The impact of COVID-19 on individual oral health: a scoping review

Poor oral health is one of the most prevalent non-communicable diseases (NCDs) worldwide consuming one-fifth of out-of-pocket health expenditure [1‐3]. In 2017, it was estimated that oral diseases affect close to 3.5 billion people worldwide, with caries (dental decay) of permanent teeth being the most common condition [4]. It is estimated that 44% of all people worldwide have untreated caries in primary and permanent teeth [5]. International data indicates that dental caries is one of the most prevalent health conditions [6‐8] and a leading cause of preventable hospitalization [6]. Poor oral health is also associated with several other chronic diseases including diabetes, stroke and cardiovascular disease [9‐12]. Oral health is impacted by a range of social, economic, environmental and political determinants [13] and the impact of COVID-19 on oral health is hypothesized to be significant [14].

The World Health Organization declared the global spread of coronavirus disease (COVID-19) a pandemic on March 11th, 2020 [15]. The impact of COVID-19 across the globe has been significant with more than 6.5 million deaths reported to the WHO to date [16]. A range of measures were implemented to manage the virus including mask-wearing, restrictions on movement, physical distancing, vaccinations, and various forms of lockdowns [17‐20]. These measures aimed to contain the virus and limit its impact on health care systems [19]. Throughout the pandemic, healthcare has been considered an essential service however access to some services has been limited or new service models introduced. This has resulted in changes to prevention and treatment services for NCDs (like oral health) and as a consequence low utilisation rate of preventive services have been reported globally [3, 14, 21‐24].

The immediate increase in stress and anxiety levels in response to the COVID-19 outbreak has impacted health-promoting behaviors, including oral hygiene [25, 26]. During the pandemic, an increase in prescribing antibiotics and opioid analgesics has been observed in oral health services [27‐29]. Significant declines in the utilisation of dental services due to restrictions and regulations on the provision of non-urgent care during the lockdown have also been reported [14, 30, 31]. A recent study in the UK highlighted that reduced access to dental services and cessation of oral health improvement programmes (like supervised toothbrushing) indicate that the COVID-19 pandemic is likely to have a major impact on oral health and result in a widening of inequalities [14]. There is abundant information in the existing literature on the perspectives and experiences of oral health service providers during the COVID-19 pandemic (see, for example, [32‐36]). However, information on the oral health impacts of COVID-19 at the individual level remains scant. As the first review in this specific area, our purpose was to undertake a comprehensive mapping and synthesis of the impact of the COVID-19 pandemic on oral health at an individual level.

Using a scoping review process our purpose was to explore the breadth or depth of the literature, map and summarize the evidence and identify or address knowledge gaps concerning the impact of COVID-19 on individual oral health [37, 38]. The review was guided by the Joanna Briggs Institute Reviewers’ Manual Methodology for JBI Scoping Reviews [37]. The review question collectively developed by the research team (including oral health and public health researchers and clinicians) was: ‘What is known about the impacts of the COVID-19 pandemic on oral health at the individual level?’.

Inclusion and exclusion criteria, consistent with our review purpose were developed and are outlined in Table 1.

A search strategy was developed in consultation with a specialist health librarian as recommended by the 2020 Methodology for JBI Scoping Reviews and peer-reviewed by using the Peer Review of Electronic Search Strategies (PRESS) checklist [39]. A combination of terms related to two themes of ‘COVID-19 pandemic’ and ‘oral health’ were searched as both, keywords and subject headings (e.g., MeSH) in the titles and abstracts. Boolean operators were used to conduct the search and search limits were applied (see Table 2 for Medline search string). The Preferred Reporting Items of Systematic Reviews extension for scoping reviews (PRISMA-ScR) checklist was used to guide the reporting of the review [40] (see Additional file 1).

The full search was conducted in Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), OVID, Proquest, Embase, Dentistry and Oral Health Sciences Source (DOSS) and Cochrane Database of Systematic Reviews. Search results were then saved and exported into EndNote, a bibliographic software program, to store, organize, and manage all results and then into Covidence [41], part of Cochrane’s systematic review toolkit. After the removal of duplicates, a four-step process was undertaken. One author (TK) independently screened all retrieved articles at the title and abstract stage, with other team members acting as independent second reviewers (VDS, RN, SD). Reviewer disagreements were flagged in Covidence as conflicts and were discussed by the team until consensus was achieved. This process was repeated at the full-text stage, with team discussion occurring where there were differences of opinion. The reference lists of included studies were hand searched and citations of all included studies were checked to ensure search completeness.

A data extraction tool was developed within Covidence and used to extract key characteristics of each included study in tabular format (see Additional file 2). Narrative summaries of the included studies were developed that described how the extracted data related to the aim of the review. Consistent with the guidelines for the effective reporting of scoping reviews [42] and the JBI framework [37] the final stage of the review included a thematic analysis of the key findings of the included studies. Study findings were imported into QSR NVivo with the coding of each line of text. These descriptive codes reflect the key aspects of the included studies related to the impact of COVID-19 at the individual level.

A preliminary protocol for this review was published in the Open Science Framework (OSF-https://​osf.​io/​7t9bq/​) preregistrations to enhance transparency and replicability and to reduce any publication or reporting biases.

The search results for this review are outlined in Fig. 1.

A total of 85 studies were included in the review. The United Nations Geoscheme system was used to classify the studies into regional groupings [43]. The studies were undertaken in the following regions: Americas, n = 17, Asia n = 38, Europe n = 25, Oceania n = 1. The highest number of studies were carried out in Brazil (n = 9), Turkey (n = 8) and China (n = 8). Two studies used international samples and 3 studies did not mention a specific geographic region. There were no studies located in Africa or Antarctica.

Data collection methods for the included studies varied with quantitative methods being used most frequently (n = 82). Table 3 provides an overview of the data collection tools.

Our synthesis of the key findings of the included studies resulted in the development of the following themes: changes to the provision of emergency dental services, provision of routine oral health services, oral hygiene maintenance at home, changes in dietary preferences, alternative models of dental provision and help-seeking and attitudes to dental care in the future. These themes are reported below. The full dataset of the included studies is provided in Additional File 2.

This scoping review aimed to undertake a comprehensive mapping and synthesis of key findings related to the impact of the COVID-19 pandemic on oral health at the individual level. Scoping reviews do not exclude studies based on study design or quality appraisals which enables a synthesis of findings that provides a useful starting point for future reviews and other research activity [37, 38].

Government responses to the spread of COVID-19 varied across the world with many countries utilising lockdowns to stem the transmission. Service restrictions and lockdowns in many places resulted in limitation or cessation of essential services including dental services in some areas [17‐20]. Our initial searches highlighted that much of the published dental and oral health research related to COVID-19 focused on the impact at the service level including risks for staff and financial impacts on dental practices. Whilst these issues are important at the professional level, we were interested in the impact that COVID-19 was having on oral health at the individual level.

Findings from this review were not surprising with many studies highlighting the impact that prolonged lockdowns had on dental treatment services (particularly emergency services) and routine oral health and preventive services. More recent studies have confirmed the impact that lockdowns had on dental service use by children, adults and older adults in the UK [14] with similar declines in paediatric services reported in Australia [31]. It is logical that closure of dental practices led to increased emergency visits and that many people would wait too long to seek care. Concerns have been raised that this could have resulted in more patients than usual requiring admission for the management of acute dental infections that can threaten airways and result in the need for intensive care [119].

Routine oral health care and preventive practices are cornerstones of good oral health across the lifespan. Reduction in these services throughout the lockdowns may have increased in oral healthcare-related disparities for vulnerable groups [14, 87, 120]. Changes to daily oral hygiene practices and home maintenance (including toothbrushing) were reported in this review (including increases and decreases). Twice daily toothbrushing with fluoride toothpaste continues to be recommended internationally to maintain oral hygiene with less frequent toothbrushing impacting overall oral health [121, 122]. Whilst changes in oral health behaviours were reported in the review the reasons for those changes were largely not reported. Stress and other disrupting events can affect the way people perceive their self-care needs and may impact people’s motivation to perform daily routines.

Changes in dietary preferences were reported in some studies with both increases and decreases in the consumption of sugary foods [97, 101]. High sugar consumption is a known risk factor for the development of dental caries [123]. A recent UK study showed that there were increases in reported purchases of confectionery, biscuits and sweet home cooking (all foods 'rich' in free sugars) among adults throughout the pandemic [14]. Whilst purchasing behaviours may not equate to consumption, high sugar consumption combined with reduced oral hygiene can lead to increases in dental disease.

The results of this review highlight the role that the internet played throughout the pandemic with many people using it for advice and/or information regarding oral health. Interruptions to dental services throughout the pandemic were challenging however access to quality information and evidence-based materials to support oral health care routines should be readily available. Help-seeking via the internet is common with previous studies highlighting using social media and search engines to find information about oral health is popular in some countries [124, 125]. However, concerns have been raised over the quality of the information provided by some sites [126]. The provision of quality information online would enable the continuation of daily oral health care routines throughout times of crisis and maybe something that dental practice, dental policymakers and other oral health-related service providers could consider in the future.

The use of teledentistry throughout the lockdown periods was reported within this review. Teledentistry may be useful to improve the ability to reach oral healthcare providers in times of crisis or to address service access issues [94], however further work is needed to explore the best models of provision (for example, prevention, consultations). In the absence of a face-to-face session with a dental professional, tele-dentistry may be a good option for oral health support and/or monitoring [45, 104]. However, teledentistry may not be available for those who do not have reliable access to technology and may increase inequalities for already vulnerable groups (rural, isolated).

Previous studies have highlighted that the widening inequalities in oral health cannot simply be “treated away” ([14]: p. 113) or addressed by increasing oral health care services. The pandemic has shown us that we need to reorient treatment systems to focus more on evidence-based systemic oral health improvement programmes like community water fluoridation, supervised toothbrushing programs, use of fluoride toothpaste to prevent the development of dental caries [14]. Whilst these activities are important, we also need to ensure that other oral health issues like periodontal disease and oral cancers that have significant economic costs [70] are included in our oral health improvement programmes in the future. Throughout the pandemic, we have also seen more emphasis on the role that oral and dental health professionals can play within the wider health system working more closely with other health providers in an integrated model of care [127]. More emphasis on these models will be central in future efforts to address oral health inequity and improve oral health across the globe [120, 127].

Many of the studies included in the review utilised cross-sectional, online, self-report surveys and existing datasets, with only one studyutilising qualitative methods. More qualitative studies could provide access to a deeper understanding of the factors that impact oral health at the individual level and could be used to inform the development of guidelines, policies and other information to improve oral health in the future [128, 129].

The searches that formed the basis of this review were carried out from March 2020 to November 2021. These dates were chosen to capture the majority of studies published while countries across the globe were under the highest level of restrictions (including lockdowns in many places). With the emergence of Omicron in November 2021, many countries lifted lockdowns as part of their approach to living with COVID-19. Whilst the searches were comprehensive, we have only captured those studies that were published in the included databases in a specific period. There may have been other studies published outside of these periods. We also limited the search to studies published in English with full-text availability which may have meant that some other studies were excluded.

As the emphasis of a scoping review is on comprehensive coverage and synthesis of the key findings, rather than on a particular standard of evidence we did not undertake a quality assessment of the included studies. This has resulted in the inclusion of a wide range of study designs and methodologies with small samples, cross-sectional designs using self-reported measures and internet-based research methods. The results of these studies provide valuable insights into the key issues faced by individuals throughout the pandemic however they must be interpreted with caution considering any specific methodological limitations.

Future research in this area should focus on addressing some of these key limitations with more research exploring the direct impacts of COVID-19 on individual oral health required. This will enable the development of specific oral health prevention activities that support good oral health through times of crisis.

COVID-19 has impacted the oral health of many people across the globe, however, there are few reviews that have explored these impacts at the individual level. This review addresses this gap. The findings demonstrate that the pandemic has impacted the provision of emergency dental services, provision of routine oral health services, oral hygiene maintenance at home, changes in dietary preferences and the use of online information and help-seeking. It is important that we are aware of these impacts and ensure that support systems are in place to overcome future periods where access to dental care might be compromised. This will include ensuring patients have access to good quality oral health services and information including preventive care. A shift in focus that ensures a coordinated interdisciplinary approach consisting of treatment, education and prevention will reduce the pressure on emergency health care systems in the future.