切牙

Objective:To investigate the effects of extraction to the morphology of symphysis and the relationship between lower incisors retraction and the changes of the symphysis by evaluating the cephalograms of patients with Angle Class II Division 1 malocclusion.,in order to provide a reference to clinical treatment.

目的： 通过对安氏Ⅱ~1类错拔牙矫治前后的X线头影测量分析，观察矫治前后颏部形态的变化，并探讨下切牙内收量与颏部厚度和倾斜度变化之间的相关关系，以期为临床矫治设计提供一定的参考。

Bimaxillary protrusion extraction cases, the application implant anchorage appliance, the incisor root resorption evident.

双颌前突拔牙病例，应用种植支抗矫治后，切牙牙根吸收明显。

The cephalometric films before and after treatment were measured and compared.

治疗前后均拍摄头颅定位侧位片，并测量切牙和磨牙的治疗变化。

The contrctile tension of the masster muscles increased and the contraction time shortened, while that of the digastric muscles increased and prolonged.

戴上颌切牙〓平面板打开下颌分开后牙咬〓后，嚼肌收缩张力增加，收缩速度加快；二腹肌前腹收缩张力增加，但收缩速度变慢。

The rest 4 cases were distracted by rigid distraction and extraoral hooks at the beginning.

结果显示，牵引后，上切牙前移距离为5-11mm（平均7.8mm）；牵引结束后，前牙反〓全部解除。

The proportion of maxillary center incisors, maxillary lateral incisors, maxillary canines curved in mesiodistal were 11.17%, 16.19% and 21.43%, in labio-lingual were 39.59%, 40.00% and 29.59%, both in labiolingual and mesiedistal directions were 4.60%, 35.24% and 24.49%.

大约50％左右的上颌前牙根管存在中度弯曲：与上颌切牙相比，上颌尖牙的弯曲度略大而弯曲半径略小。

The premature loss of primary incisors does not usually require the placement of a dental appliance for the maintenance of space because mesial movement of the adjacent teeth is not generally expected.

乳切牙的早失，不一定需要空间保持器的置放，这是因为邻牙的偏移较少会产生

The three maxillary molars at the experimental sides were moved as one unit mesially by a Sentalloy coil spring delivering a force of 10 cN over a long range of activation. The contra-lateral molars served as controls. At 1, 2, 4, 8, and 12 weeks groups of animals were killed for histological evaluation.

实验侧的三颗磨牙用结扎丝颌粘接剂固为一个整体，在超弹性拉簧作用下（力值为0.1牛顿）向切牙侧移动。l， 2， 4， 8和12周时给予大鼠过量麻醉剂，材料用于组织学研究。

Upper first molar moved 4.14mm distally, and the upper incisors moved 0.66mm mesially.

上颌第一磨牙向远中平均移动4.14mm，上颌中切牙向唇侧移动0.66mm。

Upper and lower incisor both had controlled tipping movement. The crown of incisor moved mesially and had root apex were fixed relatively. The center of rotation was close to root apex. The upper and lower molar moved differently.

结果：唇挡治疗后，SNA、SNB分别增加1.02°和0.97°(P.05)，上下切牙前移均是牙冠向近中倾斜，而根尖相对固定的控制性倾斜，旋转中心接近根尖。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。