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The ease and importance of cleaning evacuation lines

June 9, 2022
Over time, biofilm and other debris build up in the lines, which compromises the suctioning power of the system. Here's how to easily keep them flushed out.

Today’s saliva ejectors and evacuation systems undoubtedly increase efficiency and patient comfort in dental offices. Dental chair unit evacuation lines remove fluids (e.g., saliva, blood, and irrigation water) and debris (e.g., tooth particles, dental calculus, and dental amalgam) from the oral cavity during dental procedures.1 Over time, biofilm and other debris build up in the lines, which compromises the suctioning power of the system. This leads to expensive repairs and creates infection control concerns. Fortunately, maintaining vac lines is a simple and quick task.

The ease of maintaining lines

There are many systems and products available designed to clean the lines safely and efficiently. It’s important to use solutions that are meant specifically for flushing dental evacuation systems. Be sure to follow instructions on the packaging. In 2007, the American Dental Association (ADA) advised, “Don’t use bleach or chlorine-containing cleaners to flush wastewater lines.” This is because they maximize the oxidation and dissolution of mercury into the water system.2

About a decade later, the United States Environmental Protection Agency (EPA) delivered more specific guidance, stating, “Vacuum lines that discharge amalgam process wastewater to [publicly owned treatment works] must not be cleaned with oxidizing or acidic cleaners, including but not limited to bleach, chlorine, iodine, and peroxide that have a pH lower than 6 or greater than 8.”3 Specific details about the ingredients and pH of these cleaners can be found on the product label or the manufacturer’s website.

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It is recommended evacuation lines be flushed at least daily. Little research has been performed to suggest when during the day it’s best to run the lines, but most offices find this task most convenient at the end of each workday. Many offices choose to clean the lines twice a day—once before lunch and once after the last patient. Many clinicians flush the lines with warm water between each patient visit. It’s also important to clean or replace the traps. The manufacturers of dental chair units (DCUs) typically recommend cleaning traps weekly, but clinicians should not hesitate to ask companies about more specific maintenance needs.

The time required to perform these simple tasks is just a few minutes each week per dental chair unit. Ultimately, making every effort to ensure the suction lines are well maintained is worth every second, especially considering the financial and ethical consequences of neglecting these steps. 

The necessity of cleaning the lines

Neglecting to maintain the suction lines can have financial and disgusting infection control consequences that are nothing short of unethical. Many dentists do whatever they can to fix malfunctioning equipment on their own to save money, and they appreciate employees taking steps to maintain and increase the longevity of the clinical equipment.

Maintaining the suction line, which is an essential and central system in an office, can save thousands of dollars in replacement equipment and professional cleaning that can shut down an office for hours or even days. Additionally, the necessity for regular disinfection of these systems must be stressed, since biofilms can serve as a reservoir for pathogens or harbor potentially infectious material.4

Suction lines should be disinfected regularly to keep them functioning at optimum levels and help decrease the possibility of cross contamination between dental patients.5 The Centers for Disease Control and Infection (CDC) summarizes how improper use of saliva ejectors can create backflow: “Backflow occurs when previously suctioned fluids present in the suction tubing flow back into the patient’s mouth."6

This is likely to happen in three scenarios. First, backflow can happen when a patient closes their lips around the saliva ejector.7 Second, risk of backflow increases when suction tubing attached to the ejector is positioned above the patient’s mouth.6 And third, backflow can result when a saliva ejector is used at the same time as other evacuation (high-volume) equipment.6

The CDC clarifies that although no adverse health effects associated with the saliva ejector have been reported, dental health-care personnel should be aware that backflow can occur during use.6 All of these issues can be remedied, in part, by ensuring the optimum functionality of the vac systems with routine flushing of the lines and cleaning traps. Additionally, clinicians should consider running warm water through the suction between patients to help flush out any loose debris, saliva, or biofilm that might remain in the line before the suction is used on the next patient.

Overall, maintaining the evacuation system is quite easy and necessary. This chore may feel mundane, but clinicians have an ethical responsibility to be proactive in making sure the suction lines are functioning optimally.

Editor's note: This article appeared in the June 2022 print edition of RDH magazine. Dental hygienists in North America are eligible for a complimentary print subscription. Sign up here.


  1. Boyle MA, O’Donnell MJ, Russell RJ, Galvin N, Swan J, Coleman DC. Overcoming the problem of residual microbial contamination in dental suction units left by conventional disinfection using novel single component suction handpieces in combination with automated flood disinfection. J Dent. 2015;43(10):1268–1279.
  2. Best management practices for amalgam waste. American Dental Association.
  3. Effluent limitations guidelines and standards for the dental category. Federal Register website. Published June 14, 2017. Updated July 5, 2017.
  4. Barbeau J, ten Bokum L, Gauthier C, Prévost AP. (1998). Cross-contamination potential of saliva ejectors used in dentistry. J Hosp Infection, 1998;40(4):303–311.
  5. Watson CM, Whitehouse RL. (1993). Possibility of cross-contamination between dental patients by means of the saliva ejector. 1993;124(4):77–80.
  6. Saliva ejector and backflow. CDC. Page last reviewed March 3, 2016.
  7. Mann GL, Campbell TL, Crawford JJ. Backflow in low-volume suction lines: the impact of pressure changes. 1996;127(5):611–615.‌
About the Author

Rebecca “Becca” Neilson, BS, RDH

Rebecca “Becca” Neilson, BS, RDH, grew up in Provo, Utah. She graduated from Brigham Young University in 2014 with a BS in biology and Indiana University in 2020 with a BS in dental hygiene. She practices in a private dental office in Elkhart, Indiana. Neilson thrives off of interpersonal relationships and finds satisfaction in helping others learn. You can reach her at [email protected].