Department of Endodontics, Faculty of Dentistry, The British University in Egypt, Misr-Ismalia Road, El Sherouk City, Cairo, 11837, Egypt.
Department of Endodontics, Ain Shams University, Cairo, Egypt.
Odontology. 2024 Jan;112(1):279-286. doi: 10.1007/s10266-023-00829-6. Epub 2023 Jul 2.
To evaluate the influence of the loss of coronal and radicular tooth structure on the biomechanical behavior and fatigue life of an endodontically treated maxillary premolar with confluent root canals using finite element analysis (FEA). An extracted maxillary second premolar was scanned to produce intact (IT) 3D model. Models were designed with an occlusal conservative access cavity (CAC) with different coronal defects; mesial defect (MO CAC), occlusal, mesial and distal defect (MOD CAC), and 2 different root canal preparations (30/.04, and 40/.04) producing 6 experimental models. FEA was used to study each model. A simulation of cycling loading of 50N was applied occlusally to stimulate the normal masticatory force. Number of cycles till failure (NCF) was used to compare strength of different models and stress distribution patterns via von Mises (vM) and maximum principal stress (MPS). The IT model survived 1.5 × 10 cycles before failure, the CAC-30.04 had the longest survival of 1.59 × 10, while the MOD CAC-40.04 had the shortest survival of 8.35 × 10 cycles till failure. vM stress analysis showed that stress magnitudes were impacted by the progressive loss of coronal tooth structure rather than the radicular structure. MPS analysis showed that significant loss of coronal tooth structure translates into more tensile stresses. Given the limited size of maxillary premolars, marginal ridges have a critical role in the biomechanical behavior of the tooth. Access cavity preparation has a much bigger impact than radicular preparation on their strength and life span.
为了使用有限元分析（FEA）评估融合根管上颌前磨牙牙冠和根部分结构丧失对生物力学行为和疲劳寿命的影响。扫描提取的上颌第二前磨牙以生成完整（IT）3D 模型。设计了具有不同冠部缺损的牙合面保存性入口腔（CAC）模型；近中缺损（MO CAC）、牙合面、近中和远中缺损（MOD CAC）以及 2 种不同的根管预备（30/.04 和 40/.04），共产生 6 个实验模型。使用 FEA 研究每个模型。在牙合面上施加 50N 的循环加载模拟以刺激正常咀嚼力。使用失效前的循环次数（NCF）来比较不同模型的强度和通过 von Mises（vM）和最大主应力（MPS）分布的应力模式。IT 模型在失效前幸存了 1.5×10 次循环，CAC-30.04 的生存时间最长，为 1.59×10，而 MOD CAC-40.04 的生存时间最短，为 8.35×10 次循环。vM 应力分析表明，牙冠结构的逐渐丧失而不是根管结构会影响应力大小。MPS 分析表明，牙冠结构的显著丧失会转化为更多的拉伸应力。鉴于上颌前磨牙的有限尺寸，边缘嵴在牙齿的生物力学行为中起着关键作用。与根管预备相比，入口腔预备对其强度和寿命的影响更大。
