Abstract：
OBJECTIVE: The aim of the present study was to visualize and compare the cavitation effect and fluid dynamics induced by photon-induced photoacoustic streaming (PIPS) using sodium hypochlorite (NaOCl) with different concentrations as irrigant.
METHODS: Forty artificial root canals were prepared using MTWO Niti file up to size #25/.06. The canals were randomly divided into four groups (n = 10/group). High-speed camera was used to visualize and compare the cavitation effect induced by PIPS in the artificial root canals containing saline or NaOCl. Fluid velocity and Reynolds number of saline, 1%-, 2.5%- and 5.25% NaOCl irrigants induced by PIPS in the apical region were calculated using TEMA 2D software while the fluid motions were recorded.
RESULTS: Visualization profile revealed that NaOCl presented a stronger cavitation effect and fluid dynamics than saline during PIPS activation. In the apical region, 1% NaOCl group presented the highest average velocity of 3.868 m/s, followed by 2.5% NaOCl group (3.685 m/s), 5.25% NaOCl group (2.353 m/s) and saline group (1.268 m/s), corresponding to Reynolds number of 1653.173, 1572.196, 995.503 and 477.692. Statistically higher fluid velocity was calculated in 1% and 2.5% NaOCl groups compared to saline group, respectively (p < 0.05).
CONCLUSIONS: The application of NaOCl and its concentration significantly influence the cavitation effect and fluid dynamics during PIPS activation. 1% and 2.5% NaOCl groups presented a more violent fluid motion in the apical region when activated by PIPS.
METHODS: Forty artificial root canals were prepared using MTWO Niti file up to size #25/.06. The canals were randomly divided into four groups (n = 10/group). High-speed camera was used to visualize and compare the cavitation effect induced by PIPS in the artificial root canals containing saline or NaOCl. Fluid velocity and Reynolds number of saline, 1%-, 2.5%- and 5.25% NaOCl irrigants induced by PIPS in the apical region were calculated using TEMA 2D software while the fluid motions were recorded.
RESULTS: Visualization profile revealed that NaOCl presented a stronger cavitation effect and fluid dynamics than saline during PIPS activation. In the apical region, 1% NaOCl group presented the highest average velocity of 3.868 m/s, followed by 2.5% NaOCl group (3.685 m/s), 5.25% NaOCl group (2.353 m/s) and saline group (1.268 m/s), corresponding to Reynolds number of 1653.173, 1572.196, 995.503 and 477.692. Statistically higher fluid velocity was calculated in 1% and 2.5% NaOCl groups compared to saline group, respectively (p < 0.05).
CONCLUSIONS: The application of NaOCl and its concentration significantly influence the cavitation effect and fluid dynamics during PIPS activation. 1% and 2.5% NaOCl groups presented a more violent fluid motion in the apical region when activated by PIPS.
摘要：
目的：本研究的目的是可视化和比较使用不同浓度的次氯酸钠（NaOCl）作为冲洗剂的光子诱导光声流（PIPS）引起的空化效应和流体动力学。
方法:使用MTWONiti文件制备40个人工根管,其大小为#25/.06。将运河随机分为四组(n=10/组)。高速相机用于可视化和比较PIPS在含有盐水或NaOCl的人工根管中引起的空化效应。盐水的流体速度和雷诺数，1%-,使用TEMA2D软件计算PIPS在根尖区域诱导的2.5％-和5.25％NaOCl冲洗液，同时记录流体运动。
结果：可视化曲线显示，在PIPS激活过程中，NaOCl表现出比盐水更强的空化效应和流体动力学。在顶端区域，1%NaOCl组的最高平均速度为3.868m/s，其次是2.5%NaOCl组(3.685m/s)，5.25%NaOCl组(2.353m/s)和生理盐水组(1.268m/s),对应雷诺数1653.173、1572.196、995.503和477.692。与盐水组相比，1%和2.5%NaOCl组的流体速度在统计学上较高，分别为(p<0.05)。
结论：NaOCl的应用及其浓度显著影响PIPS活化过程中的空化效应和流体动力学。当被PIPS激活时，1％和2.5％NaOCl基团在顶端区域呈现更剧烈的流体运动。
方法:使用MTWONiti文件制备40个人工根管,其大小为#25/.06。将运河随机分为四组(n=10/组)。高速相机用于可视化和比较PIPS在含有盐水或NaOCl的人工根管中引起的空化效应。盐水的流体速度和雷诺数，1%-,使用TEMA2D软件计算PIPS在根尖区域诱导的2.5％-和5.25％NaOCl冲洗液，同时记录流体运动。
结果：可视化曲线显示，在PIPS激活过程中，NaOCl表现出比盐水更强的空化效应和流体动力学。在顶端区域，1%NaOCl组的最高平均速度为3.868m/s，其次是2.5%NaOCl组(3.685m/s)，5.25%NaOCl组(2.353m/s)和生理盐水组(1.268m/s),对应雷诺数1653.173、1572.196、995.503和477.692。与盐水组相比，1%和2.5%NaOCl组的流体速度在统计学上较高，分别为(p<0.05)。
结论：NaOCl的应用及其浓度显著影响PIPS活化过程中的空化效应和流体动力学。当被PIPS激活时，1％和2.5％NaOCl基团在顶端区域呈现更剧烈的流体运动。
