Honap Manjiri Nagesh, Devadiga Darshana, Hegde Mithra N
Department of Conservative Dentistry and Endodontics, Chettinad Dental College and Rsearch Institute, Kancheepuram, Tamil Nadu, India.
Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka, India.
J Conserv Dent. 2020 Jan-Feb;23(1):51-56. doi: 10.4103/JCD.JCD_462_19. Epub 2020 Oct 10.
Failures of root canal treatments are mainly attributed to missed canals and ignorance about the complex anatomy of the root canal system. One such example of anatomic variation is the middle mesial canal (MMC) in mandibular molars which is often missed, and literature on methods for identifying them is limited.
This study aimed to assess the occurrence of MMCs with cone-beam computed tomography (CBCT) and then under magnification in the mandibular first and second molars.
A total of 120 extracted intact human permanent mandibular first and second molars were selected. These were subjected to CBCT imaging and magnification for the detection of MMCs. The percentage of incidence in the detection of MMC was compared between these two methods.
The incidence of MMC detected in mandibular molars using CBCT was 13.33% (16 of 120 teeth), while using a dental operating microscope, the incidence was 18.33% (22 of 120 teeth) and the comparison between the two methods was statistically not significant. The MMCs were classified based on the Pomeranz Classification. The most prevalent canal configuration was a confluent type which was found to be in 72% cases (16 of 22), followed by fin type which was 22.7% (5 of 22) and independent type was only 4.54% (1 of 22). The incidence of the location of MMC orifice was studied. In 50% of the cases, orifice was located closer to the mesiolingual canal, whereas in 27% of the cases, it was closer to the mesiobuccal canal and in 4.95% of the cases, it was detected midway.
Since the incidence of MMC was higher with the use of a microscope, it is preferred to use simpler, chairside aids like magnification and ultrasonic troughing. On the other hand, one should be judicious while subjecting a case to preoperative CBCT evaluation owing to its ionizing radiation.
根管治疗失败主要归因于遗漏根管以及对根管系统复杂解剖结构的忽视。下颌磨牙的近中中根管（MMC）就是这样一种解剖变异情况，它常常被遗漏，且关于识别它们的方法的文献有限。
本研究旨在通过锥形束计算机断层扫描（CBCT）评估MMC的发生率，然后在放大条件下评估下颌第一和第二磨牙中MMC的发生率。
总共选取了120颗完整拔除的人类恒牙下颌第一和第二磨牙。对这些牙齿进行CBCT成像和放大检查以检测MMC。比较这两种方法检测MMC的发生率。
使用CBCT检测到下颌磨牙中MMC的发生率为13.33%（120颗牙齿中有16颗），而使用牙科手术显微镜时，发生率为18.33%（120颗牙齿中有22颗），两种方法之间的比较在统计学上无显著差异。MMC根据波美拉尼亚分类法进行分类。最常见的根管形态是融合型，占72%的病例（22例中有16例），其次是鳍型，占22.7%（22例中有5例），独立型仅占4.54%（22例中有1例）。研究了MMC口的位置发生率。在50%的病例中，口更靠近近中舌根管，而在27%的病例中，它更靠近近中颊根管，在4.95%的病例中，它在中间位置被检测到。
由于使用显微镜时MMC的发生率较高，因此更倾向于使用更简单的椅旁辅助工具，如放大和超声冲洗。另一方面，由于术前CBCT评估存在电离辐射，因此在对病例进行该评估时应谨慎。
