National Journal of Maxillofacial Surgery

: 2021  |  Volume : 12  |  Issue : 2  |  Page : 139--161

Evidence mapping and quality analysis of published dental literature on COVID-19 – A systematic review

Morankar Rahul1, Nitesh Tewari1, Vijay Mathur1, Shubhi Goel1, Gunjar Jain2,  
1 Division of Pedodontics and Preventive Dentistry, Centre for Dental Education and Research, AIIMS, New Delhi, India
2 Department of Orthopaedics, AIIMS, New Delhi, India

Correspondence Address:
Dr. Morankar Rahul
Division of Pedodontics and Preventive Dentistry, Centre for Dental Education and Research, AIIMS, New Delhi


A large number of scientific articles have been published regarding impact of COVID-19 infection on dental practice, dental professionals, and the mode of spread of infection via dental procedures. The present systematic review was planned with an aim of evidence mapping and quality analysis of published research on the dental aspects of COVID-19 infection. The protocol was registered at https://share. The search was performed in Scopus, PubMed, Cochrane, and Embase databases till 15th July 2020. There was no restriction of year of publication and language. All types of published articles related to Dentistry, Dentist, Dental practice, and Oral health education on COVID-19 were included. The Joanna Briggs Institute's (JBI) Critical Appraisal Tools were used for the risk of bias analysis of included studies. A total of 393 articles were short-listed and were checked for eligibility and finally, 380 articles were included. Among the 380 research articles published (till July 15, 2020), the majority of the included articles belonged to the lowermost strata of the evidence pyramid. There were 54 original research articles with no randomized clinical trial, systematic review or, meta-analysis pertaining to the dental perspective of COVID-19 infection. The level of available evidence about dentistry and COVID-19 infection is very low with a lack of researches of highest quality. The guidelines/recommendations for dental professionals, proposed by the different scientific organizations/societies regarding COVID-19 infection are only consensus-based necessitating the need to formulate evidence-based guidelines. There is a need to identify essential research questions and strengthen the study designs in most of the aspects related to the dentistry and COVID-19 pandemic.

How to cite this article:
Rahul M, Tewari N, Mathur V, Goel S, Jain G. Evidence mapping and quality analysis of published dental literature on COVID-19 – A systematic review.Natl J Maxillofac Surg 2021;12:139-161

How to cite this URL:
Rahul M, Tewari N, Mathur V, Goel S, Jain G. Evidence mapping and quality analysis of published dental literature on COVID-19 – A systematic review. Natl J Maxillofac Surg [serial online] 2021 [cited 2021 Dec 5 ];12:139-161
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Full Text


An illness similar to common flu with high infectivity and signs similar to pneumonia was reported in Wuhan city of China in December 2019. The condition spread rapidly to different parts of china in January 2020 and later started gripping the globe in February 2020. The investigation to find out the etiology of the infection had led to the characterization and isolation of a virus termed as the novel coronavirus (2019-nCoV).[1] This is an enveloped RNA virus comprising of strains leading to respiratory syndromes such as SARS and MERS. The 2019-nCoV has found to have wide distribution, genetic recombination, and a higher rate of infection.[2],[3]

The main infective pathways of SARS-CoV-2 are airborne and direct contact.[4] Coughing, sneezing, exhalation, or speaking are the common routes of the airborne infection that occurs through the released droplets. As they settle and contaminate the surfaces, any contact subsequent touching to eyes, nose, and mouth leads to COVID-19 infection.[3],[4],[5] The role of saliva has also been implicated in the spread of infection.[6],[7],[8],[9]

Since the emergence of this pandemic, there has been a panic among the dental fraternity across the world, especially regarding the possible spread of this infection through dental operatories. The cross-sectional studies evaluating the knowledge, attitude, and practice in dental professionals regarding the spread of COVID-19 infection through the dental procedures have also reported a high level of concern in them.[10],[11] There has been a sense of fear, anxiety, and reluctance among dental professionals to continue their dental practice in the pandemic.[12] Even the World Health Organization had released a series of guidelines (last published on August 3, 2020) advised to delay the routine nonessential oral health services until there has been sufficient reduction in COVID-19 transmission rates.[13] However, the American Dental Association in their opinion (released on August 13, 2019) strongly disagrees with these recommendations to delay routine dental care.[14] To an extent this belief is justified, since the oral cavity is in direct communication with the respiratory system which harbors the virus and aerosol generating dental procedures can pose threat to the operators, auxiliaries, and the patients.[15],[16]

After the start of the current pandemic, there are thousands of scientists working on various aspects of Coronavirus origin, epidemiology, demographic distribution, clinical symptoms, diseases progression, after effects, recovery time, prevention, and vaccination. The profession of dentistry is also largely affected by the current pandemic and there are many areas in which research is undergoing with respect to COVID-19 pandemic and dental profession as a whole. However, some of the areas are being investigated more and some are not. The published literature is quite discrete, which makes it difficult to draw any conclusion. This article is aimed at evidence mapping of the available literature, its quality analysis and pointing at areas of gap and future research.


This systematic review was carried out according to the PRISMA guidelines and principles of Global Evidence Mapping.[17],[18] The protocol was registered with (Registration/46221-C87-BA8).

Information sources

The search was performed in Scopus, PubMed, Cochrane, and Embase databases till July 15, 2020. There was no restriction of year of publication and language. Google Scholar and Open Grey search were performed for grey literature. To identify the additional studies the Cross references of eligible studies were checked. Hand searching was also performed in general and specialty journals of dentistry. Two authors (NT and MR) performed the literature search and study selection independently as per the predefined search strategy. Any disagreement was resolved after consultation with the senior reviewer (VM).

Search strategy

The four reviewers (NT, VPM, SG, and MR) identified the possible domains and subdomains which could be focused for identifying the available dentistry related literature on COVID-19 infection. They were finalized after a focused group discussion in two stages within the review team.

A broad-based search was implemented using the text words and MeSH terms. The key words were: “Dentistry”, “Dentist”, “Dental practice”, “Saliva”, “Aerosol”, “Oral Health”, “Oral disease”, “Periodontics”, “Pediatric dentistry”, “Prosthodontics”, “Endodontics”, “Orthodontics”, “Oral Surgery”, “Oral Pathology”, “Community dentistry”, “Public Health Dentitsry”, “Conservative Dentistry”, “Oral diagnosis”, “Oral Radiology”. Partial searches with “AND” and “OR” were done with the above keywords individually with “Covid-19”,”Corona virus” and “SARS-COV-2”. The strategy used for partial search was (1) Search ((Dentistry OR Dentist) OR Dental practice) (2) Search ((((Saliva) OR Aerosol) OR Oral Health) OR Oral disease) OR Periodontics) OR Pediatric dentistry) OR Prosthodontics OR Endodontics OR Orthodontics OR Oral Surgery) OR Oral Pathology) OR Community dentistry) (3) Search (((((((((((((Corona virus OR SARS-COV-2 OR Covid-19. The duplicates were removed and titles and abstracts were assessed for their eligibility as per inclusion criteria.

Study selection and eligibility criteria

Inclusion criteria-1

All types of published articles (In vitro studies/Background information/Expert opinion/Letter to editor/Case series or Case reports/Cohort studies/Case-control studies/Non-randomized clinical trials/Randomized clinical trials/Critically appraised topics (Evidence synthesis and guidelines)/Systematic reviews/Meta-analysis). (2) Dentistry, Dentist, Dental practice and Oral health education related research articles on SARS-COV-2 with no restriction of language.

Exclusion criteria-1

Researches related to virus other than SARS-COV-2. 2. Researches not relevant to dentistry, dentist, dental practice, and oral health education.

Data collection process

The self-designed sheets, pilot-tested (tested on two included studies) were used for data extraction pertaining to different categories of studies. Two calibrated reviewers (MR and NT) collected the data from the included studies. The inter reviewer agreement for different variables was found to be high with Cohen's kappa values ranging from 0.68 to 0.82. In case of any disagreement, the third reviewer (GJ) was consulted and it was resolved by consensus.

Assessment of risk of bias

The included studies were assessed for their methodological quality using the JBI Critical Appraisal Tools.[19] The case reports, case series and all the included research articles (except editorials, expert opinion, letter to editor, narrative reviews) were analyzed for their methodological quality using respective JBI tools and divided into high, moderate, and low risk of bias (ROB). The scores were assigned to each of the included study pertaining the points applicable to methodological quality assessment, and on the basis of the scores, they were categorized into high (score 75% and above), moderate (score 50%–74%), and low ROB (score below 50%).

Statistical analysis

The included studies showed wide variations in the population, aim, objectives, outcome variables, and tools used for their assessment. Considering the heterogeneity of data, it was only analyzed for the descriptive characteristics without meta-analysis. Cohen's kappa statistics was used to determine inter-reviewer agreement.


Study selection

The search conducted in different electronic databases identified 2432 articles. Twenty-five additional records were found through other sources. A total of 393 full-text articles were short-listed after removal of duplicates and evaluation of titles and abstracts. They were further assessed for eligibility and finally 380 articles were included. The details of the search have been presented as PRISMA chart [Figure 1]. The excluded studies and reasons are presented in [Appendix Table 1].[S1],[S2],[S3],[S4],[S5],[S6],[S7],[S8],[S9],[S10],[S11],[S12],[S13] The included studies were arranged in an Evidence-based pyramid according to their levels of evidence [Figure 2].[20] The ideas, editorials, letter to the editors, opinions, and narrative reviews were mapped in the present SR but not subjected to quality assessment or ROB analysis. However, the remaining articles (in vitro studies, case series or case reports, cohort studies, case–control studies, and cross-sectional studies) were included in the quality assessment. The global distribution of studies included in the quality analysis is shown in [Figure 3].{Figure 1}{Figure 2}{Figure 3}[INLINE:1]

Study characteristics

[Figure 2] shows the level of evidence of available literature pertaining to the dental perspective of SARS-COV-2. Among the 380 research articles published till July 15, 2020, the majority of the included articles belonged to the lowermost strata's of the evidence pyramid. There were 54 original articles with no randomized clinical trial, systematic review, or meta-analysis.

It was observed that 12 scientific bodies had issued guidelines/recommendations [Table 1] related to dental perspectives of novel SARS-COV-2 infection.[21],[22],[23],[24],[25],[26],[27],[28],[29],[30],[31],[32] All of them were consensus based and majority had been issued for general dentists with only few targeted for specialists such as oral-maxillofacial surgeons. Majority of them were aimed at infection control and precautions related to dental procedures during SARS-COV-2 pandemic.{Table 1}

The characteristics of questionnaire-based studies are given in [Appendix Table 2].[S14],[S15],[S16],[S17],[S18],[S19],[S20],[S21],[S22],[S23],[S24],[S25],[S26],[S27],[S28],[S29],[S30],[S31],[S32],[S33],[S34],[S35],[S36],[S37],[S38] It was found that nine out of 25 studies had assessed the knowledge, attitude, and behavior of dental professionals regarding COVID-19 infection and reported that majority of the participants were aware of its etiopathogenesis, symptoms, and transmission. Although most of the dental professionals considered it as moderately dangerous and very few were confident of avoiding the infection in their clinics. Six studies which evaluated fear and anxiety among dental professionals and patients undergoing dental treatment reported that the majority of dental professionals were in psychological distress and had changed their patient management protocol. Several of them reported to have performed only the emergency dental procedures in the pandemic. Similarly, patients undergoing treatments in the dental clinics expressed concerns about acquiring SARS-COV-2 infection during their treatments. Majority of them also believed that the dentists belonged to a high-risk category. [Appendix Table 2] also described the results of questionnaire-based studies evaluating the impact of COVID-19 pandemic on functioning of dental academic institutions and the knowledge and attitude of the parents of pediatric patients toward dental treatments, appointments, and the oral symptoms associated with the COVID-19 infection.[INLINE:2]

The results of studies elucidating the role of saliva in detection of COVID-19 and its contagion are presented in [Appendix Table 3].[7],[8],[9],[S39],[S40],[S41],[S42],[S43],[S44],[S45],[S46],[S47],[S48],[S49],[S50],[S51],[S52],[S53],[S54] It was observed that the majority of included studies evaluated the role of saliva in COVID-19 diagnosis and found it to be a reliable method of diagnosis. Similarly, there were studies which compared the reliability of saliva with nasopharyngeal and oropharyngeal swabs. They reported it to be equivalent or slightly less sensitive and/or specific but emphasized its utility as an alternative detection method, due to the ease of collection/self-collection, greater acceptance of the patients and lower risks involved during sample collection.[INLINE:3]

The included studies comprised of four case reports and case series each related to dentistry and SARS-COV-2 [Table 2].[33],[34],[35],[36],[37],[38],[39],[40] They did not report any specific oral manifestation related to SARS-COV-2 infection. It was further stated that the ones present might have developed as a consequence of the treatment regimen administered. In an assessment of the salivary viral loads, it was reported that early morning samples were of greater diagnostic importance and showed higher titers of viral RNA as compared to the nasopharyngeal and oropharyngeal swabs in early stage of disease.[33],[34]{Table 2}

The other studies included in this systematic review were focused on the application of tele-dentistry for patient management and the web-based teaching methods for dental students during the SARS-COV-2 pandemic [Table 3].[41],[42],[43],[44],[45],[46],[47],[48],[49],[50] Few in vitro and human experiments had also been conducted to evaluate the efficacy of mouthwashes for reducing the viral loads, and reported a positive effect.[49],[50]{Table 3}

Quality assessment of individual studies according to the JBI Critical appraisal tools

There was substantial agreement (75%) between the two reviewers (MR and SG) in quality assessment of the studies. Among the 25 questionnaire-based studies, six were found to have high ROB, while 14 had moderate and five had low ROB [Supplementary Figure 1]. Majority of studies had not assessed the validity and reliability of questionnaires used in their study. Similarly, among the 19 studies which had focused on the potential role of saliva in COVID-19 diagnosis, low ROB was observed in 10 studies, moderate risk bias in nine and none of the included studies had high ROB when assessed for methodological quality [Table 1]. Out of the eight case reports/series, only one case series had moderate ROB while all other had a low ROB [Supplementary Figure 2]. Among the 10 miscellaneous studies included, two had high ROB whereas four each had moderate and low ROB [Table 3].[INLINE:4][INLINE:5]


The COVID-19 pandemic has affected the livelihood of almost all the human beings across the globe. Many small-scale and large-scale industries including oral health care have suffered a significant loss during this pandemic. Dentistry, dental practice, and dental practitioners have suffered psychological, emotional, and economic impact primarily due to the scare of the spread of infection associated with the dental procedures along with its potential risk to the dental practitioners. There have been several publications, during this pandemic, which aim to evaluate the potential role of saliva in COVID-19 diagnosis and its comparison with the conventional oropharyngeal and nasopharyngeal swab technique. There were other research articles identifying the oral manifestations of COVID-19, evaluating the impact on dental education and the effect of mouth rinse used for disinfection of oral cavity on COVID-19.

An evidence pyramid helps to categorize the quality of evidence of the published literature addressing a research question. In this systematic review, we have included 380 research articles pertaining to the dental perspective of COVID-19. The present SR observed that the majority of the included articles belonged to the lowest strata of the evidence pyramid. There were 54 original articles (including two in vitro trials) with no randomized clinical trial, systematic review, or meta-analysis published pertaining to the dental aspect of COVID-19 infection. This exhibited significant paucity in the highest level of evidence. This further highlights the avenues for the primary and secondary researches for future.

The review identified 12 different guidelines/recommendations given by various scientific organizations/societies. However, it was observed that all the guidelines were consensus based without any quality evidence supporting them, especially from the literature which already existed before the emergence of COVID-19 infection as a pandemic. Although this is a novel virus, with less available literature/research, these guidelines/recommendations should have been based on the scientific literature related to similar kinds of viruses or the general principles of infection control. This necessitates the need to analyze the researches related to COVID-19 infection and formulate an evidence-based guideline pertaining to dental perspectives of this infection.

The results of questionnaire-based studies have shown that the dental professionals and the patients seeking oral health care are in significant psychological distress in this pandemic. Since the majority of these studies suffered from moderate to high ROB and lacked essential details regarding the development of questionnaires and their validity and/or reliability, it necessitates using caution before drawing any conclusion from these studies. Another interesting observation was that the fear, anxiety, and lack of confidence among dental professionals, even after having good scores of knowledge and attitude related to COVID-19 infection, this can be attributed to the lack of consensus about signs and symptoms of COVID-19 infection, lack of a proper protocol for infection control in dental operatory, and limited belief on the recommendations issued by the scientific associations. It is further warranted that there is a need to perform quality studies to address the concerns of dentists as well as patients coming to the dental operatory to reduce their fear of getting infection in the dental clinics.

According to the results of majority of studies included in this SR, saliva can be recommended as an alternative for the detection of COVID-19 to the nasopharyngeal and oropharyngeal swabs with good sensitivity and specificity. Although 10/19 studies showed low ROB, the sample size in majority of them was less. Similarly, it was observed that in early period of infection (first week) the saliva has more diagnostic potential as compared to the late stages. The use of the samples from the confirmed patients of COVID-19 can be regarded as a confounding factor, making it a less reliable alternative. Among the other studies, there was variability in research questions, scarcity of numbers and a moderate ROB. These areas must also be addressed in future researches for improving the understanding and management protocols of this infection.


The level of available evidence pertaining to the dentistry and COVID-19 infection is very low with lack of researches of highest qualityThe guidelines/recommendations for dental professionals, proposed by the different scientific organizations/societies regarding COVID-19 infection are only consensus-based necessitating the need to formulate evidence-based guidelinesThe various surveys explain the good knowledge, attitude, and practices among dental professionals and patients; however, they also report significant fear and anxiety in several aspectsSaliva can serve as an alternative for diagnostic test of COVID-19 infection, however, there is need to specify indications and appropriate phase of infection for its accuracyThere is a need to identify essential research questions and strengthen the study designs in most of the aspects related to the dentistry and COVID-19 pandemic.


Inclusion criteria could have been more specific in order to fulfill a single-study objective rather than evaluating the all the published literatureAs the majority of published literature had low level of evidence and high/moderate ROB making the results of this SR less reliableLike all the evidence mappings, the present SR suffers from the limitation of the date of the last literature search. Since the SARS-COV-2-related medical and dental literature have been constantly increasing, there would have been some researches which could not be included in the present evidence mapping.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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