title: Three-rooted premolar analyzed by high-resolution and cone beam CT.
abstract: OBJECTIVE
  The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (μCT) and cone beam computed tomography (CBCT).
  
  
  METHODS
  Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using μCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using μCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals.
  
  
  RESULTS
  Images using μCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the μCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional μCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically.
  
  
  CONCLUSIONS
  Although variation was similar in the roots and canals under study, CBCT produced poorer image details than μCT.
  
  
  CONCLUSIONS
  Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.
authors.affiliation: Department of Endodontics, Graduate Program, School of Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil. carolmarca@hotmail.com
authors.forename: Caroline
authors.initials: C
authors.lastname: Marca
authors.forename: Paul M H
authors.initials: PM
authors.lastname: Dummer
authors.forename: Susan
authors.initials: S
authors.lastname: Bryant
authors.forename: Fabiana Vieira
authors.initials: FV
authors.lastname: Vier-Pelisser
authors.forename: Marcus Vinicius Reis
authors.initials: MV
authors.lastname: Só
authors.forename: Vania
authors.initials: V
authors.lastname: Fontanella
authors.forename: Vinicius D'avila
authors.initials: VD
authors.lastname: Dutra
authors.forename: José Antonio Poli
authors.initials: JA
authors.lastname: de Figueiredo
mesh_terms: D063405:Anatomic Variation; D019412:Anatomy, Cross-Sectional / Q000379:methods; D001641:Bicuspid / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008437:Maxilla; D009811:Odontometry / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D019227:Tooth Apex / Q000000981:diagnostic imaging; D019237:Tooth Cervix / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000000981:diagnostic imaging*; D055114:X-Ray Microtomography / Q000379:methods*