Mandibular growth during adolescence

To evaluate the mandibular growth of whites according to Fishman's method.

Eighty-five subjects, 9 to 18 years of age, were selected from the files of the Department of Orthodontics, Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Brazil. Patients were evaluated at two time points. At T1, they had a lateral head film and a hand-wrist radiograph and at T2, a lateral head film. The interval between T1 and T2 was 5 to 24 months. Subjects presented a Class I or II skeletal pattern and were divided into three groups according to Fishman's method: group I, in an accelerating growth velocity phase; group II, in peak of growth velocity phase; and group III, in decelerating growth velocity phase. The cephalograms were manually traced and cephalometric points digitalized into DentoFacial Planner Plus 2.0. The absolute growth amount was adjusted to obtain an annual growth rate (mm/y). The annual growth rate was compared between sexes, between individuals with Class I or II skeletal patterns, and among the three groups.

Mandibular annual growth rate in puberty was 2.16 mm for the mandibular body length, 3.16 mm for the ramus height, and 4.31 mm for the mandibular length. The results did not show significant differences between sexes, skeletal patterns, and groups, although there was a tendency for growth acceleration in group II.

There is great individual variation in mandibular linear growth.