Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers

Sumanth Kumbargere Nagraj, Prashanti Eachempati, Martha Paisi, Mona Nasser, Gowri Sivaramakrishnan, Tony Francis, Jos H. Verbeek

Why is this question important?

Many dental procedures generate droplets that settle on a surface quickly. If high‐speed instruments, such as a drill, are used, aerosols are generated, which consist of tiny particles that remain suspended in the air and that can be inhaled or that settle farther away on surfaces. These aerosols contain a variety of micro‐organisms and may transmit infections either through direct contact or indirectly through the contaminated surfaces. To prevent the spread of infection, it may help to reduce the number of micro‐organisms that are present in these aerosols. The use of mouth rinses before a dental procedure ('preprocedural mouth rinse') has been suggested as a possible way to reduce the amount of contamination of these aerosols. Chlorhexidine, povidone iodine and cetylpyridinium chloride (CPC) are some of the commonly used mouth rinses. They act by killing or inactivating the micro‐organisms in the mouth and thereby reducing the level of contamination in the aerosol that is generated. We wanted to find out whether rinsing the mouth before a dental procedure reduces the contamination of aerosols produced during dental procedures in practice and helps prevent the transmission of infectious diseases.

How did we identify and evaluate the evidence?

We searched for all relevant studies that compared mouth rinses used before dental procedures against placebo (fake treatment), no intervention or another mouth rinse considered to be inactive. We then compared the results, and summarised the evidence from all the studies. Finally, we assessed our confidence in the evidence. To do this, we considered factors such as the way studies were conducted, study sizes and consistency of findings across studies.

What did we find?

We found 17 studies that met our inclusion criteria. These studies used chlorhexidine, CPC, essential oil/herbal mouth rinses, povidone-iodine and boric acid in comparison to no rinsing, or rinsing with water, saline (salt water) or another mouth rinse. None of the studies measured how often dental healthcare providers became infected with micro‐organisms. All the included studies measured the level of bacterial contamination in droplets or aerosols in the dental clinic. They did not examine contamination with viruses or fungi. 

Most rinses decreased bacterial contamination in aerosols to some extent, but there was considerable variation in the effects and we do not know what size of a reduction is necessary to reduce infection risk. 

The studies did not provide any information on costs, changes in micro‐organisms in the patient's mouth or side effects such as temporary discolouration, altered taste, allergic reaction or hypersensitivity. The studies did not assess whether patients were happy to use a mouth rinse or whether it was easy for dentists to implement. 

Overall, the results suggest that using a preprocedural mouth rinse may reduce the level of bacterial contamination in aerosols compared with no rinsing or rinsing with water, but we have only low or very low certainty that the evidence is reliable and we do not know how this reduction in contamination relates to the risk of infection.

What does this mean?

We have very little confidence in the evidence, and further studies may change the findings of our review. No studies measured infection risk or investigated viral or fungal contamination. 

How up‐to‐date is this review?

The evidence in this Cochrane Review is current until February 2022.

Read the full review.

Kumbargere Nagraj S, Eachempati P, Paisi M, Nasser M, Sivaramakrishnan G, Francis T, Verbeek JH. Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers. Cochrane Database of Systematic Reviews 2022, Issue 8. Art. No.: CD013826. DOI: 10.1002/14651858.CD013826.pub2