Cephalometric characteristics of Class III malocclusion In Brazilian individuals

ABSTRACT

Aim: To evaluate the cephalometric characteristics of Class III malocclusion in Caucasian Brazilian subjects. Methods: The sample comprised 71 lateral cephalograms of individuals not previously submitted to any orthodontic treatment. The Class III group (experimental group) comprised 37 patients with bilateral Class III molar relationship and ANB lower than 1 degree, with a mean age of 21.76+3.89 years (13 males and 24 females). The Class I group (control group) consisted of 34 patients with bilateral Class I molar relationship, ANB angle higher than or equal to 1° and lower than 3°, with a mean age of 21.88+3.5 years (12 males and 22 females). Dental, skeletal and soft tissue measurements were compared using the t test for independent samples. Results: The results demonstrated that the Class III individuals showed significant differences in the cephalometric characteristics, except in vertical skeletal variables. The angular variables (SNA, SNB, ANB, SND, 1.1, 1.NA, 1.NB, IMPA, NA.Pog, H.NB) and the linear variables (Pog-Nperp, Co-Gn, 1-orbit, 1-NA, 1-NB, 1-NPog, 1-ANperp, FN-Pog, H-nose, Pog-NB, E menton) demonstrated statistically significant differences between groups. Conclusions: In Class III group, subjects presented maxilla with normal size, yet retruded in relation to the anterior cranial base; protruded mandible with increased size; and concave skeletal and soft tissue profiles. The maxillary incisors were protruded and buccally tipped, and the mandibular incisors were retruded and lingually tipped. Higher prevalence of mandibular prognathism (67.6%) was observed in the Class III group.