A case-control study published in the EFP’s Journal of Clinical Periodontology which showed associations between periodontitis and complications from Covid-19 has generated considerable interest and media coverage. Three of its authors – Faleh Tamini, Nadya Marouf, and Belinda Nicolau – respond to questions about the study and what future research needs to be done in this area.
What was the background to this research? What were the reasons for undertaking it?
The main reasons to undertake this research was that, in the midst of the devastating pandemic, we felt that we had to help out in any way we could. And as scientists, the most meaningful way to help is through research. In addition, a unique opportunity presented itself to us in Qatar. The state of Qatar has digitalised its national medical and dental records in a centralised database, and the first wave of the pandemic was particularly harsh in Qatar. This meant that there was access to a substantial number of Covid-positive patients with digital dental records linked to their medical records – and this was exactly what was needed to conduct our study.
The findings were striking – Covid-19 patients with periodontitis 3.5 times more likely to be admitted to intensive care, 4.5 times more likely to need a ventilator, and almost nine times more likely to die compared to those without periodontitis. While you may have anticipated results showing an association, were you surprised by the extent to which periodontitis patients with Covid-19 were more likely to develop complications or to die?
We were expecting to see something, but we did not expect that the association would be as strong as we found it out to be. Indeed, when the results came in, we couldn’t believe them at the beginning, so we repeated the statistical analysis multiple times to make sure that this was true.
How cautious should we be in terms of these findings? After all, we are talking about a case-control study, a small sample (only 40 patients with complications from Covid-19) from only one country, and there are other limitations such as diagnosing periodontitis only from radiographic records and applying only one of the parameters from the new classification (interdental bone loss).
Our results should be taken with caution. First, the confidence interval of some of our results is quite large, especially regarding the association with death. In addition, this is just the first study demonstrating the association – more studies are needed to validate our findings and make sure that this association is also found in other populations.
Association is one thing, causality another. What do you think are the most likely explanations for the association between periodontitis and Covid-19 complications?
Our study only looked at association, so further research would be needed to demonstrate causality. Having said that, there are multiple plausible explanations for our findings. First, periodontitis and Covid-19 complications are both influenced by similar confounding factors such as diabetes. Therefore, in our statistical analysis, we adjusted for a very wide range of confounding factors. Another explanation is that the bacteria casing periodontitis could worsen the pulmonary complication of Covid-19. However, in our opinion the most plausible explanation is that the chronic inflammation caused by the periodontitis could be priming the immune system towards a worse response to Covid-19. Indeed, the results of our laboratory blood analyses point in this direction.
Clearly, more research is needed. What specific research should be performed? Are you involved in carrying out additional investigation in this area?
We are now working on expanding our study sample size. In addition, we are now looking into the association of periodontal management and treatments on Covid-19 outcomes in patients with periodontitis.
What are the implications of your findings in terms of periodontal care for patients with Covid-19?
First, the prevention of periodontitis should be prioritised in the population as a whole. The evidence is overwhelming regarding the importance and benefits of preventing periodontitis. Having said that, patients with Covid-19 could in theory also benefit from improving their oral health through simple oral hygiene and the use of mouth washes. Although future research would be needed to confirm this.
About the authors:
Professor Faleh Tamim holds academic appointments at McGill University (Montreal, Canada) and at Qatar University (Doha, Qatar) where he is associate dean of academics of the College of Dental Medicine. He is also co-director of the Quebec Network of Oral Health Research and associate editor of the Journal of Prosthodontics. His multidisciplinary and translational research covers various areas including biomaterials, tissue regeneration, inflammation, and chronobiology.
Belinda Nicolau is professor and assistant dean of research at the McGill University Faculty of Dentistry. She is also an associate member of the Department of Oncology (Faculty of Medicine, McGill University) and vice president of the International Association for Dental Research (IADR) – Canadian Division. Her research programme addresses two major public-health challenges: sharp increases in HPV-related oral/oropharyngeal cancer and obesity-related diseases (the links between periodontal diseases and systemic diseases such as diabetes and obesity).
Nadya Marouf Mahmoud is an associate consultant in endodontics at Hamad Medical Corporation, Qatar. Dr Marouf graduated as a dentist from the University of Jordan, has an MFD Diploma from the Royal College of Surgeons in Ireland, and a master’s degree in clinical endodontics from the University of Manchester. She is a co-author of the “Qatari clinical protocols and guidelines for dental care during the Covid-19 pandemic.” Her research interests are in the relation between oral health and systemic health, and the use of CBCT in endodontics.