Data set.

Objectives
The objective of this study was to evaluate the effectiveness of clinically applicable diagnostic methods such as Direct Vision (DV), Dental Operating Microscope (DOM), and two-dimensional (2D) radiographs in detecting canal orifices and root canal configurations in mandibular first premolars with deep radicular grooves. The study also aimed to compare these methods with micro-computed tomography (micro-CT) to better understand their diagnostic capabilities and to assess the applicability of the Ahmed et al. (2017) classification system across different imaging modalities.
Methods
A total of 133 mandibular first premolars with deep radicular grooves were scanned using micro-CT. After scanning, two examiners, blinded to micro-CT results, accessed and examined the root canal orifices of the study samples under DV, and DOM. Further evaluation of the root canal configurations was undertaken using exploration and 2D radiographic images. A second round of relocation of canals was undertaken if the radiographic view showed the presence of a missed canal. The data were then compared with the original reconstructed micro-CT images. Descriptive statistical analysis, Kappa and chi-square tests were performed to compare between methods and examiners, and the p-value was set at 0.05.
Results
Except for three teeth, all samples exhibited multiple canals. Micro-CT data revealed a wide range of root canal configurations, with the most common being 1MFP1-2 (19.54%), followed by 1MFP1-2-3 (15.78%), 1MFP1-2-3-2 (5.26%), and both 1MFP1-2-4 and 1MFP1-2-1 configurations, each at 4.51%. For both examiners, using the DOM resulted in detection of more canal orifices compared to DV (p < 0.001). A number of root canal configuration types including 1MFP1-2 and 1MFP1-2-1 was identified using exploration and radiographic imaging. Both examiners identified additional canals in the relocation phase. A significant difference was found when the radiographic method is compared with micro-CT results (p < 0.001), in which the latter method showed more complex root canal configuration types.
Conclusions
Mandibular first premolars with deep proximal grooves exhibit considerable variability and complexity in their root canal systems. The use of a dental operating microscope (DOM) significantly improves the detection of canal orifices compared to direct vision. The most frequently observed root canal configuration was 1MFP1-2. A high percentage of additional canals may be missed due to atypical locations of bifurcations along the root. While micro-CT imaging is not applicable in clinical settings, it remains a valuable reference tool in studies for enhancing our understanding of root canal morphology and guiding the development of clinically feasible diagnostic strategies.

### 研究目的
本研究旨在评估临床适用诊断方法——直视法（Direct Vision, DV）、牙科手术显微镜（Dental Operating Microscope, DOM）以及二维（2D）X线片——在检测伴牙根深沟的下颌第一前磨牙的根管口及根管构型方面的有效性。本研究同时旨在将上述方法与显微计算机断层扫描（micro-computed tomography, micro-CT）进行对比，以明晰其诊断性能，并评估Ahmed等人（2017）提出的分类系统在不同成像模态下的适用性。
### 研究方法
本研究共纳入133颗伴牙根深沟的下颌第一前磨牙，均接受micro-CT扫描。扫描完成后，两名对micro-CT结果不知情的检查者分别采用直视法与牙科手术显微镜对研究样本的根管口进行探查与检查；随后通过根管探查及二维X线影像进一步评估根管构型。若X线片显示存在遗漏根管，则需进行二次根管定位操作。随后将所得数据与原始重建的micro-CT影像进行比对。本研究采用描述性统计分析、Kappa检验及卡方检验开展方法间与检查者间的比较，设定检验水准p值为0.05。
### 研究结果
除3颗牙齿外，所有样本均存在多根管。micro-CT数据显示根管构型存在广泛差异，最常见的为1MFP1-2（19.54%），其次为1MFP1-2-3（15.78%）、1MFP1-2-3-2（5.26%），1MFP1-2-4与1MFP1-2-1构型各占4.51%。两名检查者采用DOM检测到的根管口数量均显著多于直视法（p<0.001）。通过根管探查与X线成像可识别包括1MFP1-2与1MFP1-2-1在内的多种根管构型类型。两名检查者均在二次定位阶段发现了额外根管。将X线成像法与micro-CT结果对比发现存在显著差异（p<0.001），后者可检出更为复杂的根管构型类型。
### 研究结论
伴近中牙根深沟的下颌第一前磨牙的根管系统存在显著的变异性与复杂性。与直视法相比，使用牙科手术显微镜（DOM）可显著提升根管口的检出率。最常见的根管构型为1MFP1-2。由于根管分叉沿牙根分布位置不典型，可能会漏诊较高比例的额外根管。尽管显微计算机断层扫描（micro-CT）无法应用于临床场景，但其仍是当前研究中用于深化根管形态认知、指导临床可行诊断策略开发的珍贵参考工具。