title: Correlation of mandibular impacted tooth and bone morphology determined by cone beam computed topography on a premise of third molar operation.
abstract: OBJECTIVE
  To determine the width and morphology of the mandible in the impacted third molar region, and to identify the location of the mandibular canal prior to planning impacted third molar operations.
  
  
  METHODS
  Cone beam computed tomography (CBCT) data of 87 mandibular third molars from 62 Japanese patients were analyzed in this study. The width of the lingual cortical bone and apex-canal distance were measured from cross-sectional images in which the cortical bone was thinnest at the lingual side in the third molar region. Images were used for measuring the space (distance between the inner border of the lingual cortical bone and outer surface of the third molar root), apex-canal distance (distance from the root of the third molar tooth to the superior border of the inferior alveolar canal) and the cortical bone (width between the inner and outer borders of the lingual cortical bone).
  
  
  RESULTS
  The means of the space, apex-canal distance and lingual cortical width were 0.31, 1.99, and 0.68 mm, respectively. Impacted third molar teeth (types A-C) were observed at the following frequencies: type A (angular) 37 %; type B (horizontal), 42 %; type C (vertical), 21 %. The morphology of the mandible at the third molar region (types D-F) was observed as: type D (round), 49 %; type E (lingual extended), 18 %; and type F (lingual concave), 32 %.
  
  
  CONCLUSIONS
  The width and morphology of the mandible with impacted teeth and the location of the mandibular canal at the third molar region could be clearly determined using cross-sectional CBCT images.
authors.affiliation: Department of Oral and Maxillofacial Radiology, The Nippon Dental University School of Life Dentistry at Tokyo, 1-9-20, Fujimi, Chiyoda-ku, Tokyo 102-8159, Japan. drmomin.orad@hotmail.com
authors.forename: M A
authors.initials: MA
authors.lastname: Momin
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Ejima
authors.forename: R
authors.initials: R
authors.lastname: Asaumi
authors.forename: T
authors.initials: T
authors.lastname: Kawai
authors.forename: Y
authors.initials: Y
authors.lastname: Arai
authors.forename: K
authors.initials: K
authors.lastname: Honda
authors.forename: T
authors.initials: T
authors.lastname: Yosue
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D002648:Child; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008875:Middle Aged; D008964:Molar, Third / Q000000981:diagnostic imaging* / Q000601:surgery; D014095:Tooth, Impacted / Q000000981:diagnostic imaging* / Q000601:surgery; D055815:Young Adult