两种桩系统修复对根管治疗牙强度的影响

Fracture resistance of endodontically treated teeth restored with two different post systems

目的比较两种不同弹性模量的桩系统对根管治疗牙修复后强度的影响。方法20颗近期拔除的完整人上颌中切牙,根管治疗后随机分成两组,每组10颗。组一进行玻璃纤维桩ParaPost Fiber white(Coltene/ whaledent Inc)、复合树脂核及铸造全冠修复。组二进行铸造镍铬桩核及铸造全冠修复。每组牙均保留1.5mm的牙本质肩领(Ferrule)。实验标本包埋于自凝树脂块中,固定在DCS5000材料试验机上。加栽头以1mm/min的速度,与牙长轴成130°进行加载直至标本断裂。断裂强度采用独立样本t检验,断裂方式采用Fisher’s精确概率法(P <0.05)。结果组一断裂强度为43.406±18.959kg,组二33.680±9.675kg,差异无显著性(P>0.05)。可修复性断裂方式见于玻璃纤维桩核,而不可修复性的破坏多见于铸造镍铬桩核组(P<0.001)。结论在牙体预备保留1.5mm牙本质肩领(Ferrule)的情况下,两种不同弹性模量的桩对根管治疗牙桩核加全冠修复后的强度影响无差异,可修复性的破坏见于弹性模量与牙本质近似的玻璃纤维桩组。

Objective To compare the fracture resistance of endodontically treated teeth restored with two post systems, comparing different moduli of elasticity. Methods Twenty recently extracted human maxillary central incisors were endodontically treated and randomly divided into two groups of ten each. Teeth in group-1 received glass fiber posts (ParaPost Fiber White (Coltene/ Whaledent Inc), composite resin cores, and full crown casts. Teeth in group - 2 received cast Ni-Cr posts and cores and full crown casts. About 1. 5mm ferrule was prepared for each of the teeth. Each specimen was embedded in acrylic resin and secured in a universal material testing machine. A compressive load was applied on the lingual surface at a 130 - degree angle to the long axis of the tooth until fracture occurred, at a crosshead speed of 1mm/min) . Independent sample t-test were used to determine the significance of the fracture loads between the two groups ( P < 0.05). Fisher's exact test was conducted for evaluation of the mode of failure ( P < 0.05). Results The fracture loads were 43.406±18.959kg and 33.680±9.675kg for groups-1 and groups- 1, respectively. There was no statistically significant difference between the two groups ( P < 0.05). Repairable fractures were observed in group - 1; whereas un - repairable fractures were observed in group - 2 ( P < 0. 001) . Conclusion When a 1. 5 mm ferrule was preserved, two post systems with different modules of elasticity had no significant influence on the fracture resistance of endodontically treated teeth restored with full crowns. Repairable fractures were observed in teeth restored with glass fiber posts, which had similar modulus of elasticity to that of dentin.