A genetic survey of maxillofacial growth in Chinese twins

虽然日本人和中国人在文化上不同，但他们在种族上却非常接近。本项目拟通过研究中国双胞胎的颌面遗传生长，并与日本儿童的颌面遗传生长进行比较，更深入地了解蒙古类人猿颌面生长的形态学变化。1994年在北京医科大学牙科学院儿科牙科门诊登记了近90例居住在北京的中国混血女双胞胎。结合DNA指纹图谱法确定合子度。接下来的两年，我们对他们进行了年度资料采集，填写问卷，测量身高体重，拍摄口腔照片，头部x光片，肠镜和牙印。在牙模型上，我们使用三维测量仪测量上颚的形态变化。除双第一磨牙宽度外，上颚的宽度和深度均受遗传因素的显著控制，而总体积和乳牙后上颚体积受遗传因素的显著控制。侧位脑电图的测点、角度测量和直线测量均根据JPDA出版的《日本儿童标准头测数据》一文确定。从角度分析来看，中国儿童的颌面颅骨外框与日本儿童基本相同，但A点和B点比日本儿童略近，内角略小。从整体上看，中国人的线形尺寸较小似乎反映了中国和日本儿童雕像的差异。前颅底遗传率在70%以下，上颌骨和下颌骨遗传率在70%左右。

Although Japanese and Chinese are different culturally, they are extremely close to each other racially. This project was planned to understand the morphological variation of maxillofacial growth in Mongoloid more deeply by studying the maxillofacial genetic growth in Chinese twins and comparing them to those of Japanese children.Almost 90 female twins of Chinese origin in mixed dentition stages lived in Beijin were enrolled at the clinic of pediatric dentistry, School of Dentistry, Beijin Medical University 1994. The zygosity was determined on the basis of the DNA finger print method. Next two years we took the annual materials of them, filling in the questionnaires, measuring heights and weights, taking oral photos, cephalograms, pantomograms and dental impressions.Concerning the dental models, we measured the morphological variation of the palate using the three dimensional measuring apparatus. The total volume and the post deciduous canine volume of the palate were significantly contorolled genetically, however, both the widths and depths of the palate, except bi-first molar width, were not significantly contorolled.On the lateral cephalograms, measuring points and both angular and linear measurements were determined according to the paper of "Standard Cephalometric Data of Japanese Children" published by JPDA.From angular analysis the outer-frame of maxillofacial cranium in Chinese children were almost same as those of the Japanese Children, however, both Point A and Point B were little bit more mesial than those of Japanese, and the interincisal angle was smaller slightly. The smaller linear measurements of Chinese on the whole seemed to be reflected the difference of the statues between the Chinese and Japanese children. The heritability of the anterior cranial base was under 70% and those of the maxilla and the mandible were around 70%.