根管冲洗对于根管治疗的成败具有决定作用，但现有根管冲洗方法根尖1/3区域清洗率较低，残存组织和细菌将严重威胁人体健康，其临床解决方法又会降低牙齿强度及引发冲洗剂穿透风险，这是目前根管冲洗的瓶颈问题；其本质则是根管内冲洗剂流动组织问题，而通过流动调控实现根尖区域的流动再激发是解决该问题的关键。因此，基于申请人发现的“根尖绕流激发产生二次射流”现象，本项目拟从根管冲洗非定常历程出发，解析单侧射流及壁射流在根管狭窄空腔内旋流回流图谱，探讨壁面效应作用下初始和激发流动的干涉机理，揭示流动控制结构介入使根尖绕流自激发产生二次射流的机制；同时探究冲洗过程对牙齿结构安全的影响，建立带自激发二次射流根管冲洗的优化调控体系。本项目对于射流流动调控技术的发展和口腔及继发性疾病的控制具有重要的理论和社会价值，项目所开展的内流流体力学、固体力学和口腔医学多学科交叉研究也将促进工程热物理与相邻学科的交叉融合发展。

Root canal irrigation is crucial for the success of root canal therapy. While, the existing root canal irrigation method is failure in the effective removal of adhesive biofilm and smear layer on the apical third of canal wall, resulting in severe threat to human health. What’s more, the clinical solving approaches available increase the risk of irrigant extrusion to periapical tissues and extra ache, as well as the loss of strength of tooth, which is now the bottleneck of root canal irrigation. The physical essence of the problem is flow organization of irrigant in root canal, and the key to solve it is exciting the flow near needle apex by means of flow regulation. Therefore, based on the phenomenon of re-jetting excited from deflected whirly flow in root canal irrigation, observed in the pre-research, self-excitation mechanism of re-jetting of jet impingement in limited cavity under the effects of flow control will be studied in this proposal. Starting from the discussions of unsteady flow of root canal irrigation, the flow structure maps of whirly flow and reflow resulting from one-sided jet impingement and resulting wall jet in the limited cavity of root canal will be analyzed. And the interference mechanisms of initial flow and excitation flow in the root canal under the influence of wall effects will be next discovered. Then, the formation mechanisms of self-excitation re-jetting arising from the deflected whirly flow will be revealed. Moreover, the influence of self-excitation re-jetting on the structural safety of canal will be clarified. Furthermore, the comprehensive optimal regulation method of root canal irrigation with self-excitation re-jetting can be obtained. The proposed research can be of great theoretical significance and social value for the improvements of impingement regulatory technology, as well as the oral disease and secondary diseases control. The interdisciplinary research involving internal flow fluid mechanism, solid mechanics and stomatology conducted in this proposal will also promote the interdisciplinarity, integration and development between engineering thermophysics and other related subjects.