|
 
 |
| ORIGINAL ARTICLE |
|
| Year : 2022 | Volume
: 12
| Issue : 3 | Page : 269-276 |
|
Estimating the prevalence of COVID-19 disease and its effect among trainees in the endodontic postgraduate programs in the kingdom of Saudi Arabia: A web-based survey study
Fahd Alsalleeh1, Sara Alaathy1, Rand Alblaihed2
1 Restorative Dental Sciences College of Dentistry King Saud University, Riyadh, Saudi Arabia
2 Department of Dentistry, Endodontic Division, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| Date of Submission | 26-Mar-2022 |
| Date of Decision | 02-May-2022 |
| Date of Acceptance | 04-May-2022 |
| Date of Web Publication | 1-Sep-2022 |
Correspondence Address:
Dr. Fahd Alsalleeh
Restorative Dental Sciences College of Dentistry King Saud University, P. O. Box 60169, Riyadh 11545
Saudi Arabia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/sej.sej_60_22
Introduction: The coronavirus disease 2019 (COVID-19) pandemic had a profound impact on dental care and academic education. This survey investigated the prevalence of the COVID-19 pandemic, symptoms, and its impact among endodontic trainees in the Kingdom of Saudi Arabia.
Materials and Methods: This cross-sectional web-based survey targeted all endodontic residents in Saudi Arabia. A 22-item questionnaire was distributed to a total of 197 participants. The questionnaire included questions related to demographic information, COVID-19 impact on endodontic postgraduate training, the incidence of testing positive, symptoms experienced, and infection control measures. Descriptive and analytic statistics (Chi-square or Fisher's exact test) were used for the analysis. The significance level was set at P ≤ 0.05.
Results: A total of 125 residents completed the survey. During June and July of 2020, most residents (45% and 50%) were required to perform only urgent endodontic care. Among the 125 residents, 52.8% reported being tested for severe acute respiratory syndrome coronavirus 2. Of these 66 who were tested, 13.6% had positive results. Eight of the nine residents who tested positive were male. Muscle pain, loss of smell and taste, fever, and headache were the most reported symptoms. A nonsurgical root canal treatment was the most common endodontic procedure performed among those surveyed (100%, n = 125), followed by endodontic emergency (84.8%, n = 106), with surgical endodontic treatment being far less frequent (27.2%, n = 34). Enhanced infection prevention and control measures were common practices during the pandemic; almost half of the residents reported using an N95 respirator or equivalent face mask. Residents continued to provide urgent care during the pandemic, and the majority returning gradually to practice as they had before the COVID-19 pandemic by December 2020.
Conclusion: This survey showed a relatively low prevalence of COVID-19 among endodontic residents compared with other frontline healthcare workers. More male residents tested positive COVID-19. A more effective protection measurement should be made available and accessible to endodontic residents to ensure their safety and prevent interruptions to their clinical training. Keywords: COVID-19, dental, endodontics, residents, severe acute respiratory syndrome coronavirus 2
How to cite this article:
Alsalleeh F, Alaathy S, Alblaihed R. Estimating the prevalence of COVID-19 disease and its effect among trainees in the endodontic postgraduate programs in the kingdom of Saudi Arabia: A web-based survey study. Saudi Endod J 2022;12:269-76 |
How to cite this URL:
Alsalleeh F, Alaathy S, Alblaihed R. Estimating the prevalence of COVID-19 disease and its effect among trainees in the endodontic postgraduate programs in the kingdom of Saudi Arabia: A web-based survey study. Saudi Endod J [serial online] 2022 [cited 2023 Mar 22];12:269-76. Available from: https://www.saudiendodj.com/text.asp?2022/12/3/269/354837 |
| Introduction | |  |
The coronavirus disease, first diagnosed in China in 2019, COVID-19, has become a pandemic. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus belongs to the Betacoronaviridae family and causes acute lung injury and acute respiratory distress syndrome, leading to pulmonary failure and a fatality.[1] As of April 20, 2022, 506,068,066 confirmed cases of COVID-19, including over 6 M deaths, were reported to the World Health Organization.[2] The main clinical manifestations reported by several studies include, but are not limited to fever, cough, fatigue, impairment of smell (anosmia), and taste (ageusia).[3]
In the Kingdom of Saudi Arabia, the first confirmed case was reported on March 2, 2020. As of May 2, 2022, the number of confirmed cases reached 754,000 and 9089 deaths.[4] Since the coronavirus outbreak, the government has implemented several unprecedented protocols and measures to limit its spread and minimize its consequences.[5]
There is no doubt that direct contact, physical contact between an infected host and a susceptible individual, is the primary transmission mode for the virus.[6],[7] However, other routes, like fomite aerosols, eye exposure, and saliva, have been shown to spread SARS-CoV-2.[8],[9] These routes are routine in dentistry, presenting a continuous risk of infection to the dentist and dental staff through direct contact with the saliva of an infected patient, contaminated surfaces or instruments, and infectious particles that have become airborne referred to as aerosols.[10] Aerosols are defined by Micik et al. as particles <50 micrometers in diameter. Particles of this size are small enough to stay airborne for an extended period before settling on environmental surfaces or entering the respiratory tract.[11]
Due to the fact that dental procedures involve the generation of aerosols and very close and prolonged contact time, infection control measures for dental treatments, which must be strident at all times, are even more critical during this pandemic. As a result, the availability of dental care was impacted substantially by the pandemic, with routine procedures discontinued for a considerable amount of time worldwide.[12] When dental services reopened, the Ministry of Health published a dental emergency protocol highlighting which types of dental procedures would be allowed during the COVID-19 pandemic, including triage protocols, case management, and an infection prevention and control protocol to ensure proper command of services provided and reduce risk of virus transmission.[13] Among the dental procedures allowed, odontogenic pain, swelling, and dental alveolar trauma are all within the scope of endodontics.
According to official data in Saudi Arabia, this pandemic has gone through three phases: during Phase I (March through June 2020), several precautionary measures were strictly applied, starting with a partial lockdown, followed by complete lockdown limiting all services except essential ones. In addition, dental services were limited to the most urgent as determined and outlined by the American Dental Association (A.D.A.),[14] and all dental residency programs were put on hold. During Phase II (July through August 2020), protocols were established, reopening the country. For dental services, protocols were based on the A.D.A. guidelines, including respirator N95 and enhanced personal protective equipment (PPE) measures.[15] Although there was a spike in the number of confirmed cases with COVID-19 during this time, residents returned to service in their training centers to continue the academic year. Finally, during Phase III (September through March 2021), the number of active cases stabilized; when below 1000 cases per day, a return to the norm was seen in certain aspects, including all dental services.
The COVID-19 pandemic has impacted the entire world. Endodontic residency in Saudi Arabia has gone through multiple phases and continued to adjust its training programs to meet new, evolving standards. Several studies have evaluated the effect of COVID-19 on medical and dental residency programs,[16],[17] but findings specific to its impact on the postgraduate endodontic programs are lacking. Since the management of dental pain, oral swelling, and dental alveolar trauma were allowed to be performed during the pandemic, endodontic specialists and residents continued to be called to treat such cases. Advanced endodontic postgraduate programs in Saudi Arabia are offered through graduate programs sponsored by universities or overseas residency programs under the Saudi Commission for Health Specialties auspices. This study aims to estimate the prevalence of COVID-19, its symptoms, and applied infection control measures among endodontic residents in Saudi Arabia over 12 months.
| Materials and Methods | | |
This study used a cross-sectional web-based survey targeting trainees in the endodontic postgraduate programs in Saudi Arabia. The online survey was conducted in March and April of 2021. The Institutional Review Board at King Saud University approved this survey (Ref. No. 21/0172/I. R. B.). All participants were counted as agreed to participate in the study by answering the questionnaire.
Administration of the questionnaire
Questions were adapted from Estrich et al.[9] The data were collected using Microsoft Office Forms (Microsoft Corp, Redmond, WA). Endodontic postgraduate trainees were invited to participate via Microsoft Teams and email. The survey, composed of 22 questions in English, took about 5 min to complete. The questionnaire's internal consistency and reliability were measured using Cronbach's alpha test and Cohen's Kappa statistic measurements. Participants were asked to complete a set of questions about demographic information (gender, age, medical health status, training program, training level, location, and type of training center), followed by a series of questions related to COVID-19 impact on their training and the incidence of having a positive test. Additional questions were related to infection control measures and endodontic procedures performed.
Eligibility criteria
All 197 endodontic residents in postgraduate programs in Saudi Arabia were included. This includes the Saudi Board of Endodontics residents and graduate students enrolled in a University program.
Statistical analysis
All data were transferred from Microsoft Office Forms into Microsoft Excel (Microsoft Corp, Redmond, WA) and analyzed with the Statistical Package of the Social Sciences (SPSS, Version 25; I. B. M. Corp, Armonk, NY). Descriptive statistics were used for the analysis. Chi-square for the goodness of fit was used to test the equality of likelihood of the participant categorical levels distribution. The subjects were grouped, and Chi-square or Fisher's exact tests were used to study the association between the categorical variables. The significance level was set at P < 0.05, and all confidence intervals were determined at 95% for all statistical calculations.
| Results | | |
A total of 125 residents participated and completed the survey, for a response rate of 63%. Most residents reported their age to be 24–30 years (n = 94, 75.2%), and 24.8% (n = 31) reported to be 41–40 years. Residents identified as male (n = 73, 58.4%), and female (n = 51, 40.8%). The majority (n = 96, 76.8%) were in governmental centers. Residents who reported being healthy were in the majority (n = 106, 84.8%). However, among the residents, 19 (15.2%) had medical conditions associated with a higher risk of developing severe illness from COVID-19, most commonly asthma (n = 5, 4%), obesity (n = 4, 3.2%), and smoking (n = 7, 5.6%). The details of the demographic analysis are shown in [Table 1].
Impact of COVID-19 pandemic mitigation on the training programs
Residents were asked about months during which they could not practice or see patients for any treatment. The months of March through June 2020 reported significantly the highest and gradually decreased after [Figure 1]a. During June and July 2020, the majority of residents (45% and 50%, respectively, Chi-square P < 0.05 for July and June compared with other months) were required to perform only urgent endodontic care [Figure 1]b. By September through December 2020, residents were significantly and gradually returning and able to practice as before the COVID-19 pandemic [Figure 1]c. | Figure 1: Impact of COVID-19 pandemic mitigation on the training programs. The Percentage of residents that were not able to treat or see patients (a), or only performed endodontic urgent care (b), and returned to practice with no restrictions (c and d) The endodontic procedures performed during the pandemic
Click here to view |
The survey also asked endodontic residents about treatments they performed during the 12 months leading into the pandemic. From March 2019 to March 2020, nonsurgical root canal treatment was highly significantly (P < 0.05) the most common (100%, n = 125), followed by endodontic emergency; pulpotomy and pulpectomy, and caries control (84.8%, n = 106, P < 0.05). Surgical endodontic treatment was less frequent (27.2%, n = 34) [Figure 1]d.
Infection control measures and personal protective equipment use
Regarding their use of enhanced infection prevention and control measures as outlined by A.D.A. and the Ministry of Health in the Kingdom, 69.6% of residents reported to have screening strategies for known or suspected SARS-CoV-2 infection by filling forms about clinical symptoms and epidemiological risk factors related (presence of fever, dry cough, loss of smell and taste, respiratory illness, travel history, and contact with known or suspected cases). In addition to that, recording patients' temperatures (84%); checking residents' temperatures (71.2%); disinfecting of high-touch surfaces and Materials (73.6%); disinfecting all equipment in the operatory between patients (80%) were routinely performed.
In addition to basic clinical PPE, including eye protection, residents reported using an N95 respirator or equivalent face mask 50.6% (n = 63), and 49.4% (n = 62) wore surgical face masks with full-face shield [Figure 2]a. Of the 125 residents, 52.8% (n = 66) had used the PPE before rubber dam application and 47.2% (n = 59) before and after [Figure 2]b. | Figure 2: Self-reported personal protective equipment and type of masks used by residents (a), and timing to wear them (b)
Click here to view |
Self-reported confirmed COVID-19 and symptoms among residents
Among the 125 residents, 52.8% (n = 66) reported being tested for SARS-CoV-2 [Figure 3]a. Most residents (75%) were tested one to three times, and the rest had more than four times [Figure 3]b. Fifty-nine residents (65%) were tested with a throat swab test, 29 (32%) with nasal swab test, and three (3%) with blood sample test. Among 66 residents tested, nine (13.6%, P = 0.136) had positive results [Figure 3]c. Eight of the nine residents who tested positive identified as males [[Table 2], P = 0.03]. | Figure 3: The incidence and frequencies of residents went to be tested for SARS-CoV-2 (a and b). The incidence of residents who had positive COVID-19 (c). SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2
Click here to view |
The Residents who had positive COVID-19 were asked to report on symptoms they experienced. Muscle pain, the new loss of smell and taste, fever, and headache were the most experienced symptoms.
Self-reported activities
Residents were asked about their activities after lifting some of the restrictions. Also, an attempt to correlate these activities with the confirmed COVID-19 cases is presented in [Table 3]. Among the nine residents with the confirmed COVID-19, five (55.6%) reported not using an N95 respirator or equivalent face mask. A Fisher's exact test showed no association (P = 0.404) [Table 4]. | Table 3: Correlation between activities done after lifting restrictions with the positive COVID-19 results
Click here to view |
 | Table 4: Correlation between the use of N95 respirator or equivalent face mask and the positive COVID-19 results
Click here to view |
| Discussion | | |
The COVID-19 pandemic had an immediate and profound impact on dental care and education.[15],[18] The Centers for Disease Control and Prevention and several international dental organizations and bodies such as the A.D.A. and the American Association of Endodontics responded quickly with protocols and guidelines measures to protect dental health providers and their patients.[14],[19] As routine and elective dental care were suspended in most countries.[12] However, management of odontogenic pain, swelling, and dental alveolar trauma, all within the scope of endodontics, was exempted. Its treatment was allowed to be offered under strict infection control measures, including enhanced PPE Highly aerosol-generating tools, highspeed handpieces, and ultrasonic devices are common in endodontic procedures. Interestingly enough, rubber dam isolation, an essential for endodontic procedures, had been linked to greater aerosol levels on the dentists' heads.[20] A recent study had confirmed aerosols generated during different endodontic procedures utilizing passive air sampling technique. In addition, the proximity and prolonged time inherited during endodontic procedures were implicated in the level of contamination.[21] Thus, endodontic specialists and residents are at risk of COVID-19 transmission. As of April 2021, 13.6% of the endodontic residents surveyed had COVID-19. The result indicated that prevalence and incidence rates among endodontic residents are lower than other frontline healthcare providers (H.C.P.s). In a cross-sectional survey of frontline H.C.P.s in the United States, the prevalence rate was 29%.[22] In a recent study, the cumulative prevalence and incidence rates of COVID-19 among U.S. dentists was 2.6%.[23] The relatively higher prevalence in the present study may be attributed to the fact that endodontic procedures often generate aerosols, carry higher risks of COVID-19 transmission. Furthermore, most endodontic residents continued to provide dental care during the spike national COVID-19 rate (Phase II, June through August 2020) and performed nonsurgical primary root canal treatment and endodontic emergencies. This result confirms that endodontic residents provided endodontic care in the frontline treatment of dental patients during this pandemic.
Several factors were investigated that might increase the risk of infection, and such associations were found among male residents; that could be because more males (58.4%) participated in the survey than females (40.8%) and the percentage of unhealthy male residents (19.2%) more than unhealthy female residents (9.8%) which make them be at high risk of infection. In addition, the high prevalence of community transmission of COVID-19 during the study period shows that residents might acquire COVID-19 outside and not related to their clinical training.
It is widely accepted that respiratory droplets are the primary route of transmission for COVID-19.[24] Since most patients with COVID-19 infections are asymptomatic or with mild symptoms, and the incubation period can range from 2 to 14 days,[25],[26] dental practitioners might treat such cases. Despite the inability to establish a direct relationship between COVID-19 transmission and dental procedures, a plausible potential for transmission still exists.[3] Hence, several PPE measures were endorsed by national and international guidelines to minimize infection risks.[27],[28] The current study showed that these measures were prevalent practices among endodontic residents regardless of their level, location, and type of workplace. Based on experimental and clinical evidence, N95 masks or respirators were required in all aerosol-generating dental procedures with close contact. N95 masks have greater than 99% efficiency in the removal of viable viruses from 20 nm (human rhinovirus) to 110 nm (human influenza A).[29] Accordingly, it is assumed that N95 masks would be adequate to prevent the transmission of viable SARS CoV-2.[30] A clinical study found that the infection rate was only 0.1% among more than 2,000 healthcare workers who wore N95 masks and treated patients with coronavirus infections in hospital settings for 4 weeks.[31] The results presented herein indicated that only 50% of endodontic residents had used N95 or equivalent, and among them, four had confirmed COVID-19 results. It should be noted that the majority of COVID-19 cases reported in this study were among male residents, perhaps males being nonadherence to N95 masks compared to females. Nevertheless, the availability of such masks and limited supply might be the reason for forcing residents to use equivalent but less effective masks.
It should be noted that the pandemic directly impacted the residents' clinical training activities. During March through August 2020, most endodontic residents could not practice or treat patients. These results are attributed to the general lockdown and compliance with strict protocol on dental service practices during the pandemic by the local Ministry of Health and international agencies. The results herein agree with a recent study in which 82.61% of the active endodontic specialists and general dentists who provided endodontic care had returned their endodontic practice partially or entirely by May 9, 2020.[32]
This is the first study to report the incidence rates of COVID-19 among endodontic residents to the best of available current evidence. The sample size represents the majority of postgraduate endodontic residents practiced during the COVID-19 pandemic. However, it should be noted that these findings are self-reported and, therefore, subject to uncontrolled variables; recall and individual biases. Furthermore, the reported prevalence did not account for asymptomatic cases where residents did not seek care or test confirmation. Previous studies with similar experimental designs reported less than a 40% response rate.[9] The lack of testing mandates unless exposed or developed signs and symptoms of COVID-19 may explain that only 52.8% of residents reported being tested for SARS-CoV-2. Furthermore, other factors; being afraid of the test or avoiding the consequences of positive results, may play some roles.[33]
The current study had limitations. First, these findings are self-reported and, therefore, subject to uncontrolled variables; recall and individual biases. Second, the study did not include contact tracing or investigate the source of infection in confirmed cases. Third, the generalization of the study may be limited due to the lack of responses from all residents. Furthermore, the reported prevalence did not account for asymptomatic cases where residents did not seek care or test confirmation. Forth, the didactic component and psychological impact were not investigated. Therefore, future research should focus on a more comprehensive analysis of all aspects of advanced endodontic training in response to the COVID-19 pandemic. Last, as the world evolves and carries on through the pandemic, countries differ in response and mitigation protocols. Therefore, the present study's findings may be limited and should be interpreted with caution.
| Conclusion | | |
This study showed a relatively low prevalence of COVID-19 among endodontic residents compared with other frontline healthcare workers. More male residents tested positive COVID-19. A more effective protection measurement should be made available and accessible to endodontic residents to ensure their safety and prevent interruptions to their clinical training.
Acknowledgment
The authors would like to thank Dr. Nassr Almaflehi, PhD for the assistance to conduct statistical analysis.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Shereen MA, Khan S, Kazmi A, Bashir N, Siddique R. COVID-19 infection: Origin, transmission, and characteristics of human coronaviruses. J Adv Res 2020;24:91-8.  |
| 2. | World Health Organization. WHO Coronavirus Disease (COVID-19) Dashboard; 2020. Available from: https://covid19.who.int. [Last accessed on 2022 Apr 20]. |
| 3. | Banakar M, Bagheri Lankarani K, Jafarpour D, Moayedi S, Banakar MH, MohammadSadeghi A. COVID-19 transmission risk and protective protocols in dentistry: A systematic review. BMC Oral Health 2020;20:275. |
| 4. | |
| 5. | Algaissi AA, Alharbi NK, Hassanain M, Hashem AM. Preparedness and response to COVID-19 in Saudi Arabia: Building on MERS experience. J Infect Public Health 2020;13:834-8. |
| 6. | Li Q, Guan X, Wu P, Wang X, Zhou L, Tong Y, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med 2020;382:1199-207. |
| 7. | Xie C, Zhao H, Li K, Zhang Z, Lu X, Peng H, et al. The evidence of indirect transmission of SARS-CoV-2 reported in Guangzhou, China. BMC Public Health 2020;20:1202. |
| 8. | Castaño N, Cordts SC, Kurosu Jalil M, Zhang KS, Koppaka S, Bick AD, et al. Fomite transmission, physicochemical origin of virus-surface interactions, and disinfection strategies for enveloped viruses with applications to SARS-CoV-2. ACS Omega 2021;6:6509-27. |
| 9. | Estrich CG, Mikkelsen M, Morrissey R, Geisinger ML, Ioannidou E, Vujicic M, et al. Estimating COVID-19 prevalence and infection control practices among US dentists. J Am Dent Assoc 2020;151:815-24. |
| 10. | Harrel SK, Molinari J. Aerosols and splatter in dentistry: A brief review of the literature and infection control implications. J Am Dent Assoc 2004;135:429-37. |
| 11. | Micik RE, Miller RL, Mazzarella MA, Ryge G. Studies on dental aerobiology. I. Bacterial aerosols generated during dental procedures. J Dent Res 1969;48:49-56. |
| 12. | Coulthard P, Thomson P, Dave M, Coulthard FP, Seoudi N, Hill M. The COVID-19 pandemic and dentistry: The clinical, legal and economic consequences – Part 1: Clinical. Br Dent J 2020;229:743-7. |
| 13. | |
| 14. | |
| 15. | Ather A, Patel B, Ruparel NB, Diogenes A, Hargreaves KM. Coronavirus disease 19 (COVID-19): Implications for clinical dental care. J Endod 2020;46:584-95. |
| 16. | Martinho FC, Griffin IL. A cross-sectional survey on the impact of coronavirus disease 2019 on the clinical practice of endodontists across the United States. J Endod 2021;47:28-38. |
| 17. | Zhao D, Yu J, Zhang T, Du M, Yang Q, Li Z, et al. Impact of COVID-19 on advanced dental education: Perspectives of dental residents in Wuhan. J Dent Educ 2021;85:756-67. |
| 18. | Alkahtani FN, Barakat RM. Academic performance and dental student satisfaction with emergency remote teaching of endodontics during COVID-19 pandemic: A retrospective cohort study. Saudi Endod J 2021;11:321-6. [Full text] |
| 19. | |
| 20. | Al-Amad SH, Awad MA, Edher FM, Shahramian K, Omran TA. The effect of rubber dam on atmospheric bacterial aerosols during restorative dentistry. J Infect Public Health 2017;10:195-200. |
| 21. | Bahador M, Alfirdous RA, Alquria TA, Griffin IL, Tordik PA, Martinho FC. Aerosols generated during endodontic treatment: A special concern during the coronavirus disease 2019 pandemic. J Endod 2021;47:732-9. |
| 22. | Firew T, Sano ED, Lee JW, Flores S, Lang K, Salman K, et al. Protecting the front line: A cross-sectional survey analysis of the occupational factors contributing to healthcare workers' infection and psychological distress during the COVID-19 pandemic in the USA. BMJ Open 2020;10:e042752. |
| 23. | Araujo MW, Estrich CG, Mikkelsen M, Morrissey R, Harrison B, Geisinger ML, et al. COVID-2019 among dentists in the United States: A 6-month longitudinal report of accumulative prevalence and incidence. J Am Dent Assoc 2021;152:425-33. |
| 24. | Prather KA, Wang CC, Schooley RT. Reducing transmission of SARS-CoV-2. Science 2020;368:1422-4. |
| 25. | Tian S, Hu N, Lou J, Chen K, Kang X, Xiang Z, et al. Characteristics of COVID-19 infection in Beijing. J Infect 2020;80:401-6. |
| 26. | Syangtan G, Bista S, Dawadi P, Rayamajhee B, Shrestha LB, Tuladhar R, et al. Asymptomatic SARS-CoV-2 carriers: A systematic review and meta-analysis. Front Public Health 2020;8:587374. |
| 27. | Ren YF, Rasubala L, Malmstrom H, Eliav E. Dental care and oral health under the clouds of COVID-19. JDR Clin Trans Res 2020;5:202-10. |
| 28. | Pan Y, Liu H, Chu C, Li X, Liu S, Lu S. Transmission routes of SARS-CoV-2 and protective measures in dental clinics during the COVID-19 pandemic. Am J Dent 2020;33:129-34. |
| 29. | Zhou SS, Lukula S, Chiossone C, Nims RW, Suchmann DB, Ijaz MK. Assessment of a respiratory face mask for capturing air pollutants and pathogens including human influenza and rhinoviruses. J Thorac Dis 2018;10:2059-69. |
| 30. | Tiwari M, Mishra D. Investigating the genomic landscape of novel coronavirus (2019-nCoV) to identify non-synonymous mutations for use in diagnosis and drug design. J Clin Virol 2020;128:104441. |
| 31. | MacIntyre CR, Chughtai AA, Seale H, Dwyer DE, Quanyi W. Human coronavirus data from four clinical trials of masks and respirators. Int J Infect Dis 2020;96:631-3. |
| 32. | Yu J, Hua F, Shen Y, Haapasalo M, Qin D, Zhao D, et al. Resumption of endodontic practices in COVID-19 hardest-hit area of China: A web-based survey. J Endod 2020;46:1577-83.e2. |
| 33. | Li S, Feng B, Liao W, Pan W. Internet use, risk awareness, and demographic characteristics associated with engagement in preventive behaviors and testing: Cross-sectional survey on COVID-19 in the United States. J Med Internet Res 2020;22:e19782. |
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]
|
Search Pubmed for