[Stages of formation and calcification of the third molar (radiographic study of 500 Mexican children and adolescents)].

Five hundred orthopantomograph radiographs of mexican children and adolescent from 7 to 18 tears old were reviewed in order to establish the third molar formation and calcification stages and the most frequent anomalies related to these teeth. We find that tooth bud presence is between 9 and 11 years; Third molar is absent in 32.4% of the population; 7.4% of the molars presented early formation stage malposition; Therefore oligodontia diagnosis and third molar malposition can not be done before 13 years of age.