title: Irrigant flow during photon-induced photoacoustic streaming (PIPS) using Particle Image Velocimetry (PIV).
abstract: OBJECTIVE
  This study aimed to compare fluid movements generated from photon-induced photoacoustic streaming (PIPS) and passive ultrasonic irrigation (PUI).
  
  
  METHODS
  Particle Image Velocimetry (PIV) was performed using 6-μm melamine spheres in water. Measurement areas were 3-mm-long sections of the canal in the coronal, midroot and apical regions for PIPS (erbium/yttrium-aluminium garnet (Er:YAG) laser set at 15 Hz with 20 mJ), or passive ultrasonic irrigation (PUI, non-cutting insert at 30% unit power) was performed in simulated root canals prepared to an apical size #30/0.04 taper. Fluid movement was analysed directly subjacent to the apical ends of ultrasonic insert or fiber optic tips as well as at midroot and apically.
  
  
  RESULTS
  During PUI, measured average velocities were around 0.03 m/s in the immediate vicinity of the sides and tip of the ultrasonic file. Speeds decayed to non-measureable values at a distance of about 2 mm from the sides and tip. During PIPS, typical average speeds were about ten times higher than those measured for PUI, and they were measured throughout the length of the canal, at distances up to 20 mm away.
  
  
  CONCLUSIONS
  PIPS caused higher average fluid speeds when compared to PUI, both close and distant from the instrument. The findings of this study could be relevant to the debriding and disinfecting stage of endodontic therapy.
  
  
  CONCLUSIONS
  Irrigation enhancement beyond needle irrigation is relevant to more effectively eradicate microorganisms from root canal systems. PIPS may be an alternative approach due to its ability to create high streaming velocities further away from the activation source compared to ultrasonic activation.
authors: Department of Mechanical and Aerospace Engineering, Allen School of Engineering, Trine University, Angola, IN, USA.
authors: Jon D
authors: JD
authors: Koch
authors: Department of Endodontics, University of Texas Health Science Center at Houston, School of Dentistry, Houston, TX, USA.
authors: David E
authors: DE
authors: Jaramillo
authors: Private Practice, Arizona Center for Laser Dentistry, Scottsdale, AZ, USA.|Arizona School of Dentistry and Oral Health, Mesa, AZ, USA.
authors: Enrico
authors: E
authors: DiVito
authors: Department of Endodontics, University of the Pacific Arthur A. Dugoni School of Dentistry, 155 5th St, San Francisco, CA, 94103, USA. opeters@pacific.edu.
authors: Ove A
authors: OA
authors: Peters
mesh_terms: D003786:Dental Pulp Cavity; D053844:Lasers, Solid-State; D010316:Particle Size; D061088:Photoacoustic Techniques; D012212:Rheology / Q000379:methods; D012388:Root Canal Irrigants / Q000493:pharmacokinetics*; D018915:Root Canal Preparation / Q000295:instrumentation; D007507:Therapeutic Irrigation / Q000379:methods*; D014465:Ultrasonics
chemical_list: D012388:Root Canal Irrigants
keywords: Endodontics; Irrigation; Particle image velocimetry; Photon-induced photoacoustic streaming; Ultrasonics