title: A comparative investigation of cone-beam computed tomography and periapical radiography in the diagnosis of a healthy periapex.
abstract: BACKGROUND
  This research aimed to compare the appearance of healthy periapical tissues on cone-beam computed tomography (CBCT) with periapical radiography and to measure the periodontal ligament (PDL) space on CBCT for teeth with healthy and necrotic pulps.
  
  
  METHODS
  Patient records from specialist endodontic practices were examined for teeth that had a high-resolution (0.08-mm voxel) and small field-of-view CBCT scan, a periapical radiograph, and clinical pulp tests (CO2 and electric pulp testing). The periapical regions of the CBCT scans and radiographs were scored individually by 2 calibrated, blinded examiners by using a modified CBCT-periapical index (CBCT-PAI) for both and represented as CBCT-PAI and PAI, respectively. The Fisher exact and χ(2) statistics tested the relationships between CBCT-PAI, PAI, and pulp status.
  
  
  RESULTS
  Of 200 teeth included in the study, 166 showed clinical signs of pulpal health, and the CBCT-PAI score was greater than the PAI in 72% (119 of 166), with a vital pulp likely to have a radiographic PDL space widening of 0-1 mm (P < .001). Although 2 healthy teeth showed radiolucencies 2-4 mm on CBCT scan when the periapical radiograph showed none, a PDL space of greater than 1-2 mm was indicative of a necrotic pulp (P < .001).
  
  
  CONCLUSIONS
  Teeth with necrotic pulps were more likely to have PDL widening, but the PDL space of a healthy tooth demonstrated significant variation when examined by CBCT. The radiographic interpretation of health and disease on CBCT must be further investigated before usage in outcome or epidemiologic investigations. This research questions the traditional radiographic interpretation of the PDL space.
authors.affiliation: Melbourne Dental School, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Oliver
authors.initials: O
authors.lastname: Pope
authors.affiliation: Melbourne Dental School, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Chankhrit
authors.initials: C
authors.lastname: Sathorn
authors.affiliation: Melbourne Dental School, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: parashos@unimelb.edu.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Parashos
mesh_terms: D019412:Anatomy, Cross-Sectional / Q000379:methods; D002245:Carbon Dioxide; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000379:methods*; D003790:Dental Pulp Necrosis / Q000000981:diagnostic imaging; D003791:Dental Pulp Test / Q000379:methods; D004560:Electricity; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D010474:Percussion; D010486:Periapical Tissue / Q000000981:diagnostic imaging*; D010513:Periodontal Ligament / Q000000981:diagnostic imaging; D016300:Radiography, Bitewing / Q000379:methods*; D012189:Retrospective Studies
chemical_list: D002245:Carbon Dioxide
keywords: Cone-beam computed tomography; diagnosis; intraoral radiographs; periapical lesions