不同牙体预备时机对纤维桩粘结强度的影响

Effect of different timing of coronal preparation on bond strength of fiber post

目的:研究不同牙体预备时机对纤维桩粘结强度的影响,为临床纤维桩粘结后何时进行牙体预备提供理论依据。方法:收集新鲜下颌单根前磨牙35颗,截冠,完善根管治疗并进行桩道预备,使用ParaPostRParaCoreTM双固化桩核-复合树脂水门汀粘结玻璃纤维桩(Tenax fiber white)并形成桩核。将形成桩核后的35颗下颌单根前磨牙随机分为5组,其中4组在粘结结束后分别即刻、15、30 min、24 h时间点进行牙体预备,余下1组为空白组,不进行牙体预备。室温下贮存24 h后,将所有5组下颌单根前磨牙的牙根部切割为1 mm厚的试件,按照根管的深度分为上部、中部和下部,测试纤维桩推出强度。最后在光学显微镜下观察每组试件纤维桩的断裂方式。结果:纤维桩粘结后不同时机进行牙体预备,其粘结强度差异有统计学意义。粘结后即刻、15、30 min组与空白组比较差异有统计学意义(P<0.05),随牙体预备时机延后,牙体预备对纤维桩的粘结强度影响逐渐减小,24 h组与空白组比较差异无统计学意义(P>0.05)。同一组内不同粘结部位进行比较,显示根管冠1/3部的粘结强度显著高于根尖1/3(P<0.05)。结论:为了获得最大的粘结强度,应尽量在纤维桩粘结结束后24 h后进行牙体预备,尤其要注意根冠1/3处的粘结质量。

Objective：To evaluate the effect of different timing of coronal preparation on the bond strength of fiber post after cementation and provide theoretical basis for clinical practice.Methods： A total of thirty-five freshly extracted mandibular premolars with single-root canal were collected,sectioned and endodontically treated.Following post space preparation,high-strength glass fiber posts（tenax fiber white）were luted by dual-curing core and resin cement（ParaPostR ParaCoreTM） and the cores were formed.Then the roots were divided into five groups randomly（n=7） and the tooth preparation was performed immediately,and at the 15th min,30th min and 24th hours after splicing in four groups respectively.The other group without tooth preparation served as control.Twenty-four hours later,the roots with cemented posts were sectioned into slices with 1mm thickness and the slices were classified as coronal,middle and apical section.The push-out strength was tested and the fiber post fracture modes were observed under an optical microscope.Results： The push-out strength of fiber posts significantly increased as the time to prepare increased.The push-out strength in the 24th h group was significantly higher than in the other three prepared groups（P0.05）,and not significantly higher than in the control group（P0.05）.In the same tooth,the push-out strength at crown 1/3 was significantly higher than that of the apical 1/3（P0.05）.Conclusion：In order to obtain better retention,it is suggested to perform tooth preparation 24 hours after cementation,and pay more attention to crown 1/3.