Age and Sequence of Eruption about Permanent Teeth

Objective: The aim of this study was to find out the median age and sequence of eruption of permanent teeth in children of China now. Methods: Cross-sectional data on permanent teeth eruption were collected by examining the children of 2-17 years old from pre-school, primary school, junior school and senior high school in Xian of China. There were 6,755 subjects, including 3,637 boys and 3,118 girls. Results: In our study, median age of eruption about each permanent tooth was given (Table 1). All the data in our sample exhibited advanced eruption age compared with that of previous report published 48 years ago in the same area. Meanwhile, there were no significant differences in median age of teeth eruption between the left and the right. All mandibular teeth except the premolars, tended to erupt earlier than their maxillary counterparts. The age of eruption in girls was earlier than that in boys. The sequence of eruption was as D1, C1, C6, D6, B6, A6, D2, A1, B1, C2, A2, B2, A4, C3, B4, D3, C4, D4, B3, A5, A3, C5, D5, B5, C7, D7, B7 and A7. Conclusion: Although our results should be verified by future study, it was concluded that changes have taken place in the pattern of teeth eruption of Chinese children compared with 50 years ago.

Table 1

tooth    age of eruption(years)   tooth      age of eruption(years)

A1       6.57±0.93             C1        5.84±0.61 A2       7.53±0.87             C2        6.63±0.67 A3      10.24±1.20             C3        9.66±1.03 A4       9.57±1.16             C4        9.83±1.01 A5      10.23±1.38             C5       10.38±1.20 A6       6.13±0.69             C6        5.87±0.75 A7      12.06±1.13             C7       11.47±1.18 B1       6.58±0.79             D1        5.69±0.49 B2       7.71±0.98             D2        6.55±0.78 B3      10.19±1.15             D3        9.76±1.05 B4       9.73±1.03             D4        9.89±1.18 B5      10.65±1.34             D5       10.40±1.39 B6       6.11±0.60             D6        5.90±0.74 B7      11.79±1.19             D7       11.57±1.19