Background: Considering the different results of dental age estimation tests for different populations and lack of sufficient studies on the Iranian race, this study was designed to compare the conformity rate of Demirjian and Nolla methods in dental age estimation. Materials and Methods: In the present cross-sectional study, 185 panoramic radiographs were assessed using patients' medical documents of pediatric and orthodontic departments. The maturation of each mandible left side permanent teeth except the third molars was categorized as A-H in Demirjian and 0-10 in the Nolla method. Results: The mean age of the participants was 9.6±2.8 years. For both genders, the Nolla and Demirjian methods had underestimation and overestimation, respectively, compared to chronological age. Pearson correlation coefficients for chronological age in the Nolla and Demirjian methods were (Pmale=0.982, Pfemale=0.985) and (Pmale=0.987, Pfemale=0.988), respectively. The difference between chronological age and dental age in the Nolla method ranged from -0.02 to 0.77 and -0.1 to 0.70 for boys and girls, respectively and ranged from 0.02 to 0.76 and 0.05 to 0.9 similarly in the Demirjian method. Conclusion: The Demirjian and Nolla methods are always associated with an overestimation and underestimation respectively compared to chronological age. Considering the difference between chronological age and dental age in the two methods, the average of differences in the Nolla method was lower compared to Demirjian. So, the Nolla method has more accurate estimation of chronological age. Therefore, in the present study, the Nolla method is more preferable than the Demirjian method
