title: Acoustic streaming induced by an ultrasonically oscillating endodontic file.
abstract: Ultrasonically activated irrigation is an advanced dental technique for irrigation of the root canal system during a root canal treatment. The basic cleaning mechanism is a result of acoustic streaming induced by an oscillating file, leading to mixing of the irrigant and pressure and shear stresses on the walls of the root canal. Here the induced acoustic streaming, pressure, and shear stress are investigated in a two-dimensional cross-section of the root canal, using a combination of theory, numerical predictions, and experimental validation through high-speed particle tracking velocimetry. Acoustic streaming theory describes very well the flow induced by an ultrasonically oscillating endodontic file. It consists of an oscillatory component, which is dominant near the file, and a steady component, or jet, along the axis of oscillation. The importance of the oscillatory component for both the pressure and the shear stress is apparent, as it is two to three orders of magnitude higher than the steady component. A confinement affects the formation of the steady jets; meanwhile the oscillatory velocities and associated pressure and shear stress are increased. Previous work considering only the steady component of the flow therefore, underestimated the hydrodynamic effects induced by ultrasonic files.
authors.affiliation: Physics of Fluids group and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Verhaagen
authors.affiliation: Department of Cariology, Endodontology, Pedodontology, Academic Centre for Dentistry Amsterdam (ACTA), Gustav Mahlerlaan 3004 1081LA Amsterdam, The Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Boutsioukis
authors.affiliation: Center for Dentistry and Oral Hygiene, University Medical Center Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands.
authors.forename: L W M
authors.initials: LW
authors.lastname: van der Sluis
authors.affiliation: Physics of Fluids group and MIRA Institute for Biomedical Technology and Technical Medicine and MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Versluis