Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
J Endod. 2010 Oct;36(10):1664-8. doi: 10.1016/j.joen.2010.06.023. Epub 2010 Aug 17.
The aim of this study was to evaluate the effect of needle-insertion depth on the irrigant flow inside a prepared root canal during final irrigation with a syringe and two different needle types using a Computational Fluid Dynamics (CFD) model.
A validated CFD model was used to simulate irrigant flow from either a side-vented or an open-ended flat 30-G needle positioned inside a prepared root canal (45 .06) at 1, 2, 3, 4, or 5 mm short of the working length (WL). Velocity, pressure, and shear stress in the root canal were evaluated.
The flow pattern in the apical part of the root canal was similar among different needle positions. Major differences were observed between the two needle types. The side-vented needle achieved irrigant replacement to the WL only at the 1-mm position, whereas the open-ended flat needle was able to achieve complete replacement even when positioned at 2 mm short of the WL. The maximum shear stress decreased as needles moved away from the WL. The flat needle led to higher mean pressure at the apical foramen. Both needles showed a similar gradual decrease in apical pressure as the distance from the WL increased.
Needle-insertion depth was found to affect the extent of irrigant replacement, the shear stress on the canal wall, and the pressure at the apical foramen for both needle types.
本研究旨在使用计算流体动力学（CFD）模型评估在使用注射器和两种不同类型的针进行最终冲洗时，针插入深度对预备根管内冲洗剂流动的影响。
使用经过验证的 CFD 模型模拟侧孔或开口式平 30-G 针在预备根管（45°）内的位置，距离工作长度（WL）分别为 1、2、3、4 或 5 毫米。评估根管内的速度、压力和剪切应力。
不同针位的根管根尖部分的流动模式相似。两种针型之间观察到明显差异。侧孔针仅在 1 毫米位置才能实现冲洗剂到达 WL 的置换，而开口式平针即使在 WL 短 2 毫米的位置也能实现完全置换。随着针远离 WL，最大剪切应力降低。平针在根尖孔处产生较高的平均压力。两种针都表现出随着距离 WL 增加而逐渐降低的根尖压力。
针插入深度会影响两种针型的冲洗剂置换程度、管壁剪切应力和根尖孔压力。
