Su Zheng, Li Zhibo, Shen Ya, Bai Yuhao, Zheng Ying, Pan Chong, Hou Benxiang
Department of Endodontics, Beijing Stomatological Hospital, Capital Medical University, Beijing, 100050, PR China.
Institute of Fluid Mechanics, Beihang University, Beijing, 100191, PR China.
Lasers Surg Med. 2020 Sep 10. doi: 10.1002/lsm.23317.
Photon-induced photoacoustic streaming (PIPS) and shockwave-enhanced emission photoacoustic streaming (SWEEPS) are two promising laser-activated irrigation (LAI) methods for root canal irrigation. Their performance in driving irrigant flush in a complex root canal system will be evaluated by microscale particle image velocimetry (μPIV) measurement and will be compared with that of ultrasonic-activated irrigation (UAI).
STUDY DESIGN/MATERIALS AND METHODS: A μPIV system with 7 μm fluorescent tracer particles was adopted to measure two-dimensional (2D) velocity fields around the junction region, with a size of 1.8 mm × 1.5 mm, between one main canal and one lateral canal in an endodontic training block, which was driven by SWEEPS (Er:YAG laser) operating at 15 Hz and 20 mJ. The flow field driven by PIPS (Er:YAG laser) at the same frequency and energy, as well as by UAI (with non-cutting insert) operating at 40% unit power, was also measured for a direct comparison.
It was found that both SWEEPS and PIPS can activate a so-called "breath mode" during the irrigation. Namely, the induced irrigant flush presented a back-and-forth oscillation along both the main canal and the lateral one. The maximum flow speed in the lateral canal was observed to be up to 10 m/s in the SWEEPS modality, while reduced to around 7 m/s in the PIPS modality. The penetration length in the lateral canal in both modalities was estimated to be larger than 1 mm. In comparison, the flow field induced by UAI was characterized as irregular vortical structures, the maximum flow speed in the lateral canal was 0.15 m/s and significantly lower than LAI (P < 0.01), and the penetration length was less than 300 μm and lower than LAI (P < 0.05).
Compared to UAI, PIPS, and SWEEPS are more capable of delivering the irrigant deeper into the lateral canal. Furthermore, the back-and-forth flush in the breath mode is ideal for removing debris during irrigation. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.
光子诱导光声流（PIPS）和冲击波增强发射光声流（SWEEPS）是两种很有前景的根管冲洗激光激活灌溉（LAI）方法。将通过微尺度粒子图像测速技术（μPIV）测量来评估它们在复杂根管系统中驱动冲洗液冲洗的性能，并与超声激活灌溉（UAI）的性能进行比较。
研究设计/材料与方法：采用配备7μm荧光示踪粒子的μPIV系统，测量牙髓训练模块中一条主根管和一条侧根管之间1.8mm×1.5mm大小的连接区域周围的二维（2D）速度场，该区域由频率为15Hz、能量为20mJ的SWEEPS（铒：钇铝石榴石激光）驱动。还测量了相同频率和能量下PIPS（铒：钇铝石榴石激光）以及40%单位功率运行的UAI（带非切割插入件）驱动的流场，以便进行直接比较。
发现SWEEPS和PIPS在冲洗过程中都能激活一种所谓的“呼吸模式”。也就是说，诱导的冲洗液冲洗在主根管和侧根管中都呈现出往复振荡。在SWEEPS模式下，侧根管中的最大流速高达10m/s，而在PIPS模式下降至约7m/s。两种模式下侧根管中的穿透长度估计都大于1mm。相比之下，UAI诱导的流场特征为不规则的涡旋结构，侧根管中的最大流速为0.15m/s，明显低于LAI（P<0.01），穿透长度小于300μm，低于LAI（P<0.05）。
与UAI相比，PIPS和SWEEPS更能将冲洗液输送到侧根管更深处。此外，呼吸模式下的往复冲洗非常适合在冲洗过程中清除碎屑。《激光外科与医学》。©2020威利期刊有限责任公司。
