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桩冠是利用金属钉插入根管内以获得固位的一种全冠修复体,其优点是形态与色泽均较美观,固位好,制作简便,是一种较为理想的修复体。但是有个别病例出现桩冠脱落,我们分析有以下几种原因:1 桩钉不足 前牙特别是尖牙和中切牙的牙根比较长,通常冠桩的长度应为根长的2/3或3/4,这样才能牢固的固位。如果短于2/3或3/4,或更短,固位就更差。所以桩冠时应十分注意。因桩冠的固位力主要依靠冠桩与根管壁之间的摩擦力和粘固剂的粘结力,因此要充分利用牙根的长度,力求冠桩与根管的密合。在临床看大部分脱落的桩冠是由于桩钉不够长度而导致的。2 牙根管的直径与桩钉的比例失调 有的牙根由于反复多次的钻磨,制备钉道,使根管壁变薄,根管粗大,而桩钉选择的比
Post crown is the use of metal nail inserted into the root canal to obtain retention of a full crown restoration, which has the advantages of morphology and color are beautiful, good retention, easy to make, is an ideal prosthesis. However, there are individual cases of crown off, our analysis for the following reasons: 1 pile of insufficient anterior teeth, especially teeth and incisors, the root length is relatively long, usually the length of the crown should be 2/3 of the root length or 3/4, so as to be firmly fixed. If shorter than 2/3 or 3/4, or shorter, retention is even worse. So pile crown should be very careful. Due to the retentive force of the crown mainly relies on the friction between the crown and the root canal wall and the adhesive force of the cement, it is necessary to make full use of the length of the root to make close contact between the crown and the root canal. Most of the clinically lost pile crown is due to insufficient length of the pile. 2 root canal diameter and pile nail imbalance in the root due to repeated drilling many times, the preparation of pinhole, root canal wall thinning, root canal thick, and the ratio of pile selection