Reduction of microbial concentration in the air of dental operating rooms. I. High-efficiency particulate air filters

The implementation of portable air-cleaning technologies in healthcare settings - a scoping review

The COVID-19 pandemic revealed opportunities to improve prevention practices in healthcare settings, mainly related to the spread of airborne microbes (also known as bioaerosols). This scoping review aimed to map methodologies used to assess the implementation of portable air cleaners in healthcare settings, identify gaps, and propose recommendations for future research. The protocol was registered in the Open Science Framework and reported following the checklist provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis - an extension for Scoping Reviews (PRISMA-ScR) statement. The search strategy was performed in five databases and one grey literature source. At the last selection phase, 24 articles that fulfilled our inclusion criteria were summarized and disseminated. Of these, 17 studies were conducted between 2020 and 2022; one of them was a protocol of a multicentre randomized controlled trial. The outcomes measured among the studies include airborne microbe counts, airborne particle concentrations, and rate of infections/interventions. The leading healthcare settings assessed were dental clinics (28%), patient's wards (16%), operating rooms (16%), and intensive care units (12%). Most of the devices demonstrated a significant potential to mitigate the impact of bioaerosols. Although some indoor air quality parameters can influence the mechanics of aerosols, only a few studies controlled these parameters in their analyses. Future clinical research should assess the rate of infections through randomized controlled trials with long-term follow-up and large sample sizes to determine the clinical importance of the findings.

The Usage of an Air Purifier Device with HEPA 14 Filter during Dental Procedures in COVID-19 Pandemic: A Randomized Clinical Trial

The aim of the present study was to evaluate the efficacy of an air purifier device (professional XXl inn-56 innoliving) with HEPA 14 filter in reducing the number of suspended particles generated during dental procedures as a vector of COVID-19 transmission. The survey was conducted on 80 individuals who underwent Oral Surgery with dental Hygiene Procedures, divided into two groups based on the operational risk classification related to dental procedures: a Test Group (with application of filtering device) and a Control Group (without filtering device). All procedures were monitored throughout the clinical controls, utilising professional tools such as molecular particle counters (Lasair III 350 L 9.50 L/min), bacteriological plates (Tryptic Soy Agar), sound meters for LAFp sound pressure level (SPL) and LCpk instantaneous peak level. The rate of suspended particles, microbiological pollution and noise pollution were calculated. SPSS software was used for statistical analysis method. The results showed the higher efficacy of the TEST Group on pollution abatement, 83% more than the Control fgroup. Additionally, the contamination was reduced by 69–80%. Noise pollution was not noticeable compared to the sounds already present in the clinical environment. The addition of PAC equipment to the already existing safety measures was found to be significantly effective in further microbiological risk reduction.

Ultrasonic scaling in COVID-era dentistry: A quantitative assessment of aerosol spread during simulated and clinical ultrasonic scaling procedures

Objective

Healthcare agencies recommend limited use of aerosol‐generating procedures to mitigate disease (COVID‐19) transmission. However, total dispersion patterns of aerosols, particularly respirable droplets, via dental ultrasonic units is unclear. The purpose of this study was to characterize and map total spatter, droplet and aerosol dispersion during ultrasonic scaling in simulated and clinical contexts.

Methods

Ultrasonic scaling was performed on dental simulation units using methylene blue dye‐stained water. All resultant stain profiles were photoanalysed to calculate droplet size and travel distance/direction. Airborne particle concentrations were also documented 0–1.2 m (0–4ft.) and 1.2–2.4 m (4–8ft.) from patients during in vivo ultrasonic scaling with a saliva ejector.

Results

Stain profiles showed droplets between 25 and 50µm in diameter were most common, with smaller droplets closer to the mouth. In‐vivo particle concentrations were uniformly low. The smallest (<1 µm, PM1) and largest (>10 µm, PM10+) particles were most common, especially within 1.2 m (4ft.) of the patient. Respirable particles (PM2.5) were uncommon.

Conclusions

Tests showed the highest concentration of small droplets in zones nearest the patient. While uncommon, particles were detected up to 2.4 m (8ft.) away. Furthermore, observed particle sizes were consistent with those that can carry infectious agents. Efforts to mitigate the spread of inhalable aerosols should emphasize proximate regions nearest the procedure, including personal protective equipment and the use of evacuation devices.

Methods to mitigate infection spread from aerosol-generating dental procedures

Infection control measures play a critical role in preventing the spread of disease in healthcare settings. Concerns that SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus that causes Coronavirus Disease 2019, may be transmitted through droplets and aerosols from both symptomatic and asymptomatic individuals has turned the spotlight on healthcare interventions that involve aerosol generation in the oral cavity, such as many dental and periodontal procedures. This commentary seeks to familiarize the dental practitioner with various infection control methods that may be implemented to mitigate spread of infection in dental settings through aerosol-generating dental procedures.

Effects of mechanical ventilation and portable air cleaner on aerosol removal from dental treatment rooms

Objectives

To evaluate the mechanical ventilation rates of dental treatment rooms and assess the effectiveness of aerosol removal by mechanical ventilation and a portable air cleaner (PAC) with a high-efficiency particulate air (HEPA) filter.

Methods

Volumetric airflow were measured to assess air change rate per hour by ventilation (ACH_vent). Equivalent ventilation provided by the PAC (ACH_pac) was calculated based on its clean air delivery rate. Concentrations of 0.3, 0.5 and 1.0 μm aerosol particles were measured in 10 dental treatment rooms with various ventilation rates at baseline, after 5-min of incense burn, and after 30-min of observation with and without the PAC or ventilation system in operation. Velocities of aerosol removal were assessed by concentration decay constants for the 0.3 μm particles with ventilation alone (K_n) and with ventilation and PAC (K_n+pac), and by times needed to reach 95 % and 100 % removal of accumulated aerosol particles.

Results

ACH_vent varied from 3 to 45. K_n and K_n+pac were correlated with ACH_vent (r = 0.90) and combined ACH_total (r = 0.81), respectively. Accumulated aerosol particles could not be removed by ventilation alone within 30-min in rooms with ACH_vent<15. PAC reduced aerosol accumulation and accelerated aerosol removal, and accumulated aerosols could be completely removed in 4 to 12-min by ventilation combined with PAC. Effectiveness of the PAC was especially prominent in rooms with poor ventilation. Added benefit of PAC in aerosol removal was inversely correlated with ACH_vent.

Conclusions

Aerosol accumulation may occur in dental treatment rooms with poor ventilation. Addition of PAC with a HEPA filter significantly reduced aerosol accumulation and accelerated aerosol removal.

Clinical significance

Addition of PAC with a HEPA filter improves aerosol removal in rooms with low ventilation rates.

Dental Risks and Precautions during COVID-19 Pandemic: A Systematic Review

OBJECTIVE

To provide dentists and dental team with insights concerning risk and precautions during COVID-19 outbreak crisis as it would help in decision making among dental community.

MATERIALS AND METHODS

A comprehensive review of all English and non-English articles was carried out using the available CORD-19 dataset with MEDLINE via PubMed, Cochrane library, Google Scholar and ScienceDirect databases. The study included all articles that matched the search terms.

RESULTS

A total of 353 were retrieved, of which 13 articles were reviewed comprehensively. Studies included in this systematic review emphasized on reinforcing strict infection control measures and minimizing human-to-human contact during COVID-19 outbreak. All surfaces in operatory room including waiting area need adequate ventilation and disinfection. Dental patients need to be screened using COVID-19 targeted questions as well as measuring their body temperature. Restricting dental treatments to only emergency cases and rescheduling all routine visits is advised with careful attention to minimize aerosol generation and following highest level of personal protection when treating COVID-19 confirmed cases. Dental offices need to establish a standard protocol of case reporting and referral to other well-prepared facilities. Lastly, online platforms are beneficial tools in providing psychological support to distressed dentists, dental team and dental patients and educating public during COVID-19 crisis.

CONCLUSION

Dental team need to follow strict infection control measures and minimize aerosol generation during COVID-19 outbreak. It is the responsibility of dental care workers to keep themselves informed and ensure safety and control transmission within dental facilities. Further research is required.

Bacterial aerosols in the dental clinic: a review

A number of sources of bacterial aerosols exist within and outside the dental clinic. The concentration of bacterial aerosols and splatters appears to be highest during dental procedures, especially those generated by some procedures such as ultrasonic scaling, or using a high speed drill. Several infectious diseases could be transmitted to staff and patients by airborne bacterial and other contaminants in the dental clinic. Air-conditioning and ventilation systems should be regularly maintained to reduce environmental contaminants and to prevent recirculation of bacterial aerosols. Pre-procedural rinsing by patients with mouthwashes as well as vacuum and electrostatic extraction of aerosols during dental procedures could also be employed. Dental staff should also consider appropriate immunizations and continue to use personal protective measures, which reduce contact with bacterial aerosols and splatters in the dental clinic.

Bacterial aerosols in the dental clinic: effect of time, position and type of treatment

OBJECTIVES

The objectives of this study were to investigate changes in the concentration of total bacterial aerosols before, during, and after the working period at different positions within the same multichair dental clinics. Also to investigate the contribution to total bacterial aerosols, if any, of the aerosols generated from different types of dental procedures, as well as the environment.

METHODS

Air sampling using a Slit-to-Agar air sampler at three positions in a multichair dental clinic, performed three times per day over a three week period before work, during work and after work. The second part of the study, in another multichair dental clinic, was performed before working and during three types of dental procedures.

RESULTS

The concentration of total bacterial aerosols and Bacillus sp. in air which circulated in the dental clinic was lower at the end of the day than at the beginning. There was no significant change in the concentration of total bacterial aerosols in different positions in the dental clinic or after the three types of dental treatments. The concentration of Bacillus sp. in air not mainly generated during dental procedures and which may come from an environmental source, was reduced.

CONCLUSIONS

This study suggests that the proportions of different types of bacteria in air may change before, during and after dental treatment. Preventive measures may need to be instituted to reduce build up of bacterial aerosols in the dental clinic during non-working periods.

The effectiveness of an aerosol reduction device for ultrasonic scalers

Intraoral use of ultrasonic scalers may generate aerosols that contain infectious microorganisms and therefore pose a hazard to the health of the dental professional. The purpose of this in vivo study was to determine if an aerosol reduction device for an ultrasonic scaler would be effective in reducing the amount of contaminated aerosols produced during ultrasonic instrumentation. Twelve adult subjects participated in the study. A split-mouth design was utilized, and two treatments (in separate rooms) were performed on each subject: 1) ultrasonic scaling for 5 minutes with the aerosol reduction device; and 2) ultrasonic scaling for 5 minutes without the aerosol reduction device. The right or left side of the subject's mouth was randomly assigned to one of the two treatment groups. After instrumentation, the subject and operator remained motionless for 25 minutes during collection of aerosol particles. Air samples were collected on blood agar plates 6 inches from the subject's mouth. Replicate organism detection and counting plates were used to sample microorganisms present on the investigator's face shield. All plates were incubated for 3 days at 37 degrees C. The results, using the paired t-test (P < 0.001), indicate that the ultrasonic scaler without the aerosol reduction device had a significantly greater quantity of mean colony forming units (CFUs) 6 inches from the subject's mouth (45.1 +/- 28.9) than the ultrasonic scaler with the aerosol reduction device (2.6 +/- 3.6). No significant difference was evident in the number of CFUs found on the investigator's face shield. These data suggest that an aerosol reduction device is effective in reducing the number of microorganisms generated during ultrasonic scaling, therefore decreasing the risk of disease transmission.

The efficacy of the rubber dam as a barrier to the spread of microorganisms during dental treatment

This study evaluated the rubber dam as an infection control barrier during standard restorative procedures. Microbial collection was performed during preparation and placement of amalgam and composite resin restorations with and without the rubber dam, and during handpiece and air-water syringe spraying with and without the rubber dam. The results showed a significant reduction in microorganisms with the use of the rubber dam--70% to 88% and 95% to 99%, respectively; and 90% to 98% when all data were combined. These results indicate that using the rubber dam is a method of reducing microbial contamination at the primary source. Used with gloves, mask, and protective eyewear, the rubber dam provides an excellent barrier to the potential spread of infectious disease in the dental office.