State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China; School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing, China.
Comput Biol Med. 2024 Sep;179:108940. doi: 10.1016/j.compbiomed.2024.108940. Epub 2024 Jul 25.
Root canal irrigation is crucial for infection control during root canal treatment. Side-vented needles for positive pressure irrigation are commonly used in clinical practice. However, variations in needle design among manufacturers can impact the fluid dynamics of irrigation. This study aims to use computational fluid dynamics to explore the flow characteristics of different needle aperture lengths and positions, and their effects on the effectiveness and safety of irrigation, using a validated passive scalar transport numerical model.
The validation of the CFD irrigant model was achieved by comparing it with an in vitro irrigation experiment model. The CFD model used scalar concentration, while the in vitro experiment model used red dye tracing. Using a standard 30G side-vented needle as a reference, virtual needle models featuring four aperture lengths and three positions were created. These virtual irrigation needles were then placed in two root canal geometries for CFD simulation to evaluate fluid exchange capabilities and related fluid dynamic parameters.
The results of the CFD simulation, using a scalar transport model, closely matched the in vitro tracer tests for irrigation experiments across seven root canal geometries. The CFD analysis indicated that positioning the aperture lower increased the irrigant exchange distance. Notably, decreasing the aperture length to 0.25x, and positioning it at the lower end of the needle significantly increased exchange distance and shear stress, while reducing apical pressure.
These results indicate that the position and length of the aperture affect the exchange distance of irrigant flow, wall shear stress, and apical pressure. The CFD validation model for scalar transport, based on a steady state, can function as a valuable tool for optimizing the side-vented needle in research. Further research on the design of side-vented needles will enhance the understanding of flow characteristics beneficial for irrigation efficiency in clinical practice.
根管冲洗在根管治疗过程中对于感染控制至关重要。正压冲洗用侧口针在临床实践中被广泛应用。然而，制造商之间的针设计差异会影响冲洗的流体动力学。本研究旨在使用计算流体动力学（CFD）通过验证的被动标量传输数值模型，探讨不同针孔径长度和位置的流动特性，及其对冲洗效果和安全性的影响。
通过将 CFD 冲洗模型与体外冲洗实验模型进行比较，实现了 CFD 模型的验证。CFD 模型使用标量浓度，而体外实验模型使用红色染料示踪。以标准的 30G 侧口针为参考，创建了四个孔径长度和三个位置的虚拟针模型。将这些虚拟冲洗针放置在两种根管几何形状中进行 CFD 模拟，以评估流体交换能力和相关的流体动力学参数。
使用标量传输模型的 CFD 模拟结果与七个根管几何形状的体外示踪剂冲洗实验结果非常吻合。CFD 分析表明，将孔口定位在较低位置会增加冲洗剂的交换距离。值得注意的是，将孔径长度缩短至 0.25x，并将其定位在针的下端，可显著增加交换距离和壁面剪切应力，同时降低根尖压力。
这些结果表明，孔口的位置和长度会影响冲洗剂流动的交换距离、壁面剪切应力和根尖压力。基于稳态的标量传输 CFD 验证模型可以作为研究中优化侧口针的有价值工具。进一步研究侧口针的设计将有助于深入了解对临床实践中冲洗效率有益的流动特性。
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