title: Prediction of the size of unerupted canines and premolars in an Iranian population.
abstract: OBJECTIVE
  One of the important aspects of diagnosis and treatment planning in the mixed dentition is estimation of the size of unerupted permanent canines and premolars. One of the most commonly used the prediction methods are Tanaka and Johnston, which are based on data from a sample of Northern European descent children. The accuracy of this method when applied to a different ethnic population is questionable. The aim of this study was to determine the modified equations from Tanaka and Johnston for Iranian population.
  
  
  METHODS
  This study was an analytic and cross-sectional investigation with the randomized cluster sampling in Ahwaz. Fifty four students of 14-18 years age (32 girls, 22 boys) were selected between 320 students and plaster models of their maxillary and mandibular arches were prepared. Subjects had fully erupted teeth, class I canine and molar relationship and presented no proximal caries or fillings, morphological anomalies, missing teeth or occlusal abrasion, and bruxism. The mesiodistal crown diameters of the permanent teeth were measured with using the sharpened boley gauge (accuracy 0.01 mm). The data were analyzed by using the regression correlation analyses and t-test.
  
  
  RESULTS
  The size of permanent canines and premolars were larger in maxilla than mandible and males than females. These values in Iran were different from other countries.
  
  
  CONCLUSIONS
  In this study to predict the space (in mm) required for alignment of unerupted canine and premolars in Iranian children, halve the sum of mesiodistal dimension of the four mandibular incisors and add the respective constants 10.5 for upper jaw and 10 for lower jaw.
authors.affiliation: Department of Pediatric Dentistry, Dental School, Ahwaz Jundishapur University of Medical Sciences, Ahwaz, Iran.
authors.forename: Mashaallah
authors.initials: M
authors.lastname: Khanehmasjedi
authors.forename: Leila
authors.initials: L
authors.lastname: Bassir
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007180:Incisor / Q000033:anatomy & histology*; D007492:Iran; D008297:Male; D014078:Tooth Eruption