Background: The study of tooth mineralization is one of the most reliable approaches to determining the age of individuals. Given the presence of various ethnicities in Iran, this study aimed to determine the exact age at different stages of the development of permanent mandibular teeth in children aged 5-16 years in Mashhad, Iran. Methods: In this cross-sectional study, 235 digital panoramic radiographs of children aged 5-16 years were assessed. Maturation of the permanent teeth was evaluated according to Demirjian’s classification system. Data was analyzed using SPSS 16.0. T-test was performed to compare the homologous teeth of the same arch as well as boys and girls in different stages of tooth calcification. Results: The mean age of participants was 9.78 ± 2.53 years. Homologous teeth were not significantly different in terms of maturation time in all cases. In some stages, certain teeth developed more quickly in girls while some others developed faster in boys. These differences were statistically significant only in certain stages and for certain teeth. Conclusions: As far as developmental stages were concerned, girls were at a significantly lower age. The dental charts presented in this article includes information that could be beneficial for dental clinicians in making appropriate diagnosis and planning for orthodontic and surgical procedures. These charts also provide datasets for estimation of dental age for a sample of Iranian children.