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American Journal of Orthodontics and Dentofacial Orthopedics, 2021-07-01, Volume 160, Issue 1, Pages 3-4, Copyright © 2021 American Association of Orthodontists

Thank you for reading and commenting on our article. The article you cite by Chate is a valuable article about the effect of using special disinfectants on reducing biofilm in the waterline of dental units. In our article, if we meant flushing without disinfectant, we would use the phrase “flushing without disinfectant,” as Chate did in his Conclusions. This sentence is written under the “disinfection and sterilization” section, and flushing without disinfectants was not mentioned. According to the new Centers for Disease Control and Prevention guidelines, flushing alone cannot be relied on as the only way to improve the unit’s water quality. Flushing the unit water lines alone has been shown to reduce the levels of planktonic bacteria in the water but has not been shown to be effective on the biofilm that accumulates in the unit water lines. According to Rice et al, 3 minutes of flushing significantly reduced heterotrophic plate count levels alone, but it did not significantly reduce Legionella spp. and protozoa. This issue, and its comparison with flushing with disinfectants, was not the subject of discussion in our article. Flushing with a disinfectant is reasonable for coronavirus, and we have included this in our article on the basis of Chate’s study and other evidence about coronavirus in orthodontics. However, these recommendations are not conclusive in specific cases such as coronavirus and require further high-quality evaluations.


  • 1. Chate R.A.C.: An audit improves the quality of water within the dental unit water lines of general dental practices across the East of England. Br Dent J 2010; 209: pp. E11.
  • 2. Centers for Disease Control and Prevention: Guidelines for infection control in dental health-care settings — 2003. Available at:
  • 3. Rice E.W., Rich W.K., Johnson C.H., Lye D.J.: The role of flushing dental water lines for the removal of microbial contaminants. Public Health Rep 2006; 121: pp. 270-274.