部分的下颌管近中的管壁不完整。
结果：下颌管是下颌骨的骨松质内形成较薄的骨密质骨管。
Results: mandibular canal was formed by a thin layer of compact bone in spongy bone of mandibular bone.
②下颌管中心（M）到与M点在同一水平线的颊侧点（O）的距离；
The distance of Mandible of the Centre (M) and M points to the horizon at the same point of the buccal (O);
目的：研究单根的下颌第二磨牙的根管形态。
Objective: to investigate the root canal anatomy of one-rooted mandibular second molars.
但有资料表明下颌切牙的根管解剖形态较为复杂，变异较多。
However, some research data show that mandibular incisors' root canal anatomy is comparatively complex, and root canal system has many variations.
目的：探讨下颌第二磨牙根管系统的特征及临床诊断和治疗方法。
AIM: To discuss the clinical diagnosis and treatment of root canal system of mandibular second molars.
目的：研究离体下颌前磨牙的牙根及根管形态。
Objective: To investigate the root and canal morphology of extracted mandibular premolars.
目的：观察根管治疗后的下颌磨牙冠缺损类型与冠根折的关系。
Objective: To evaluate the relationship between crown defect types and crown fractures of root-canal-treated mandibular molars.
方法：从6颗离体的形态正常的人右下颌第一磨牙中，选取密合度最好且形态接近临床要求的1颗进行根管治疗，制作制锁式的带桩嵌体修复体。
METHODS: 1 of the 6 first mandibular molars on the right side with normal morphology in vitro was selected for pulpectomy, which was the best in density and near to clinical requirement in morphology.
目的：了解下颌前牙根管弯曲情况。
Objective: To investigate root canal curvatures in mandibular anteriors.
目的：调查下颌第二磨牙扇形根管的出现率与牙根形态的关系。
AIM: To study the relationship between root form and frequency of C-shaped canals in the mandibular second molars.
结论：下颌第二磨牙的C形根管在根管的数量和形态有较大变化。
Conclusions: C-shaped canals in mandibular second molars vary in canal number and shape.
目的：探讨下颌骨舌侧管的发生频率和解剖结构。
Objective:To discuss the frequency and anatomical structure of lingual vascular canal of mandible.
方法：检查了23例干燥下颌骨标本，测量了舌侧管的数目、位置、管口直径、长度和走向。
Methods: On23dry mandibles, the number, location, diameter, length and direction of lingual vascular canals were measured.
目的探索预备下颌第二磨牙C形根管的有效方法。
Objective To explore the effective method for C-shaped root canal preparation.
下颌切牙中，双根管、根管分支和根管分歧都有一定的发生率。
The two root canals, root canal diverge and root canal branch et al have considerable incidence. Besides, mesial-distal root canal walls of mandibular incisor teeth are thin.
方法：选取40个下颌磨牙近中颊侧弯曲根管，随机分为两组，每组20个根管。
Method:40 curved mesial-buccal canals in mandibular molars were selected and divided into two groups randomly. Each group had 20 canals.
结论：下颌第二磨牙根管变异较多。
Conclusion: The C-shape mandibular second molars would be detrimental to canals debridement and obturation.
结论CBCT影像精密度高，可从三维角度分析根管，在根管治疗中诊断治疗下颌第二磨牙C型根管具有临床指导意义。
Conclusions CBCT can analyze the configuration of root canals in a three-dimensional view, which is of prime importance in the diagnosis and treatment of C-shaped canals of mandibular second molars.
结论CBCT影像精密度高，可从三维角度分析根管，在根管治疗中诊断治疗下颌第二磨牙C型根管具有临床指导意义。
Conclusions CBCT can analyze the configuration of root canals in a three-dimensional view, which is of prime importance in the diagnosis and treatment of C-shaped canals of mandibular second molars.
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