State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, P.R. China.
BMC Med Imaging. 2011 Jun 15;11:14. doi: 10.1186/1471-2342-11-14.
Together with diagnosis and treatment planning, a good knowledge of the root canal system and its frequent variations is a necessity for successful root canal therapy. The selection of instrumentation techniques for variants in internal anatomy of teeth has significant effects on the shaping ability and cleaning effectiveness. The aim of this study was to reveal the differences made by including variations in the internal anatomy of premolars into the study protocol for investigation of a single instrumentation technique (hand ProTaper instruments) assessed by microcomputed tomography and three-dimensional reconstruction.
Five single-root premolars, whose root canal systems were classified into one of five types, were scanned with micro-CT before and after preparation with a hand ProTaper instrument. Instrumentation characteristics were measured quantitatively in 3-D using a customized application framework based on MeVisLab. Numeric values were obtained for canal surface area, volume, volume changes, percentage of untouched surface, dentin wall thickness, and the thickness of dentin removed. Preparation errors were also evaluated using a color-coded reconstruction.
Canal volumes and surface areas were increased after instrumentation. Prepared canals of all five types were straightened, with transportation toward the inner aspects of S-shaped or multiple curves. However, a ledge was formed at the apical third curve of the type II canal system and a wide range in the percentage of unchanged canal surfaces (27.4-83.0%) was recorded. The dentin walls were more than 0.3 mm thick except in a 1 mm zone from the apical surface and the hazardous area of the type II canal system after preparation with an F3 instrument.
The 3-D color-coded images showed different morphological changes in the five types of root canal systems shaped with the same hand instrumentation technique. Premolars are among the most complex teeth for root canal treatment and instrumentation techniques for the root canal systems of premolars should be selected individually depending on the 3-D canal configuration of each tooth. Further study is needed to demonstrate the differences made by including variations in the internal anatomy of teeth into the study protocol of clinical RCT for identifying the best preparation technique.
根管系统及其常见变异的良好知识，除了诊断和治疗计划外，对于成功的根管治疗也是必要的。对于牙齿内部解剖结构的变异，器械技术的选择对成形能力和清洁效果有显著影响。本研究的目的是揭示将前磨牙内部解剖结构的变异纳入研究方案后，使用微计算机断层扫描和三维重建评估单一器械技术（手动 Protaper 器械）时所产生的差异。
对 5 颗单根前磨牙进行扫描，这些前磨牙的根管系统被分为 5 种类型之一。在使用手动 Protaper 器械预备之前和之后，使用微 CT 进行扫描。使用基于 MeVisLab 的自定义应用程序框架在 3-D 中对器械特性进行定量测量。获得了根管表面积、体积、体积变化、未触及表面的百分比、牙本质壁厚度和去除的牙本质厚度的数值。还使用彩色重建评估了预备误差。
器械预备后，根管体积和表面积增加。所有 5 种类型的预备根管均变直，向 S 形或多曲线的内侧面发生运输。然而，在 II 型根管系统的根尖三分之一曲线处形成了一个嵴，记录到未改变的根管表面百分比的范围很广（27.4-83.0%）。除了从根尖表面 1 毫米范围内和 II 型根管系统的危险区域外，牙本质壁厚度超过 0.3 毫米。
3-D 彩色编码图像显示了用相同的手动器械技术成形的 5 种根管系统的不同形态变化。前磨牙是根管治疗最复杂的牙齿之一，对于前磨牙的根管系统，应根据每个牙齿的 3-D 根管形态单独选择器械技术。需要进一步的研究来证明将牙齿内部解剖结构的变异纳入临床 RCT 研究方案对确定最佳预备技术的影响。
