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目的通过锥体束CT(cone-beam computed tomography,CBCT)数据的三维测量,研究下颌前徙后颅面型、自然头颈姿势位的变化。方法收集2008年3月-2015年3月在伊利诺伊大学颅颌面外科中心接受下颌双侧矢状劈开术(bilateral sagittal split osteotomy,BSSO)前徙的病例25例,男4例,女21例,平均年龄(17.95±1.43)岁。均为安氏二类牙颌面发育性骨性错颌畸形患者。分为A组(单颌BSSO前徙)8例、B组(双颌前徙)12例、C组(双颌前徙+颏成型)5例。将入选病例术前(T1)、术后1.5~3个月(T2)、术后1~2年(T3)的CBCT数据导入第三方软件进行三维测量并记录T1、T2、T3的颅面型和自然头颈姿势位(natural head posture,NHP)。主要测量指标:1)上颌颅面型测量指标:NSPNS(后鼻棘点PNS与颅底成角)、PNS-S_CP(PNS到三维坐标系冠状面距离)、PNS-S_FH(PNS到坐标系横断面距离)、GPF R_L(双侧腭大孔的空间距离在坐标系横断面上的投影,其变化值代表上颌水平宽度的变化);2)下颌颅面型测量指标:NSL(下颌正中联合舌侧最凸点L与蝶鞍中心点S连线与颅底所成角度)、L-S_CP(L到坐标系冠状面距离)、L-S_FH(L到坐标系横断面距离);3)NHP测量指标:NSC2(颅颈角,颅底与第二颈椎轴线所成空间角度在坐标系矢状面上的投影角度)、CIP-S_CP(第二颈椎椎体最后下点CIP与坐标系冠状面的距离)和CSP-S_CP(第二颈椎椎体最后上点CSP与坐标系冠状面的距离);4)颅面型与NHP关系测量指标:NSC2-NSL(NSC2与NSL两个角度差值)、L-CIP(L与CIP距离在坐标系矢状面的投影)、PNS-CSP(PNS与CSP距离在坐标系矢状面的投影)。分析颅面型和NHP的测量值及两者变化值的相关性。结果颅面型测量指标在T1、T2、T3的测量值差异有统计学意义(P<0.05):其中NSPNS(P<0.001)、NSL(P=0.015)、L-S_CP(P<0.001),且L-S_CP在分组间有交互作用(P=0.018)。NHP测量指标CSP-S_CP(P=0.03)在分组间有交互作用。颅面型与NHP关系测量指标在T1、T2、T3的测量值差异有统计学意义(P<0.05):其中L-CIP(P=0.005)、PNS-CSP(P<0.001)。颅下颌角NSL与颅颈角NSC2在T1(r=0.487,P=0.014)、T2(r=0.576,P=0.003)、T3(r=0.675,P<0.001)时相线性相关。结论下颌前徙可使颅颌面形态和NHP产生变化,在三维坐标系中重叠颅底可以一定程度减少由于NHP变化而导致的颅面型误判,从而获得立体、全面的正颌正畸疗效评估。
Objective To study the changes of craniofacial and natural head and neck position after mandibular anterior migrations by three-dimensional measurement of cone-beam computed tomography (CBCT) data. Methods Twenty-five cases of pre-bilateral bilateral sagittal split osteotomy (BSSO) were recruited from March 2008 to March 2015 in the Department of Craniomaxillofacial Surgery at the University of Illinois, with 4 males and 21 females , The average age (17.95 ± 1.43) years old. All of them are Class 2 patients with maxillofacial deformity. There were 8 cases in group A (single maxilla pre-BSSO migration), 12 cases in group B (bilateral maxillary anterior migration), and 5 cases in group C (bimaxillary migration + chin formation). CBCT data of preoperative (T1), postoperative 1.5 to 3 months (T2) and postoperative 1 to 2 years (T3) were imported into third-party software for three-dimensional measurement and the craniofacial patterns of T1, T2 and T3 were recorded And natural head posture (natural head posture, NHP). The main measurement indicators: 1) cranial craniofacial measurement indicators: NSPNS (posterior nasal plexus and skull base angle), PNS-S_CP (PNS to three-dimensional coordinate system coronal distance), PNS-S_FH Surface distance), GPF R_L (the projection of the spatial distance between the bilateral palatal foramen in the cross-section of the coordinate system, the change value represents the horizontal width of the maxillary); 2) The measurement of mandibular craniofacial index: NSL L-S_CP (L to the coronal plane of the coordinate system), L-S_FH (L to the cross-sectional distance of the coordinate system); 3) NHP Measurement index: NSC2 (craniocervical angle, the projection of the angle of the skull base and the second cervical spine in the sagittal plane of the coordinate system), CIP-S_CP (CIP of the second cervical vertebra and the coronal plane of the coordinate system ) And CSP-S_CP (the distance between the last point of the second cervical vertebra and the coronal plane of the coordinate system); 4) The measurement of the relationship between the craniofacial shape and NHP: NSC2-NSL (the difference between the two angles of NSC2 and NSL) , L-CIP (projection of L and CIP distance in the sagittal plane of the coordinate system), PNS-CSP (projection of distance between PNS and CSP in the sagittal plane of the coordinate system). Analysis of craniofacial and NHP measurements and the correlation between the two changes. Results There were significant differences in the measurement of craniofacial measurement between T1, T2 and T3 (P <0.05): NSPNS (P <0.001), NSL (P = L-S_CP interacts with each other (P = 0.018). The NHP measurement CSP-S_CP (P = 0.03) had an interaction between the groups. There were significant differences between craniofacial type and NHP in measurement of T1, T2 and T3 (P <0.05): L-CIP (P = 0.005), PNS-CSP (P <0.001). The cranial mandibular angle NSL and the craniocerebral angle NSC2 were linearly correlated at T1 (r = 0.487, P = 0.014), T2 (r = 0.576, P = 0.003) and T3 (r = 0.675, P <0.001). Conclusion The maxilla and maxillofacial morphology and NHP changes may be caused by the mandibular anterior migration. The overlapping skull base in the three-dimensional coordinate system may reduce the craniofacial misclassification due to the change of NHP to obtain a stereoscopic and comprehensive orthognathic orthodontic effect Evaluation.