冠-根方向的根管预备普遍而不可避免的问题是将根管碎屑推出根尖孔,引起疼痛肿胀。最近,推出一种新的根管预备法即冠-根向无压力扩大法(Crown-down Pressureless Technique,简称CDPT);用GG钻和大号K型钻先预备根管的冠2/3,再以小号K型钻扩至全长行无压力的扩大,以减少碎屑对根尖的污染。本文将比较这两种方法将碎屑推出根尖孔的量。 Coronal - root direction of the root canal preparation The common but inevitable problem is the root canal debris introduced into the apical foramen, causing pain swelling. Recently, a new root canal preparation method, Crown-down Pressureless Technique (CDPT), was introduced. The crown 2/3 of the root canal was prepared by using a GG drill and a large K type drill, And then a small K-type drill to expand to full length without pressure to expand, in order to reduce debris pollution of the apical. This article will compare the amount of detritus introduced into the apical foramen by both methods.