遗传因素对同卵双生子颅颌面部软硬组织形态的影响研究

目的通过投影测量和模型测量的方法，比较同卵双生子间颅骨、颌骨、牙齿、软组织的形态学差异，初步探索遗传因素和环境因素对同卵双生子颅颌面部软硬组织形态发育的影响。方法正畸治疗前，对12对同卵双生子同期拍摄X线头颅定位侧位片，并取记存模型，采用计算机头影测量软件和数显游标卡尺分别对颅颌面部软硬组织及牙齿进行测量分析。综合Downs、Steiner等分析法对12对同卵双生子的35个骨骼和牙齿参数进行测量；同时按照Holdaway等分析法对6个软组织参数进行测量分析。结果①双生子中颅骨及上下颌骨间形态位置关系无显著差异；②双生子牙-牙槽骨测量参数中，U1-SN和U1-NA间距及上颌前牙不齐指数和上颌牙列拥挤度有显著性差异。结论①遗传因素对颅骨和上下颌骨及上、下颌牙弓的形态起到决定性作用；②环境因素对上颌切牙的唇倾度有显著的影响作用，对下颌前牙的唇倾度影响不大。

Effect of genetic factors on soft and hard tissues of craniofacial regions in homozygotic twin

Objective To investigate the influence of genetic and environmental factors on cranial bones, jaw bones, teeth and soft tissues of homozygotic twin by cephalometric images and dental model measurement. Methods The lateral cephalograms and dental models of 12 homozygotic twin were selected for orthodotic treatment. Soft and hard tissues and teeth were detected by computer cephalometry software and vernier caliper. Twelve homozygotic twins with thirty-five bone and tooth parameters were measured by Downs and Steriner methods, and six soft tissue parameters were measured by Holdaway method simultaneously. Results （1）There were no significant differences between cranial bones and jaw bones in homozygotic twin. （2）U1-SN angle, U1-NA distance and maxillary anterior teeth irregularity index showed significant differences among alveolar bone parameters in homozygotic twin. Conclusion （1） Genetic factors have decisive effects on cranial and jaw bones and jaw arch.（2） Environmental factors have outstanding effects on the maxillary incisor inclination, but weak effects on mandibulary anterior teeth.