Objective: To evaluate the ability of different techniques on removal of smear layer in dental canal. Methods: Forty extracted single-rooted human teeth were randomly distributed into 4 groups. The teeth were prepared by ProTaper rotary instruments and subjected to different techniques for the removal of smear layer in dental canals. Hydrogen peroxide ( H2O2 ) and normal saline ( NS )were used in group A; 5.25％ sodium hypochlorite(NaClO) and ethylenediamine tetraacetis(EDTA) gel in group B; ulrasonics in group C; 5.25％ NaC10 and EDTA gel with ultrasonics in group D. Samples were examined under the scanning electron microscope and scored for smear layer removal and the erosion on the surface of the root canal walls. Results: The whole surfaces of root canals in group A were covered by smear layer. The smear layer of root canals in group B, C and D was removed. Statistical analysis showed that the removal effect in group B, C and D was significantly better than that in group A at coronal, middle and apical portions. There were not significant differences among group B, C and D. In group D the surface of root canal at coronal, middle portion was eroded. Conclusion: 5.25％ NaClO with EDTA gel, ultrasonics with 5.25％ NaClO, EDTA gel and ultrasonic can effectively remove the smear layer in root canal, but the dentin can be eroded by using 5.25％ NaClO with EDTA gel and ultrasonics.%目的:评价4种不同方法去除根管壁玷污层的能力.方法:将40颗离体牙随机分为4组进行根管预备,使用不同方法去除玷污层,分别为:A组H2O2和生理盐水,B组EDTA凝胶和5.25%的NaClO,C组超声波,D组超声波联合5.25%NaCIO+EDTA.将处理后的样本纵剖开,扫描电镜观察4组根管壁的界面,比较3个不同部位玷污层的去除情况、根管壁的清洁程度、牙本质小管的开放程度及腐蚀程度.结果:对照组(A组)根管壁被玷污层覆盖,实验组(B、C、D组)根管壁玷污层去除明显,B、C、D组与A组间冠1/3、中1/3、尖1/3玷污层评分差异有显著性(P<0.05);3个实验组间冠1/3、中t/3、尖1/3玷污层评分差异无显著性(P>0.05);D组冠1/3和中1/3可见到根管壁有不同程度的腐蚀.结论:NaClO与EDTA,超声波以及超声联合NaClO与EDTA均可有效地去除根管壁上的玷污层,但超声联合NaClO与EDTA能造成牙本质小管的腐蚀.
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