Timing of Permanent Tooth Development in an Iranian Subpopulation

Studies conducted on the Iranian population have mainly focused on tooth eruption or estimation of chronological age of children. This study aimed to assess the time of onset and completion of calcification of permanent teeth in an Iranian subpopulation.  

This descriptive, cross-sectional study was performed on 778 panoramic radiographs of subjects presenting to a public clinic in Tehran. Date of birth and exact date of taking the radiograph were recorded. The Demirjian’s method was used for determination of dental developmental stage. The median age for different calcification stages was separately determined for the maxillary and mandibular teeth. Time of each calcification stage in the maxilla and mandible in males and females was compared using the Wilcoxon signed rank test and independent sample t-test.

The chronological age of subjects was between 3 to 18 years. The median age for different developmental stages of teeth was determined. All developmental stages began sooner in the mandible (P<0.05). In comparison of males and females, no significant difference was noted in development of maxillary central incisors and first molars and mandibular central and lateral incisors and first molars (P>0.05). Completion of crown and root of other teeth specially the canines occurred faster and terminated sooner in females than males (P<0.05).

The present results showed that the development of teeth in female children occurred sooner and in a different order. This difference was more significant in development of root of last erupted teeth during late mixed dentition period.