title: Radiographic assessment of third molars development and it's relation to dental and chronological age in an Iranian population.
abstract: BACKGROUND
  The aim of the present study was to estimate chronological age based on third molar development and to determine the association between dental age and third molar calcification stages.
  
  
  METHODS
  In this cross-sectional study, 505 digital panoramic radiographs of 223 males (44.2%) and 282 females (55.8%) between the age of 6 and 17 were selected from patients who were treated in Departments of Pediatrics and Orthodontics of Isfahan University of Medical Sciences between the years of 2009 and 2013. Correlation between chronological age and third molar development was analyzed with SPSS 21 using Spearman's Rank correlation coefficient, Chi-square test and multiple regression statistical tests (P < 0.05).
  
  
  RESULTS
  All third molars demonstrated a highly significant correlation with dental age (P < 0.001). The teeth showing the highest relationship with dental age were mandibular left third molar in males and mandibular right third molar in females (r s = 0.072). When multiple regression was used to predict dental age based on molar calcification stage, the only significant correlation was between maxillary left third molar in males (P < 0.05). There was no statistically significant correlation for any of third molars in females. Relationship between chronological age and molars development stage was significant in all age subgroups and in both gender (P < 0.001).
  
  
  CONCLUSIONS
  Strong correlation was observed between left third molars and dental age in males. Results showed that third molar calcification stage can be used as an age predictor and in general mandibular teeth seems to be more reliable for this purpose in both genders and in all ages.
authors.affiliation: Dental Materials Research Center and Department of Orthodontics, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Monirifard
authors.affiliation: Department of Orthodontics Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Yaraghi
authors.affiliation: Department of Pediatric Dentistry, Khorasgan University of Dental Sciences, Isfahan, Iran.
authors.forename: Ava
authors.initials: A
authors.lastname: Vali
authors.affiliation: Dentistry Student, Dental Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Asana
authors.initials: A
authors.lastname: Vali
authors.affiliation: Department of Endodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Amrita
authors.initials: A
authors.lastname: Vali
keywords: Chronological age; demirjian system; dental age