Dummer P M, Hutchings R, Hartles F R
Department of Conservative Dentistry, Dental School, University of Wales College of Medicine, Cardiff, UK.
Int Endod J. 1993 Jul;26(4):209-17. doi: 10.1111/j.1365-2591.1993.tb00561.x.
The objective of this study was to establish the effect of altering the non-cutting tips on Shaper files during canal preparation with the MM1500 Sonic Air handpiece. A total of 90 simulated canals in clear resin blocks of various angles and positions of curvature were prepared using Shaper files activated by an MM1500 Sonic Air handpiece. Thirty canals were prepared with unmodified files having non-cutting tips, 30 canals were prepared with files which had their tips removed completely and a further 30 canals were prepared with files which had tips reduced by half. All canals were prepared using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The parameters investigated included loss of canal length, weight loss from the blocks, smoothness of canal walls, transportation and overall shape of the prepared canals. The effect of altering the file tips was to increase significantly the loss of working distance and the prevalence of canal aberrations such as zips and danger zones. Altering the tips also had a detrimental effect on the pattern and extent of transportation as well as widening canals excessively in their apical third. Overall, under the conditions of this study, alterations to the non-cutting tips of Shaper files was counterproductive and resulted in canals displaying many adverse features. Conversely, retention of the non-cutting tips allowed canal preparation to proceed rapidly and effectively producing canal shapes which displayed many desirable features.
本研究的目的是确定在使用MM1500声波气动手持器械进行根管预备时，改变Shaper锉的非切割尖端所产生的影响。使用MM1500声波气动手持器械激活的Shaper锉，在各种角度和弯曲位置的透明树脂块中制备了总共90条模拟根管。30条根管使用具有非切割尖端的未改性锉进行预备，30条根管使用完全去除尖端的锉进行预备，另外30条根管使用尖端减少一半的锉进行预备。所有根管均采用相同的预备程序，包括直线锉削运动和弯曲根管中的抗弯曲技术。所研究的参数包括根管长度的损失、树脂块的重量损失、根管壁的光滑度、根管偏移以及预备后根管的整体形状。改变锉尖的影响是显著增加工作长度的损失以及根管异常（如拉链状和危险区）的发生率。改变锉尖还对根管偏移的模式和程度以及根管根尖三分之一处过度扩宽产生不利影响。总体而言，在本研究条件下，改变Shaper锉的非切割尖端会适得其反，导致根管呈现许多不良特征。相反，保留非切割尖端可使根管预备快速有效地进行，产生具有许多理想特征的根管形状。
