Ahmed Hany Mohamed Aly, Farook Mohideen Salihu
Department of Restorative Dentistry, Faculty of Dentistry, Universiti Malaya, Kuala Lumpur, 50603, Malaysia.
BMC Oral Health. 2025 Apr 7;25(1):498. doi: 10.1186/s12903-025-05781-1.
Mandibular first premolar teeth show a wide range of root and canal anatomical variations including accessory roots, deep root proximal grooves and multiple canals. This study provides qualitative and quantitative morphological analysis of a rare four-rooted mandibular first premolar scanned using micro-CT. In addition, it provides clinical implications through endodontic access cavity preparation and negotiation of canals under dental operating microscope (DOM) to assess the difficulty for locating the canals.
An extracted four-rooted mandibular first premolar tooth sample was subjected to 2D radiographic imaging in two views and micro-computed tomography (micro-CT) scanning with a resolution of 25 μm. Subsequently, 3D- reconstruction of the tooth sample was performed using Mimics software (Materialise, Leuven, Belgium). 3D (volume and surface area) and 2D measurements (distances between orifices, area, perimeter, maximum and minimum diameter, roundness, aspect ratio and form factor) were obtained. In addition, endodontic access was prepared, and the canals were explored under the DOM. Location of the canals were confirmed by periapical radiographs with the aid of hand files.
The 2D imaging showed the presence of four canals. Micro-CT analysis showed a complex canal anatomy which was classified using Ahmed et al. coding system as 44 MB DB (ML DL). Quantitative analysis showed that the MB root had the highest canal volume and surface area compared to other canals. The 2D measurements showed wide variations among canals, which reflects the complexity of the canals in terms of size and geometry. The MB and DB canals tend to have more aspect ratio values (more oval/flattened) than other canals. After access cavity preparation and exploration, six root canals were identified [mesio-buccal one (MB1), mesio-buccal two (MB2), disto-buccal (DB), mesio-lingual (ML), disto-lingual (DL) and lingual disto-buccal (LDB)]. The canals in the MB root showed two locations of splitting.
Mandibular first premolars may have complex variations in the number of roots and canal configurations. The different anatomical presentations demonstrated in the 2D and 3D measurements of the six canals presented in this report signifies the anatomical variabilities, which could complicate the detection and negotiation of canals during root canal treatment. Ahmed et al. coding system is useful in classifying teeth with complex root and canal anatomy.
下颌第一前磨牙的牙根和根管解剖结构存在广泛变异，包括副根管、深的牙根近中沟和多根管。本研究对一颗罕见的四根管下颌第一前磨牙进行了微计算机断层扫描（micro-CT），并提供了定性和定量的形态学分析。此外，通过牙髓治疗开髓洞形制备以及在牙科手术显微镜（DOM）下探查根管，评估根管定位难度，得出临床意义。
对一颗拔除的四根管下颌第一前磨牙样本进行两个角度的二维放射成像以及分辨率为25μm的微计算机断层扫描（micro-CT）。随后，使用Mimics软件（Materialise，比利时鲁汶）对牙齿样本进行三维重建。获得三维（体积和表面积）和二维测量值（根管口之间的距离、面积、周长、最大和最小直径、圆度、纵横比和形状因子）。此外，制备牙髓治疗开髓洞形，并在DOM下探查根管。借助手动锉通过根尖片确认根管位置。
二维成像显示有四条根管。微计算机断层扫描（micro-CT）分析显示根管解剖结构复杂，根据艾哈迈德等人的编码系统分类为44 MB DB（ML DL）。定量分析表明，与其他根管相比，近中颊根的根管体积和表面积最大。二维测量显示各根管之间差异很大，这反映了根管在大小和几何形状方面的复杂性。近中颊根管和远中颊根管的纵横比值往往比其他根管更多（更呈椭圆形/扁平状）。在开髓洞形制备和探查后，确定了六条根管[近中颊一根（MB1）、近中颊二根（MB2）、远中颊根（DB）、近中舌根（ML）、远中舌根（DL）和舌侧远中颊根（LDB）]。近中颊根的根管显示出两个分叉位置。
下颌第一前磨牙的牙根数量和根管形态可能存在复杂变异。本报告中对六条根管进行的二维和三维测量所显示的不同解剖表现表明了解剖变异，这可能使根管治疗期间根管的检测和探查变得复杂。艾哈迈德等人的编码系统有助于对具有复杂牙根和根管解剖结构的牙齿进行分类。
