前磨牙根管治疗后牙体抗折强度的实验研究

目的研究前磨牙根管治疗后不同洞型、不同材料充填后牙体抗折强度的改变。方法选用因正畸拔除的无龋、无损伤、完整的前磨牙，左右同名牙配对，共48对，分为6组。每对配对牙中，一个做试验，另一个完整牙做对照。实验牙根管治疗后分别制备MO／DO洞，MOD洞，O洞，再分别用银汞、光固化复合树脂充填。置于万能实验机上测试每对牙的最大载荷。用t检验比较各实验组与对照组的抗折强度的差别。结果银汞充填MO／DO洞的抗折强度明显低于对照牙（P〈0．01）。光固化复合树脂充填各类洞的抗折强度与对照牙无显著性差别（P〉0．05）。结论根管治疗后用光固化树脂充填前磨牙的各类洞，牙体的抗折强度优于用银汞充填者。

The resistance to fracture of premolar after endodontical treatment: A study in vitro

Objective To compare the fracture resistance of premolar with various restorative materialas and the cavity types. Methods Fourty eight pairs of maxillary and mandibullar premolars were selected which extracted from orthodontic. The teeth were non - carious and intact and were randomly divided into six groups. One of each pair was an experiment ,the other was used as the control . After root canal treatment, the six groups were prepared MO/DO, MOD, O cavity and filled with amalgam, composite resin separately. Then the samples were tested with Universal Testing Machine. T tests was used to compare the results. Results The MO/DO cavity group filled with amalgam had lower fracture resistance than that of the control group. And no significance was found in the other groups. Conclusion The fracture strength of premolar teeth filled with light curing composite resin was higher than filled with amalgam after root canal therapy.