Huysmans M C D N J M, Klein M H J, Kok G F, Whitworth J M
Academic Center Oral Health Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Int Endod J. 2007 Oct;40(10):778-85. doi: 10.1111/j.1365-2591.2007.01286.x. Epub 2007 Aug 14.
To determine the deviation of parallel-sided twist-drills during post-channel preparation and relate this to tooth type and position.
Human teeth with single root canals were selected: maxillary second premolars (group i); maxillary lateral incisors (group ii); mandibular canines (group iii); mandibular first premolars (group iv; all groups n = 16). The teeth were reduced to 17 mm length by sectioning the crown, and the root canals prepared and filled. Microradiographs were made in two directions. The teeth were individually embedded in a gypsum jaw and placed in a phantom head. Two operators performed parallel post-space preparation (12 mm length, 1.25 mm diameter) to the following protocol: gutta-percha removal with Gates Glidden drills numbers 2 and 3 and post-space enlargement with parallel drills numbers 3, 4 and 5, consecutively. Subsequently, microradiographs were re-exposed. The original and post-operative microradiographs were digitized and superimposed, and deviation of the post-space from the filled canal and remaining dentine thickness measured.
Overall, the mean deviation was 0.07 mm to the mesial (95% CI: 0.01-0.12), and 0.27 mm to the buccal (95% CI: 0.18-0.35). Group ii had significantly more buccal deviation than other groups (P = 0.004-0.008). A remaining dentine thickness of <0.5 mm occurred 16 times in 14 teeth, and of <1 mm occurred 97 times in 52 teeth.
Deviation during parallel post-preparation was common, predominantly in mesial and buccal directions, especially in maxillary incisors. This deviation increased the risk of perforation considerably.
确定平行侧麻花钻在根管后预备过程中的偏差，并将其与牙齿类型和位置相关联。
选择具有单根管的人类牙齿：上颌第二前磨牙（第一组）；上颌侧切牙（第二组）；下颌尖牙（第三组）；下颌第一前磨牙（第四组；所有组n = 16）。通过切割牙冠将牙齿长度缩短至17mm，然后预备并充填根管。在两个方向上制作显微放射照片。将牙齿分别嵌入石膏颌中并放置在模拟头中。两名操作者按照以下方案进行平行桩道预备（长度12mm，直径1.25mm）：先用2号和3号盖茨·格利登钻去除牙胶，然后依次用3号、4号和5号平行钻扩大桩道。随后，再次进行显微放射照片曝光。将原始和术后的显微放射照片数字化并叠加，测量桩道相对于已充填根管的偏差以及剩余牙本质厚度。
总体而言，平均偏差向近中为0.07mm（95%可信区间：0.01 - 0.12），向颊侧为0.27mm（95%可信区间：0.18 - 0.35）。第二组的颊侧偏差明显大于其他组（P = 0.004 - 0.008）。14颗牙齿中有16次出现剩余牙本质厚度<0.5mm，52颗牙齿中有97次出现剩余牙本质厚度<1mm。
平行桩道预备过程中的偏差很常见，主要发生在近中和颊侧方向，尤其是在上颌切牙中。这种偏差显著增加了穿孔的风险。
