title: The accuracy of estimating chronological age from Demirjian and Nolla methods in a Portuguese and Spanish sample.
abstract: BACKGROUND
  Age determination has great importance in many clinical decisions, being commonly used in odontopediatrics, orthodontics, pediatrics, and forensic medicine. The Nolla and Demirjian et al. methods have been used for these purposes. However, estimating chronological age by means of the dental mineralization stage is not a straightforward analysis, and it is fundamental to test the validity of these methods and their applicability to populations. In this article we intend to compare the accuracy of estimating chronological age from dental age measured with the Nolla and Demirjian methods in a Portuguese and Spanish sample, considering the variables of sex and age-group.
  
  
  METHODS
  The sample was composed of 821 orthopantomographs of healthy Portuguese (n = 270) and Spanish (n = 551) subjects from 4 to 34 years old. For the Nolla and Demirjian methods, seven mandibular left teeth were examined, staged according to the dental maturity scale of each method. We obtained a good index of inter-rater agreement, a good internal consistency for the teeth assessment, and a good temporal consistency.
  
  
  RESULTS
  Dental age was calculated for each method. The Demirjian et al. method tends to overestimate the real age of participants and the Nolla method tends to underestimate it. The accuracy of both methods varied between the sexes and age groups. Both methods were found to be more precise with males. As the age-group increases, the predictive capacities of both methods diminish. The Nolla method was more accurate than the Demirjian method in early and late childhood for both sexes. Neither method could predict chronological age in adults.
  
  
  CONCLUSIONS
  We can estimate chronological age for early and late childhood, through the Nolla and Demirjian methods, with the former showing greater predictive capacities than the latter. The Demirjian method tends to overestimate age and the Nolla method tends to underestimate it, leading to the importance of forming regression equations adapted to the population studied. Nolla and Demirjian formulas adapted to our sample were created as a function of sex and age-group.
authors.affiliation: School of Medicine and Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. luistomas.md@gmail.com.
authors.forename: Luís F
authors.initials: LF
authors.lastname: Tomás
authors.forename: Lisete S M
authors.initials: LS
authors.lastname: Mónico
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Tomás
authors.forename: Purificación
authors.initials: P
authors.lastname: Varela-Patiño
authors.forename: Benjamín
authors.initials: B
authors.lastname: Martin-Biedma
mesh_terms: D000293:Adolescent; D000328:Adult; D000366:Age Determination by Teeth / Q000379:methods*; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D005260:Female; D005544:Forecasting; D006801:Humans; D008297:Male; D011174:Portugal; D011237:Predictive Value of Tests; D011862:Radiography, Panoramic; D012737:Sex Factors; D013030:Spain; D014074:Tooth Calcification / Q000502:physiology; D055815:Young Adult