Department of Surgical Sciences, Dental School, Endodontics, University of Turin, via Nizza, 230, 0126, Turin, Italy.
Politecnico di Torino, Turin, Italy.
BMC Oral Health. 2022 Nov 10;22(1):482. doi: 10.1186/s12903-022-02531-5.
Endodontic ledge (EL) formation is the most common complication of endodontic treatment. Although various etiological factors have been identified, canal curvature is the most significant variable correlated with EL formation. The aim of this micro-computed tomographic (micro-CT) study was to evaluate EL position in the mesial canals of the lower molars in relation to the degree of canal curvature.
Forty intact mandibular first molars with independent mesial canals with 20°-40° primary mesio-distal curvature, 10°-30° buccal-lingual canal curvature and 4 < r ≤ 8 mm main curvature radius were selected. Working length was measured with a K-File #10 and a high resolution pre-operative micro-CT analysis was performed. Ledges were created at the point of maximum canal curvature using stainless steel K-Files #30-35, alternating irrigation with 5% NaOCl and 10% EDTA. A post-operative high-resolution micro-CT analysis was then completed. Pre- and post-operative images were analyzed. The angle (α) formed between the vector passing through the geometric center of the EL and the center of the original canal lumen and the line joining the centers of the mesio-buccal and mesio-lingual canal orifices was calculated, and a descriptive statistical analysis was achieved. The α angle values were analyzed in relation to canal curvature using Kruskal-Wallis and post hoc Dunn's tests. The level of significance was set at P < 0.05.
The α angles appeared inversely proportional to canal curvatures in the buccal-lingual and mesio-distal projections. The mean α angle was 36.4° (standard deviation 10.64; 95% confidence interval 34.1-40.9).
Within the limitations of this study, endodontic ledges develop in the opposite direction to the three-dimensional canal curvature and their position is influenced by the degree of curvature. Clinically, the α angle values may be related to the recommended direction to manage endodontic ledges.
根管肩台（EL）的形成是根管治疗中最常见的并发症。尽管已经确定了各种病因因素，但根管弯曲是与 EL 形成最相关的重要变量。本微计算机断层扫描（micro-CT）研究的目的是评估下颌磨牙近中根管内 EL 的位置与根管弯曲程度的关系。
选择 40 颗具有 20°-40°原发性近远中向弯曲、10°-30°颊舌向弯曲和 4 < r ≤ 8 mm 主弯曲半径的独立近中根管的完整下颌第一磨牙。用 K-File #10 测量工作长度，并进行高分辨率术前 micro-CT 分析。在最大根管弯曲处使用不锈钢 K-File #30-35 制作 EL，用 5% NaOCl 和 10% EDTA 交替冲洗。然后进行术后高分辨率 micro-CT 分析。分析术前和术后图像。计算穿过 EL 几何中心和原始根管腔中心的向量与连接近颊和近舌根管口中心的线之间形成的角度（α），并进行描述性统计分析。使用 Kruskal-Wallis 和事后 Dunn 检验分析α角值与根管弯曲的关系。显著性水平设为 P < 0.05。
在颊舌向和近远中向投照中，α角似乎与根管弯曲呈反比。平均α角为 36.4°（标准差 10.64；95%置信区间 34.1-40.9）。
在本研究的限制范围内，根管肩台向三维根管弯曲的相反方向发展，其位置受弯曲程度的影响。临床上，α角值可能与处理根管肩台的推荐方向有关。
