COVID-19 and periodontitis: reflecting on a possible association

The role of viruses in oral mucosal lesions

The mucosa of the oral cavity is exposed to a large number of different microorganisms such as archaea, bacteria, fungi, parasites, and viruses. Among those, viruses cause specific infections, which can easily be transmitted from one person to another. The infectious route may not only include patients and their relatives but also the dental professional team. Thus, a wide knowledge regarding specific viral infections is crucial for the daily routine. Signs and symptoms of oral viral infections can be completely absent or develop into a pronounced clinical picture, so that early detection and information determine the further course of the infection and its influence on other inflammatory diseases, such as periodontitis, as well as the safety of family members and the social environment. As the clinical manifestation of viral infections may be highly variable leading to heterogenous mucosal lesions it is, in most cases, mandatory to differentiate them by specific microbiological tests in addition to clinical examination procedures. This article will give an overview of the role of viruses infecting the oral mucosa, and in addition, describe their clinical manifestation and management.

Herpesviruses and SARS-CoV-2: Viral Association with Oral Inflammatory Diseases

The oral cavity is a niche for diverse microbes, including viruses. Members of the Herpesviridae family, comprised of dsDNA viruses, as well as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an ssRNA virus, are among the most prevalent viruses infecting the oral cavity, and they exhibit clinical manifestations unique to oral tissues. Viral infection of oral mucosal epithelia triggers an immune response that results in prolonged inflammation. The clinical and systemic disease manifestations of HHV have been researched extensively, and several recent studies have illuminated the relationship between HHV and oral inflammatory diseases. Burgeoning evidence suggests the oral manifestation of SARS-CoV-2 infection includes xerostomia, dysgeusia, periodontal disease, mucositis, and opportunistic viral and bacterial infections, collectively described as oral post-acute sequelae of COVID-19 (PASC). These diverse sequelae could be a result of intensified immune responses initially due to the copious production of proinflammatory cytokines: the so-called "cytokine storm syndrome", facilitating widespread oral and non-oral tissue damage. This review explores the interplay between HHV, SARS-CoV-2, and oral inflammatory diseases such as periodontitis, endodontic disease, and peri-implantitis. Additionally, the review discusses proper diagnostic techniques for identifying viral infection and how viral diagnostics can lead to improved overall patient health.

Unraveling the Link between Periodontitis and Coronavirus Disease 2019: Exploring Pathogenic Pathways and Clinical Implications

Periodontitis involves the inflammation of the periodontal tissue, leading to tissue loss, while coronavirus disease 2019 (COVID-19) is a highly transmissible respiratory disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is amplified by poor systemic health. Key facilitators of SARS-CoV-2's entry into host cells are angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). This review reveals that periodontal pockets can serve as a hotspot for virus accumulation, rendering surrounding epithelia more susceptible to infection. Given that ACE2 is expressed in oral mucosa, it is reasonable to suggest that poor periodontal health could increase the risk of COVID-19 infection. However, recent studies have not provided sufficient evidence to imply a significant effect of COVID-19 on periodontal health, necessitating further and more long-term investigations. Nevertheless, there are hypotheses linking the mechanisms of the two diseases, such as the involvement of interleukin-17 (IL-17). Elevated IL-17 levels are observed in both COVID-19 and periodontitis, leading to increased osteoclast activity and bone resorption. Lastly, bidirectional relationships between periodontitis and systemic diseases like diabetes are acknowledged. Given that COVID-19 symptoms may worsen with these conditions, maintaining good oral health and managing systemic diseases are suggested as potential ways to protect against COVID-19.

Association between periodontal diseases and COVID-19 infection: a case-control study with a longitudinal arm

Some studies have suggested potential relationships between periodontal disease and COVID-19, explained by many possible pathological pathways. The aim of this case-control study with a longitudinal arm was to investigate this association. 80 systemically healthy individuals (apart from COVID-19) were involved in this study, divided into 40 patients who had recently had COVID-19 (test, divided into severe and mild/moderate cases) and 40 who had not had COVID-19 (control). Clinical periodontal parameters and laboratory data were recorded. Mann-Whitney U test, Wilcoxon test, and chi-square test were performed to compare variables. Multiple binary logistic regression method was used to estimate adjusted ORs and 95% confidence interval. Hs-CRP-1 and 2, Ferritin-1 and 2, lymphocyte count-1 values, and neutrophil/lymphocyte ratio-1 were higher in patients with severe COVID-19 than patients with mild/moderate COVID-19 (p < 0.05). All of these laboratory values significantly decreased after COVID-19 treatment (p < 0.05) in the test group. Presence of periodontitis (p = 0.015) was higher and periodontal health was lower (p = 0.002) in the test group than in the control group. All clinical periodontal parameters were significantly higher in the test group than in the control group (p < 0.05), except plaque index. Prevalence of periodontitis was associated with increased odds of having COVID-19 infection (PR = 1.34; 95% CI 0.23-2.45) in the multiple binary logistic regression. COVID-19 is associated with periodontitis prevalence, through a series of possible mechanisms including local and systemic inflammatory responses. Further studies should investigate whether the maintenance of periodontal health may be a factor in the reduction of the severity of COVID-19 infections.

Association between the severity of periodontitis, COVID-19, C-reactive protein and interleukin-6 levels in hospitalized patients: a case‒control study

BACKGROUND

The COVID-19 pandemic is perhaps one of the most important events of the 21st century. Periodontitis is one of the most prevalent diseases of the oral cavity. Due to possible pathways of interaction between these two diseases, we investigated their association.

METHODS

The study population consisted of hospitalized patients with established COVID-19 diagnoses. Patients with mild to moderate COVID-19 were considered controls, while cases had severe to critical COVID-19. Periodontal examination and serum and saliva sampling were performed for each patient. Relevant medical data were extracted from patients' hospital files.

RESULTS

Of the enrolled patients, 122 were included in the statistical analyses. The severity of periodontitis was directly and significantly correlated with the severity of COVID-19 (P < 0.001). Patients with generalized stage III or IV periodontitis displayed an adjusted odds ratio of 4.24 for severe to critical COVID-19. Salivary and serum interleukin-6 levels were significantly associated with COVID-19 severity (P values: 0.002 and 0.004, respectively). Hospitalization length was significantly associated with the severity of periodontitis (P = 0.004). Clinical attachment level and gingival index were associated with increased odds for adverse events (P values: 0.004 and 0.035, respectively), while number of remaining teeth was associated with decreased odds for adverse events (P = 0.023).

CONCLUSIONS

This study showed that the severity of periodontitis is associated with the severity of COVID-19. This association might manifest as increased odds of adverse events. COVID-19 severity was associated with higher levels of salivary and serum interleukin-6 levels.

Relationship between periodontitis and COVID-19: A bidirectional two-sample Mendelian randomization study

Background and Aims

Coronavirus disease (COVID-19) is a major danger to world health and has been linked to periodontitis in a number of epidemiological observational studies. However, it is unclear whether COVID-19 causes periodontitis. COVID-19's causal influence on periodontitis was determined using bidirectional Mendelian randomization (MR).

Methods

Large-scale COVID-19 and periodontitis genome wide association study data were analyzed. Inverse variance weighting, MR-Egger, weighted median, and MR-PRESSO were used to estimate causal effects. Sensitivity studies were conducted using the Cochran's Q test, the MR-Egger intercept test, the MR-PRESSO, and the leave-one-out (LOO) analysis. Further investigation of potential mediating factors was performed using risk factor analysis.

Results

The MR presented no causal relationship between periodontitis and hospitalization for COVID-19 (odds ratio [OR] = 0.97, 95% confidence interval [CI] 0.78-1.20; p = 0.76), vulnerability to COVID-19 (OR = 1.04, 95% CI 0.88-1.21; p = 0.65), COVID-19 disease severity (OR = 1.01, 95% CI 0.92-1.11; p = 0.81). Meanwhile, a noncausal effect of genetic hospitalization for COVID-19, illness severity, and vulnerability to periodontitis was detected. Other MR methods yielded identical results to inverse variance weighting. According to sensitivity analysis, horizontal pleiotropy is unlikely to affect causal estimation.

Conclusion

Periodontitis had no link to the risk of COVID-19 hospitalization, susceptibility, or severity. However, the substance in COVID-19 that is responsible for this effect must be studied further.

Relationship between the Social Development Index and Self-Reported Periodontal Conditions

Inequalities in oral health are influenced by the social strata of the population. Few studies have focused on the multitude of factors related to social development as indicators of living conditions and periodontal health status. The aim of this study is to evaluate the association between self-reported periodontal conditions and the Social Development Index (SDI). A cross-sectional validated questionnaire was carried out among 1294 Mexican adults. Descriptive statistics and multivariate logistic regression models were used to identify the best predictors of self-reported periodontal conditions. Bone loss reporting was used as a proxy for the presence of periodontal disease. We found that higher global scores on the SDI and quality and available space in the home (QASH) increase the probability of having bone loss. Global SDI (OR = 7.27) and higher QASH (OR = 3.66) were indeed the leading societal factors related to periodontal disease. These results have pointed out how SDI and its indicators, in particular QASH, can be used to further explore inequities related to privileged access to dental care in the context of periodontal diseases.

Oral and systemic health: is there a "new" link with COVID-19?

OBJECTIVES

The objective of the present narrative review was to evaluate the evidence of a possible association between periodontitis and COVID-19, and its biological plausibility, using as models the potential associations with cardiovascular diseases, diabetes, and some respiratory diseases.

METHODS

A recent systematic review was used as main reference to explore the associations of periodontitis with different respiratory diseases, including COVID-19, following two focussed questions: a PECOS question, aimed to explore epidemiological evidence, and a PICOS question, designed to explore the evidence derived from intervention studies. In addition to that evidence, other relevant scientific documents, including consensus papers, were carefully selected and appraised.

FINDINGS

Convincing evidence was found to support the association of periodontitis and cardiovascular diseases, diabetes, and some respiratory diseases. The biological plausibility behind those associations is based on four factors: (1) bacteraemia of oral bacteria and periodontal pathogens, (2) increased systemic inflammation, (3) common genetic factors, and (4) common environmental risk factors. Limited initial evidence is available to support an association between periodontitis and COVID-19 complications. Among the proposed factors to explain the suggested association, a combination of the previously mentioned factors, plus additional factors related with SARS-CoV-2 characteristics and pathogenicity, has been suggested.

CONCLUSIONS

Initial evidence suggests that periodontitis may be associated with a more severe COVID-19 and with a higher risk of death due to COVID-19.

CLINICAL RELEVANCE

Due to the possible association between periodontitis and an increased severity for COVID-19, additional efforts should be made to improve oral and periodontal health, including the promotion of oral healthy habits, such as oral hygiene.

Periodontitis and COVID-19: Immunological Characteristics, Related Pathways, and Association

Both periodontitis and Coronavirus disease 2019 (COVID-19) pose grave threats to public health and social order, endanger human life, and place a significant financial strain on the global healthcare system. Since the COVID-19 pandemic, mounting research has revealed a link between COVID-19 and periodontitis. It is critical to comprehend the immunological mechanisms of the two illnesses as well as their immunological interaction. Much evidence showed that there are many similar inflammatory pathways between periodontitis and COVID-19, such as NF-κB pathway, NLRP3/IL-1β pathway, and IL-6 signaling pathway. Common risk factors such as gender, lifestyle, and comorbidities contribute to the severity of both diseases. Revealing the internal relationship between the two diseases is conducive to the treatment of the two diseases in an emergency period. It is also critical to maintain good oral hygiene and a positive attitude during treatment. This review covers four main areas: immunological mechanisms, common risk factors, evidence of the association between the two diseases, and possible interventions and potential targets. These will provide potential ideas for drug development and clinical treatment of the two diseases.

Periodontal disease and COVID-19: Prognosis and potential pathways of association in their pathogenesis

Objective

The objective of this narrative review is to determine if periodontal disease is a factor in the development of a poor prognosis for COVID-19.

Method

A bibliographic search was conducted in PubMed, Virtual Health Library, Google Scholar, and in the databases of Science Direct, Scopus, Lilacs, Bireme, Scielo, and Web of Science, using the following keywords: "COVID-19," "SARS-CoV-2," and "periodontal diseases."

Results

Fifty-six records were retrieved from the database searches. After screening, 39 articles were selected for study: 13 reviews, 2 case-control studies, 1 systematic review, 8 letters to the editor, 2 cohort studies, 1 thesis, 7 hypotheses, 1 short communication, 3 commentaries, and 1 scoping review.

Discussion

Both periodontal disease and COVID-19 produce an inflammatory response. This immune response generates an over-production of inflammatory cytokines that can harm overall health.

Conclusion

The mouth serves as the entryway for many microorganisms that can harm health in general, among them SARS-CoV-2. It is important to maintain good oral health to lower the inflammatory load present in periodontal disease, lessening the possibility of complications from COVID-19.

Diabetes Prevention and Measures to Ensuring a Healthy Lifestyle during COVID-19 Pandemic and after

The incidence of diabetes mellitus (DM) is increasing exponentially globally, with 90% of the confirmed cases being type 2 DM. The global incidence of DM is expected to increase by 48% during 2017-2045. The coronavirus disease 2019 (COVID-19) pandemic continues to have a massive impact on human health, causing sudden lifestyle changes through quarantine measures, such as lockdown, social distancing, various curfews, and isolation at home. This in turn might increase the risk of developing numerous chronic diseases, such as DM, obesity, and cardiovascular diseases, which increase the severity of COVID-19. To this end, we performed a comprehensive review to determine viable measures for the prevention of DM and its subsequent upsurge globally. Additionally, we have determined strategies that should be adopted globally to ensure a healthy lifestyle during the COVID-19 pandemic and later.

Changes in the organs and tissues of the oral cavity in the new coronavirus infection (COVID-19): A review

SARS-CoV-2 infection can cause changes in the organs and tissues of the oral cavity, which is associated with a wide distribution of angiotensin-converting enzyme type 2 in the oral cavity, mainly epithelial cells of the oral mucosa, gums and fibroblasts of the periodontal ligament. Thus, the oral mucosa is susceptible to SARS-CoV-2 infection and may act as a gateway for the virus, as well as a reservoir for SARS-CoV-2. We searched the literature for the period from the beginning of the pandemic until May 30, 2022, devoted to the study of changes in the organs and tissues of the oral cavity with a new coronavirus infection (COVID-19) in the electronic search engines PubMed/MEDLINE and Scopus. A special place in the study of changes in the organs and tissues of the oral cavity with a new coronavirus infection (COVID-19) is occupied by periodontal pathology. A number of reviews and clinical studies conclude the importance of good oral hygiene and periodontal health as an important aspect of COVID-19 prevention and management. Oral probiotics can be considered as a promising direction for correcting changes in organs and tissues of the oral cavity in COVID-19.

Association between Periodontitis and COVID-19 Based on Severity Scores of HRCT Chest Scans

BACKGROUND

A relationship between periodontitis and COVID-19 may exist, as highlighted by several hypothetical models. However, the evidence is limited. Hence, the present study was conducted to determine whether an association exists between periodontitis and COVID-19.

METHODS

A cross-sectional study was carried out with patients diagnosed with COVID-19 who were divided into three groups-mild, moderate, and severe COVID-19-based on the COVID-19 severity score of high-resolution computed tomography (HRCT) chest scans. Periodontal parameters-including the plaque index (PI), ratio of sites with gingival bleeding (BOP), pocket depth (PD), gingival recession (REC), clinical attachment loss (CAL), and mean numbers of mobile and missing teeth due to periodontitis-were recorded for all three groups. Statistical analyses were applied to the data.

RESULTS

Of 294 patients with COVID-19, approximately 50.68% (n = 149) had periodontitis, and the highest percentage (87.5%) was reported in the severe COVID-19 group. Additionally, severe and advanced stages of periodontitis (stage III-IV) were found to be significantly more frequent in subjects with severe COVID-19 than in the other two groups. The HRCT severity score (CT-SS) was moderately correlated with increased levels of periodontal parameters.

CONCLUSIONS

Results of logistic regression analyses showed that the probability of developing severe COVID-19 was 2.81 times higher in patients with periodontitis. An association exists between periodontitis and severe COVID-19.

Impact of COVID-19 on Periodontitis and Peri-Implantitis: A Narrative Review

COVID-19 is reported as one of the most widespread diseases in the world. An extraordinary number of articles and manuscripts have focused on the inflammatory cascade and sequelae, showing the important roles of cytokines and renin-angiotensin levels and possible links to other pathologies. Nowadays, interest regarding the possible correlation between COVID-19 and periodontal and Peri-implant diseases is increasing. This mini-review aims to collect data regarding the possible correlation between COVID-19 and periodontitis or Peri-implantitis through the analysis of articles published in the last 3 years. The following keywords were used: ([periodontitis OR periodontal disease] AND [COVID-19]); ([Peri-implantitis OR mucositis] AND [COVID-19 OR Sars-CoV-2]). The inclusion criteria were studies on COVID-19 or SARS-CoV-2 and periodontitis or Peri-implantitis, and studies on the molecular and cellular aspect of COVID-19 in periodontal or Peri-implant tissues. The search revealed 484 articles in total (PubMed 208 and Scopus 276). After a screening of titles and abstracts, 47 articles were included in the full-text analysis. Two articles comprised the Peri-implant group: a short communication and a review. Regarding the periodontal group, 45 articles were selected and analyzed according to the type of study, population, and aim. Of these, 10 articles were clinical studies, and the other 35 were hypotheses, reviews, letters to the editor, or commentaries. In conclusion, according to the data extracted, a mutual correlation between COVID-19 and periodontitis can be stated; however, data linked to Peri-implantitis are still missing, and future clinical studies are still needed.

Periodontal disease increases the host susceptibility to COVID-19 and its severity: a Mendelian randomization study

Background

Emerging evidence shows that periodontal disease (PD) may increase the risk of Coronavirus disease 2019 (COVID-19) complications. Here, we undertook a two-sample Mendelian randomization (MR) study, and investigated for the first time the possible causal impact of PD on host susceptibility to COVID-19 and its severity.

Methods

Summary statistics of COVID-19 susceptibility and severity were retrieved from the COVID-19 Host Genetics Initiative and used as outcomes. Single nucleotide polymorphisms associated with PD in Genome-wide association study were included as exposure. Inverse-variance weighted (IVW) method was employed as the main approach to analyze the causal relationships between PD and COVID-19. Three additional methods were adopted, allowing the existence of horizontal pleiotropy, including MR-Egger regression, weighted median and weighted mode methods. Comprehensive sensitivity analyses were also conducted for estimating the robustness of the identified associations.

Results

The MR estimates showed that PD was significantly associated with significantly higher susceptibility to COVID-19 using IVW (OR = 1.024, P = 0.017, 95% CI 1.004–1.045) and weighted median method (OR = 1.029, P = 0.024, 95% CI 1.003–1.055). Furthermore, it revealed that PD was significantly linked to COVID-19 severity based on the comparison of hospitalization versus population controls (IVW, OR = 1.025, P = 0.039, 95% CI 1.001–1.049; weighted median, OR = 1.030, P = 0.027, 95% CI 1.003–1.058). No such association was observed in the cohort of highly severe cases confirmed versus those not hospitalized due to COVID-19.

Conclusions

We provide evidence on the possible causality of PD accounting for the susceptibility and severity of COVID-19, highlighting the importance of oral/periodontal healthcare for general wellbeing during the pandemic and beyond.

Assessment of Oral Microbiome Changes in Healthy and COVID-19-Affected Pregnant Women: A Narrative Review

During pregnancy, there are several metabolic changes and an alteration in the composition of microorganisms that inhabit the oral cavity, with an increase in pathogenic bacteria that promote the onset of gingival diseases. This review is based on research in reference to the PICO model (Problem/Intervention/Comparison/Outcome), related to changes in the oral microbiome of pregnant women and possible oral consequences in patients with COVID-19. The results showed a growth of some pathogenic bacteria in pregnant women, including Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum, and the selective growth of the Prevotella intermedia, Porphyromonas gingivalis and Tannerella species, probably due to the fact that these bacteria use progesterone as a source of nutrition. These same bacteria are implicated in the development of periodontal disease. Periodontal pockets have bidirectional interactions between the oral cavity and the systemic circulatory system through the peripheral gingival blood vessels. The affinity of the SARS-CoV-2 virus to specific membrane receptors is now clear, and could involve the internal and external epithelial lining or the fibroblasts of the periodontal ligament. According to the results of the present review, the control of oral microbiome changes during pregnancy would be welcomed. The use of probiotics could help clinicians manage pregnant patients, reducing inflammatory indexes. Future studies should focus not only on changes in the level of the oral microbiome in pregnancy or the correlation between periodontal disease and COVID-19, but also on oral changes induced by both clinical situations.

Oral Health and Teledentistry Interest during the COVID-19 Pandemic

BACKGROUND

The COVID-19 pandemic outbreak has significantly changed access to dental treatments.

METHODS

The data related to oral health and teledentistry topics were collected from the open database Google Trends. The analyzed material was collected from 19 June 2016 to 6 June 2021 among anonymous search engine users. The following expressions were analyzed: "dental care", "emergency dental care", "oral health", "periodontitis", "teledentistry", "is it safe to go to the dentist", and "COVID-19" and "PPE dentist".

RESULTS

During the first lockdown in 2020, a significant increase in "emergency dental care" phrase queries was detected, with a simultaneous decrease in regular "dental care" questions, as well as a peak in the queries for "periodontitis" preceded by lower interest in "oral health." The number of searches stated for "teledentistry" increased during the time of the pandemic 5 times and for and "PPE dentist" 30 times. The risk of visiting the dental studio was seen in almost 40 times increase in the query "is it safe to go to the dentist."

CONCLUSIONS

The COVID-19 imprinted a stigma on oral health care. In this difficult epidemiological situation, teledentistry might become a helpful solution.