Newman Marcela P, Yaman Peter, Dennison Joseph, Rafter Mary, Billy Edward
School of Dentistry, University of Michigan, Ann Arbor, Mich 48109, USA.
J Prosthet Dent. 2003 Apr;89(4):360-7. doi: 10.1067/mpr.2003.75.
The most recent application of fiber-reinforced composites involves their use as post and core systems to restore endodontically treated teeth. Even though this last application has been advertised and used clinically by many dentists, there is very little information regarding the physical properties of these post systems.
The purpose of this study was to compare the effect of 3 fiber-reinforced composite post systems on the fracture resistance and mode of failure of endodontically treated teeth.
Ninety maxillary central incisors were divided into 8 experimental groups and 1 stainless steel (ParaPost) control group of 10 specimens each. Eighty teeth were assigned to 2 main experimental groups called "narrow" and "flared" canals. For the narrow canal group, post spaces were prepared with the corresponding reamer to restore the teeth with FibreKor, Luscent anchors, and Ribbond posts of 1.5 mm, 1.6 mm, and 2.0 mm in diameter, respectively. For the flared canals group thin-walled canals were simulated. Teeth for the flared canals were restored with the same posts but were cemented into tapered 2 mm wide canals created with a tapered diamond bur. Prefabricated posts (FibreKor and Luscent anchors) for narrow and flared canals were cemented with an autopolymerized resin cement and a flowable composite, respectively, whereas customized Ribbond posts were luted with a light-polymerized flowable composite for both canal types. An additional set of 20 Ribbond posts with coronal portions of variable size and shape referred to as "Ribbond nonstandardized" were also prepared and evaluated. Specimens were loaded to failure (kg) with a universal testing machine at a crosshead speed of 0.05 cm/min until failure occurred. Data were analyzed with analysis of variance and Student t tests (P<.05).
Statistical analysis revealed no significant difference between flared and narrow canals in mean load to failure between the post systems except for the Ribbond posts (P<.01). For the narrow canal, the mean load ranged from a low of 4.55 (+/-1.49) kg for the Ribbond standard to a high of 12.9 (+/-1.64) kg for the Luscent anchors. For the flared canal the low mean was 9.04 (+/-1.76) kg for FibreKor and the high was equal for both Luscent anchors and Ribbond standard, 12.87 (+/-2.69) and 12.87 (+/-3.54), respectively. Overall, the ParaPost control group had the highest load value (18.33 +/- 3.27 kg) (P<.05). Ribbond nonstandardized had a mean load to failure of 24.91 (+/-11.53) Kg for the narrow canal group and 31.95 (+/-11.98) kg for the flared canal. Results from these groups were excluded from the statistical analysis because of the uncontrolled core sizes and high standard deviations. No root fractures occurred in any of the experimental groups.
Results from the study show that the load to failure of the stainless steel posts were significantly stronger than all the composite posts studied. However, the mode of failure or deflection of the fiber-reinforced composite posts is protective to the remaining tooth structure.
纤维增强复合材料的最新应用是将其用作桩核系统来修复经牙髓治疗的牙齿。尽管这种最新应用已被许多牙医在临床上宣传和使用，但关于这些桩系统物理性能的信息却非常少。
本研究的目的是比较3种纤维增强复合桩系统对经牙髓治疗牙齿的抗折性和失效模式的影响。
将90颗上颌中切牙分为8个实验组和1个不锈钢（ParaPost）对照组，每组10个样本。80颗牙齿被分配到2个主要实验组，称为“窄”根管组和“喇叭口状”根管组。对于窄根管组，用相应的扩孔钻制备桩道，分别用直径为1.5 mm、1.6 mm和2.0 mm的FibreKor、Luscent anchors和Ribbond桩修复牙齿。对于喇叭口状根管组，模拟薄壁根管。用相同的桩修复喇叭口状根管的牙齿，但用锥形金刚砂车针制备的2 mm宽的锥形根管将其粘固。窄根管和喇叭口状根管的预制桩（FibreKor和Luscent anchors）分别用自凝树脂粘固剂和流动复合树脂粘固，而定制的Ribbond桩则用光固化流动复合树脂为两种根管类型粘固。还制备并评估了另外一组20个冠部尺寸和形状可变的Ribbond桩，称为“Ribbond非标准化桩”。用万能试验机以0.05 cm/min的十字头速度对样本加载直至失效（kg）。数据采用方差分析和Student t检验进行分析（P<0.05）。
统计分析显示，除Ribbond桩外（P<0.01），桩系统之间喇叭口状根管和窄根管的平均失效载荷无显著差异。对于窄根管，平均载荷范围从Ribbond标准桩的低至4.55（±1.49）kg到Luscent anchors桩的高至12.9（±1.64）kg。对于喇叭口状根管，FibreKor桩的低平均载荷为9.04（±1.76）kg，Luscent anchors桩和Ribbond标准桩的高平均载荷相等，分别为12.87（±2.69）kg和12.87（±3.54）kg。总体而言，ParaPost对照组的载荷值最高（18.33±3.27 kg）（P<0.05）。窄根管组Ribbond非标准化桩的平均失效载荷为24.91（±11.53）kg，喇叭口状根管组为31.95（±11.98）kg。由于核心尺寸不受控制且标准差较高，这些组的结果被排除在统计分析之外。所有实验组均未发生牙根折断。
研究结果表明，不锈钢桩的失效载荷明显强于所有研究的复合桩。然而，纤维增强复合桩的失效模式或挠度对剩余牙体结构具有保护作用。
