title: The validity of transverse intermaxillary analysis by traditional PA cephalometry compared with cone-beam computed tomography.
abstract: OBJECTIVE
  To assess the validity of using jugale (J) and Antegonion (Ag) on Posterior-Anterior cephalograms (PAC) as landmarks for transverse intermaxillary analysis when compared with Cone Beam Computed Tomography (CBCT).
  
  
  METHODS
  Conventional PAC and CBCT images were taken of 28 dry skulls. Craniometric measurements between the bilateral landmarks, Antegonion and Jugale, were obtained from the skulls using a microscribe and recorded as the base standard. The corresponding andmarks were identified and measured on CBCT and PAC and compared with the base standard measurements. The accuracy and reliability of the measurements were statistically evaluated and the validity was assessed by comparing the ability of the two image modalities to accurately diagnose an arbitrarily selected J-J/Ag-Ag ratio. All measurements were repeated at least 7 weeks apart. Intra-class correlations (ICC) and Bland-Altman plots were used to analyse the data.
  
  
  RESULTS
  All three methods were shown to be reliable as all had a mean error of less than 0.5 mm between repeated measurements. When compared with the base standard, CBCT measurements were shown to have higher agreement (ICC: 0.861-0.964) compared with measurements taken from PAC (ICC: 0.794-0.796). When the arbitrary J-J/Ag-Ag ratio was assessed, 18 per cent of cases were incorrectly diagnosed with a transverse discrepancy on the PAC compared with the CBCT which incorrectly diagnosed 8.7 per cent.
  
  
  CONCLUSIONS
  CBCT was shown to be more reliable in assessing intermaxillary transverse discrepancy compared with PAC when using J-J/Ag-Ag ratios.
authors.affiliation: Department of Orthodontics, School of Dentistry, The University of Western Australia, Nedlands, Western Australia, Australia.
authors.forename: Gordon
authors.initials: G
authors.lastname: Cheung
authors.forename: Mithran Suresh
authors.initials: MS
authors.lastname: Goonewardene
authors.forename: Syed Mohammed Shamsul
authors.initials: SM
authors.lastname: Islam
authors.forename: Kevin
authors.initials: K
authors.lastname: Murray
authors.forename: Bernard
authors.initials: B
authors.lastname: Koong
mesh_terms: D059925:Anatomic Landmarks / Q000033:anatomy & histology*; D002508:Cephalometry / Q000379:methods* / Q000706:statistics & numerical data; D054893:Cone-Beam Computed Tomography / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008334:Mandible / Q000033:anatomy & histology*; D008437:Maxilla / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D015050:Zygoma / Q000033:anatomy & histology