Một số đặc điểm sọ - mặt ở nhóm bệnh nhân phẫu thuật chỉnh hình tiền hàm điều trị vẩu hai hàm

Abstract

Objective: To describe some anthropometric measurements of hard and soft tissue values on preoperative cephalometric radiographs of a bimaxillary protrusion patient group that required anterior segmentation surgery. Subject and method: The subjects included the cephalometric X-rays of 21 patients (21 females, 0 male) who were diagnosed as bimaxillary protrusion and underwent anterior segmental osteotomy on the maxilla and mandible. Lateral cephalograms taken preoperatively were analysed and results are compared with groups of subjects with harmonious facial profile and groups of subjects with bimaxillary protrusion. Result: A group of 21 Vietnamese subjects aged 17 - 44 with bimaxillary protrusion. All patients were treated with anterior segmental osteotomy surgery. Measurements of the pre-surgical lateral cephalometric film showed that the subjects had maxilla protrudes in relation to the cranial plane (FH/NA (º): 93.5 ± 4.1) while mandible was positioned backwards and downwards (SN-GoGn (º): 36.4 ± 6.6; SL (mm): 38.4 ± 7.3), skeletal class II malocclusion (ANB (º): 5.7 ± 3.2), a convex profile (N’SnPog’ (º): 161.2 ± 6.1), protruding upper lip-lower lip (Li-E line (mm): 5.5 ± 2.6; Ls-E line (mm): 1.8 ± 2.2) with a decreased inter-incisor angle (IIA (º): 110.1 ± 10.9). The maxillary and mandibular incisors tended to be buccally inclined and protruded (I/MxP (º): 132.8 ± 7.6; 1u-NA (mm): 7.4 ± 2.7; IMPA (º): 101.1 ± 7.9; 1l-NB (mm): 10.3 ± 2.3). The results suggest that the SNA angle (83.4 ± 3.7) and the nasolabial angle (Cm-Sn-Ls (º): 91.7 ± 10.0) were not sensitivity indicators in the bimaxillary protrusion diagnosis. Conclusion: Generally, subjects with bimaxillary protrusion generally had a convex profile, protruding upper-lower lips, acute interincisal angle, retruding and downward-rotated mandible. Compare to Vietnamese subjects with bimaxillary protrusion who receive orthodontic treatment, our group have less protruding lips and less inclining incisors; on the contrary, skeletal discrepancy was of greater degree, which suggest that the indication for surgical treatment is reasonable. The craniofacial and dental characteristics in the Vietnamese subjects with bimaxillary protrusion were quite similar to those of other ethnic groups. SNA angle and nasolabial angle were not sensitive indicator ​​for diagnosis of bimaxillary protrusion in Vietnamese.