下颌前磨牙牙根及根管系统形态的锥形束CT研究

目的：利用锥形束CT（CBCT）研究下颌前磨牙牙根及根管系统形态的解剖特征和对称性。方法：收集413例CBCT影像（下颌第一前磨牙794颗，下颌第二前磨牙770颗）。运用NNTViewer软件分析其牙根数、根面沟位置、根管数、根管构型，统计根管构型的对称性。结果：下颌第一前磨牙大部分为单根，13颗为双根。根管构型发生率分别为I型87.66%，II型1.76%，III型2.52%，IV型2.14%，V型5.92%，C形根管（横截面）12.21%。118颗牙齿在牙根近中舌侧发现根面沟，93.70%根管构型对称。下颌第二前磨牙均为单根，其中99.48%为I型，0.52%为V型。4颗牙齿在牙根近中舌侧发现根面沟，99.48%根管构型对称。结论：下颌前磨牙牙根及根管形态解剖结构复杂多样，具有一定对称性，运用CBCT可帮助确定根管系统特征和变异。

Cone beam CT study of root anatomy and root canal morphology in mandibular premolars

Objective: To investigate the root anatomy and root canal morphology of mandibular premolars using Cone Beam CT and to determine their degree of bilateral symmetry. Methods: CBCT images of 413 patients were included (794 mandibular first premolars and 770 mandibular second premolars). The images were analyzed using NNTViewer software to check for the number of roots, the location of radicular grooves, the number of root canals, the canal configurations, and the bilateral symmetry of root canals. Results: The majority of the mandibular first premolars were single-rooted, only 13 teeth were double-rooted. The canal configuration of mandibular first premolars was type I: 87.66%, type II: 1.76%, type III: 2.52%, type IV: 2.14%, type V: 5.92%, and C-shaped canal: 12.21% (according to the cross-section), respectively. 118 mandibular first premolars had radicular grooves, which were all located on the mesio-lingual side. The bilateral symmetry rate of canal configuration was 93.70%. All the mandibular second premolars were single-rooted. 99.48% of root canals were type I and 0.52% were type V. Four mandibular second premolars had radicular grooves on the mesiolingual side. 99.48% of mandibular second premolars exhibited bilateral canal symmetry. Conclusion: The root anatomy and root canal morphology of mandibular premolars are complex but symmetrical. CBCT aids in characterizing the the configurations of the canal system, which can improve the success rate of root canal treatment.