对西安地区４０例乳牙期反病人头影测量研究结果显示：１、乳牙反主要存在颌间关系不调。面中部发育受限及上下切牙位置异常等改变。２、乳牙反颌间关系不调主要为下颌功能位置的改变造成，下颌骨实际长度的改变不具有决定意义。３、乳牙期反以牙性—机能性改变为主，但亦存在颅颌形态结构的异常，提示乳牙反的形成机制与遗传有关 40 cases of Xi'an decidua patients with deciduous head Cephalometric measurement results show that: 1, the main existence of deciduous deciduous intermaxillary relationship does not transfer. Face central and limited development of upper and lower incisors and other abnormal position changes. 2, the deciduous relationship between the deciduous teeth is mainly due to changes in mandibular function position, the actual length of the mandible changes are not decisive. In primary deciduous period, the dentinal-functional changes were dominant, but there was also the abnormality of cranial jaw morphology, which suggested that the formation mechanism of deciduous ankle was related to the genetics