Sexual Dimorphism in the Development, Emergence, and Agenesis of the Mandibular Third Molar

Abstract

The development, alveolar emergence, and agenesis of the mandibular third molars, in a homogeneous group of French-Canadian children and young adults ranging in age from seven to 25 yr, were evaluated from 4640 panoramic radiographs using the method of Demirjian et al. 8 Clinical emergence was recorded from dental casts of children between 15 and 19 yr. The occurrence of bilateral agenesis was about 9%, without significant sexual difference. The left and right third molars had the same pattern of crown and root development and emergence. Girls were ahead of boys up to the second half of crown formation, but this sexual difference disappeared at the first stage of root formation. The root development course was faster in males than in females. At the apex closure, the sexual difference was much more marked for retarded cases (about 2.7 yr) than for median (1.5 yr) or advanced cases (0.4 yr). For alveolar and clinical emergence, males were about six mo ahead of females at the median level.