title: Forensic age estimation based on magnetic resonance imaging of third molars: converting 2D staging into 3D staging.
abstract: BACKGROUND
  Established methods to stage development of third molars for forensic age estimation are based on the evaluation of radiographs, which show a 2D projection. It has not been investigated whether these methods require any adjustments in order to apply them to stage third molars on magnetic resonance imaging (MRI), which shows 3D information.
  
  
  OBJECTIVE
  To prospectively study root stage assessment of third molars in age estimation using 3 Tesla MRI and to compare this with panoramic radiographs, in order to provide considerations for converting 2D staging into 3D staging and to determine the decisive root.
  
  
  METHODS
  All third molars were evaluated in 52 healthy participants aged 14-26 years using MRI in three planes. Three staging methods were investigated by two observers. In sixteen of the participants, MRI findings were compared with findings on panoramic radiographs.
  
  
  RESULTS
  Decisive roots were palatal in upper third molars and distal in lower third molars. Fifty-seven per cent of upper third molars were not assessable on the radiograph, while 96.9% were on MRI. Upper third molars were more difficult to evaluate on radiographs than on MRI (p < .001). Lower third molars were equally assessable on both imaging techniques (93.8% MRI, 98.4% radiograph), with no difference in level of difficulty (p = .375). Inter- and intra-observer agreement for evaluation was higher in MRI than in radiographs. In both imaging techniques lower third molars showed greater inter- and intra-observer agreement compared to upper third molars. MR images in the sagittal plane proved to be essential for staging.
  
  
  CONCLUSIONS
  In age estimation, 3T MRI of third molars could be valuable. Some considerations are, however, necessary to transfer known staging methods to this 3D technique.
authors.affiliation: a Department of Radiology and Nuclear Medicine , Ghent University , Gent , Belgium.
authors.forename: Jannick
authors.initials: J
authors.lastname: De Tobel
authors.affiliation: a Department of Radiology and Nuclear Medicine , Ghent University , Gent , Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Hillewig
authors.affiliation: a Department of Radiology and Nuclear Medicine , Ghent University , Gent , Belgium.
authors.forename: Koenraad
authors.initials: K
authors.lastname: Verstraete
mesh_terms: D000293:Adolescent; D000328:Adult; D000366:Age Determination by Teeth / Q000379:methods*; D001530:Belgium; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008964:Molar, Third / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D011862:Radiography, Panoramic; D012016:Reference Values; D055815:Young Adult
keywords: Third molar root; panoramic radiograph; sub-adult; surface head coil