The Bidirectional Association Between Periodontitis and COVID-19: A Review of Current Evidence (preprint)

The COVID-19 pandemic has brought marked changes worldwide to the management of airborne infectious diseases. It sparked the development of the SARS-CoV-2 vaccine and pharmacotherapeutics to prevent infection and increase the survival rate during the acute viral phase and the comorbidities associated with COVID-19. Periodontal disease may increase the morbidity and perhaps the mortality of a COVID-19 infection. However, the molecular interaction between periodontitis and COVID-19 infection remains undetermined. A potential pathogenic co-morbidity may involve periodontal pathogenic release of destructive cytokines in the highly inflamed connective tissue and risk for COVID-19. Additional biomarkers such as C-reactive proteins appear to play a role for risk and pathogenesis of COVID-19. The potential of herpesviruses, especially as it is related to aggressive periodontitis may also be a comorbidity for COVID-19. This paper reviews available evidence on the bidirectional association between periodontitis and COVID-19.

Hand instrumentation provides improved tissue response over ultrasonic scaler and substantiates safe dental practice: An in vivo study in rats.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of hand debridement (HD) versus ultrasonic dental scaler (UDS) for the treatment of experimental periodontitis (EP) in rats. MATERIAL AND METHODS: Thirty 3-month-old male rats were used. EP was induced around the mandibular first molars (right and left). Seven days after induction, the treatments with either HD (n = 30) or UDS (n = 30) were randomly performed in each molar. Euthanasia were performed at 7, 15, and 30 days after treatment. Histometric (percentage of bone in the furcation [PBF]), histopathological, and immunohistochemical (for detection of tartrate-resistant acid phosphatase [TRAP] and osteocalcin [OCN]). Parametric data (PBF and TRAP) was analyzed by One-way ANOVA followed by Tukey's post-test. OCN was analyzed by Kruskal-Wallis followed by Student-Newman-Keuls post-test. The level of significance was 5%. RESULTS: Group HD presented higher PBF and lower TRAP-immunolabeling at 30 days as compared with UDS in the same period (p≤0.05). Group HD presented higher OCN immunolabeling at 30 days as compared with 7 and 15 days (p≤0.05). Persistent and exacerbated inflammatory process was observed in some specimens from group UDS at 30 days, as well as the bone trabeculae presented irregular contour, surrounded by many active osteoclasts. CONCLUSION: Nonsurgical periodontal therapy with HD resulted in higher PBF and lower expression of TRAP as compared with UDS. Also, HD increased the expression of OCN over time.

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.

Correlation of Redondovirus and Entamoeba gingivalis Detections in the Human Oral Cavity Suggests That This Amoeba Is Possibly the Redondovirus Host.

The virome of the human oral cavity and the relationships between viruses and diseases such as periodontitis are scarcely deciphered. Redondoviruses were reported in the human oral cavity in 2019, including in periodontitis patients. Here, we aimed at detecting redondoviruses and at searching for a potential viral host in human saliva. Non-stimulated saliva was collected between December 2020 and June 2021. These samples were tested using real-time PCR regarding the presence of redondovirus and Entamoeba gingivalis DNA. Similarity searches were performed using BLAST against eukaryotic and prokaryotic sequences from GenBank. The redondovirus DNA was detected in 46% of the 28 human saliva samples. In addition, short fragments of redondovirus genomes were detected in silico within Entamoeba sequences. Finally, Entamoeba gingivalis DNA was detected in 46% of the 28 saliva samples, with a strong correlation between redondovirus DNA and E. gingivalis DNA detections, in 93% of the cases. Regarded together, these findings and previous ones strongly support the presence of redondoviruses in the human oral cavity and their association to E. gingivalis as their likely host.

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity.

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

Association between periodontal diseases and cardiovascular diseases, diabetes and respiratory diseases: Consensus report of the Joint Workshop by the European Federation of Periodontology (EFP) and the European arm of the World Organization of Family Doctors (WONCA Europe).

AIM: To explore the implications for dentists and family doctors of the association between periodontal and systemic diseases and the role of dentists and family doctors in managing non-communicable diseases (NCDs) and promoting healthy lifestyles. MATERIALS AND METHODS: The consensus reports of the previous Focused Workshops on the associations between periodontitis and diabetes (2017) and periodontitis and cardiovascular diseases (2019) formed the technical reviews to underpin discussions on both topics. For the association with respiratory diseases, a systematic review was specifically commissioned for the Workshop discussions. Working groups prepared proposals independently, and then the proposals were discussed and approved at plenary meetings. RESULTS: Periodontitis is independently associated with cardiovascular diseases, diabetes, chronic obstructive pulmonary disease (COPD), obstructive sleep apnea and COVID-19 complications. Dentists and family doctors should collaborate in managing NCDs, implementing strategies for early detection of periodontitis in primary care centres and of cardiovascular diseases or diabetes in dental settings. Family doctors should be informed about periodontal diseases and their consequences, and oral health professionals (OHPs) should be informed about the relevance of NCDs and the associated risk factors. CONCLUSIONS: Closer collaboration between OHPs and family doctors is important in the early detection and management of NCDs and in promoting healthy lifestyles. Pathways for early case detection of periodontitis in family medicine practices and of NCDs in dental practices should be developed and evaluated.

Association between severity of COVID-19, Periodontal health and disease in Riyadh subpopulation.

Background: Periodontitis and coronavirus disease (COVID-19) both exhibit an exaggerated inflammatory response as common traits. Given that periodontal diseases have been linked to respiratory illnesses like pneumonia, it is quite possible that periodontitis and COVID-19 are related. Therefore, the purpose of the current study was to ascertain whether the severity of COVID-19 and periodontal disease are related. Methods: A retrospective study was done using the 3 years of patients' medical and dental records in the University Hospital. A telephone interview was employed to estimate the severity of symptoms got through COVID-19 infection. The data obtained were subjected to statistical analysis. 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. Results: It was seen that there was a strong relationship between the severities of COVID-19 disease and periodontal disease. The mildest gingivitis cases (63%), Stage 1 periodontitis (62.9%), were associated with the COVID-19-negative group, whereas the most severe gingivitis cases (85.7%), Stage 4 periodontitis group (66.66%), were associated with COVID-19-positive group. In comparison to those without periodontitis, patients with periodontitis had a 1.54 times higher risk of COVID-19 complications (P = 0.048). Patients who had comorbidities were 2.49 times to have COVID-19 complications (P = 0.02). Conclusion: The observations presented above lead to the conclusion that COVID-19 and periodontal disease severities are related. Understanding the potential association between periodontitis and COVID-19 through systemic inflammation could be a means of achieving a high-quality medical care. To validate the findings, additional research with larger samples is required.

Propolis effects in periodontal disease seem to affect coronavirus disease: a meta-analysis.

This meta-analysis aimed to investigate the effects of propolis on the severity of coronavirus disease symptoms by reducing periodontal disease. PubMed, EMBASE, SciELO, Web of Science, and SCOPUS databases were systematically searched. Studies have been conducted analyzing propolis's effects on COVID-19 and periodontitis. The study was conducted according to the PRISMA statement and registered in PROSPERO. Risk of Bias (RoB) assessment and meta-analysis of clinical studies were performed (Review Manager 5, Cochrane). The certainty of the evidence was assessed using GradePro (GDT). Studies have shown propolis flavonoids inhibit viral replication in several DNA and RNA viruses, including coronaviruses. Propolis components have an aminopeptidase inhibitor activity that can inhibit the main proteases of SARS viruses and seem to inhibit protein spikes, which are sites of most mutations in SARS-CoV strains. The meta-analysis showed favorable results with the use of propolis on probing depth (95%CI: 0.92; p < 0.001), clinical attachment level (95%CI: 1.48; p < 0.001), gingival index (95%CI: 0.14; p = 0.03), plaque index (95%CI: 0.11; p = 0.23), and blending on probing (95%CI: 0.39; p < 0.001). The antibacterial activity of propolis could be mediated through its direct action on microorganisms or the stimulation of the immune system, activating natural defenses. Thus, propolis inhibits the replication of SARS-CoV-2 as well as its bacterial activity. Treatment with propolis improves general health and facilitates the activation of the immune system against coronavirus.

Severe generalized periodontitis as a risk factor for serious outcomes of COVID- 19: a structural equation modelling approach (preprint)

Objectives This study aimed to assess the periodontal condition in COVID-19 patients and determine the multidirectional association between severe generalized periodontitis and COVID-19 outcomes.Materials and Methods Periodontal conditions were clinically assessed in 214 hospitalized patients due to COVID-19, and the course of the disease was registered prospectively from hospital admission. A conceptual model was developed to predict the impact of severe generalized periodontitis on poor symptomatology, intensive care unit (ICU) admission, and death of COVID-19 patients. The model was tested using Structure Equation Modeling (SEM) to predict severe COVID-19 outcomes as affected by periodontitis, when including comorbidities, patient's age, and smoking habit as potential confounding variables.Results Severe generalized periodontitis was diagnosed in 51 (23.8%) patients, and 52 (26.8%) died due to aggravated COVID-19. SEM analysis revealed that severe generalized periodontitis was positively associated with severe-critical COVID-19 symptoms in hospitalized patients [standard coefficient (sc) = 0.166; 95%CI = 0.014–0.319; p = 0.032] and influenced by confounders (age and smoking). Significant associations were observed in the pathway from presentation of severe-critical symptoms to ICU admission (sc = 0.995; 95%CI = 0.924–1.065; p < 0.001) and death (sc = 0.512; 95%CI = 0.392–0.631; p < 0.001].Conclusions Findings suggest that severe generalized periodontitis may play a role in the aggravation of COVID-19 symptoms and the risks of subsequent need for ICU admission and death.Clinical Relevance: These results elucidate the probable course of the relationship between periodontitis and COVID-19, emphasizing the importance of periodontitis as a risk factor and accentuating the needs of prevention and handle of periodontal disease in the inhibition of COVID-19 complications.

Periodontal disease and COVID-19: a systematic review and meta-analysis of observational studies (preprint)

Background: A larger proportion of people with severe cases of Coronavirus Disease 2019 (COVID-19) appears to have comorbidities compared to the general population. However, evidence regarding the roles of periodontal disease(PD), in context of Coronavirus Disease 2019(COVID-19), is limited. Thus, to explore the association between PD and COVID-19, this systematic review and meta analysis was conducted. Methods: 7 online databases were searched by January 31, 2023. Heterogeneity was tested by I2 index. OR and 95% CI were pooled through either random-effect or fixed-effect models. Subgroup analyses, sensitivity analyses, and publication bias assessments were also conducted. Results: Of the 823 articles identified and reviewed, 11 articles with 16,708 subjects met inclusion criteria and were included. PD was found to be associated with a statistically significant increase in risk of progression to severe diseases for COVID-19 patients(OR=2.20, 95% CI=1.38-3.49). Further analysis suggested that  PD was associated with assisted ventilation(OR=5.01, 95% CI:2.61-9.63), ICU admission(OR=1.61, 95% CI:1.24-2.09), pneumonia(OR=5.19, 95% CI:1.17-23.00), and death(OR=2.25, 95% CI:1.55-3.28) for COVID-19 cases. Conclusions: Our results show that individuals with PD have an increased risk for ICU admission, assisted mechanical ventilation therapy, and a significantly increased risk of pneumonia and death. This suggests, to some extent, that the oral cavity is the gateway to COVID-19 infection; in other words, periodontitis is a risk factor for COVID-19 severity.

The underlying molecular mechanisms and biomarkers between periodontitis and COVID- 19 (preprint)

Objective Emerging evidence shows the clinical consequences of patient with COVID-19 and periodontitis are not promising, and periodontitis is a risk factor. Periodontitis and COVID-19 probably have a relationship. Hence, this study aimed to identify the common molecular mechanism that may help to devise potential therapeutic strategies in the future.Material and methods We analyzed two RNA-seq datasets for differential expressed genes, enrichment of biological processes, transcription factors (TFs) and deconvolution-based immune cell types in periodontitis, COVID-19 and healthy controls. Relationships between TFs and mRNA were established by Pearson correlation analysis, and the common TFs-mRNA regulatory network and nine co-upregulated TFs of the two diseases was obtained. The RT-PCR detected the TFs.Results A total of 1616 and 10201 DEGs from periodontitis and COVID-19 are found. Moreover, nine shared TFs and common biological processes associated with lymphocyte activation involved in immune response were identified across periodontitis and COVID-19. The cell type enrichment revealed elevated plasma cells among two diseases. The RT-PCR further confirmed the nine TFs up-regulation in periodontitis.Conclusion The pathogenesis of periodontitis and COVID-19 is closely related to the expression of TFs and lymphocyte activation, which can provide potential targets for treatment.

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-1ß 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.

Association between periodontitis and COVID-19 infection: a two-sample Mendelian randomization study.

Background and Objective: Epidemiological studies report associations between coronavirus disease 2019 (COVID-19) and periodontitis; however, causality has not been proven. The aim of this study is to assess the associations between COVID-19 susceptibility and periodontitis with two-sample Mendelian randomization (MR) analyses. Methods: A two-sample summary MR analysis was performed using data for outcome and exposure from the OpenGWAS database on people of European descent. Periodontal complex traits (PCTs) were chosen as a proxy for the periodontitis phenotype. The causal association between PCT3 (Aggregatibacter actinomycetemcomitans), PCT5 (Porphyromonas gingivalis), and gingival crevicular fluid (GCF) interleukin-1ß (IL-1ß) and COVID-19 were considered. Genome-wide association study (GWAS) data with the two largest sample sizes were selected as COVID-19 outcomes (datasets ebi-a-GCST010776 and ebi-a-GCST010777). Single-nucleotide polymorphisms (SNPs) associated with PCT3, PCT5, and GCF IL-1ß at statistical significance at genome-wide level (P < 5 × 10-8) were identified as genetic instruments. We used two-sample summary MR methods and tested the existence of a pleiotropic effect with MR-Egger. Results: Inverse-variance weighted (IVW) estimates showed that there was a positive association between COVID-19 risk and periodontitis (ebi-a-GCST010776: odds ratio [OR] = 1.02 (95% confidence interval (CI), 1.00-1.05), P = 0.0171; ebi-a-GCST010777: OR = 1.03 (95% CI, 1.00-1.05), P = 0.0397). The weighted median also showed directionally similar estimates. Exploration of the causal associations between other PCTs and COVID-19 identified a slight effect of local inflammatory response (GCF IL-1ß) on COVID-19 risk across the two datasets (ebi-a-GCST010776: IVW OR = 1.02 (95% CI, [1.01-1.03]), P < 0.001; ebi-a-GCST010777: IVW OR = 1.03 (95% CI, [1.02-1.04]), P < 0.001). The intercepts of MR-Egger yielded no proof for significant directional pleiotropy for either dataset (ebi-a-GCST010776: P = 0.7660; ebi-a-GCST010777: P = 0.6017). Conclusions: The findings suggests that periodontitis and the higher GCF IL-1ß levels is causally related to increase susceptibility of COVID-19. However, given the limitations of our study, the well-designed randomized controlled trials are needed to confirm its findings, which may represent a new non-pharmaceutical intervention for preventing COVID-19.

The association between respiratory diseases and periodontitis: A systematic review and meta-analysis.

AIM: To evaluate (1) whether periodontitis has an influence on the prevalence/incidence of respiratory diseases (chronic obstructive pulmonary disease [COPD], asthma, community-acquired pneumonia [CAP], obstructive sleep apnoea [OSA] and COVID-19), and (2) what is the impact of periodontal therapy on the onset or progression of respiratory diseases. MATERIALS AND METHODS: An electronic search was performed on Pubmed, Cochrane Library and Scopus databases up to October 2021, to identify studies answering the PECOS and PICOS questions. RESULTS: Seventy-five articles were selected. Meta-analyses identified statistically significant associations of periodontitis with COPD (nstudies  = 12, odds ratio [OR] = 1.28, 95% confidence interval [CI] [1.16; 1.42], p < .001), and OSA (ns  = 6, OR = 1.65, 95% CI [1.21; 2.25], p = .001), but not for asthma (ns  = 9, OR = 1.53, 95% CI [0.82; 2.86], p = .181). For acute conditions, two studies were found for CAP, while for COVID-19, significant associations were found for the need of assisted ventilation (ns  = 2, OR = 6.24, 95% CI [2.78; 13.99], p < .001) and COVID-related mortality (ns  = 3, OR = 2.26, 95% CI [1.36, 3.77], p = .002). Only four intervention studies were found, showing positive effects of periodontal treatment on COPD, asthma and CAP. CONCLUSIONS: A positive association between periodontitis and COPD, OSA and COVID-19 complications has been found, while there is a lack of intervention studies.

Potential links between COVID-19 and periodontitis: a bioinformatic analysis based on GEO datasets.

BACKGROUND: 2019 Coronavirus disease (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The COVID-19 pandemic has already had a serious influence on human existence, causing a huge public health concern for countries all around the world. Because SARS-CoV-2 infection can be spread by contact with the oral cavity, the link between oral illness and COVID-19 is gaining traction. Through bioinformatics approaches, we explored the possible molecular mechanisms linking the COVID-19 and periodontitis to provide the basis and direction for future research. METHODS: Transcriptomic data from blood samples of patients with COVID-19 and periodontitis was downloaded from the Gene Expression Omnibus database. The shared differentially expressed genes were identified. The analysis of Gene Ontology, Kyoto Encyclopedia of Genesand Genomes pathway, and protein-protein interaction network was conducted for the shared differentially expressed genes. Top 5 hub genes were selected through Maximal Clique Centrality algorithm. Then mRNA-miRNA network of the hub genes was established based on miRDB database, miRTarbase database and Targetscan database. The Least absolute shrinkage and selection operator regression analysis was used to discover possible biomarkers, which were then investigated in relation to immune-related genes. RESULTS: Fifty-six shared genes were identified through differential expression analysis in COVID-19 and periodontitis. The function of these genes was enriched in regulation of hormone secretion, regulation of secretion by cell. Myozenin 2 was identified through Least absolute shrinkage and selection operator regression Analysis, which was down-regulated in both COVID-19 and periodontitis. There was a positive correlation between Myozenin 2 and the biomarker of activated B cell, memory B cell, effector memory CD4 T cell, Type 17 helper cell, T follicular helper cell and Type 2 helper cell. CONCLUSION: By bioinformatics analysis, Myozenin 2 is predicted to correlate to the pathogenesis and immune infiltrating of COVID-19 and periodontitis. However, more clinical and experimental researches are needed to validate the function of Myozenin 2.

The bidirectional biological interplay between microbiome and viruses in periodontitis and type-2 diabetes mellitus.

Periodontitis was an inflammatory disease associated with a dysbiosis of the oral flora characterized by a chronic sustained inflammation inducing the resorption of alveolar bone and leading to tooth loss. Type 2 diabetes mellitus (T2D) was a metabolic disease caused by impaired insulin action. The oral microbiome played a crucial role in modulating both the innate and adaptive immune system during the trigger and exacerbation of periodontitis and T2D. The bidirectional relationship of T2D and periodontitis had been the focus of intensive research, but those were not well explored. In this commentary, an in-depth analysis of the changes of microbiome and bacterial metabolites in periodontitis with or without diabetes was described. The promotion of periodontitis to T2D might involve inflammatory factors/receptors, oxidative stress, microRNA and so on. The effect of diabetes on periodontitis might involve adipose factor pathway, AGE/RAGE and RANK/RANKL pathway etc. Generally, periodontitis and diabetes are closely related to the microecological-epithelial interaction, soft tissue degradation, bone coupling disorder, immune regulation and gene transcription. The viruses, including HBV, HCV, HSV-1, Coronavirus, HCMV, EBV, HIV, phageome and so on, played an important role in the development of T2D and periodontitis. An in-depth understanding of the relationship between microbiome and host was of great significance to clarify the bidirectional mechanisms, suggesting that the periodontitis or T2D remission will have a positive impact on the other.

A pilot clinical and radiographic study on the association between periodontitis and serious COVID-19 infection.

BACKGROUND: During the pandemic of COVID-19, the scientific community tried to identify the risk factors that aggravate the viral infection. Oral health and specifically periodontitis have been shown to have a significant impact on overall health. Current, yet limited, evidence suggests a link between periodontal status and severity of COVID-19 infection. OBJECTIVES: The present pilot study aimed to assess whether younger patients (≤60 years) that have been hospitalized in the intensive care unit (ICU) for severe COVID-19 infection were susceptible to severe periodontitis. MATERIAL AND METHODS: All dentate patients ≤60 years of age diagnosed with COVID-19 and surviving hospitalization in the ICU were considered for inclusion. Susceptibility to periodontitis was determined by assessing radiographic bone loss (RBL) in recent dental radiographs (posterior bitewings, periapical, and panoramic X-rays). RBL in % was obtained from the most affected tooth and patients were classified into: Stage I, RBL ≤ 15%; Stage II, RBL = 15%-33% and Stage III/IV, RBL ≥ 33%. The grade was defined using the RBL to age ratio on the most severely affected tooth. Patients were attributed to: Grade A, ratio <0.25; Grade B, ratio 0.25-1 and Grade C, ratio >1. Patients classified into Stage III/IV and Grade C were considered highly susceptible to periodontitis. RESULTS: Of 87 eligible patients, 30 patients were finally assessed radiographically and/or clinically; from the remaining 57 patients, 16 refused participation for various reasons and 41 could not be reached. Based on the radiographic assessment, all patients were periodontally compromised. Half of them were classified with Stage III/IV and Grade B or C; 26.7% were classified with Stage III/IV and Grade C. CONCLUSIONS: The present pilot study showed that about half of the patients suffering from severe forms of COVID-19 infection in need of ICU admission suffered also from severe periodontitis, and about one-fourth of them were highly susceptible to it.

Association of periodontal therapy, with inflammatory biomarkers and complications in COVID-19 patients: a case control study.

BACKGROUND: In previous studies, COVID-19 complications were reported to be associated with periodontitis. Accordingly, this study was designed to test the hypothesis that a history of periodontal therapy could be associated with lower risk of COVID-19 complications. METHODS: A case-control study was performed using the medical health records of COVID-19 patients in the State of Qatar between March 2020 and February 2021 and dental records between January 2017 and December 2021. Cases were defined as COVID-19 patients who suffered complications (death, ICU admissions and/or mechanical ventilation); controls were COVID-19 patients who recovered without major complications. Associations between a history of periodontal therapy and COVID-19 complications were analysed using logistic regression models adjusted for demographic and medical factors. Blood parameters were compared using Kruskal-Wallis test. RESULTS: In total, 1,325 patients were included. Adjusted odds ratio (AOR) analysis revealed that non-treated periodontitis was associated with significant risk of need for mechanical ventilation (AOR = 3.91, 95% CI 1.21-12.57, p = 0.022) compared to periodontally healthy patients, while treated periodontitis was not (AOR = 1.28, 95% CI 0.25-6.58, p = 0.768). Blood analyses revealed that periodontitis patients with a history of periodontal therapy had significantly lower levels of D-dimer and Ferritin than non-treated periodontitis patients. CONCLUSION: Among COVID-19 patients with periodontal bone loss, only those that have not received periodontal therapy had higher risk of need for assisted ventilation. COVID-19 patients with a history of periodontal therapy were associated with significantly lower D-dimer levels than those without recent records of periodontal therapy. CLINICAL RELEVANCE: The fact that patients with treated periodontitis were less likely to suffer COVID-19 complications than non-treated ones further strengthen the hypothesis linking periodontitis to COVID-19 complications and suggests that managing periodontitis could help reduce the risk for COVID-19 complications, although future research is needed to verify this.