Efficacy of personal protective equipment against coronavirus transmission via dental handpieces

Aerosol-generating procedures and associated control/mitigation measures: Position paper from the Canadian Dental Hygienists Association and the American Dental Hygienists' Association

Background

Since the outbreak of COVID-19, how to reduce the risk of spreading viruses and other microorganisms while performing aerosolgenerating procedures (AGPs) has become a challenging question within the dental and dental hygiene communities. The purpose of this position paper is to summarize the evidence of the effectiveness of various mitigation methods used to reduce the risk of infection transmission during AGPs in dentistry.

Methods

The authors searched 6 databases-MEDLINE, EMBASE, Scopus, Web of Science, Cochrane Library, and Google Scholar-for relevant scientific evidence published between January 2012 and December 2022 to answer 6 research questions about the risk of transmission, methods, devices, and personal protective equipment (PPE) used to reduce contact with microbial pathogens and limit the spread of aerosols.

Results

A total of 78 studies fulfilled the eligibility criteria. The literature on the risk of infection transmission including SARS-CoV-2 between dental hygienists and their patients is limited. Although several mouthrinses are effective in reducing bacterial contaminations in aerosols, their effectiveness against SARS-CoV-2 is also limited. The combined use of eyewear, masks, and face shields is effective in preventing contamination of the facial and nasal region while performing AGPs. High-volume evacuation with or without an intraoral suction, low-volume evacuation, saliva ejector, and rubber dam (when appropriate) have shown effectiveness in reducing aerosol transmission beyond the generation site. Finally, the appropriate combination of ventilation and filtration in dental operatories is effective in limiting the spread of aerosols.

Discussion and Conclusion

Aerosols produced during clinical procedures can pose a risk of infection transmission between dental hygienists and their patients. The implementation of practices supported by available evidence will ensure greater patient and provider safety in oral health settings. More studies in oral health clinical environments would shape future practices and protocols, ultimately to ensure the delivery of safe clinical care.

High-volume evacuation mitigates viral aerosol spread in dental procedures

Dental healthcare personnel (DHCP) are subjected to microbe-containing aerosols and splatters in their everyday work. Safer work conditions must be developed to ensure the functioning of the healthcare system. By simulating dental procedures, we aimed to compare the virus-containing aerosol generation of four common dental instruments, and high-volume evacuation (HVE) in their mitigation. Moreover, we combined the detection of infectious viruses with RT-qPCR to form a fuller view of virus-containing aerosol spread in dental procedures. The air-water syringe produced the highest number of aerosols. HVE greatly reduced aerosol concentrations during procedures. The air-water syringe spread infectious virus-containing aerosols throughout the room, while other instruments only did so to close proximity. Additionally, infectious viruses were detected on the face shields of DHCP. Virus genomes were detected throughout the room with all instruments, indicating that more resilient viruses might remain infectious and pose a health hazard. HVE reduced the spread of both infectious viruses and viral genomes, however, it did not fully prevent them. We recommend meticulous use of HVE, a well-fitting mask and face shields in dental procedures. We advise particular caution when operating with the air-water syringe. Due to limited repetitions, this study should be considered a proof-of-concept report.

Efficacy of Surgical Masks Versus N95 Respirators for the Prevention of COVID-19 in Dental Settings: A Systematic Review

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2. (SARS-CoV-2). It spreads mainly through saliva droplets or nasal discharge. Dentists are among the professionals with the greatest risk of contracting and transmitting COVID-19. We compared the efficacy of surgical masks versus N95 respirators in preventing COVID-19 infection in dental settings. PubMed, Scopus, Web of Science, and Cochrane Library databases were searched. Search terms corresponded to a predefined PICOS (patient/population, intervention, comparison, and outcomes) question. The risk of bias was evaluated using AMSTAR-2 (A Measurement Tool to Assess Systematic Reviews-2), ROBIS (Risk of Bias in Systematic Reviews), and Health Evidence tools. A total of 191 articles were screened, and nine of them were further evaluated for eligibility, of which five articles (fulfilled the selection criteria) and were included in this study. Two studies concluded that surgical masks could provide equivalent protection to N95 respirators. Another study found that N95 respirators were superior to surgical masks. The fourth study found that better protection can be achieved when using surgical masks by the aerosol source than when the recipient uses an N95 respirator, while the last study concluded that surgical masks or N95 respirators alone do not provide full protection. Thus, according to this systematic review, N95 respirators provide better protection against COVID-19 infection compared to surgical masks.

Efficacy of mouthrinses in reducing oral SARS-COV-2 load: a review

Accumulated evidence has shown that the oral cavity may be an important reservoir for SARS-CoV-2. Some authors have suggested that the use of mouthrinses could reduce SARS-CoV-2 viral load in the saliva. Thus, the aim of this review was to synthesize evidence about the efficacy of mouthrinses in reducing the salivary viral load of SARS-CoV-2. 2. Nine randomized controlled trials (RCTs) have investigated the efficacy of different mouthrinses in reducing salivary SARS-CoV-2 loads. Various active ingredients have been tested in these trials: 0.5%,1% and 2% povidone-iodine, 0.2% and 0.12% chlorhexidine (CHX), 0.075% cetylpyridinium chloride (CPC), 0.075% CPC with Zinc lactate, 1% and 1.5% hydrogen peroxide (HP), 1.5% HP + 0.12% CHX and ß-cyclodextrin and citrox. The studies reported an intra-group reduction in the salivary levels of the virus, when compared with the baseline. However, the majority of these trials failed to demonstrate a significant inter-group difference between active groups and the control group relative to the decrease in salivary SARS-CoV-2 loads. Although promising, these results should be confirmed by larger trials.

Bioburden Variation of Filtering Face Piece Respirators over Time: A Preliminary Study

BACKGROUND

The microbial contamination of a respirator can be evaluated through a count of the number of bacteria living on a non-sterilized surface (bioburden). This preliminary study investigated the external contamination of two different FFP2s over time by studying the bioburden values in increasing exposure times.

METHODS

FFP2 respirators of two different brands were used during routine clinical settings and examined through the bioburden test; for each brand, three devices were tested at 8, 16, and 30 h.

RESULTS

No significant differences were observed between mask brands (p = 0.113). There were only significant CFU differences between each mask and its control (p = 0.027 and p = 0.004).

CONCLUSIONS

Both brands of respirators were found to be contaminated and this contamination increased with the increase in exposure time. Further studies are needed to investigate the exact amount of contamination that could be considered acceptable before discarding each used mask.

Coronavirus outbreaks and infection prevention in dentistry: a narrative review

OBJECTIVE

This narrative review aims to compile and analyse infection prevention and control (IPAC) practices followed by dental clinics during 3 coronavirus outbreaks: SARS (2002-2004), MERS (2012-2014), and COVID-19 (2019-); and to draw parallels from them for future epidemics.

METHODS

Data were collected from 3 databases: Google Scholar, PubMed, and Embase using search terms "SARS," "MERS," "COVID-19," "infection control," "disinfection," and "sterilization".

RESULTS

Careful examination of 108 peer-reviewed articles on the 3 outbreaks revealed the following commonalities in the IPAC practices of dental clinics: use of sodium hypochlorite (surface disinfectant), ethanol and 1-propanol (hand hygiene), povidone-iodine (oral rinse), high-volume evacuation (HVE), rubber dam isolation, anti-retraction handpieces, and fogging.

DISCUSSION & CONCLUSION

Ethanol, 1-propanol, sodium hypochlorite, povidone-iodine, photocatalysis, and fogging have been shown to be effective against various coronaviruses. However, more studies are required to validate the effectiveness of anti-retraction handpieces, rubber dam isolation, HVE, and cold atmospheric plasma specifically in infection control of the current coronavirus strain, SARS-CoV-2.

Assessment of dental health care personnel protocol deviations and self-contamination during personal protective equipment donning and doffing

Background

Dental health care personnel (DHCP) may be at increased risk of exposure to severe acute respiratory syndrome coronavirus 2, the virus that causes COVID-19, as well as other clinically important pathogens. Proper use of personal protective equipment (PPE) reduces occupational exposure to pathogens. The authors performed an assessment of PPE donning and doffing practices among DHCP, using a fluorescent marker as a surrogate for pathogen transmission.

Methods

Participants donned PPE (that is, disposable gown, gloves, face mask, and eye protection) and the fluorescent marker was applied to their palms and abdomen. DHCP then doffed PPE according to their usual practices. The donning and doffing processes were video recorded, areas of fluorescence were noted, and protocol deviations were assessed. Statistical analyses included frequency, type, and descriptions of protocol deviations and factors associated with fluorescence.

Results

Seventy DHCP were enrolled. The donning and doffing steps with the highest frequency of protocol deviations were hand hygiene (66% of donning and 78% of doffing observations involved a deviation) and disposable gown use (63% of donning and 60% of doffing observations involved a deviation). Fluorescence was detected on 69% of DHCP after doffing, most frequently on hands. An increasing number of protocol deviations was significantly associated with increased risk of fluorescence. DHCP with a gown doffing deviation, excluding doffing out of order, were more likely to have fluorescence detected.

Conclusions

DHCP self-contamination was common with both donning and doffing PPE.

Practical Implications

Proper use of PPE is an important component of occupational health.

Oral Manifestations of COVID-19 in Hospitalized Patients: A Systematic Review

Background: COVID-19 disease first appeared in 2019 and quickly spread worldwide, causing a global pandemic. The oral cavity represents a target of SARS-CoV-2, and oral lesions are observed in both non-hospitalized and hospitalized patients. This systematic review aims to investigate the frequency of oral manifestations in COVID-19 hospitalized patients. Methods: An electronic search was conducted in PubMed, Scopus, and Web of Science databases, including articles published up to September 2021. The review protocol was based on PRISMA-P. The risk of bias of the studies was assessed using the Joana Briggs Institute. The certainty of evidence was assessed using the GRADE instrument. Results: Fifty-nine articles were included: 19 case reports, 17 case series, 2 case-control studies, 13 cross-sectional studies, 4 observational studies, and 4 retrospective studies. Oral ulcers, cheilitis, and tongue lesions were more common in patients before hospitalization, while perioral pressure ulcers, macroglossia, blisters, and oral candidiasis were more recurrent in patients during hospitalization. The first could be related directly to COVID-19, while the latter could be caused by medical devices, treatments, prone position, and immunological impairment. Conclusions: An accurate oral examination during the hospital admission of all confirmed COVID-19 cases is encouraged to recognize oral early manifestations and to apply appropriate treatments.

The Spread of Droplets and Aerosols of Surgical Motor Handpiece Irrigation Using Different Suction Systems

Objective: This study aimed to compare the effectiveness of various combinations of dental suction devices in reducing the amount and distance of spread of aerosols and droplets using an electrical surgical motor model with a self-irrigation system.

Materials and Methods: In a standard single-chaired air-conditioned ventilated dental clinic, an electrical dental surgical motor with a high-speed handpiece (Implantmed) cooled with 0.2% fluorescein containing normal saline was used to drill a gypsum block mounted on a phantom head in a supine position. A single operator performed thrice each of the following suction settings: (a) no suction, (b) low-volume suction, (c) low-volume + high-volume suctions, and (d) low-volume + external oral suctions. Aerosols (0.1–5 μm) were measured with a particle counter at the mouth opening of the phantom head, and droplet sizes and distances were analyzed via a machine learning algorithm by identifying fluorescence droplets on pre-loaded pieces of paper on the floor for each group.

Results: The different suction systems have different performances in terms of droplet distance (p = 0.007), whereas using (c) high volume suctions (41.1 ± 22.9 cm) and (d) external oral suction unit (39 ± 18.2 cm) had significantly reduced the spread of droplets when compared with (a) without suction (58.9 ± 17.1 cm). Using (d) external oral suction or (c) high volume suction could reduce the number for all droplet sizes. The use of (c) high volume suction was most effective in reducing aerosol count of 0.3–1 μm, while (d) external oral suction was most effective in reducing aerosol count of 3–5 μm.

Conclusions: Both external oral suction and high-volume suction were effective in reducing aerosols and droplets generated by the irrigation of a surgical high-speed motor handpiece. External oral suction could be an effective alternative to high volume suction in dental surgical procedures to reduce the spread of aerosols and droplets.

Clinical Relevance: External oral suction or high-volume suction should be used in conjunction with low-volume suction in surgical procedure to reduce the spread of aerosols and droplets in a dental clinic environment.