the detection of tooth cracks. The reliability of the SS-OCT images was verified by comparing the crack lines with those detected using conventional methods. After performing preprocessing of the obtained SS-OCT images to emphasize cracks, an algorithm was developed and verified to detect tooth cracks automatically.
  
  
  RESULTS
  The detection capability of SS-OCT was superior or comparable to that of trans-illumination, which did not discriminate among the cracks according to depth. Other conventional methods for the detection of tooth cracks did not sense initial cracks with a width of less than 100 μm. However, SS-OCT detected cracks of all sizes, ranging from craze lines to split teeth, and the crack lines were automatically detected in images using the Hough transform.
  
  
  CONCLUSIONS
  We were able to distinguish structural cracks, craze lines, and split lines in tooth cracks using SS-OCT images, and to automatically detect the position of various cracks in the OCT images. Therefore, the detection capability of SS-OCT images provides a useful diagnostic tool for cracked tooth syndrome.
authors.affiliation: Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea .
authors.forename: Jun-Min
authors.identifier: 0000-0003-3443-4862
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Department of Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Korea .
authors.forename: Se-Ryong
authors.identifier: 0000-0002-0016-1790
authors.initials: SR
authors.lastname: Kang
authors.affiliation: Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea.; Department of Oral and Maxillofacial Radiology, Seoul National University School of Dentistry, Seoul, Korea.
authors.forename: Won-Jin
authors.identifier: 0000-0002-5977-6634
authors.initials: WJ
authors.lastname: Yi
keywords: Computer-assisted image interpretation; Cracked tooth syndrome; Optical coherence tomography; Tooth fractures