Purpose: The aims of this study were to compare the radiographic development of permanent teeth in a group of children with and without supernumerary teeth (ST), determine whether using cone-beam computed tomography or panoramic radiography improves the accuracy of dental age (DA) estimation and investigate the effects of factors including the numbers and positions of ST. Methods: One hundred fifty dental radiographs of children with and without ST at the ages of 6.0 to 14.9 years were included in this study. The children in both groups were age and sex-matched. The lower left-side 7 permanent teeth were evaluated according to the Demirjian method, DA was determined. The difference between chronological age (CA) and DA (CA-DA) for the children with and without ST and further based on the number and localization of ST were calculated. Results: For all groups, the mean DA values were higher than the mean CA values. The difference between the CA and DA values in the children with ST was higher than the difference in the children without ST. Supernumerary teeth in posterior localization, multiple ST and among boys were observed to increase the differences between the mean CA and DA values. The mean age difference between radiographies in the children with and without ST was similar. Conclusion: Panoramic radiography was found adequate in determination of dental development with the Demirjian method. Dental development was even more advanced in the children with ST in comparison to the control group. Clinicians should keep in mind that the dental developments of children with supernumerary teeth may be advanced.