Analysis of familial tendency in skeletal class III malocclusion

Lee, Chang Hwan; Lee, Sang Han; Kim, Hyun Soo; Kwon, Tae Geon

Abstract

The purpose of this study was to examine the familial tendency of the patients with mandibular prognathism in three generations and to define the relationship between the familial tendency and the skeletal class III morphology. The probands of this study were 103 orthognathic surgery patients with skeletal Class III malocclusions who had undergone (48 men, 55 women) mandibular set-back surgery. A questionnaire was given to patients who sought surgical treatment for excessive mandibular length, and all answers were confirmed in interviews. Lateral cephalograms were analyzed in cranial base parameters, mandibular positional parameters and mandibular skeletal parameters. In the examined families, 58.3% had at least one member other than the proband who had mandibular prognathism. The affected ratio of total relatives was 4.5%, and the value was higher in first-degree (13.4%) than second-degree (5.9%) and third-degree relatives (1.7%). The affected ratio was 51.9% in the offsprings who had at least one affected father or mother. The comparison of the groups according to the familial tendency showed no significant craniofacial skeletal measurments. In conclusion, skeletal class III malocclusion showed high familial tendency, suggesting a significant genetic influence in the etiology. However, the patient's familial tendency did not show the special craniofacial patterns compare to the subjects without familial tendency.