Abstract:

Objective This study aims to compare the incidence of dentinal microcracks produced by ProTaper Universal (PTU) and ProTaper Gold (PTG) file systems during root canal procedures in different curved canals using a dyeing technique. Methods Sixty extracted human molars were divided into 3 groups of 20 samples each in terms of root curvature (mild bending group, 10 °-19 °; moderate bending group, 20 °-29 °; severe bending group, 30 °-39 °). Ten samples of each group were then randomly allocated to the PTU and PTG file systems. After preparation, all roots were stained using a dyeing method and sectioned at the most curved plane and 2 mm below and above the most curved plane with a low-speed saw under cold water. A stereomicroscope was used to inspect dentinal microcracks at 60 × magnification, and differences between these three instrument groups were analyzed using the chi-square test. Results The PTG file system induced significantly fewer dentinal microcracks for total, incomplete and complete cracks (P < 0.05), and the effect was more obvious with increasing canal curvature. Conclusion With the limitations of this in vitro study, it can be concluded that ProTaper Gold can result in fewer dentinal microcracks than ProTaper Universal.

Key words: dentinal cracks, root canal procedure, ProTaper Gold, ProTaper Universal, curved root canal

摘要：

目的 本研究通过染色分析观察ProTaper Gold（PTG）与ProTaper Universal（PTU）预备不同弯曲程度根管所产生牙本质微裂之间的差异。方法 将收集的成人恒牙分为3组,分别为轻度弯曲组（10 °~19 °）,中度弯曲组（20 °~29 °）,重度弯曲组（30 °~39 °）,每组20颗;每组随机分为2亚组,每亚组10颗,分别使用PTG和PTU镍钛机械锉进行根管预备。预备后对所有根管进行染色,并使用慢速切割技术,在其最弯曲处、最弯曲处上和下2 mm进行切割并打磨抛光。所有样本使用体视显微镜放大60倍观察,记录样本牙本质微裂纹的程度和数目并进行统计学分析。结果 PTG预备弯曲根管所产生的牙本质微裂纹少于PTU预备根管所产生的牙本质微裂纹（P<0.05）,且在重度弯曲根管组更具优势。结论 与PTU相比,PTG在弯曲根管预备中产生较少的牙本质微裂纹。

关键词: 牙本质微裂, 根管预备, ProTaper Gold, ProTaper Universal, 弯曲根管