Chhabra Sanjay, Yadav Seema, Talwar Sangeeta
Department of Conservative Dentistry & Endodontics, Army Dental Center (R&R), Delhi Cantonment, New Delhi, India.
Maulana Azad Institute of Dental Sciences, Bahadur Shah Zafar Marg, New Delhi, India.
J Conserv Dent. 2014 May;17(3):238-43. doi: 10.4103/0972-0707.131785.
The study was aimed to acquire better understanding of C-shaped canal systems in mandibular second molar teeth through a clinical approach using sophisticated techniques such as surgical operating microscope and cone beam computed tomography (CBCT).
A total of 42 extracted mandibular second molar teeth with fused roots and longitudinal grooves were collected randomly from native Indian population. Pulp chamber floors of all specimens were examined under surgical operating microscope and classified into four types (Min's method). Subsequently, samples were subjected to CBCT scan after insertion of K-files size #10 or 15 into each canal orifice and evaluated using the cross-sectional and 3-dimensional images in consultation with dental radiologist so as to obtain more accurate results. Minimum distance between the external root surface on the groove and initial file placed in the canal was also measured at different levels and statistically analyzed.
Out of 42 teeth, maximum number of samples (15) belonged to Type-II category. A total of 100 files were inserted in 86 orifices of various types of specimens. Evaluation of the CBCT scan images of the teeth revealed that a total of 21 canals were missing completely or partially at different levels. The mean values for the minimum thickness were highest at coronal followed by middle and apical third levels in all the categories. Lowest values were obtained for teeth with Type-III category at all three levels.
The present study revealed anatomical variations of C-shaped canal system in mandibular second molars. The prognosis of such complex canal anatomies can be improved by simultaneous employment of modern techniques such as surgical operating microscope and CBCT.
本研究旨在通过临床方法，利用手术显微镜和锥形束计算机断层扫描（CBCT）等精密技术，更好地了解下颌第二磨牙的C形根管系统。
从印度本地人群中随机收集42颗有融合根和纵沟的拔除下颌第二磨牙。在手术显微镜下检查所有标本的髓室底，并根据Min法分为四种类型。随后，在每个根管口插入#10或#15号K锉后对样本进行CBCT扫描，并与牙科放射科医生协商，利用横断面和三维图像进行评估，以获得更准确的结果。还在不同水平测量了沟槽处外牙根表面与根管内放置的初始锉之间的最小距离，并进行了统计分析。
在42颗牙齿中，样本数量最多的（15个）属于II型。共向86个不同类型标本的根管口插入了100根锉。对牙齿的CBCT扫描图像评估显示，共有21个根管在不同水平完全或部分缺失。所有类型中，最小厚度的平均值在冠部最高，其次是中部和根尖三分之一水平。III型牙齿在所有三个水平的数值最低。
本研究揭示了下颌第二磨牙C形根管系统的解剖变异。同时采用手术显微镜和CBCT等现代技术可改善此类复杂根管解剖结构的预后。
