三种方式修复严重缺损的上颌中切牙抗折性能研究

目的：比较三种方式修复严重缺损的上颌中切牙的抗折性能,探讨保存残根残冠更合理的修复方式。方法：36颗上颌中切牙随机分为3组,根管治疗后平齐唇侧釉牙本质界垂直与牙体长轴截冠。分别行铸造镍铬合金桩核、铸造镍铬合金桩树脂核及玻璃纤维桩树脂核＋金属全冠修复。在万能测试机进行力学测试,记录最大载荷和断裂模式。结果：3组的抗折强度分别为292.06±155.51N、439.89±89.55N和284.98±133.56N,铸造镍铬合金桩树脂核组明显高于另外2组,差异具有统计学意义。铸造镍铬合金桩均导致牙根垂直折裂,玻璃纤维桩10颗桩折,2颗桩折合并唇侧颈1/3折裂。结论：无箍作用时应充分利用树脂与牙体的粘结作用,高强度的铸造镍铬合金桩较玻璃纤维桩能更好地抵抗外力,结合高强度的树脂核强度更大。

Fracture resistance of severely compromised maxillary central incisors restored with three types of post-core

Objective： To compare the fracture resistance of severely compromised maxillary central incisors restored with three types of post-core. Methods： A total of 36 recently extracted maxillary central incisors were randomly distributed into 3 groups. In group A the teeth were restored with cast Ni-Cr post-core; in group B with Ni-Cr alloy dowel and composite core; and in group C with glass fiber-reinforced composite （FRC） post and composite core. The size and shape of posts were identical in the 3 groups. All teeth were fully covered with Ni-Cr alloy cast crown. Fracture resistance was measured by applying a point force at 130 degrees to the long axis of the teeth. Results： Mean fracture threshold was （292.06± 155.51） N in group A, （439.89± 89.55） N in group B and （284.98± 133.60） N in group C. In group A and B, tooth fracture occurred, whereas in group C, the post always failed first. Conclusion： The bonding of resin to dentin can increase the fracture resistance of severally compromised maxillary central incisors. Ni-Cr post combined with composite core has higher fracture threshold than FRC post with composite core and cast Ni-Cr post-core.