Australian Dental Perspectives

The aerosolisation of oral microbes which occurs during certain dental procedures can potentially result in cross contamination of equipment and transmission of bacteria to dental professionals and their patients.1

The topic of preprocedural rinsing to prevent aerosol transmission has been the source of much debate and discussion by the dental profession, with opinion divided over the necessity of the practice and the benefits derived for patients and dentists alike.

At the last meeting of the PDF, Ms Mary Beare, provided an overview of the recent literature which suggests that antimicrobial mouthrinses may potentially help reduce the risk of cross-contamination when used prior to aerosol-generating procedures.

It is the use of ultrasonic scalers and backsprays associated with air turbine handpieces, combined with poor air filtration, that produce significant amounts of aerosolised microbes. Ms Beare commenced by outlining the three options currently available to reduce aerosol:

1. Hand scaling
2. An aerosol reduction device
3. Preprocedural rinsing

Ms Beare stated there were limitations with both hand scaling and the use of an aerosol reduction device. Hand scaling involves a significant level of physical effort from the dental professional and can quickly become tiring, while the use of an aerosol reduction device requires an assistant for the hygienist, an option not available or practicable in all dental surgeries. As such, Ms Beare pointed out that preprocedural rinsing should be considered a viable option for the reduction of aerosol.

A study published in the Journal of Periodontology by Fine et al examined the efficacy of preprocedural rinsing with an antiseptic mouthwash to reduce aerosol transmission of bacteria. The double-blind, controlled, cross-over clinical study examined eighteen subjects who received a 10-minute ultrasonic scaling on one half of their mouth (which served as an unrinsed control) and then rinsed with either an antiseptic or control rinse.

Rinsing with an antiseptic mouthwash produced a 94.1 per cent reduction in bacteria compared to those who did not rinse, while the control rinse produced a 33.9 per cent reduction.¹ The authors concluded that pre-procedural rinsing with an antiseptic mouthwash could reduce the bacteria content of aerosols produced during ultrasonic scaling and could be used as part of an in-surgery infection control regime.¹

Fine et al also published a controlled clinical study in the Journal of the American Dental Association in 1996, which examined the effect of subgingival irrigation and rinsing with an antiseptic mouthwash, (Cool Mint Listerine) before ultrasonic scaling of a quadrant containing inflamed gingiva. The results showed that preprocedural subgingival irrigation and rinsing can significantly reduce the level of bacteremia associated with ultrasonic scaling.² Overall, the antiseptic mouthrinse resulted in aerobic counts that were 92.3% lower than the control rinse, and anaerobic counts that were 87.8% lower.²

Ms Beare asked "What does this mean to the dental professional?" Barrier techniques such as mask and gloves are not enough protection from viruses. When an ultrasonic scaler or air rotor handpieces are used, the microbe-laden aerosol stays in the dental operatory environment for up to 30 minutes. Ms Beare suggested an easy, 30 second preprocedural rinse with Listerine antiseptic mouthwash or a 60 second rinse with Chlorhexidine is a low cost procedure to get a reduction of aerosolised microbes.

Following Ms Beare's presentation, the PDF members debated whether preprocedural rinsing is really necessary, with some arguing there are bacteria present at all times and in all locations, not just in the dental surgery. However, it was agreed that it is a well known occupational risk that dental professionals are continually exposed for approximately 8 hours every day to a particularly high level of microbes in their surgeries, and that therefore, rinsing is a worthwhile exercise for risk management.

Dental professionals are 10 times more likely to get exposed to rhinovirus and adenovirus. These are lipid, enveloped viruses which are easily destroyed by a 30 second rinse with Listerine. Often, when the patient is most infectious, they will not be aware they have the virus. PDF members considered the cost to the dental business with having a staff member off sick for even one day, compared to preprocedural rinsing.

Members agreed the studies by Fine et al showed good, evidence-based results to support the case for preprocedural rinsing.

The group also noted that these studies showed strong results with an antiseptic mouthwash in particular. They agreed Listerine is quick and is as effective to use as Chlorhexidine. It also offers a wider spectrum of microbial kill.

Consensus was reached that dental professionals should promote the practice as a personal hygiene method for the risk management benefit of the dental professional rather than infection control, as there is limited evidence of cross contamination in the dental operatory.

1. Fine, D.H. et al. Efficacy of Preprocedural Rinsing with an Antiseptic in Reducing Viable Bacteria in Dental Aerosols. J Periodontol 1992; 63:821-824.
2. Fine, D.H. et al. Assessing Pre-Procedural Subgingival Irrigation and Rinsing with an Antiseptic Mouthrinse to Reduce Bacteremia, JADA 1996; 127: 641-646.