Wang Ruyan, Shen Ya, Ma Jingzhi, Huang Dingming, Zhou Xuedong, Gao Yuan, Haapasalo Markus
State Key Laboratory of Oral Diseases, West China College and Hospital of Stomatology, Sichuan University, Chengdu, China.
Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, Canada.
J Endod. 2015 Jun;41(6):931-6. doi: 10.1016/j.joen.2015.02.002. Epub 2015 Mar 17.
The purpose of this study was to investigate the effect of the orientation of a side-vented needle on the irrigant flow pattern in a C-shaped root canal system using computational fluid dynamics and to evaluate the real-time replacement of irrigant in the lateral canal (LC).
A mandibular second molar with a complete C-shaped canal system was chosen for this study. The root canals were prepared and scanned, and then the images were exported to design software. A 30-G, side-vented irrigation needle was positioned with the open notch facing the lateral canal (case A) and rotated 90°, 180°, and 270° clockwise (cases B, C, and D, respectively). The flow pattern, irrigant replacement, velocity distribution, wall stress distribution, and apical pressure in the canal were analyzed.
Most of the irrigant flowed to the canal outlet from the adjacent instrumented canal space with different trajectories in the 4 cases. The concentration of scalar immediately below the tip of the needle was exchanged quickly; the length of the cleared zone extended 3 mm beyond the tip of the needles. The depth of circulation in the LC in all cases increased during the first 0.2 seconds. After that, the exchange of irrigant reached a stable phase. Irrigant penetration in the LC was greatest in cases A and B (<1.1 mm). Apical pressure in case B was significantly lower than in other groups.
The scalar concentration can be used to evaluate the replacement of irrigant in the root canal over time. Orientation of the opening of the side-vented needle influences the flow pattern, velocity, apical wall pressure, and penetration into the LC.
本研究旨在使用计算流体动力学研究侧孔针的方向对C形根管系统中冲洗液流动模式的影响，并评估侧支根管（LC）中冲洗液的实时置换情况。
本研究选用了具有完整C形根管系统的下颌第二磨牙。对根管进行预备和扫描，然后将图像导出至设计软件。将一根30G的侧孔冲洗针放置在开口凹槽朝向侧支根管的位置（病例A），并分别顺时针旋转90°、180°和270°（分别为病例B、C和D）。分析根管内的流动模式、冲洗液置换、速度分布、壁应力分布和根尖压力。
在4种情况下，大部分冲洗液从相邻的预备根管空间以不同轨迹流向根管出口。针尖端下方标量的浓度迅速交换；清除区的长度超出针尖端3mm。在所有情况下，侧支根管内的循环深度在最初0.2秒内增加。此后，冲洗液的置换达到稳定阶段。病例A和B中冲洗液在侧支根管内的渗透最大（<1.1mm）。病例B中的根尖压力显著低于其他组。
标量浓度可用于评估根管内冲洗液随时间的置换情况。侧孔针开口的方向会影响流动模式、速度、根尖壁压力以及向侧支根管内的渗透。
