锉尖设计对镍钛机动器械根管成形效果的影响

 目的]比较切割型锉尖Quantec SC和非切割型锉尖Quantee LX两种镍钛机动器械预备弯曲根管的成形效果。方法]12颗离体下颌第一、二磨牙近中弯曲根管24个，随机分为2组，分别用Quantec SC和Quantec LX器械完成根管预备。牙根包埋在Branmante模型中并在根尖、根中和根分叉水平截断，对预备前后的根管横截面形态进行数字化处理。比较各组间的牙本质切削面积、根管壁最小厚度和根管中心偏移量，并记录偏移方向。结果]两组器械牙本质切削面积无统计学差异（P〉0．05），减少根管壁厚度的方式相似。在3个水平上，Quantec SC产生的根管中心偏移量均较Quantec LX多，但两组间差异无统计学意义（P〉0．05）。根尖区大部分根管中心移向近中；根中段大部分的根管中心移至根分叉侧，少部分移向近中。结论]不同锉尖设计的两种镍钛机动器械Quantec SC和Quantec LX预备弯曲根管的成形效果相似。

Effect of Tip Design of Ni-Ti Rotary Instruments on Their Performance in Curved Root Canals

Objective] To compare the shaping ability of two nickel-titanium rotary instruments with same body but different tip design, ad modem Quantec SC and Quantec LX, for preparing curved root canals. Methods]Twenty-four curved canals in the mesial roots of 12 extracted human mandibular first and second molars were randomly assigned to two groups. The teeth were embedded in the Branmante models and their roots were sectioned horizontally at the apical, mid-root and furcation levels respectively. Instrumentation was carried out following the manufacturer's instructions. The pre- and post-operative canal shapes of each section were digitized. Three measurements were made: least remaining dentine thickness of canal wall on both the mesial and furcal aspects, area of dentine removed, and transportation of canal centers. Results] The two groups showed a similar pattern in the reduction of canal wall thickness after instrumentation. The amount of dentine removed by the two instruments was not significantly different. At each level, Quantec SC tended to produce more pronounced transportation of canal centre than Quantec LX, although a statistically significant difference was not detected. A majority of the canal centers were moved towards the mesial aspect at the apical level in both groups. In the mid-root sections, over half of the canal centers were transported towards the furcal aspect and a minority moved mesially. Conclusion] Quantec SC and LX instruments exhibited similar shaping ability for preparing curved root canals in spite of the difference in tip design.