An experimental and computational study of the hydrodynamics of high-velocity water microdrops for interproximal tooth cleaning.

A Rmaile, D Carugo, L Capretto, J A Wharton, P J Thurner, M Aspiras, M Ward, M De Jager, P Stoodley

Journal: Journal of the mechanical behavior of biomedical materials 2016;46():148-57

PMID: 25792412

Full Text on Elsevier Science View on PubMed

Abstract

The flow field and local hydrodynamics of high-velocity water microdrops impacting the interproximal (IP) space of typodont teeth were studied experimentally and computationally. Fourteen-day old Streptococcus mutans biofilms in the IP space were treated by a prototype AirFloss delivering 115 µL of water at a maximum exit-velocity of 60 ms(-1) in a 33-ms burst. Using high-speed imaging, footage was generated showing the details of the burst, and demonstrating the removal mechanism of the biofilms. Footage was also generated to characterize the viscoelastic behavior of the biofilms when impacted by an air-only burst, which was compared to the water burst. Image analysis demonstrated the importance of fluid forces on the removal pattern of interdental biofilms. X-ray micro-Computed Tomography (µ-CT) was used to obtain 3D images of the typodont and the IP spaces. Computational Fluid Dynamics (CFD) simulations were performed to study the effect of changing the nozzle position and design on the hydrodynamics within the IP space. Results confirmed our previous data regarding the wall shear stress generated by high-velocity water drops which dictated the efficacy of biofilm detachment. Finally, we showed how CFD models could be used to optimize water drop or burst design towards a more effective biofilm removal performance.

Address: nCATS, Faculty of Engineering and the Environment (FEE), University of Southampton, UK. Electronic address: [email protected].; Bioengineering Science Research Group, Faculty of Engineering and the Environment (FEE), University of Southampton, UK.; nCATS, Faculty of Engineering and the Environment (FEE), University of Southampton, UK.; Philips Oral Healthcare Inc. (POH), Bothell, WA, USA.; Philips Research, Oral Healthcare Research, Eindhoven, The Netherlands.; nCATS, Faculty of Engineering and the Environment (FEE), University of Southampton, UK; Center for Microbial Interface Biology, Departments of Microbial Infection and Immunity, and Orthopaedics, The Ohio State University, Columbus, OH, USA.

DOI: 10.1016/j.jmbbm.2015.02.010

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MeSH Terms: Biofilms, Computer Simulation, Dental Equipment, Dentistry, Elasticity, Hydrodynamics, Imaging, Three-Dimensional, Microscopy, Confocal, Streptococcus mutans, Tooth, Viscosity, Water