上颌低位尖牙矫治的应力释放

李毕超 任利玲

[摘要]上颌尖牙唇侧异位萌出在临床上较为常见，其病因可能是因牙列拥挤导致。由于唇侧异位萌出的尖牙低位程度不一，传统固定矫治技术认为当尖牙低位严重时，矫治弓丝不可直接将其纳入，否则会导致邻牙压低局部开牙合，甚至出现牙合平面的切斜等。Damon系统则建议矫治早期尽量将错位牙纳入全牙列矫治，目前仅有文献报道尖牙异位的平均高度为（10.5±3.8）mm，而无唇侧异位萌出尖牙平均高度的研究，萌出的尖牙低位程度不一，能否将其直接纳入全牙列矫治，需要谨慎对待。本文综述了将低位尖牙纳入矫治系统后，尖牙及邻牙的应力释放情况，以期为临床矫治低位尖牙提供指导。

[关键词]异位尖牙；低位；应力释放；Damon系统；低摩擦

[中图分类号]R783.5 [文献标志码]A [文章编号]1008-6455（2018）06-0152-03

Abstract： It is more common in patients with maxillaryapically displaced canine caused by crowded dentition in literatures.The anterior openbite which was the result of the intrusion of lateral incisor and first premolar would occur when engaged the severe infraversion of canine in conventional stainless steel ligature system. Damon system recommended thatthe malposed teeth were included in the orthodonticsas early as possible. Although there are a few reports that the mean values for the distance of the displaced maxillary canines from the occlusal plane were （10.5±3.8）mm，it is still unclear about the infraversion of etrupted canine.The average height of the ectopic canine from the occlusal plane were varied，whether it can level a vertically displaced canine using a continuous arch wire directly， the stress release of the orthodontic systemwith apical canine will be the main content of this review.

Key words： displaced canine； infraversion； stress release； damon system； low friction

尖牙异位是指尖牙牙胚偏离正常萌出道而向唇颊侧（buccally displaced canine，BDC）或腭侧异位（palatally displaced canine，PDC），是牙列发育过程中一种常见的异位，常可导致尖牙阻生或异位萌出[1-3]。异位萌出（ectopic eruption）是指恒牙在萌出过程中未在牙列的正常位置萌出[4]。低位（infraversion），又称牙牙合下错位，指牙齿未萌出至牙合平面而低于牙合平面[5-6]。

1 尖牙低位的病因学

尖牙异位与尖牙发育、萌出延迟有无因果关系尚不十分明确，Becke等[7-8]认为尖牙腭侧异位（PDC）患者常伴有尖牙发育迟缓，而尖牙唇侧异位（BDC）则与之无关；Ingrid等学者[9]则认为尖牙唇、腭向异位均可能伴有尖牙发育或萌出延迟。虽然Lindauer等[10]定义尖牙阻生为未萌出尖牙牙根已发育完全者或对……