The principal mechanism of mandibular growth is endochondral bone formation therefore, it is assumed that the mandibular condyle is affected more than the maxillary and mandibular corpus because condylar height is mainly controlled by endochondral bone formation. These results indicated that the interstitial cartilage growth of the mandibular condyles due to growth hormones stimulated by sex hormones had a greater influence in girls with CPP. Additionally, the mandibular gonial angle and mandibular plane angle were lesser in the CPP group than in the reference group, indicating the counterclockwise, anterior rotation of the mandible in girls with CPP. Although there was no significant difference in the maxilla–mandible relation between the groups, the mandible–cranial base relation (SNB) was greater in the CPP group than in the reference group. 5 In this study, the mandibular ramus height and total mandibular length of girls with CPP were higher than those in the reference group. Previous studies reported that lack of sex hormone production led to greater disturbances in both femoral and mandibular growth immediately after birth in mice. 7 The TW3 method assigns a standard degree of skeletal maturity to each of the 13 bones constituting the left hand and determines bone age by converting the standards into corresponding scores. Bone age was evaluated by an observer by using the Tanner–Whitehouse 3 (TW3) method and evaluating hand–wrist radiographs. Clinical data, such as chronological age, bone age, height, weight, and body mass index (BMI), were collected for all participants. Written informed consent was obtained from all participants and their parents before taking lateral cephalometric, panoramic, and hand–wrist radiographs. They had normal transverse and anteroposterior skeletal development (such as a menton deviation of ≤4 mm and an ANB angle of ≥0 mm and ≤4 mm) and dental characteristics and were referred for treatment of simple crowding or spacing of the maxillary and mandibular anterior dentition. The reference group consisted of 28 healthy girls who visited the Department of Orthodontics, Yonsei Dental Hospital, Seoul, Korea, from July 2009 to May 2016.
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