title: Measuring mesiodistal width of impacted maxillary canines: CT-assisted determination.
abstract: OBJECTIVE
  Precise, three-dimensional localization of impacted maxillary canines is central to their clinical management. Predicting precisely the crown's mesiodistal width is paramount in planning orthodontic treatment. The aim of this study was to verify the exact mesiodistal width of impacted canines via MSCT (multislice spiral computed tomography) examinations.
  
  
  METHODS
  3D MSCT images from 17 patients with a total of 24 impacted maxillary canines were taken to obtain the largest mesiodistal diameter using mesial and distal contact points. All existing maxillary canines were included in this study. Mesiodistal tooth width was also determined using callipers on a plaster model after canine eruption. Each measurement was taken twice by 3 observers after a 10-day interval. Statistical analysis entailed calculating and comparing the systematic error, intrarater and interrater standard deviations (Deming regression and ANOVA with random effects).
  
  
  RESULTS
  Comparison of the different methods revealed good agreement between the pre-eruption and post-eruption values regarding the canine's mesiodistal width. Total standard deviation was 0.16 mm for values obtained from MSCT measurements and 0.12 mm for those taken with callipers. For both methods intrarater measurement error differed by a factor of 2 (repeatability; model versus MSCT: 0.07 mm versus 0.12 mm), while interrater deviation did not differ significantly (reproducibility; model versus MSCT: 0.10 mm versus 0.10 mm). The reproducibility of our measurements whether taken on the model or with CT was below biological variability.
  
  
  CONCLUSIONS
  The volumetric data from an MSCT system gives highly accurate information on the mesiodistal width of displaced canines.
authors.affiliation: Department of Orthodontics, University Hospital, Erlangen-Nuremberg, Erlangen, Germany. elisabeth.hofmann@uk-erlangen.de
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Hofmann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Medelnik
authors.forename: Thomas
authors.initials: T
authors.lastname: Keller
authors.forename: Stefanie
authors.initials: S
authors.lastname: Steinhäuser
authors.forename: Ursula
authors.initials: U
authors.lastname: Hirschfelder
mesh_terms: D002648:Child; D003481:Cuspid / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011861:Radiography, Dental / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014095:Tooth, Impacted / Q000000981:diagnostic imaging*