Use of Preprocedural Rinses to Reduce Risk of Dental Aerosols

It should be no surprise that in the midst of the COVID-19 pandemic infection prevention in the delivery of safe care is top of mind for practitioners and patients. To protect dental staff and patients, all team members should have a strong grasp of asepsis protocols meant to prevent disease transmission — including preventive measures designed to minimize risk of exposure to dental aerosols and SARS-CoV-2. This includes the use of preprocedural mouthrinses to reduce the patient’s oral microbial load prior to treatment.¹

Contaminated aerosols create a potential route of infection for arboviruses, alphaviruses, coronaviruses and influenza type B.² Generally speaking, the production of aerosols is inevitable in routine dental care. While treating patients, clinicians are exposed to aerosols during restorative treatment, many forms of periodontal therapy, prophylaxis, and a host of other procedures involving low- or high-speed handpieces, as well as sonic and ultrasonic instruments that use compressed air and water — all of which generate aerosols.

The highest concentration of dental aerosols has been found 1 to 2 feet from the patient’s mouth, which is precisely the clinician’s work area.³ Saini⁴ compared general dental procedures with dental hygiene procedures and found that dental hygiene treatment produced higher microbial aerosol concentrations. The study also found that ultrasonic scaling yielded more aerosol production and potential for disease transmission than caries preparation performed by a dentist and dental assistant. As such, the U.S. Centers for Disease Control and Prevention (CDC) recommends clinicians avoid using aerosol-generating techniques — such as high-speed handpieces, air/water syringes and ultrasonic scalers — and to focus on the use of hand instruments during the COVID-19 pandemic.⁵

Reduce Aerosol Risk

Dental patients can transmit viruses and bloodborne or respiratory pathogens through spatter, droplets and aerosols to other patients and dental staff.⁶ Ideally, patients with COVID-19 would refrain from elective dental treatment until medically cleared, but individuals may be asymptomatic or simply unaware they are infected. Besides avoiding the use of aerosol-generating procedures, following the standard asepsis precautions for oral health professionals established by the CDC is key to minimizing the production and transmission of aerosols. The CDC defines standard precautions as “the minimum infection prevention practices that apply to all patient care, regardless of suspected or confirmed infection status of the patient, in any setting where healthcare is delivered.”⁷

The first step in reducing aerosol risk is the proper use of personal protective equipment (PPE): wearing a surgical mask within 1 meter of the patient; donning a gown, gloves and eye protection upon entering the room; and removing all equipment upon exiting the room.⁸ Next is using equipment designed to control aerosols, such as high-volume evacuation, which has been shown to reduce aerosols by 89.7% to 90.8%.³ Lastly, the use of a preprocedural mouthrinse may reduce contaminated aerosol production up to 94.1%.^1,6

Role of Preprocedural Rinsing

As noted, the goal of having patients rinse with an antimicrobial agent immediately prior to dental treatment is to reduce the microbial load in the oral cavity. While there is no evidence supporting the effectiveness of preprocedural rinsing in preventing SARS-CoV-2 infection, the ability of some therapeutic ingredients to decrease transmission of pathogens suggests there may be efficacy in reducing the presence of the novel coronavirus in dental aerosols.⁹

Several mouthrinse ingredients are bactericidal and bacteriostatic. Mouth­rinses with chlorhexidine gluconate (CHX) and essential oils can rapidly reduce the level of pathogenic bacteria found in dental aerosols.² Agents such as ozonated water, CHX and essential oils are also capable of exerting significant antiviral effects against herpes simplex virus, human immunodeficiency virus, and influenza.²

Extensive research supports CHX as the gold standard in preprocedural mouthrinses.^10–12 In patients who rinse with CHX prior to dental treatment, the antimicrobial properties of CHX are activated as soon as dental aerosols are generated.⁴ Essential oils, such as eucalyptol, menthol, methyl salicylate and thymolpopular, are also effective agents in preprocedural mouthrinses.¹³ Patients who rinse with essential oils for 30 seconds prior to dental treatment experience a reduction in viral contamination for up to 60 minutes.²

Cetylpyridinium chloride (CPC), chlorine dioxide (ClO₂), povidone-iodine, and hydrogen peroxide have all been studied for their efficacy in reducing the bacterial or viral loads in contaminated aerosols.⁴ In a comparison study of CHX and ClO₂, the ClO₂ rinse was equally effective to CHX in its ability to decrease contamination in aerosols.⁴ Similarly, results from a study comparing a mouth­rinse containing CPC, zinc lactate and sodium fluoride with a CHX mouthrinse found the CPC rinse was equally effective to CHX in reducing bacterial contamination in aerosols.¹⁴ Additionally, CPC has been shown to reduce the volume of pathogenic bacteria produced during high-speed instrumentation.¹⁴

Povidone-iodine exhibits high levels of antiviral activity in mouthrinse, and has shown similar efficacy to CHX.^15,16 SARS-CoV-2 is contained within a lipid membrane, and research demonstrates that povidone-iodine can penetrate this membrane, reducing the potential for transmission.¹⁷ Another alternative is hydrogen peroxide. A study comparing the anti-gingivitis effects of CHX and hydrogen peroxide found that at levels above 1% hydrogen peroxide yields several beneficial effects, including antimicrobial effects on bacteria, yeasts, fungi, viruses and spores.¹⁸

Alternative Uses

Although therapeutic mouthrinses are generally  used pre- and postprocedurally, investigations into alternative uses are emerging. When it comes to essential oils, preprocedural rinsing used in conjunction with preprocedural subgingival irrigation has proven to significantly decrease the level of bacteremia associated with subgingival ultrasonic scaling.² Moreover, as ultrasonic use (at least prior to the pandemic) was ubiquitous in dental settings, using mouthrinses as ultrasonic coolants may help reduce pathogen levels. For instance, cinnamon within the essential oil cinnamaldehyde has antibacterial, anti-inflammatory and antifungal properties.² Although research proving cinnamon’s efficacy as a bacteriostatic or bactericidal preprocedural mouthrinse ingredient is limited, a study did show that when used as an ultrasonic device coolant, dental aerosol contamination was significantly reduced.¹⁹

Conclusion

During the COVID-19 pandemic and beyond, all infection prevention precautions should be maintained and executed at the highest level to not only protect patients, but also oral health professionals. The use of antimicrobial preprocedural mouthrinse may help promote a safe work environment and reduce the transmission of oral pathogens.

Key Takeaways

• All dental team members should have a strong grasp of asepsis protocols meant to limit disease transmission — including preventive measures designed to minimize risk of exposure to dental aerosols and SARS-CoV-2.
• Preventive strategies might include the use of preprocedural mouthrinses to reduce the patient’s oral microbial load prior to treatment.¹
• To help reduce aerosols, the U.S. Centers for Disease Control and Prevention recommends clinicians avoid using aerosol-generating techniques — such as high-speed handpieces, air/water syringes and ultrasonic scalers — and to focus on the use of hand instruments during the COVID-19 pandemic.⁵
• That said, the production of aerosols is intrinsic to many procedures performed during routine dental care.
• While there is no evidence supporting the effectiveness of preprocedural rinsing in preventing SARS-CoV-2 infection, the ability of some therapeutic ingredients to decrease transmission of pathogens suggests there may be efficacy in reducing the presence of the novel coronavirus in dental aerosols.⁹

References

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2. Walsh LJ. Antiviral and antibacterial effects of preprocedural mouthrinses. Australasian Dental Practice. 2011;22(4):112–118.
3. Akanksha S, Shiva Manjunath RG, Deepak S, et al. Aerosol, a health hazard during ultrasonic scaling: a clinico-microbiological study. Indian J Dent Res. 2016;27:160–162.
4. Saini R. Efficacy of preprocedural mouth rinse containing chlorine dioxide in reduction of viable bacterial count in dental aerosols during ultrasonic scaling: a double-blind, placebo-controlled clinical trial. Dental Hypotheses. 2015;6(2):65–71.
5. U.S. Centers for Disease Control and Prevention. Guidance for Dental Settings. Available at: https://www.cdc.gov/coronavirus/2019-ncov/hcp/dental-settings.html. Accessed November 10, 2020.
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15. Imran E, Khurshid Z, Al Qadhi AA, Al-Quraini AA, Tariq K. Preprocedural use of povidone-iodine mouthwash during dental procedures in the COVID-19 pandemic. Eur J Dent. 2020;10. Epub ahead of print.
16. Kariwa H, Fujii N, Takashima I. Inactivation of SARS coronavirus by means of povidone-iodine, physical conditions and chemical reagents. Dermatology. 2006;212(Suppl 1):119–123.
17. Bidra AS, Pelletier JS, Westover JB, Frank S, Brown SM, Tessema B. Rapid in-vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using povidone-iodine oral antiseptic rinse. J Prosthodont. 2020;29:529–533.
18. Rashed HT. Evaluation of the effect of hydrogen peroxide as a mouthwash in comparison with chlorhexidine in chronic periodontitis patients: a clinical study. J Int Soc Prev Community Dent. 2016;6:206–212.
19. Sethi K, Mamajiwala A, Mahale S, Raut C, Karde P. Comparative evaluation of the chlorhexidine and cinnamon extract as ultrasonic coolant for reduction of bacterial load in dental aerosols. J Indian Soc Periodontol. 2019;23:226–233.

From Decisions in Dentistry. December 2020;6(11): 8,10.