Delgaudio Pignataro Rossana Reim, Samico Renata De Paula, Mendes Campaner Larissa, Bottino Marco Antonio, Borges Alexandre, Tribst João Paulo
Department of Dental Materials and Prosthodontics, Institute of Science and Technology, Unesp, São José dos Campos/SP, Brazil.
Eur Endod J. 2021 Apr 13;6(2):170-6. doi: 10.14744/eej.2020.95967.
There are no reports in the literature on whether FGP geometry influences the bond strength of the endodontically restored tooth. This study aimed to determine the stress distribution and the pull-out bond strength of different FGP geometries, before and after chewing loads simulation.
One hundred and twenty root analogues were prepared and randomly distributed in six groups according to the post geometry. Half of the specimens were aged in water at 37 °C using a mechanical fatigue machine (84 N, 2 bar, 45°, 106 cycles, 4 Hz); while the remaining specimens were immediately submitted to the pull-out bond strength test. The specimens were tested in a universal testing machine and the bond strength in MPa was calculated. To assess the stress concentration, the finite element method was used simulating the same post geometries that were used in the in vitro test.
Two-way ANOVA (95%) showed no influence of post geometry on the bond strength (P=0.055) while fatigue cycling was statistical significant to reduce the bond strength values (P=0.000). The factors interaction was significant (P=0.019); however, TUKEY test (5%) showed no significant difference between post geometries after mechanical cycling. The tensile stress result showed critical areas in the post's cervical region regardless of the design.
The FGP geometry does not affect the root stress distribution and the long-term bond strength. However, FGP that allow a reduced cement layer thickness can improve the immediate pull-out bond strength value.
文献中尚无关于纤维桩几何形状是否会影响根管治疗后修复牙的粘结强度的报道。本研究旨在确定在模拟咀嚼负荷前后，不同纤维桩几何形状的应力分布和拔出粘结强度。
制备120个牙根模拟体，并根据桩的几何形状随机分为六组。一半的标本使用机械疲劳试验机在37°C的水中老化（84 N，2 bar，45°，106个循环，4 Hz）；而其余标本立即进行拔出粘结强度测试。在万能试验机上对标本进行测试，并计算出以MPa为单位的粘结强度。为了评估应力集中，使用有限元方法模拟了体外测试中使用的相同桩几何形状。
双向方差分析（95%）显示桩的几何形状对粘结强度没有影响（P = 0.055），而疲劳循环对降低粘结强度值具有统计学意义（P = 0.000）。因素交互作用显著（P = 0.019）；然而，TUKEY检验（5%）显示机械循环后不同桩几何形状之间没有显著差异。拉伸应力结果显示，无论设计如何，桩的颈部区域都存在关键区域。
纤维桩的几何形状不会影响牙根应力分布和长期粘结强度。然而，允许减小粘结剂层厚度的纤维桩可以提高即时拔出粘结强度值。
