Association between periodontitis and rheumatoid arthritis is long established, but which comes first has long been debated by scientists.
Researchers have uncovered compelling evidence of a two-way relationship between rheumatoid arthritis (RA) and periodontitis (gum disease), showing that treating gum disease can significantly reduce inflammation and improve RA symptoms for patients.
The study, published in the Journal of Clinical Periodontology, examined how microbial imbalances in the mouth – known as dysbiosis – contribute to systemic inflammation in RA patients.
Led by University of Birmingham researchers from the Periodontal Research Group and the National Institute for Health and Care Research (NIHR) Birmingham Biomedical Research Centre, the University of Michigan and Queen Mary University of London, the study investigated the interactions between oral bacteria and immune molecules, and correlated the molecular interactions with clinical outcomes in 159 participants, including RA patients with and without gum disease, individuals with gum disease alone, and healthy controls.
We found that treating gum disease through intensive periodontal therapy broke this cycle: it improved RA activity scores, reduced antibodies to oral pathogens, and re-established a balanced interaction between oral microbes and the immune system within three months.
Key Findings
Professor Iain Chapple, co-lead for the oral, intestinal and systemic health theme of Birmingham’s NIHR Biomedical Research Centre, said:
“These findings are extremely significant, as it’s the first time that rheumatoid arthritis (RA) and periodontitis (gum disease) have been shown to be linked in a circular relationship, creating a vicious cycle of inflammation. RA-driven systemic inflammation disrupts the oral microbiome, fostering harmful bacteria that trigger gum disease; in turn, these bacteria worsen oral inflammation and impair immune responses, which in turn fuel RA by generating antibodies linked to joint damage.
“We found that treating gum disease through intensive periodontal therapy broke this cycle: it improved RA activity scores, reduced antibodies to oral pathogens, and re-established a balanced interaction between oral microbes and the immune system within three months.”
Professor Purnima Kumar, senior author and Chair of the Department of Periodontics and Oral Medicine at the University of Michigan said: “Oral health is the result of an evolutionary balance between the resident oral bacteria and the mucosal immune system. We discovered that RA disrupts this microbial-mucosal interaction, leading to a self-perpetuating cycle of inflammation and dysbiosis.
“When we treat periodontitis, we reboot these molecular interaction networks, thereby moving the oral ecosystem towards balance and disrupting the cycle of systemic inflammation. This is yet another reminder that the body functions as an integrated biological system, and therefore, therapeutic interventions need to be integrated to be effective.
RA is a leading cause of disability in the UK, affecting around 1% of the population; whilst gum disease is widespread and often overlooked in systemic health management. This research highlights the importance of integrated care to improve the overall health and wellbeing of patients navigating inflammation.
The study also evaluated the impact of intensive non-surgical periodontal therapy – professional cleaning combined with oral hygiene coaching – compared to oral hygiene advice alone:
Dr Isabel Lopez-Oliva, a NIHR Academic Clinical Lecturer from Queen Mary University of London and a co-author of the study, added: “We’ve demonstrated that periodontal therapy offers measurable benefits for RA patients, even when the disease is established. This opens the door to new strategies for reducing inflammation and improving quality of life.”
The research was supported by the National Institute of Dental and Craniofacial Research and delivered through the National Institute for Health and Care Research (NIHR) Birmingham Biomedical Research Centre (BRC), which brings together multidisciplinary research teams specialising in a wide range of inflammatory conditions – including inflammatory arthritis and periodontitis. The study builds on previous work from the OPERA trial, which first suggested that periodontal treatment could improve RA outcomes.
For media enquiries and more information please contact Holly Young, Press Office, University of Birmingham, tel: +44 (0)7815 607 157.
‘Dysbiosis-Mediated Inflammation: A Pathophysiological Link Between Rheumatoid Arthritis and Periodontitis’ - Isabel Lopez-Oliva, Iain L. Chapple, Purnima S. Kumar et al is published in Journal of Clinical Periodontology.
About the University of Birmingham
The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, educators and more than 40,000 students from over 150 countries.
England’s first civic university, the University of Birmingham is proud to be rooted in of one of the most dynamic and diverse cities in the country. A member of the Russell Group and a founding member of the Universitas 21 global network of research universities, the University of Birmingham has been changing the way the world works for more than a century.
About the University of Michigan
One of the nation’s top public universities, the University of Michigan has been a leader in research, learning and teaching for more than 200 years. With one of the highest research volumes of any public university in the country, U-M is advancing new solutions and knowledge in areas ranging from the COVID-19 pandemic to driverless vehicle technology, social justice and carbon neutrality. Its main campus in Ann Arbor comprises 19 schools and colleges; there are also regional campuses in Dearborn and Flint, and a nationally ranked health system, Michigan Medicine. The university also boasts a world-renowned intercollegiate athletics program and has been the site of many important events in U.S. history, including JFK’s announcement of the Peace Corps, LBJ’s “Great Society” speech, and the clinical trials of the Salk polio vaccine. U-M’s alumni body is one of the largest in the world and includes a U.S. president, scientists, actors, astronauts and inventors.
About the National Institute for Health and Care Research
The mission of the National Institute for Health and Care Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:
The NIHR Birmingham Biomedical Research Centre (BRC) is part of the NIHR and hosted by University Hospitals Birmingham NHS Foundation Trust (UHBFT) in partnership with the University of Birmingham (UoB). The BRC’s research programme focuses on inflammation and the diagnosis, prevention and treatment of its associated long-term illnesses.
Professor of Periodontology and Consultant in Restorative Dentistry
Professor Iain Chapple. Professor of Periodontology and Consultant in Restorative Dentistry. ICS Head of Research
Associate Professor & Honorary Consultant in Restorative Dentistry
Staff Profile for Dr Praveen Sharma, Associate Professor in Restorative Dentistry, School of Dentistry at the University of Birmingham
