Journal of International Oral Health

: 2020  |  Volume : 12  |  Issue : 8  |  Page : 64--68

Masks and respirators, selection criteria for periodontal therapy: Challenges for a periodontist during COVID-19

Sudhir Rama Varma 
 Department of Clinical Sciences, College of Dentistry, Ajman University, Ajman, UAE

Correspondence Address:
Dr. Sudhir Rama Varma
Department of Periodontics, College of Dentistry, Ajman University, Ajman


Coronavirus disease-2019 (COVID-19) has created a pandemic, which has upgraded most medical services across the globe to the level of emergency preparedness and the highest infection control measures. Use of personal protective equipment and masks along with respirators is possibly the only way to combat the spread and its use in areas where the personnel is in high-risk category offers a lifeline. This review aimed to examine, summarize the available evidence related to use of masks and respirators, and possibly provide a recommendation for the periodontist and dental fraternity as a whole. A literature search was conducted on the PubMed, PubMed Central, MEDLINE, and Embase databases with the keyword “surgical masks,” “COVID-19,” “Respirators,” “N95,” “health care worker,” “oral,” and “dental treatment.” Masks and respirators offer prevention and control of the spread of the pandemic. Respirators are found to be more effective than masks in the ability to prevent aerosol transmission to health care workers. More studies are needed to be carried out to evaluate efficacy and vital characteristics of the respirators available to rule out any possibility of breach caused either by noncompliance or otherwise. Although the virus transmission is caused by varied clinical presentations, the use of masks and respirators offers hope in reducing the risk of cross transmission both to the dentists and patients.

How to cite this article:
Varma SR. Masks and respirators, selection criteria for periodontal therapy: Challenges for a periodontist during COVID-19.J Int Oral Health 2020;12:64-68

How to cite this URL:
Varma SR. Masks and respirators, selection criteria for periodontal therapy: Challenges for a periodontist during COVID-19. J Int Oral Health [serial online] 2020 [cited 2021 May 14 ];12:64-68
Available from:

Full Text


Periodontal disease is a multifactorial disease with an established dysbiosis as a result of a compromised host-immune response. Treatment approaches for most of the periodontal conditions start with a nonsurgical phase and depending on the patient response, if required, surgical therapy is indicated. Challenges in performing basic periodontal treatment in the current scenario owing to coronavirus disease-2019 (COVID-19) pandemic are challenging and have implications for both the dental personnel and patients. Use of personal protective equipment (PPE) such as face masks has found to reduce infections by 85% in health-care settings.[1] The importance of masks in periodontal treatment is due to the use of ultrasonic as an initial mode of debridement which contributes to the generation of aerosols, which has been confirmed in various studies.[2],[3],[4] Both respirators and surgical masks have been recommended in high-risk category professions. Respirators such as N95 prevent inhaling aerosols and surgical masks prevent transmission.[5],[6],[7] Periodontal treatment is done on a close communicatory basis where the dentists lateralize the tongue in most positions to facilitate visibility and ease of instrumentation. The resultant reaction from the patient is initiating a cough that can cause projectile expulsion of aerosols in the surrounding environment increasing the risk of infecting the dental personnel, provided the patient is in an established state of viral infection or incubatory phase.[6] Conflicting recommendations by the World Health Organization (WHO) for health-care workers (HCWs) caring for suspect COVID-19 patients where using masks in low-risk cases and routine care and respirators in high-risk cases such as aerosol-generating procedure, whereas the Centers for Disease Control and Prevention (CDC) advocating use of respirators in both low-risk and high-risk situations has been intriguing.[8],[9] The use of face masks along with PPE has been decisive and offers optimal infection control measures for the dental personnel; the choice is confounded with new evidences related to mask efficiency and updation of technical parameters related to mask performances. This review is a validation of studies pertaining to performance of masks in a clinical setting and offers dental personnel performing periodontal treatment to make informed decisions.

 Materials and Methods

A literature search was conducted on PubMed, PubMed Central, MEDLINE, and Embase databases. The search was updated till June 2020 with keywords “surgical masks,” “COVID-19,” “Respirators,” “N95,” “health care worker,” “oral,” and “dental treatment.” Bibliographic search was also done. Articles from a period 2011 till May 2020 were selected. A total of 448 articles were screened, of which 32 articles were selected and are included in the reference list. All the literature was assessed for relevancy to be included in the narrative review.

From the studies selected, about 26 articles addressed masks and its efficacy with relation to prevention of transmissible diseases. The rest six articles addressed both prevention of transmission and evaluated particle expulsion trajectory, force calculation, mask dynamics such as flame spread, particulate filtration efficiency, and bacterial filtration efficiency (BFE).


Face mask specification factors

Face masks have evolved with the presence of newer communicable diseases such as SARS and MERS which have posed challenges to the dental personnel as there were limitations in delivering treatment.[10] The American Society for Testing and Standard Specification (ASTM) has evaluated masks based on four main categories:[11] first, fluid resistance––which is the ability of the mask to offer resistance to penetration by blood or body fluids, meaning higher fluid resistance means higher protection. Second, filtration efficiency––which is further categorized into BFE where bacterial particles are filtered at a size of 0.3 microns and particle filtration efficiency (PFE) where particles are filtered at a size of 0.1 microns. Third factor is breathability––which is categorized by the ability of the operator to breathe easily; it is normally labeled on the mask as Delta P; it denotes the pressure drop across a face mask and is expressed as pascal or mm H20/cm2. The higher the delta P, more is the difficulty to breathe through. Fourth factor is flame spread which measures the flame spread of the mask material. Depending on these four categories, masks can be selected depending on the procedures performed.[11] Recommendations of masks that can be used in select periodontal therapies along with its specifications have been provided in this review. This could be used as a guideline to ease operator efficiency [Table].

Face masks and types available

Masks have been further classified accordingly as surgical masks and respirators. Some of the masks commonly available are N95, FFP3, FFP2, Type 1 and 2 masks, and Type 1R and Type 2 R. The main difference between Type 1, Type 1R and Type 2 and Type 2R is the BFE where the former has a BFE of 95% and the latter has 98%. It is tested for exhalation (inside to outside).[10]

The FFP2 and FFP3 are categorized as respirators and are indexed as European class. Unlike Type 1, 1R and Type 2, 2R, they are tested for inspiration (outside to inside). In terms of filtration efficiency, that is, a 94% filtration percentage, they are equivalent to N95 and are recommended by the WHO for protecting the operator from viral transmission.[9],[10]

The FFP3 stands at the top of the hierarchy with relation to filtration efficiency at a percentage of 99%.[10] They offer the highest protection in terms of viral transmission. They are normally equipped with a valve, to decrease moisture buildup and increase lifespan of the mask.[10]

Standardization of masks

The regulations and standards operated by the United States of America (USA) and European countries are stringent and most countries have adopted these regulations as a sign of quality assessment.[10]

Medical or surgical masks in Europe are usually graded by three levels of BFE (BFE1, BFE2, and Type R), whereas in the US, grading is done with relation to fluid protection recommended by ASTM regulations and are graded according to three levels.[10]

Standardization for respirators in Europe includes three classes FFP1, FFP2, and FFP3. Respirators in the US should comply with the occupational safety and health administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) regulations.

A more interesting fact related to dental treatment is the use of masks, which could offer oil resistance. Some of the masks that offer oil resistance are Class R and P. The distinction between the two is that in Class R, the mask offers oil resistance for a period of 8h, masks are usually labeled as R95, R99, and R100, where the numerics correspondingly denote BFE. In Class P masks, it is a complete oil-resistant mask and like the R class. It is categorized as P95, P99, and P100[10] [Table 1].{Table 1}

Contributory data for type of mask compatible with periodontal treatment

Periodontal treatment involves use of ultrasonic and hand instrumentation where the risk of aerosol production and risk of saliva and blood splatter is high. Which mask provides superior protection is debatable.

Studies showing contradictory results taking into factors such as overall risk assessment, limited randomized clinical trials have been done, to evaluate the efficacy of these masks in relation to COVID-19, SARS, or MERS.[12],[13] Data from randomized trials and systematic reviews have extrapolated evidences to COVID-19 as a result of seasonal influenza.[14] Though use of masks curtails the spread of infection caused by SARS-COV-2 and betacoronaviruses such as SARS and MERS, it did not provide a significant reduction.[13] The use of mask has shown to reduce the transmissibility of SARS-CoV-2 while coughing.[15],[16] SARS-COV-2 have shown to be present in aerosols <5 µm in diameter and the use of surgical masks and respirators such as N95 have shown to reduce Influenza-like illness in HCWs.[17]

In terms of periodontal treatment, this is of significance when dealing with suspected or symptomatic patients. Moreover, the CDC has also proposed “cough etiquette” in healthcare settings and most importantly in dental clinics.[18] Masks worn by patients reduce the accumulation of infectious particles when coughing, sneezing, or talking. In terms of protection for the dental operator, surgical masks do not offer much respiratory functional advantages.[19] A pilot study found that only one in four patients were protected from respiratory conditions when comparing surgical mask against N95 respirators.[20] The use of N95 masks in dental settings has been highly advocated, its fluid resistance and filtration efficiency quotient is more superior when compared to other masks. It is mainly indicated for treating patients with tuberculosis and Influenza, and in recent times SARS, MERS, and more recently SARS-CoV-2.[21] N95 is currently recommended for HCWs who work within 2 m of patients. Effectiveness of N95 was also evaluated in another study involving subjects wearing N95 respirators exposed to live attenuated influenza vaccine strain; it was found to be 90% effective.[22],[23] One study has shown presence of viral pathogens on rough surfaces for 8–12h compared to smooth surfaces where its presence was seen for about 28h.[24] Another point to be considered by the dental operator is possibility of respirator contamination that can result in transmission to the operator.[25],[26] In one of the studies involving HCW in a randomized clinical trial, intermittent use of N95 was compared to continuous use over a time frame of one week and it was found that using N95 in a continuous model offered better protection for respiratory infection and this protection was present after adjusting lurking variables such as hand washing and vaccination for influenza.[27]

Studies have reported conflicting results with relation to the use of N95. In one study performed in an experimental model showed superior protection from viral respiratory infections by N95,[17] and in another study showed statistically insignificant relation over the use of N95 for protection against viral associated respiratory illnesses.[28]

N95 masks are associated with discomfort such as headache, excessive facial heat, itchy nose, and lacrimation and communication difficulties. This affects concentration in settings where the HCWs are expected to work in 12h shifts. Eczema and other dermatological problems arise and have been advertised in public media.[29] An interesting observation made regarding noncompliance of adjusting N95, HCWs with higher body mass index (BMI) shows higher noncompliance values.[30]

Powered air-purifying respirators

As the name implies, it is a battery-operated device that filters out inspired air and provides positive pressure by delivering filtered air into the facepiece or medical helmet with the help of a canister or a cylinder placed in the back pack.[19] PAPR has been advocated in treating confirmed COVID-19 or suspected cases.[31] The main issue is the high cost and providing training to HCWs to doff PAPR without contamination.


An important point to be considered is, though, masks offer barrier protection, and breathing resistance is increased while using respirators such as N95, and is not an ideal support device for dental operators suffering from respiratory diseases. In periodontal treatment that involves extended periods of time such as root surface debridement and flap surgical procedures, it can pose challenging situations to the operators who suffer from respiratory ailments.

Long-term data related to use of N95 and other respirators in relation to in vivo or in “in operatory” situations are limited. Research needs to be done on the dispersion of the particle, its possible trajectory, pattern, and size of the particle containing the live virus strain.


Not applicable.

Financial support and sponsorship

Not applicable.

Conflicts of interest

There are no conflicts of interest.

Author contribution

SRV: Conceptualization, methodology, validation, investigation, resources, writing original draft, editing, revision and formatting.

Ethical policy and institutional review board statement

Not applicable.

Declaration of patient consent

Not applicable.

Data availability statement

The data used to support the findings of this study are included within the manuscript.


1Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis. Lancet 2020;395:1973-87.
2Feara AC, Klimatra WB, Duprex P, Hartman A, Weaver SC, Plante KC, et al. Comparative dynamic aerosol efficiencies of three emergent coronaviruses and the unusual persistence of SARS-CoV-2 in aerosol suspensions. medRxiv 2020. doi:10.1101/2020.04.13.20063784.
3Guo ZD, Wang ZY, Zhang SF, Li X, Li L, Li C, et al. Aerosol and surface distribution of severe acute respiratory syndrome coronavirus 2 in hospital wards, wuhan, china, 2020. Emerg Infect Dis 2020;26:1583-91.
4Santarpia JL, Rivera DN, Herrera V, Morwitzer M, Creager H, Santarpia GW, et al. Aerosol and surface transmission potential of SARS-CoV-2. medRxiv 2020. doi:10.1101/2020.03.23.20039446.
5Zhiqing L, Yongyun C, Wenxiang C, Mengning Y, Yuanqing M, Zhenan Z, et al. Surgical masks as source of bacterial contamination during operative procedures. J Orthop Translat 2018;14:57-62.
6Sandaradura I, Goeman E, Pontivivo G, Marriott D, Harkness J, Andresen D, et al. A close shave? Performance of P2/N95 respirators in healthcare workers with facial hair: results of the BEARDS (BEnchmarking Adequate Respiratory DefenceS) study. J Hosp Infect 2020;104:529-33.
7Offeddu V, Yung CF, Low MSF, Tam CC Effectiveness of masks and respirators against respiratory infections in healthcare workers: A systematic review and meta-analysis. Clin Infect Dis 2017;65:1934-42.
8World Health Organization. Infection prevention and control during health care when novel coronavirus (nCoV) infection is suspected. Interim guidance. Available from: [Last accessed on 2020 Jun 16].
9Centers for Disease Control and Prevention. Interim healthcare infection prevention and control recommendations for patients under investigation for 2019 novel coronavirus. Available from: [Last accessed on 2020 Jun 16].
10Bissett J COVID-19: A guide to face masks. The Dent Nurs J. Available from: [Last accessed on 2020 Jun 17].
11American Society for Testing and Materials Standard specification for performance of materials used in medical face masks. F2100-11 Standard. Available from: [Last accessed2020 Jun 18].
12Cheng HY, Jian S-W, Liu D-P, Ng T-C, Huang W-T, Lin H-H High transmissibility of COVID-19 near symptom onset. medRxiv 2020. doi:10.1101/2020.03.18.20034561.
13Wang X, Pan Z, Cheng Z Association between 2019-ncov transmission and N95 respirator use. J Hosp Infect 2020;105:104-5.
14Chu DK, Akl EA, Duda S, Solo K, Yaacoub S, Schünemann HJ, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis. Lancet 2020;395:1973-87.
15Guyatt GH, Oxman AD, Kunz R, Woodcock J, Brozek J, Helfand M, et al; GRADE Working Group. GRADE guidelines: 7. Rating the quality of evidence–inconsistency. J Clin Epidemiol 2011;64:1294-302.
16Leung NHL, Chu DKW, Shiu EYC, Chan KH, McDevitt JJ, Hau BJP, et al. Author correction: Respiratory virus shedding in exhaled breath and efficacy of face masks. Nat Med 2020; 26:981.
17Long Y, Hu T, Liu L, Chen R, Guo Q, Yang L, et al. Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis. J Evid Based Med 2020;13:93-101.
18Centers for Disease Control and Prevention (CDC), National Center for Immunization and Respiratory Diseases (NCIRD), Respiratory hygiene/cough etiquette in healthcare settings. 2009. Available from: [Accessed 2020 Mar 26].
19Centers for Disease Control and Prevention (CDC). Hospital Respiratory Protection Program Toolkit. The National Institute for Occupational Safety and Health; 2015. Available from: [Last accessed on 2020 Jun 18].
20Bischoff WE, Reid T, Russell GB, Peters TR Transocular entry of seasonal influenza-attenuated virus aerosols and the efficacy of n95 respirators, surgical masks, and eye protection in humans. J Infect Dis 2011;204:193-9.
21van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson BN, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N Engl J Med 2020;382:1564-7.
22Ha JF The covid-19 pandemic, personal protective equipment, and respirator: A narrative review. Int J Clin Pract 2020:e13578. doi:10.1111/ijcp.13578.
23Bischoff WE, Turner J, Russell G, Blevins M, Missaiel E, Stehle J How well do N95 respirators protect healthcare providers against aerosolized influenza virus? Infect Control Hosp Epidemiol 2018;18:1-3.
24Fisher EM, Shaffer RE Considerations for recommending extended use and limited reuse of filtering facepiece respirators in health care settings. J Occup Environ Hyg 2014;11:D115-28.
25Coulliette AD, Perry KA, Edwards JR, Noble-Wang JA Persistence of the 2009 pandemic influenza A (H1N1) virus on N95 respirators. Appl Environ Microbiol 2013;79:2148-55.
26Phan T Novel coronavirus: From discovery to clinical diagnostics. Infect Genet Evol 2020;79:104211.
27MacIntyre CR, Wang Q, Seale H, Yang P, Shi W, Gao Z, et al. A randomized clinical trial of three options for N95 respirators and medical masks in health workers. Am J Respir Crit Care Med 2013;187:960-6.
28Smith JD, MacDougall CC, Johnstone J, Copes RA, Schwartz B, Garber GE Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: A systematic review and meta-analysis. CMAJ 2016;188:567-74.
29Wong J, Goh QY, Tan Z, Lie SA, Tay YC, Ng SY, et al. Preparing for a COVID-19 pandemic: A review of operating room outbreak response measures in a large tertiary hospital in Singapore. Can J Anaesth 2020;67:732-45.
30Rebmann T, Carrico R, Wang J Physiologic and other effects and compliance with long-term respirator use among medical intensive care unit nurses. Am J Infect Control 2013;41:1218-23.
31Roberts V To PAPR or not to PAPR? Can J Respir Ther 2014;50:87-90.