Investigating the time and order of eruption of permanent mandibular central and first molar in 5-8 years old children in Tehran

knowledge about the correct timing of eruption in children can have a significant impact on the diagnosis of abnormalities in children. There is limited information about eruption of teeth in Tehran. In this study, the time and order of eruption  of permanent mandibular central and first molar in students aged 5-8 years in Tehran were determined.

To conduct this descriptive and cross sectional research, two regions (5 and 16) were randomly selected from 19 educational districts of Tehran .A designed questionnaire was completed by examining 1116 students aged 5 to 8 years and 11 months. The statistical test (chi 2) was used to investigate the related factors such as age and sex and (Confidence .Interval) was used to evaluate the time of eruption.

The mean time of permanent mandibular first molar eruption in girls was 6.7 ± 0.9 and in boys 6.9 ± 0.7 and the average time of permanent mandibular central eruption in girls was 6.8 ± 0.8 and in boys was7.2 ± 0.9. The lowest age was related to the permanent mandibular first molar in girls and the highest age was related to the permanent mandibular centrals in boys.

In girls and boys, permanent mandibular first molar erupted earlier than permanent mandibular central And the time of eruption of these teeth in girls was earlier than boys. Permanent mandibular first molar had the lowest mean age of eruption in girls and permanent mandibular central had the highest mean age of eruption in boys.