Avoiding the Reflux: The Cleaning and Disinfection of Suction Units

During treatment of a patient, the suction unit removes liquids and solid substances from the oral cavity, thereby reducing the creation of aerosol. However, the inner wall of the suction hose is an ideal habitat and breeding ground for germs. Fortunately, this can be successfully avoided by flushing the unit regularly with a suitable cleaner and disinfectant.

Microorganisms from the oral cavity have the potential to contaminate an entire suction system. There is a serious risk of infection if fluids from the suction unit flow backward into the oral cavity of the patient, a so-called reflux. This can occur through poor handling of the suction hose or if the cannula adheres to the tongue or mucous membrane of the oral cavity. The dental and technical personnel is also at risk as the aspirating units are generally highly contaminated and they are responsible for the maintenance and cleaning work.

Modern processes of cleaning and disinfection provide for an excellent reduction in the number of germs and prevent the development of biofilm in the suction unit; this helps to eliminate, or at least to lower, the risks to the patients and dental team. However, it is still unknown to what extent the criteria of a regular disinfection can actually be fulfilled.

A Perfect Hiding Place for Microorganisms

On the inner walls of the suction unit, microorganisms find a perfect environment: moist and warm. An extensive microorganism colonization results in a biofilm in which many different types of pathogens live together. The waste products of the microorganisms combined with the unit’s water supply create a slimy and gel-like consistency. Accumulations of materials such as dirt, calcification, saliva, or blood will then become attached to and embedded in this biofilm that makes the removal of the biofilm a very difficult task. On the barrier between the biofilm and water, microorganisms or even entire pieces of the biofilm can be torn loose and carried away by the flowing water leading to a very high risk of infection.

Biofilms develop a very unpleasant odor. The biological processes of the biofilm create hydrogen sulfide, a chemical compound also responsible for the smell of rotten eggs.

Targeted Protection Against Biofilm

It is easier to prevent the accumulation of biofilm than to try to eliminate existing biofilm. This prevention can only be accomplished by means of a daily cleaning and disinfection of the suction unit. After every patient treatment, the suction unit should be flushed with one liter of cold tap water in order to guarantee the functionality of the unit and to lower the standing time of the water in the hose and pipes.

The inner walls of the unit can be cleaned by means of a regular flushing with a combined cleaner/disinfectant. One liter of the solution should be suctioned through the unit at least once per day – possibly twice per day if the unit is constantly used. Using these cleaner substances is required in order to break down the protective surface layers of the biofilm. The flowing liquid will wash away the individual fragments, allowing the disinfectant to reach the biofilm‘s pathogens.

The characteristics of a suitable disinfectant are as follows:

• Effective against blood and saliva
• Effective against bacteria (particularly tuberculosis), fungi, and HBV, HCV, and HIV (comparable to the requirements for a surface disinfectant)
• Contains anticorrosion inhibitors
• Should have little foam to prevent any problems with the suction unit
• Can be diluted with water
• Biodegradable, as the disinfectant will be disposed of in the wastewater system

Further Infection Control Measures

Besides the cleaning and disinfection of the suction unit, there are other important preventative measures that can help to avoid a reflux.

During the patient treatment, the vacuum and the suction hose must be held as low as possible; this helps to prevent a gravitational reflux of fluids. The adherence of the cannula to the soft tissue of the oral cavity and the resulting reflux is a technical problem that can be solved with certain modifications. Drilling air holes in the sides of the suction cannulas allows for a regular suction, even when the main opening is blocked.

Furthermore, the following cleaning, disinfection, and maintenance measures must be carried out on the suction unit:

• The attached coupling, suction hose, and the spittoon bowl must be prepared between patients with a simple wipe disinfection. The spittoon bowl should be flushed once daily with a liter of cleaner/disinfectant.
• The removable coupling and suction hoses are considered to be semi-critical A medical products and should be prepared respectively after every treatment.
• Changing and cleaning of the filter should be done regularly as instructed by the manufacturer – normally once a week. Before removing the filter, the suction unit should be disinfected.
• The amalgam separator should be changed or emptied when needed. Changing or emptying the collection container should be done according to the manufacturer‘s instructions. This should also be preceded by a disinfection of the entire suction unit.
• The contaminated parts of the separator should never be touched. The separated material should be given to a waste management company in closed airtight containers.
• Work with the filter and amalgam separator must be done with gloves, dental mask, and protective goggles. When removing the collection container, wearing a liquid-proof apron is highly recommended.

Recommended Hygienic Measures for the Suction Unit