El Sweify Haya Mohamed, Abdelsalam Nelly, Hashem Nasr, Fouda Ahmed Mahmoud, Bourauel Christoph, Sharaan Marwa
BDS Faculty of Dentistry, Suez Canal University, Ismailia, Egypt.
Faculty of Dentistry, Department of Endodontics, Suez Canal University, Ismailia, Egypt; Restorative Dental Sciences Department, College of Dentistry, Gulf Medical University, Ajman, United Arab Emirates.
J Endod. 2025 Sep;51(9):1278-1284. doi: 10.1016/j.joen.2025.06.009. Epub 2025 Jun 19.
This study aimed to locate the anatomical apical constriction (AC) of root canals using micro-computed tomography (micro-CT) and microscopy, and to correlate these findings with the flash bar of the Root ZX electronic apex locator. The objective was to identify the protocol that positions the file closest to the AC.
The working lengths of 30 extracted single-rooted teeth were measured using Root ZX electronic apex locator with 3 employment protocols. Group I: Files were advanced in the canals to the "APEX" mark and then withdrawn to the "end of the Blue zone" mark. Group II: Files were advanced to the "APEX" mark and then withdrawn to the "0.5" mark. Group III: Files were advanced only to reach the "APEX" mark. Files were then cemented in place and examined using micro-CT and surgical operating microscope to identify the actual location of the AC. The discrepancies between the locations of the file's tip and the ACs were assessed by 3D slicer software and statistically analyzed.
Significant differences were observed among the 3 groups based on micro-CT and surgical operating microscope measurements. The end of the blue zone achieved 100% accuracy, the 0.5 mark 85%-80%, and the apex mark protocol 0%-5% (within a tolerance of ±0.5 mm). An overall positive correlation was found between micro-CT and surgical microscopy measurements (r = 0.91). Working length overestimation beyond the major foramen occurred in 30% of the samples in the 0.5 mark protocol and 60% of the Apex mark group.
The "end of the Blue zone" mark protocol provided the greatest accuracy without file extrusion, followed by the "0.5" mark. The "APEX" mark protocol is not recommended since this protocol placed the file at an average of 1.24 mm apical to the AC.
本研究旨在使用微型计算机断层扫描（micro-CT）和显微镜定位根管的解剖根尖缩窄（AC），并将这些结果与Root ZX电子根尖定位仪的闪烁条进行关联。目的是确定能将锉尖定位在最接近AC处的方案。
使用Root ZX电子根尖定位仪，通过3种操作方案测量30颗拔除的单根牙的工作长度。第一组：将锉在根管中推进至“根尖”标记处，然后回拉至“蓝色区域末端”标记处。第二组：将锉推进至“根尖”标记处，然后回拉至“0.5”标记处。第三组：仅将锉推进至“根尖”标记处。然后将锉固定到位，使用micro-CT和手术操作显微镜检查以确定AC的实际位置。通过3D切片软件评估锉尖位置与AC位置之间的差异，并进行统计学分析。
基于micro-CT和手术操作显微镜测量，3组之间观察到显著差异。蓝色区域末端的准确率达到100%，“0.5”标记处为85%-80%，根尖标记方案为0%-5%（在±0.5毫米的公差范围内）。micro-CT和手术显微镜测量之间总体呈正相关（r = 0.91）。在“0.5”标记方案的30%的样本和根尖标记组的60%的样本中，出现了工作长度超出主要根尖孔的高估情况。
“蓝色区域末端”标记方案在无锉尖超出的情况下提供了最高的准确性，其次是“0.5”标记。不建议使用“根尖”标记方案，因为该方案将锉平均放置在AC根尖侧1.24毫米处。
