Hou Rui, Chen Xinming, Wu Junhua, Chang Huijun
Department of Prosthodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
Sichuan Da Xue Xue Bao Yi Xue Ban. 2003 Jul;34(3):510-2, 558.
To assess the effect of rehabilitation of flared root canal on the fracture resistance of root and post-core system.
Thirty-two simulated tooth roots made of polymethyl methacrylate were divided into 4 groups, including the normal root canal group and 3 flared root canal groups. One flared root canal group was rehabilitated by light-cared composite, another group was rehabilitated by amalgam, and the third flared root conal group was not treated. Casting post and core restored every simulated tooth root. Each specimen was embedded in acrylic resin and then fixed in a special jig on the universal load-testing machine. A compressive load was applied at a 90-degree angle to the long axis of the core until fracture, at a crosshead speed of 1 mm/min; the maximum of load was recorded.
The means of load in normal root canal group, light-cared composite rehabilitated group, amalgam rehabilitated group, not treated group were 202.92 N, 194.60 N, 146.89 N, 142.09 N. It was shown that the load of normal root canal group is significantly greater than the load of not-treated group (P < 0.01); the light-cared composite rehabilitated group is significantly stronger than the not-treated group (P < 0.01), but there is no significant difference between the light-cared composite rehabilitated group and normal root canal group, and no significant difference between the amalgam rehabilitated group and not-treated group (P > 0.05).
The rehabilitation of flared root canal using suitable material not only changes the shape of root canal, but also increases the fracture resistance of root canal because of its thicker and stronger root canal wall which obviously improves the fracture resistance of post and core.
评估根管扩口修复对牙根及桩核系统抗折性能的影响。
将32个由聚甲基丙烯酸甲酯制成的模拟牙根分为4组，包括正常根管组和3个根管扩口组。一个根管扩口组用光固化复合树脂修复，另一组用汞合金修复，第三组根管扩口组不做处理。每个模拟牙根均采用铸造桩核进行修复。将每个标本嵌入丙烯酸树脂中，然后固定在万能试验机的专用夹具上。以1 mm/min的十字头速度，在与桩核长轴呈90度角的方向施加压缩载荷，直至断裂；记录最大载荷。
正常根管组、光固化复合树脂修复组、汞合金修复组、未处理组的载荷均值分别为202.92 N、194.60 N、146.89 N、142.09 N。结果显示，正常根管组的载荷显著大于未处理组（P < 0.01）；光固化复合树脂修复组显著强于未处理组（P < 0.01），但光固化复合树脂修复组与正常根管组之间无显著差异，汞合金修复组与未处理组之间也无显著差异（P > 0.05）。
使用合适的材料修复根管扩口不仅改变了根管形态，还因其根管壁更厚更强而提高了根管的抗折性能，明显改善了桩核的抗折性能。
