RESEARCH ARTICLE Open Access The accuracy of estimating chronological age from Demirjian and Nolla methods in a Portuguese and Spanish sample

†Equal contributors 1School of Medicine and Dentistry, University of Santiago de Compostela,a function of sex and age-group.and Benjamín Martin-Biedma1† 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 rea