The severe acute respiratory infection known as coronavirus disease (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was first identified in Wuhan, China, and has since spread throughout the world. The coronavirus (SARr-CoV) is a member of the family Coronaviridae and a strain of the SARS-CoV. As of December 22, 2020, this newly emerged infection of the respiratory tract was responsible for over 75 million confirmed cases and almost 1.6 million deaths.
Although risk variables such as age, gender, and comorbidities that raise the risk of complications and mortality have been discovered, there is still a significant proportion of patients without documented risk factors who experience severe COVID-19-related side effects and problems.
The role of the oral cavity in COVID-19 has been the subject of extreme discussion. Although the evidence suggests that the oral mucosa plays a crucial role in the transmission and progress of SARS-CoV-2, an association between oral disease and the severity of COVID-19 has not been demonstrated.
Gingivitis and periodontitis are the chronic, multifactoral, and inflammatory illness that is associated with plaque biofilms and is defined by the progressive loss of tooth-supporting structures. Gingivitis and Periodontitis cause th inflammation of periodontal tissues which eventually release host-derived proinflammatory cytokines and tissue death mediators into the circulatory system. This can activate an acute-phase response in the liver, which can further aggravate systemic inflammation.
According to research, the cytokine expression profile of periodontal disease and the cytokine storm of severe COVID-19 infections are comparable; this suggests that there may be a connection between periodontitis and COVID-19 and the consequences that are connected with it.[7,8] There is a possibility that the SARS-CoV-2 infection rate will rise as a result of the increased expression level of angiotensin-converting enzyme 2 (ACE2) in the oral cavity, which is boosted by periodontopathic bacteria. Patients with periodontal disorders may have an increased inflammatory response, which may make the systemic symptoms and clinical course of COVID-19 worse. According to the findings of a study that relied on radiographic examinations, periodontitis is strongly linked to significantly higher risks of COVID-19 problems as well as significantly higher blood marker levels. There are a very few studies that provide clinical data available on the link between COVID-19 and periodontal diseases. The purpose of this study was to determine the relationship between the severity of periodontal disease and the severity of COVID-19 symptoms, as well as whether periodontal disease can be considered a risk factor for COVID-19.
Study design and setting
The current retrospective study was conducted at the College of Dentistry, KSA. For this study, 3 years of patient’s medical and dental records at the University Hospital from 2018 to 2020 were used.
Study participants and data collection
A total of 196 individuals, aged between 18 and 60 years, were included in the study; of which, 62 were male and 36 were female. To estimate the severity of symptoms, a telephone interview was employed to identify whether the patient got COVID-19 infection. From the electronic health records, we extracted our main exposure variables (gingivitis and periodontitis), covariates (such as demographics and medical conditions), and COVID-19 outcomes. Information regarding whether the disease was managed at home or at the hospital, using ventilation, at ICU, or death was collected. In the literature, certain factors have been linked to the severity of COVID-19 disease. The covariants such as smoking, body mass index, and various medical conditions, such as hypertension, diabetes, cardiovascular and cerebrovascular disorders, and asthma were also taken into account before clinical examination. Adult patients who received periodontal treatment (scaling and root planning) at DAU hospital were included, and the patients under the age of 18 years, files with incomplete periodontal recordings, and patients who did not respond to the telephone calls were excluded. Due to the inability to objectively confirm the presence of periodontitis, patients whose records contained no dental radiographs were excluded. Periodontitis was characterized by loss of bone at two or, on the other hand, more nonadjoining teeth, in the wake of barring neighborhood factors connected with periodontal-endodontic lesions, broken or cracked roots, and impacted maxillary and mandibular molars. Two blinded examiners assessed each radiograph.
The gathered information was placed in microsoft excel and the measurable analysis was performed by the Statistical Package for the Social Sciences version 21 (SPSS 21) (IBM, NY, USA) software. A quality control check of the information sections was directed before the information investigation. We used descriptive analysis (percentage and frequency) depending on the nature of the variables – for instance, demographic- and profession-related data. The Chi-square test, with statistical significance set at 0.05, was used to determine the relationship between the severity of periodontal disease and the severity of COVID-19. To identify the predictors of complication development, a logistic regression analysis was performed. COVID-19 complications were considered as the dependent variables, and the independent variables were chosen based on the clinical judgment (eg:demographic variables, gingivitis, periodontitis, comorbidities, and smoking). The results are presented as odds ratios with 95% confidence intervals and P values. P = 0.05 was deemed statistically significant.
Characteristics of the study subjects
Based on their previous records, 196 participants with gingivitis (98) and periodontitis (98) were included in the current retrospective study. Sixty-two percent of the participants chosen were systemically healthy, while 37.76% were medically compromised. A telephone interview with the participants revealed that approximately 36.1% of the systemically healthy controls and 64.9% of the medically compromised participants tested positive for COVID-19. Table 1 shows the percentage distribution of the study population’s selected characteristics.
Relationship of COVID-19 and periodontal disease
Table 2 shows the relationship between COVID-19 infection and various levels of gingivitis and periodontitis. Furthermore, the statistics revealed a statistically significant link between gingivitis and periodontitis. The majority of mild gingivitis cases (63%) was associated with the COVID-19-negative group, whereas the majority of severe gingivitis groups (85.7%) was associated with the COVID-19-positive group (χ2 = 9.94; P = 0.007). Similarly, the majority of Stage 1 periodontitis (62.9%) was associated with COVID-19-negative participants, whereas the majority of Stage 4 periodontitis (P = 0.007) was associated with COVID-19-positive groups (χ2 = 22.51; P = 0.047).
Relationship of COVID-19 severity and severity periodontal disease
Table 3 describes the association of COVID-19 severity with different levels of gingivitis (χ2 = 15.88; P = 0.004) and periodontitis (χ2 = 27.87; P = 0.006), and statistics show that the difference is statistically significant. According to Table 3, the majority of mild gingivitis and stage 1 periodontitis was reported as COVID-19-negative participants, whereas the majority of severe gingivitis (57.1%) was reported as “home isolation”-related COVID-19 severity, and Stage 4 periodontitis (66.7%) was reported as “ventilation” type of COVID-19 severity.
Factors associated with COVID-19 complications
Table 4 shows that male patients were 3.2 times more likely than females to have COVID-19 complications (P = 0.042). Patients with comorbidities were 2.49 times more likely than systemically healthy individuals to have COVID-19 complications (P = 0.02). Patients with gingivitis were 2.15 times more likely than those without gingivitis to have COVID-19 complications (P = 0.043). In comparison to those without periodontitis, patients with periodontitis had a 1.54 times higher risk of COVID-19 complications (P = 0.048).
The aim of this study was to evaluate any potential association between the severity of COVID-19 and periodontal disease. The findings corroborate those of recently published studies linking periodontitis to a greater COVID-19 severity in patients with periodontitis compared to those without periodontitis. Periodontitis is a multifactorial disease that ultimately results in the loss of the supporting structures of the teeth. Its relationship with systemic disorders has been the subject of a significant amount of research.[11,12]
A systematic review by Scannapieco et al. found a strong correlation between improper dental care and the development of nosocomial pneumonia. Both chronic obstructive pulmonary disease and pneumonia have been associated with periodontitis, which can either cause the aspiration of oral infections into the lungs or modify the mucosal surfaces in the respiratory system, allowing for greater adhesion and the subsequent invasion of pathogens.[13,14] This may also contribute in explaining the connection between periodontal disease and COVID-19 seen in the present study; whereas in comparison to those with mild periodontitis, patients with severe periodontitis were associated with COVID-19.
The severity of COVID-19 was found to vary with the degree of gingivitis and periodontitis in the current study. The strong correlations between COVID-19 severity and periodontitis can be explained in a variety of ways. By increasing the expression of ACE2, a receptor for SARS-CoV2, and inflammatory cytokines in the lower respiratory tract, Takahashi et al. hypothesized that aspiration of periodontopathic bacteria might exacerbate COVID-19. In addition, it was proposed that periodontopathic bacteria may increase the virulence of SARS-CoV2 by cleaving its S glycoprotein, and that the oral cavity, particularly periodontal pockets, may serve as a viral reservoir.[10,15]
Periodontopathic bacteria are responsible for the secretion of pro-inflammatory cytokines in the lower respiratory tract, and it is possible that these cytokines are involved in the development of COVID-19. It has also been hypothesized that periodontitis and the bacteria that cause it can contribute to an increase in the amount of SARS-CoV-2 that colonizes the oral cavity; hence, the oral cavity may operate as a reservoir for the virus.[9,16] It has been proven in the past that periodontal lesions can harbor viruses, and it has also been demonstrated that periodontal pockets and dental plaque can harbor pathogens like Helicobacter Pylori and may therefore act as reservoirs for infection.[17,18] In the current study, patients with gingivitis were 2.15 times more likely than those without gingivitis to have COVID-19 complications. Thus, periodontal disease can be considered a risk factor for the development of COVID-19 disease.
Periodontitis may promote SARS-CoV-2 infection through the CD147 pathway due to the high levels of CD147 expression in the oral, subgingival component epithelial cells of periodontal pockets. Periodontitis could weaken the protective role of the oral epithelial cells by inducing gingival ulceration, putting patients at an increased risk of SARS-CoV-2 invasion.
In the current study, it was seen that males were 3.2 times more likely to have COVID-19 complications compared to females. It was also seen that patients with comorbidities were 2.49 times more likely than systemically healthy individuals to have COVID-19 complications. However, this could have been a confounding factor.[21,22]
Studies investigating the relationship between periodontitis and COVID-19 are lacking, and the current study was undertaken to investigate it. However, this retrospective study is subjected to several limitations. As a result of the restricted access to resources caused by the COVID-19 lockdown, the data for the current study were collected through the use of telephonic interviews. As a result, the data that were acquired can be inflated. As retrospective studies are intended to analyze data that has already been collected, and as a result, they are prone to several biases. Since periodontal damage is a gradual process, it is likely that the individuals included in the study had periodontitis before contracting the SARS-CoV-2 infection. Most individuals with periodontal disease are likely to be affected by several systemic risk factors such as smoking, diabetes, obesity, and osteoporosis in postmenopausal women[24–27] which may act like a confounding factor and have its direct influence on the study results. However, because this was a preliminary investigation, the information produced may be used to guide future studies and a larger sample size to better comprehend the relationship between the severity of periodontal disease and SARS-CoV-2 infection.
SARS-CoV-2-caused coronavirus illness (COVID-19) is currently the most urgent health issue faced by the entire world. The present study shows that there is a significant association between the presence of periodontal disease and COVID-19 infection. The severity of COVID-19 was observed to be directly proportional to the severity of periodontal disease, and hence, it can be studied as a risk factor for the disease. A high-quality medical care may be attainable through research into the link between periodontitis and COVID-19, specifically in the context of systemic inflammation. For these results to hold up, more research using larger samples is needed.
Ethical clearance (No. 006-009- 2021) was obtained before the start of the study from the Institutional Ethics Committee of the College of Dentistry, Dar Al Uloom University.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
The authors extend their appreciation to the Deanship of Postgraduate Studies and Scientific Research at Dar Al Uloom University, Riyadh, KSA, for their support in this project.
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