PhD student, Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, UNESP, São José dos Campos, SP, Brazil.
Assistant Professor, Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University, UNESP, São José dos Campos, SP, Brazil.
J Prosthet Dent. 2023 Mar;129(3):456-463. doi: 10.1016/j.prosdent.2021.05.020. Epub 2021 Jul 5.
Various strategies have been proposed to reduce the cement space of foundation restorations for endodontically treated teeth. However, they may add more operative steps, or the dentist must keep different sizes of drills and posts in stock. A 2-piece universal adjustable post system has been developed to overcome this problem, but whether the system has acceptable fatigue survival performance is unclear.
The purpose of this in vitro study was to evaluate the fatigue survival and stress distribution of endodontically treated teeth without a ferrule and restored with different glass fiber post strategies versus a recently introduced universal 2-piece fiber post system.
Bovine incisor roots were randomly assigned to 3 groups as per the post used (n=13): adapted glass fiber post with post space preparation of the same size, composite resin-custom glass fiber post (CTM), and universal 2-piece glass fiber-reinforced composite resin post (UNI). The posts were adhesively luted, the composite resin core was added, and a composite resin crown was produced with computer-aided design and computer-aided manufacturing (CAD-CAM), and then adhesively luted to each core. A fatigue test was performed with the stepwise stress method (10 000 cycles/step; 20 Hz; load=100 N to 750 N; step=50 N) until fracture, and the failure mode analyzed. The stress distribution was evaluated by finite element analysis with the maximum principal stress criteria by following the parameters of the in vitro test. The solids were considered homogeneous, linear, and isotropic, except for the glass fiber post (orthotropic), and a load of 450 N at 30 degrees was applied. The fatigue failure load and the number of cycles for failure were analyzed with Kaplan-Meier and Mantel-Cox (log rank test) (α=.05). The finite element analysis results were analyzed with colorimetric graphs.
The highest fatigue failure load and the number of cycles for failure were found in the UNI system, whereas the lowest results were found in the CTM group. All groups exhibited repairable failures. The finite element analysis showed the lowest stress in root dentin in the UNI system. The CTM system had the largest stress regions at the dentin and dentin-core interface.
The use of a 2-piece universal glass fiber post system resulted in more fatigue behavior compared with composite resin-custom glass fiber posts.
为了减少根管治疗牙的基牙修复的水泥空间，已经提出了各种策略。然而，这些策略可能会增加更多的操作步骤，或者牙医必须储备不同尺寸的钻头和桩。一种 2 部分通用可调桩系统已经被开发出来以克服这个问题，但该系统的疲劳生存性能是否可接受尚不清楚。
本体外研究的目的是评估无金属环并且使用不同玻璃纤维桩策略修复的根管治疗牙的疲劳生存和应力分布与最近引入的通用 2 部分纤维桩系统相比。
根据使用的桩将牛切牙牙根随机分为 3 组（n=13）：同大小桩腔预备的改良玻璃纤维桩、复合树脂-定制玻璃纤维桩（CTM）和通用 2 部分玻璃纤维增强复合树脂桩（UNI）。将桩黏固，添加复合树脂核，通过计算机辅助设计和计算机辅助制造（CAD-CAM）制作复合树脂冠，并黏固到每个核上。用逐步应力法（10000 个循环/步；20 Hz；负载=100 N 至 750 N；步长=50 N）进行疲劳试验，直到断裂，并分析失效模式。用有限元分析通过最大主应力标准评估应力分布，根据体外试验的参数。除玻璃纤维桩（各向异性）外，固体被认为是均质的、线性的和各向同性的，施加 450 N 的 30 度负载。用 Kaplan-Meier 和 Mantel-Cox（对数秩检验）（α=.05）分析疲劳失效负载和失效循环数。用比色图谱分析有限元分析结果。
UNI 系统的疲劳失效负载和失效循环数最高，而 CTM 组的结果最低。所有组均表现为可修复性失效。有限元分析显示 UNI 系统根牙本质的应力最低。CTM 系统在牙本质和牙本质-核界面处有最大的应力区域。
与复合树脂定制玻璃纤维桩相比，使用 2 部分通用玻璃纤维桩系统会导致更多的疲劳行为。
