Dental practice closure during COVID-19 and associated professional, practice and structural determinants: a multi-country survey

Background: The outbreak of novel coronavirus disease (COVID-19) in China has inuenced every aspect of life worldwide. Due to the characteristics of dental settings, the risk of cross infection may be high between dental practitioners and patients. Being on the list of high-risk professions, dentists are very much expected to develop severe anxiety about the current pandemic situation. In addition, the limited provision of services and closure of dental practices raised concerns among dental professionals about the nancial consequences of this closure. Therefore, the study assessed the extent of dental practice closure in various countries around the world, factors associated with this closure and whether closure and associated factors differed between private and non-private sectors. Methods: From April to May 2020, a web-based survey was sent to dentists in several countries. The survey assessed professional factors, practice factors and country-level structural factors. Multilevel logistic regression was used to assess the association of practice closure with these factors. Effect modication due to private and non-private sectors was assessed. Results: Dentists (n= 3243) participated from 29 countries. The majority (75.9%) reported practice closure with signicantly higher percentage in the private than non-private sector. Fears were associated with signicantly higher likelihood of closure in private (OR= 1.54, 95%CI= 1.24, 1.92) and non-private sectors (OR= 1.38, 95%CI= 1.04, 1.82). Non-private, governmental sector dentists (OR= 0.54, 95%CI= 0.31, 0.94) and those in rural areas (OR= 0.58, 95%CI= 0.42, 0.81) and those in hospitals (overall OR= 0.60, 95%CI= 0.36, 0.99) reported low likelihood of closure. High likelihood of closure was reported by those in academia (OR= 2.13, 95%CI= 1.23, 3.71). More hospital beds were associated with lower likelihood of closure in the non-private sector (OR= 0.65, 95%CI= 0.46, 0.91) and private sector dentists in high income countries (HICs) reported less closure than in non-HICs (OR= 0.55,


Background
On January 8 th 2020, the Chinese Center for Disease Control and Prevention declared that the novel coronavirus caused COVID-19 [1]. Since that time, COVID-19 has become a major public health problem for all countries globally, changing all aspects of life [2]. As of 19 June, COVID-19 cases have been reported in 47 countries in Africa, 15 countries in the Western Paci c region, 53 countries in the European region, 10 countries in South East Asia, 21 countries in the Eastern Mediterranean region and 35 countries in the region of Americas with a total of 8.7 million laboratory-con rmed cases and about half a million deaths [3].
Transmission of COVID-19 occurs interpersonally via respiratory droplets and contact [4], inhalation, ingestion or direct mucous contact with saliva droplets [5]. The virus can survive on hands, objects or surfaces previously exposed to infected saliva [5]. COVID-19 incubation period ranges from 5 to 14 days [1,6]. The clinical manifestations may present as mild, u-like symptoms, including fever (98%) and dry cough (76%). Patients may develop respiratory failure and multiple organ failure leading to death. Lymphocytopenia is observed, and chest CT examination usually shows ground-glass appearance of the lungs. No vaccine or speci c antiviral therapy is available and supportive treatment, with organ support in intensive care units, remain the clinical management strategies [7].
Healthcare professionals are at the forefront of the ght against COVID-19 with cases of infection and varying numbers of fatality in different countries [8]. Due to the unique nature of dental practice, the risk of cross-infection is high among dental health personnel compared to other health care professionals [9,10]. In addition, the virus was recently identi ed in the saliva of infected patients [11]. These factors increase dentists' fears and anxiety due to the COVID-19 pandemic compared to what is reported for the general public in the media [12].
After the pandemic, routine dental care was restricted to help atten the curve and protect patients and personnel against infection. Urgent care was delivered using personal protective equipment (PPE) with additional precautions including taking patients' recent travel history, assessing signs and symptoms of infection, recording patients' body temperature, using 1% hydrogen peroxide as mouth rinse before dental procedures, using rubber dam and high volume suction and frequently cleaning and disinfecting public contact areas including door handles, chairs and washrooms [13]. The reduced availability of dental care might have increased the demand on the already burdened hospitals emergency departments [14], with potential impact on oral health and quality of life of patients. In addition, the limited provision of services and closure of dental practices raised concerns among dental professionals about the nancial consequences of this closure [15]. Reports show that dental economy and other health care sectors were at a virtual standstill because of the pandemic [15,16].
The disruption of the delivery of dental care may affect dental care providers, other health care sectors and the general public. Assessing the extent of this service disruption and its determinants is important to help mitigate its impact and plan supportive measures. The present study assessed the extent of dental practice closure among dentists from countries all over the world, the factors associated with this closure and whether closure and associated factors differed between the private and non-private sectors. The null hypothesis of the study was that dental practice closure was affected neither by professional dentist attributes (such as COVID-19 knowledge and fears), practice attributes (working in private or non-private sectors, urban or rural areas and solo or group practices) nor country attributes (number of hospital beds representing the country's ability to mobilize resources to control the disease and income level indicating the level of support to dentists in case of practice closure).

Design
A cross-sectional, multi-country, web-based survey was conducted from April to May 2020. The Ethics Review Committee approved the study, and it was carried out in agreement with the Declaration of Helsinki.

Participants and sample size
The target population was dentists of various specialties across the globe. The study recruited specialists and non-specialists practicing in various sectors during the study period. Dental students and interns were excluded. Sample size was estimated based on assuming that 50% of dentists would report practice closure. Thus, based on a margin of error= 5% and 95% con dence level, sample size was calculated [17] to be 377 dentists. A greater number of participants was included because of the multi-country nature of the study and because it was not possible to limit the number of participants on social media once the link was posted.

Questionnaire design and pilot testing
The questionnaire (Additional le 1) was designed based on information in the websites of the World Health Organization (WHO), American Dental Association, and Center for Disease Control about dental settings and considerations for treatment during the COVID-19 outbreak in addition to previous studies [18]. A group of experts evaluated the original English questionnaire and con rmed its content validity and the logical structure of the questions. The questionnaire was further tested among 15 dentists, and few modi cations for clari cation were done. In addition, the survey was translated into German and Italian by two independent bilingual dentists. Using back translation, the translated questionnaires were compared with the original English version to identify discrepancies and resolve vagueness. The German version was pilot tested by 14 dentists and 11 dentists tested the Italian version. Pilot testing results were not included in the analysis.
At the beginning of the survey, a short introduction described the study purpose and assured participants of the con dentiality of their responses. There were 31 close-ended questions divided into three sections.
Section 1 gathered information about the sociodemographic and practice characteristics of participants, including age, gender, country of practice, specialty, area of practice (rural or urban), and type of practice (private, governmental or academic sectors, solo, group or hospital practices). Section 2 consisted of 8 items assessing dentists' fears regarding COVID-19, with responses on a 5-point Likert scale ranging from strongly agree (code 5) to strongly disagree (code 1). Section 3 consisted of 15 questions assessing knowledge of measures to control the transmission of COVID-19 with possible responses being yes, no and do not know. A nal question assessed whether dental practice was closed at the time of the survey.

Data collection
A link to the web-based questionnaire was created using the online survey platform "Survey Monkey". Respondents could revise and change their answers before submission and no duplicate entries were allowed. The questionnaire took 5-7 minutes to complete. The link was sent to collaborators in several countries. Convenience and snowball sampling were used to promote the link via Facebook and Instagram dentist-only groups, LinkedIn, Twitter, and WhatsApp. All participants were asked to share the survey with their dental contacts.

Statistical Analysis
The overall fears and threats score were calculated by averaging the scores of the 8 items to give a score ranging from 1 to 5. The overall knowledge score was created by assigning one point for each correct answer and adding the points of the 15 items with potential score ranging from zero to 15. Cronbach's alpha was used to assess the internal consistency of the fears and knowledge items [19]. Multilevel logistic regression analysis was used to assess the association between the dependent variable (practice closure with yes/ no responses) and explanatory variables as xed effects. These included level 1 professional and practice factors in addition to level 2 country-level structural factors including number of beds per 1000 population obtained from the World Bank Databank [20]. In the absence of multicountry data about the number of intensive care units needed to care for patients with COVID-19 complications, we used the number of beds per 1000 population. This is an indicator of the availability of inpatient services [21], and re ects demand and supply health care factors [20]. Country level structural factors also included income level based on the World Bank classi cation of countries into high income (HICs) with gross national income (GNI) > 12,375 US$, upper middle income (UMICs) with GNI between 3,996 and 12,375 US$, lower middle income (LMICs) with GNI between 1,026 and 3,995 US$ and low income (LICs) with GNI<1,026 US$ [22]. These categories were recoded into HICs and non-HICs. Country was included as random effect factor. Robust estimation was used to handle violations of model assumptions. A model was developed for the whole sample and two additional models were developed for participants working in the private sector and those working in the non-private sector. Odds ratios and 95% con dence intervals (CIs) were calculated. Effect modi cation by private sector status was assessed and p values were computed for this interaction. Signi cance level was set at 5%. SPSS version 25.0 [23] was used for statistical analysis.

Results
About 3243 dentists responded from 29 countries (Additional le 2). Of these, 49.2% were 20-30 years old, 56.8% were females and 70.6% were specialists. Also, 65.6% worked in the private sector, 52.3% were in group practice and 81.8% worked in urban locations. The mean (SD) number of beds/ 1000 population was 1.70 (0.99) and 71.7% of dentists were from non-HICs. Most participants (75.9%) reported that their practices were closed because of the pandemic (Table 1). Signi cantly higher percentage of dentists working in the private sector than non-private sector reported practice closure (78.3% and 71.3%, P< 0.0001). Table 2 shows the level of fear due to COVID-19. The greatest fear was about family members catching infection (mean= 4.36) and the high infection risk among health care personnel (mean= 4.21). Cronbach alpha for the internal consistency of fear items was 0.70. The mean fear score= 4.14 out of 5, SD= 0.54. Figure 1 shows that >95% of dentists had correct knowledge of COVID-19 symptoms, that it can be transmitted through respiratory secretions, that speci c training is needed to prevent infection and that precautions are needed against droplet, contact and airborne infections. Cronbach alpha for the internal consistency of knowledge items was 0.62. The mean knowledge score= 13.08 out of 15, SD= 1.89. Table 3 shows the factors associated with practice closure. Working in the private sector signi cantly modi ed the association between practice closure and specialization (P= 0.03) with signi cantly greater likelihood of closure reported by private sector general practitioners than specialists (OR= 1.38, 95%CI= 1.04, 1.95). The association among non-private sectors dentists was weaker and not statistically signi cant (OR= 1.08, 95%CI= 0.77, 1.53). Fears were associated with signi cantly more closure among private sector (OR= 1.54, 95%CI= 1.24, 1.92) and non-private sector (OR= 1.38, 95%CI= 1.04, 1.82) dentists.
There were no signi cant differences between the private and non-private sectors in the association between closure and some practice factors such as working in academia (P= 0.13) and in hospitals (P= 0.64). Working in academia was associated with signi cantly higher odds of closure overall than not working in academia (OR = 2.13, 95%CI= 1.23, 3.71) while working in hospitals was associated with signi cantly lower odds of closure overall than not working in hospitals (OR = 0.60, 95%CI= 0.36, 0.99).
There were signi cant differences between the private and non-private sectors in the association between practice closure and working in the governmental sector (P= 0.01) and urban/ rural location of practice (P= 0.001). Non-private sector dentists who worked in the governmental sector were signi cantly less likely than those in non-governmental sector to report practice closure (OR= 0.54, 95%CI= 0.31, 0.94). Private sector dentists working in the governmental sector reported higher but non-signi cant odds of closure (OR= 1.19, 95%CI= 0.87, 1.62). For the whole sample (OR= 0.58, 95%CI= 42, 0.81) and non-private sector dentists (OR= 0.58, 95%CI= 0.42, 0.81), the odds of practice closure were lower in rural than urban areas. For private sector dentists, the odds of practice closure were non-signi cantly higher in rural than urban locations (OR= 1.29, 95%CI= 0.91, 1.82).
There were no signi cant differences between private and non-private sectors in the association between practice closure and structural factors such as the number of hospital beds (P= 0.96) and country high income (P= 0.64). More hospital beds were associated with signi cantly lower odds of practice closure among dentists in non-private sector (OR= 0.65, 95%CI= 0.46, 0.91). Private sector dentists from HICs were non-signi cantly less likely to report practice closure than those from non-HICs (OR= 0.55, 95%CI= 0.15, 1.93).

Discussion
The study showed that from April to May 2020, 75.9% of dentists reported closure with higher percentage in than outside the private sector. Dentists in the private sector, who were general practitioners, in solo practices, in rural areas and with greater COVID-19 fears were more likely to report practice closure. Country-level determinants also affected practice closure: better prepared health care systems were associated with less closure outside the private sector while the private sector in rich countries was less likely to close. The null hypothesis can, thus, be rejected. The study provides evidence of the impact of COVID-19 on dental practice closure which jeopardizes the provision of dental care. These ndings have implications for planning support packages for the profession and the public.
In the present study, 75% of dentists reported practice closure. International guidelines related to provision of dental care during the pandemic ranged from allowing only public stomatological and general hospitals to deal with emergency cases in China [24], urging practitioners to shut their practices in California, USA [25]; decreasing the number of daily check-ups in the UK [26] to no guidance [27]. The level of dental practice closure in the present study was higher than that reported for non-dental specialties in a WHO survey of 155 countries where 53% reported disruption of treatment services for hypertension, 49% for diabetes and related complications, 42% for cancer and 31% for cardiovascular emergencies [28]. The level of practice closure in the present study was similar to that reported in the USA where 79% of dental of practices were closed except for emergency care [29]. The impact of this suspension of dental care on the oral health of the population is yet to be quanti ed.
In the present study, fear of reduced income because of the pandemic was among the three top fears. Similarly, reports showed lower patient volume following the public's avoidance of healthcare settings due to fear of COVID-19 which lead to nancial losses in dental practices and reduced ability to pay employees. A US survey conducted in March 2020 reported that 28% of dentists were unable to pay their staff and 45% made partial payments [30,31]. It was estimated that if the current lockdown continues to September 2020, 46% of dentists may need to le for bankruptcy [29]. This nancial crisis is not likely to end in the coming period with potentially huge impact on the profession in the future. In the present study, fear of infection was one of the strongest factors associated with practice closure among self-employed dentists in the private sector which agrees with a study reporting that high level of anxiety was associated with more dentists indicating a desire to close their practices [32].
In the present study, dentists in academia were more likely to report practice closure. This agrees with previous data from North America indicating that dental care in teaching clinics was suspended and only emergency treatment was offered [30]. The study also showed that dentists working in hospitals were less likely to report practice closure. This may be attributed to the high level of preparedness of hospitals. For example, some hospitals designated for the care of COVID-19 patients were equipped with high level PPE for aerosol generating dental procedures [33,34] with strict infection control measures and more dental units to meet patients' need for emergency dental services [27,35,36].
The study showed less closure in group practices and more closure in solo practices. Large, group practices may be more resilient at times of nancial hardship than small solo practices because they generally have more reserves and can pool resources to bridge the crisis. Small-scale health care providers tend to be less pro table which may increase their vulnerability to nancial threats [37].
The study showed that compared to urban practices, there was more closure in private sector rural practices and less closure in non-private sector rural practices. Private sector rural healthcare facilities usually operate on thin pro t margins, have small number of staff and less PPE against COVID-19 which put them at greater risk of closure to reduce nancial and infection risks [38][39][40]. Consequently, nonprivate sector rural practices may be the only type of facility left to provide care for the local population and hence the reported less closure.
In the present study, practice closure was also associated with country-level determinants. More hospital beds were associated with less closure in the non-private sector. Countries with low-resources and underprepared healthcare systems may have less capacity to manage COVID-19 complications resulting in higher mortality rates, panic and anxiety that increase the chances of dental practice closure [41,42]. In addition, the study showed less private practice closure in HICs. This agrees with reports that some HICs governments-such as Canada, Ireland and the UK-providing nancial support for dental practices to avoid closure due to economic losses; offering funds, loans and credits to face issues of payment of salaries and supplies [31,[43][44][45][46]. In addition, the generally higher income in HICs may provide nancial sustainability in spite of decreased revenues and reduce the need for practice closure. No such measures were reported from LICs, LMICs or UMICs where no economic response plans were made to support the dental industry despite their needs.
The study is limited by its cross-sectional design which cannot provide proof of causality and by the convenience sampling which cannot support statistical representativeness. However, it included a large number of dentists from many countries all over the world with different professional and healthcare systems background which increases the generalizability of ndings. The ndings provide estimates of practice closure in many countries around the world that can be used to assess COVID-19 impact on the oral health of the public with potential implications for dental education. Assisting the dental industry, especially self-employed dentists in the private sector, may help retain skillful personnel and avoid devastating impact on dental services. Future studies are needed to assess the long-term impact of closure on the nancial, psychologic and professional outcomes of dentists.

Conclusions
COVID-19 had a considerable impact on dental practice around the globe. Most dentists reported practice closure because of COVID-19 with greater impact in the private than non-private sector. Personal, professional and country-level factors were associated with practice closure. The ndings help provide a pro le of dentists with practices at greater risk of closure to plan for support packages. The Ethics Review Committee, Faculty of Dentistry, Alexandria, Egypt approved the study (IRB No: 00010556-IORG 0008839), and the study was carried out in agreement with the Declaration of Helsinki. Ethical explanations of the study's purposes, anonymous data collection, con dentiality, and publication were mentioned in the rst page of the online survey's webpage.

Consent for publication
Not applicable.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests.

Funding
This research did not receive any speci c grant from funding agencies in the public, commercial, or notfor-pro t sectors.
Authors' contributions HA, SA, MI and MET conceptualized and designed the study, coordinated the data collection in Egypt, supported the analysis and interpretation of the data and drafted the manuscript. MN collected data in Mynamar and reviewed drafts of the manuscript. DAM and AR contributed to the design of the study, collected and analyzed the data in Indonesia and reviewed drafts of the manuscript. MS contributed to data collection and organization in UK and reviewed drafts of the manuscript. KS contributed to the analysis and interpretation of the KSA's data and reviewed drafts of the manuscript. SB, AS and LB contributed to the analysis and interpretation of the data from India, Yemen and Pakistan, respectively and reviewed drafts of the manuscript. All authors contributed to the interpretation and ndings of the discussion, as well as the critical revision and nal approval of the version to publish.   Figure 1 Correct responses regarding knowledge about COVID-19 pandemic

Supplementary Files
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