Objective To investigate the relationship between the stages of calcification of the third molar and age among children in Chengdu.Methods The study subjects consisted of children between 2009 and 2011 at the Department of Orthodontics, West China Hospital of Stomatology, Sichuan University. Panoramic radiographs were ob-tained. The stages of calcification of the third molar were analyzed by Demirjian’s method. The development of the third molar between the male and female was evaluated by independent samples t-test analysis. The Spearman rank correlation was applied to analyze the stages of calcification of the third molar and chronological age.Results The development of the third molar of the male was different from that of the female at stage A of calcification of the third molar(P=0.026). The Spearman rank correlation coefficient revealed highly significant relationships between the stages of calcification of the third molar and chronological age of the three groups（male, r=0.808, P=0.000; female, r=0.729, P=0.000; all, r=0.760, P=0.000）. Furthermore, the linear regression equations were established as follows: Yall=4.898+2.036X; Ymale=4.987+2.046X; Yfemale=4.819+2.036X.Conclusion The stages of calcification of the third molar may be an available indicator in judging chronological age of teenager.
