Hafezi Ladan, Sakhdari Shirin, Moaiyedmohseni Negin
Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Tehran Medical Science, Islamic Azad University, Tehran Iran.
Dentist, Private Practice; Tehran, Iran.
Iran Endod J. 2019 Fall;14(4):283-288. doi: 10.22037/iej.v14i4.24837.
Adequate knowledge about the anatomy of the roots and canals of mandibular third molars is imperative for a successful treatment. This study aimed to use cone-beam computed tomography (CBCT) to evaluate the morphology of the roots and canals of mandibular third molars and their symmetry.
Totally, 110 CBCT images of bilateral mandibular third molars were evaluated in terms of the number of roots and canals, canal type, isthmus location, location of accessory canals, degree of root curvature and its direction, age and sex of patients and the symmetry of variables in the right and left sides of the mandible. The descriptive statistics, -test and -square test were applied to analyze data.
Of all, 71.36% of mandibular third molars had two roots, 20.9% had one single root and 7.72% had three roots. The distal root had one single canal in 89.08%. The mesial root had one single canal in 44.25% and two canals in 49.42%. The Vertucci's types I (45.40%) and IV (34.48%) had the highest frequency in the mesial root while type I (91.95%) had the highest frequency in the distal root. The deviation of mesial root was towards the distal while distal roots were mainly straight.
The symmetry between the right and left mandibular third molars was significantly high. In case of encountering anatomical complexities in dental treatment of a mandibular third molar, dental clinicians should consider the high possibility of presence of the same condition in the contralateral mandibular third molar.
对于下颌第三磨牙牙根和根管的解剖结构有充分的了解是成功治疗的必要条件。本研究旨在使用锥形束计算机断层扫描（CBCT）评估下颌第三磨牙的牙根和根管形态及其对称性。
共评估了110例双侧下颌第三磨牙的CBCT图像，内容包括牙根和根管数量、根管类型、峡部位置、副根管位置、牙根弯曲程度及其方向、患者年龄和性别以及下颌左右两侧变量的对称性。应用描述性统计、t检验和卡方检验分析数据。
总体而言，71.36%的下颌第三磨牙有两根牙根，20.9%有一根单根，7.72%有三根牙根。远中根89.08%有一个单根管。近中根44.25%有一个单根管，49.42%有两个根管。近中根中维尔图奇I型（45.40%）和IV型（34.48%）出现频率最高，而远中根I型（91.95%）出现频率最高。近中根偏向远中，而远中根主要是直的。
左右下颌第三磨牙之间的对称性非常高。在下颌第三磨牙的牙科治疗中遇到解剖复杂性情况时，牙科临床医生应考虑对侧下颌第三磨牙存在相同情况的可能性很大。
