Department of Fixed Prosthodontics, University of Tanta Faculty of dentistry, Tanta.
Department of Dental Materials, University of Alexandria Faculty of dentistry, Alexandria.
J Prosthodont Res. 2021 Feb 24;65(1):78-85. doi: 10.2186/jpr.JPOR_2019_485. Epub 2020 Sep 9.
This in vitro study aimed to evaluate the influence of fatigue loading on fracture resistance of endodontically treated molars restored with endocrowns using different machinable blocks.
Endodontically treated mandibular first molars were prepared using a standardized method. Specimens were divided into 4 groups (n = 10).Anatomically shaped endocrowns groups were manufactured using VITA ENAMIC (VE) and KATANA Zirconia (KZ). Layered endocrowns groups were manufactured using IPS e.max CAD (EM) and BioHPP (BH). Half of the specimens of each group were subjected to fracture resistance test, while the other half were subjected to thermocycling and chewing simulation. After fatigue loading, specimens were loaded until failure. Specimens were examined using stereomicroscopy. Data were analyzed using ANOVA analysis of variance and Bonferroni post hoc test (α=0.05).
KZ group had the highest initial fracture resistance value (1810.20± 119.56 N) and BH had the lowest value (579.50± 76.15 N). The reduction of fracture resistance after fatigue loading was significant for KZ group (1588.30±216.25 N) and BH group (502.60±11.53 N) and non-significant to VE group (1101.70±77.05 N) and EM group (1112.10±74.12 N). Failure modes of KZ and EM groups showed high percentage of non-restorable fractures, while VE and BH groups showed high percentage of restorable fractures.
Within the limitations of this study, the following can be concluded: Poly infiltrated ceramics should be considered as a proper material to be used as an endocrown material because of its ability to be restorable if failure occurred.
本体外研究旨在评估疲劳加载对使用不同可加工块修复的根管治疗后磨牙的根管内全冠抗折性能的影响。
采用标准化方法预备下颌第一磨牙根管治疗后的牙体。将样本分为 4 组（n = 10）。使用 VITA ENAMIC（VE）和 KATANA Zirconia（KZ）制造解剖形态的根管内全冠；使用 IPS e.max CAD（EM）和 BioHPP（BH）制造分层根管内全冠。每组的一半样本进行抗折强度测试，另一半样本进行冷热循环和咀嚼模拟。疲劳加载后，将样本加载至破坏。使用立体显微镜检查样本。使用方差分析和 Bonferroni 事后检验（α=0.05）对数据进行分析。
KZ 组的初始抗折强度值最高（1810.20±119.56 N），BH 组的最低（579.50±76.15 N）。KZ 组（1588.30±216.25 N）和 BH 组（502.60±11.53 N）的抗折强度在疲劳加载后的降低有显著差异，VE 组（1101.70±77.05 N）和 EM 组（1112.10±74.12 N）无显著差异。KZ 和 EM 组的失效模式显示高比例的不可修复性骨折，而 VE 和 BH 组显示高比例的可修复性骨折。
在本研究的限制范围内，可以得出以下结论：聚渗透陶瓷因其具有可修复性，如果发生失效，应考虑作为根管内全冠材料的合适材料。
