Abstract:

Objective    To evaluate the effects of the root filling methods on the amount of dentin removed during the post space preparation and push-out bond strength of a fiber post. Methods    Totally 10 pairs of first mandibular premolars，each was from the same patient，were collected and divided into 2 groups randomly： group A were endodontically treated with the apical third of the root canal filled and group B with the full length of the root canals filled．Both groups were prepared for a fibre post restoration，and the volumn of the root canals were measured before and after the preparation．After the bonding of the fibre post，two 2-mm-thick slices were obtained from each root sample and bond strength was measured using a push-out test setup．The data were analyzed using a one-tail paired samples t-test，with P = 0.05. Results    Statistical analysis demonstrated that the root canals volume increased of group A was （6.1 ± 1.5） μL，which was significantly less than group B（7.7 ± 1.9） μL（P = 0.012）．The bond strength of the fibre post in the cervical and middle third of the root canal was （11.8 ± 2.0）MPa and（11.7 ± 2.0） MPa in group A，and in group B（11.1 ± 2.1） MPa，（10.5 ± 1.4） MPa，with the average differences at （0.7 ± 0.4） MPa and （1.2 ± 1.4） MPa，respectively．Paired samples t-test demonstrated that there were significant differences between the two groups both in the cervical and the middle third of the root canal（P < 0.05），but no significant differences between the cervical and middle third，whether in group A or B（P > 0.05）. Conclusion    Filling the apical third of the root canal only before post space preparation can significantly reduce the amount of dentin removed and increase the bond strength of the fibre post．

Key words: root canal filling, fibre post, post space preparation, bond strength

摘要：

目的    研究不同根充方式对桩道预备的牙体组织切削量及粘接强度的影响。方法    选取同一个体成对拔除的下颌第一前磨牙20颗，常规根管预备后随机分为两组，实验组仅根充根尖1/3，对照组热牙胶垂直加压充填整段根管。两组样品分别进行纤维桩桩道预备，测量预备前后根管容积变化。按临床操作要求，纤维桩粘接后，截取根颈部及根中部各2 mm切片行推出实验测定粘接强度。测量结果使用配对t检验分析组间差异。结果           实验组样品根管容积增加（6.1 ± 1.5）μL，显著低于对照组的变化（7.7 ± 1.9）μL（P = 0.012）。实验组样品在根颈部及根中部粘接强度分别为（11.8 ± 2.0）MPa和（11.7 ± 2.0）MPa，对照组样品在根颈部及根中部粘接强度分别为（11.1 ± 2.1）MPa和（10.5 ± 1.4）MPa，两组样品的粘接强度差值分别为（0.7 ± 0.4）MPa和（1.2 ± 1.4）MPa。配对t检验表明，在根颈部和根中部，实验组和对照组样品粘接强度差异均具有统计学意义（P < 0.05）；实验组或对照组样品中，根颈部与根中部粘接强度差异均无统计学意义（P > 0.05）。结论    与常规热牙胶垂直加压充填整段根管后桩核修复比较，根充根尖1/3后直接纤维桩核修复可减少牙体组织切削量，增加纤维桩粘接强度。

关键词: 根管充填, 纤维桩, 桩道预备, 粘接强度