A Alharbi Fahad, Nathanson Dan, Morgano Steven M, Baba Nadim Z
College of Dentistry, University of Dammam, Dammam, Saudi Arabia.
Dent Traumatol. 2014 Aug;30(4):317-25. doi: 10.1111/edt.12095. Epub 2014 Feb 7.
Fracture of restored endodontically treated teeth is a common complication. The mechanical properties of post systems may play a role in the incidence of tooth fracture.
The purpose of this study was to evaluate in vitro the fracture resistance and pattern of fracture of endodontically treated teeth restored with three different post systems.
Posts used were fiber-reinforced composite resin posts (FRC post), custom cast silver-palladium, and nickel-chromium posts and cores. A 3-point bending test was performed to calculate flexural strengths and elastic moduli of the specimens. Sixty extracted human maxillary canines were endodontically treated and divided into three groups (n = 20). All-ceramic crowns were fabricated and cemented with Variolink II resin cement. Ten specimens of each group were subjected to a constantly increasing load until fracture. The other 10 specimens were fatigued for 106 cycles in a custom-made fatigue machine. Recorded failure loads and modes were statistically compared with one-way anova and Tukey-HSD tests (α = 0.05).
The resistance to fracture of teeth restored with FRC posts, composite resin cores, and Empress II crowns was similar to that of teeth restored with cast posts and cores (P = 0.162). Supracrestal (above root/level of acrylic resin base) oblique fracture was the predominant mode of fracture associated with teeth restored with FRC posts (70%), while vertical root fractures were more common with teeth restored with cast posts and cores.
Teeth restored with the FRC post system did not exhibit vertical root fractures and were less likely to show root fracture. Sixty to 80% of teeth restored with both types of cast posts and cores showed vertical and subcrestal root fractures.
根管治疗后修复牙的折断是一种常见并发症。桩系统的力学性能可能在牙折发生率中起作用。
本研究的目的是在体外评估用三种不同桩系统修复的根管治疗牙的抗折性和折断模式。
使用的桩为纤维增强复合树脂桩（FRC桩）、定制铸造银钯桩以及镍铬桩核。进行三点弯曲试验以计算标本的弯曲强度和弹性模量。60颗拔除的人上颌尖牙进行根管治疗并分为三组（n = 20）。制作全瓷冠并用Variolink II树脂水门汀粘固。每组10个标本承受不断增加的载荷直至折断。另外10个标本在定制疲劳试验机中进行106次循环疲劳试验。记录的失效载荷和模式通过单因素方差分析和Tukey-HSD检验进行统计学比较（α = 0.05）。
用FRC桩、复合树脂核和Empress II冠修复的牙的抗折性与用铸造桩核修复的牙相似（P = 0.162）。龈上（牙根/丙烯酸树脂基台水平以上）斜折是与用FRC桩修复的牙相关的主要折断模式（70%），而垂直根折在用铸造桩核修复的牙中更常见。
用FRC桩系统修复的牙未表现出垂直根折，且根折可能性较小。用两种铸造桩核修复的牙中有60%至80%表现出垂直和龈下根折。
