Private Practice, St Louis, Missouri.
Department of Prosthodontic Sciences, College of Dentistry in Ar Rass, Qassim Univesity, Al Qassim, Saudi Arabia.
J Endod. 2021 Jun;47(6):932-938. doi: 10.1016/j.joen.2021.03.008. Epub 2021 Mar 25.
This study compared the residual tooth strength and stress distribution of a mandibular molar prepared with different variable tapered file systems using finite element analysis (FEA).
Two preaccessed mandibular molar TruTeeth (Endo 3DP; Acadental, Lenexa, KS) were subjected to simulated endodontic treatment in this study. One tooth was instrumented with ProTaper Gold (Dentsply Tulsa Dental Specialties, Tulsa, OK), and the other was instrumented with V-Taper 2H (SS White Dental, Lakewood, NJ). The 2 teeth were scanned using micro-computed tomographic imaging, and stereolithographic surface meshes were developed for FEA. Each model was subjected to a 200-N multipoint load-simulating mastication. The results of the FEA provided quantitative and qualitative measurements for von Mises stress distribution and total deformation.
The maximum von Mises stress was greater in the ProTaper Gold-prepared model than the V-Taper 2H prepared model. In both models, total deformation values were highest in the clinical crown on the buccal aspect of the tooth. The highest stress values were found in the pericervical dentin, and stress decreased apically through the root.
Within the limitations of this study, it can be concluded that the maximum stress values within the tooth prepared by ProTaper Gold were higher than those in the tooth prepared by V-Taper 2H. Canal preparation with the V-Taper 2H system preserves more pericervical dentin, which may increase the resistance to fracture.
本研究通过有限元分析（FEA）比较了使用不同变锥度锉系统预备下颌磨牙后的剩余牙体强度和应力分布。
本研究对 2 颗经过预处理的下颌磨牙 TruTeeth（Endo 3DP；Acadental，Lenexa，KS）进行了模拟根管治疗。其中 1 颗牙用 ProTaper Gold（Dentsply Tulsa Dental Specialties，Tulsa，OK）进行预备，另 1 颗牙用 V-Taper 2H（SS White Dental，Lakewood，NJ）进行预备。用微计算机断层扫描对 2 颗牙进行扫描，并为 FEA 开发了立体光刻表面网格。每个模型都受到 200-N 多点模拟咀嚼的作用。FEA 的结果提供了用于 von Mises 应力分布和总变形的定量和定性测量。
ProTaper Gold 预备模型的最大 von Mises 应力大于 V-Taper 2H 预备模型。在这两种模型中，牙体的临床冠在颊侧的总变形值最高。最高的应力值出现在近中牙本质，并且随着根尖方向的延伸，应力逐渐降低。
在本研究的限制范围内，可以得出结论，ProTaper Gold 预备的牙内的最大应力值高于 V-Taper 2H 预备的牙内的最大应力值。使用 V-Taper 2H 系统进行根管预备可以保留更多的近中牙本质，这可能会增加抗折能力。
