title: A comparison of conventional panoramic radiographs with volumetric computed tomography images in the preoperative assessment of impacted mandibular third molars.
abstract: OBJECTIVE
  In the present study, we evaluated the geometric, topographic, and anatomic reliability of volumetric computed tomography (VCT) images by comparing conventional panoramic radiographs with reconstructed VCT panoramic and paraxial images before performing third molar surgery.
  
  
  METHODS
  A total of 6 anatomic sites on 10 patients who showed a topographic relationship between the apices of the third molar root and the mandibular canal were preoperatively assessed by 5 oral surgeons using conventional panoramic radiographs; these were complemented and compared with secondary reconstructed paraxial and panoramic VCT images.
  
  
  RESULTS
  The position of the apices in relation to the mandibular canal could be revealed on 94% of VCT reconstructed paraxial images. Assessment of VCT paraxial images could be facilitated by using a toolbar marker in 70% of the paraxial images. In 90% of the paraxial images, it was possible to assess the relationship of the mandibular canal and its adjacent anatomy. The visual grading scores for conventional panoramic images were significantly better on all 7 assessed anatomic sites compared with the reconstructed VCT panoramic images.
  
  
  CONCLUSIONS
  The results showed that the VCT paraxial images gave a significantly clearer perception of the mandibular nerve than conventional panoramic radiographs. However, conventional panoramic radiographs were shown to be better than the VCT reconstructed panoramic images and were therefore an invaluable tool in the "expert-derived" assessment and posed the potential for identifying the need for further VCT diagnostic procedures.
authors.affiliation: Received from Heinrich-Heine University, Duüsseldorf, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Pawelzik
authors.forename: M
authors.initials: M
authors.lastname: Cohnen
authors.forename: R
authors.initials: R
authors.lastname: Willers
authors.forename: J
authors.initials: J
authors.lastname: Becker
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008875:Middle Aged; D008964:Molar, Third / Q000000981:diagnostic imaging* / Q000601:surgery; D011300:Preoperative Care; D011446:Prospective Studies; D011862:Radiography, Panoramic; D014057:Tomography, X-Ray Computed / Q000379:methods; D014081:Tooth Extraction; D014095:Tooth, Impacted / Q000000981:diagnostic imaging* / Q000601:surgery