Characteristics of the Irrigant Flow in a Simulated Lateral Canal Under Two Typical Laser‐Activated Irrigation Regimens. Issue 4 (10th September 2020)

• Record Type: Journal Article
• Authors: Su, Zheng; Li, Zhibo; Shen, Ya; Bai, Yuhao; Zheng, Ying; Pan, Chong; Hou, Benxiang
• Is Part Of: Lasers in surgery and medicine. Volume 53:Issue 4(2021)
• Page Start: 587
• Page End: 594
• Publication Date: 2020-09-10
• Subjects: lateral canal -- microscale particle image velocimetry -- photon‐induced photoacoustic streaming -- shockwave‐enhanced emission photoacoustic streaming -- ultrasonic‐activated irrigation; Lasers in medicine -- Periodicals; Lasers in surgery -- Periodicals; 617
• DOI: 10.1002/lsm.23317
• Languages: English
• ISSNs: 0196-8092

Abstract

Abstract : Background and Objectives: 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. Results: 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). Conclusion: 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