Department of Endodontics, The British University in Egypt, Cairo, Egypt.
Department of Endodontics, The British University in Egypt, Cairo, Egypt.
J Endod. 2022 Jul;48(7):902-908. doi: 10.1016/j.joen.2022.03.013. Epub 2022 Apr 6.
This study investigated the significance of pericervical dentin after coronal canal flaring on the biomechanical behavior and life span of a maxillary molar using finite element analysis (FEA).
In addition to the intact tooth (IT) model, 4 experimental FE models were designed: conservative access cavity model (CON), and 3 models with different radicular preparations for the coronal 4 mL considering 3 instruments: ProTaper SX model (SX), OneFlare model (OF), and Gates-Glidden model (GG). Cyclic loading of 50 N was applied on the occlusal surface and number of cycles until failure (NCF) was compared with the IT model. Mathematical analysis was done to evaluate the stress distribution patterns and calculated maximum von Mises (VM) and maximum principal stresses.
Access cavity preparation (CON) decreased NCF significantly when compared with the IT model (93.99%). The coronal preparation of the root canal did not have a significant effect even when the preparation was taken to the extreme (GG: 92.02%). VM analysis confirmed apical dispersion of stresses, with maximum value registered on the occlusal surface in the GG model (7.88 MPa), and minimum on the IT model (7.01 MPa). The furcation area showed higher maximum principal stresses, yet stress values remained minimal and distributed over larger surfaces with the progressive enlargement among models.
Within the limitations of this study, coronal canal flaring affects tooth integrity minimally, and when loading conditions lie within normal functional ranges, tooth structure has the capacity to disperse increasing stresses over a wider surface area.
本研究通过有限元分析（FEA）探讨了牙颈部牙本质对上颌磨牙根管冠向敞开后生物力学行为和寿命的意义。
除完整牙（IT）模型外，还设计了 4 个实验有限元模型：保守入口腔模型（CON），以及考虑 3 种器械的 4 种不同根管根向预备的 3 个模型：ProTaper SX 型号（SX）、OneFlare 型号（OF）和 Gates-Glidden 型号（GG）。在咬合面施加 50N 的循环载荷，并与 IT 模型比较失效前的循环次数（NCF）。进行数学分析以评估应力分布模式，并计算最大 von Mises（VM）和最大主应力。
与 IT 模型相比，入口腔预备（CON）显著降低了 NCF（93.99%）。即使根管的冠向预备达到极端（GG：92.02%），也没有显著影响。VM 分析证实了根尖处的应力分散，GG 模型的咬合面记录到最大的数值（7.88MPa），而 IT 模型的数值最小（7.01MPa）。分叉区域显示出更高的最大主应力，但随着模型的逐步扩大，应力值仍保持最小，并分布在更大的表面上。
在本研究的限制范围内，根管冠向敞开对牙齿完整性的影响很小，并且在加载条件处于正常功能范围内时，牙齿结构有能力在更大的表面区域分散增加的应力。
