Yang G B, Zhou X D, Zhang H, Wu H K
Key Laboratory of Oral Biomedical Engineering of Ministry of Education, Sichuan University, Chengdu, China.
Int Endod J. 2006 Oct;39(10):791-9. doi: 10.1111/j.1365-2591.2006.01151.x.
To compare the shaping ability of progressive versus constant taper shaft designed instruments in simulated root canals.
Simulated L- and S-shaped resin canals were prepared by ProTaper (progressive taper) and high elasticity in rotation 642 (Hero 642) (constant taper) instruments (n = 10 canals in each case). The pre- and post-instrumentation images were recorded and assessment of the canal shape was completed with image pro plus 5.0. The width of resin removed was measured at 9 measuring points. Incidence of canal aberrations, instrument fracture, preparation time and change of working length were recorded. In addition, the change of curvature and centring ability were also assessed. The data were analysed statistically using Student's t-test or Fisher's exact-test.
In both canal types, Hero 642 instruments prepared canals more rapidly (P < 0.01) and maintained working length significantly more accurately than ProTaper instruments (P < 0.05). In canals prepared with Hero 642 instruments, there was less change in curvature. Instrumentation with ProTaper results in transportation towards the outer aspect of the L-shaped curved canals in the apical part and the inner aspect of the S-shaped canals at the curve. Hero 642 instruments had a better centring ability in the apical part of the canal, but resulted in shapes with a poor taper.
ProTaper and Hero 642 instruments prepared curved canals rapidly, maintained working length well and were relatively safe without creating perforations and danger zones. In both canal types, Hero 642 instruments maintained the original canal curvature better, and had a better centring ability in curved canals because of its constant taper design. The taper prepared by Hero 642 instruments in the coronal part of the canal was generally poor.
比较渐进式与恒锥度设计的器械在模拟根管中的塑形能力。
使用ProTaper（渐进锥度）器械和高弹性旋转镍钛器械642（Hero 642）（恒锥度）制备模拟L形和S形树脂根管（每种情况各10个根管）。记录器械预备前后的图像，并使用图像分析软件Image Pro Plus 5.0完成根管形态评估。在9个测量点测量去除树脂的宽度。记录根管偏移、器械折断、预备时间和工作长度变化的发生率。此外，还评估了弯曲度变化和定心能力。数据采用Student's t检验或Fisher精确检验进行统计学分析。
在两种根管类型中，Hero 642器械预备根管的速度更快（P < 0.01），并且比ProTaper器械更能显著准确地保持工作长度（P < 0.05）。使用Hero 642器械预备的根管，弯曲度变化较小。使用ProTaper器械进行预备会导致L形弯曲根管根尖部分向外侧、S形根管弯曲处向内侧出现根管偏移。Hero 642器械在根管根尖部分具有更好的定心能力，但导致的根管锥度较差。
ProTaper和Hero 642器械能快速预备弯曲根管，较好地保持工作长度，相对安全，不会造成穿孔和危险区。在两种根管类型中，Hero 642器械由于其恒锥度设计，能更好地保持原始根管弯曲度，在弯曲根管中具有更好的定心能力。Hero 642器械在根管冠部预备的锥度通常较差。
