Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Int Endod J. 2013 Aug;46(8):763-8. doi: 10.1111/iej.12056. Epub 2013 Feb 12.
To evaluate the potential effects of endodontic procedures (instrumentation and filling) on crack initiation and propagation in apical dentine.
Forty extracted single-rooted premolars with two canals were selected, 1.5 mm of the apex was ground perpendicular to the long axis of the tooth and the surface polished. The specimens were divided into 4 groups. The buccal canals of groups A, B and C were enlarged to size 40 with manual K-files. Group A was filled with gutta-percha using lateral condensation and vertical compaction without sealer. Group B was filled with the same method as group A except only lateral condensation was used. Group C was left unfilled, while group D was left unprepared and unfilled. Images of the resected surface were taken after resection (baseline), after canal preparation, after filling and after 4-week storage. The images were then inspected for cracks originating from the canal.
A significant effect of preparation on crack initiation (P < 0.05) and no significant effect of filling (P > 0.05) or 4-week storage on crack initiation (P > 0.05) was found (logistic regression). Fisher's exact test revealed a significant effect of filling on crack propagation (P < 0.05) and no effect of 4-week storage on crack propagation (P > 0.05).
Root canal procedures can potentially initiate and propagate cracks from within the root canal in the apical region.
评估根管治疗程序（器械预备和根管充填）对根尖牙本质中裂纹起始和扩展的潜在影响。
选择 40 颗具有两个根管的单根前磨牙，距根尖 1.5mm 处垂直于牙长轴磨除，表面抛光。将标本分为 4 组。A、B 和 C 组的颊侧根管用手动 K 锉扩大至 40 号。A 组用侧向加压和垂直压实法填充牙胶，不使用封闭剂。B 组采用与 A 组相同的方法，但只使用侧向加压。C 组未填充，D 组未预备也未填充。根管预备后、根管充填后和 4 周储存后，对切除表面进行图像采集（基线）。然后检查图像，看是否有源自根管的裂纹。
根管预备对裂纹起始有显著影响（P<0.05），根管充填（P>0.05）或 4 周储存对裂纹起始无显著影响（P>0.05）（逻辑回归）。Fisher 确切检验显示，根管充填对裂纹扩展有显著影响（P<0.05），4 周储存对裂纹扩展无影响（P>0.05）。
根管治疗程序可能会导致根尖区根管内的裂纹起始和扩展。
