Understanding and Explaining the Relationship Between Oral Health and Rheumatoid Arthritis

What is rheumatoid arthritis?

Rheumatoid is a chronic inflammatory disease that primarily affects the joints. It is capable of causing cartilage damage, bone damage, and disability. As we’ll explore shortly, this disease can also affect other parts of the body, including the mouth, with a number of known oral manifestations.

Physiopathology and risk factors of rheumatoid arthritis

“Although knowledge of the pathogenesis underlying RA has increased substantially during the last decade, its etiology is still unknown,” explained González-Febles, et al. (2020).

“A complex interplay of genetic, environmental, and hormonal factors seems to influence the host immune tolerance leading to the characteristic autoimmune response of RA mainly characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs).”

It is noted that these factors can affect, among other things, the periodontium. Although the process that creates them (citrullination) is not exclusive to rheumatoid arthritis, the formation of ACPAs are mostly seen in RA patients, with evidence suggesting these antibodies can be indicators of a more aggressive form of the disease. While the exact cause of rheumatoid arthritis is unknown, there are a number of associated risk factors, including:

• Age
• Gender
• Genetic predisposition
• Smoking
• Poor oral hygiene
• Viral infections

You will note several shared risk factors with periodontal disease.

Oral health and rheumatoid arthritis

The relationship between oral health and rheumatoid arthritis has been widely studied, and their interlinking nature is unsurprising given the role of inflammatory response. This same factor helps explain a vast range of links between periodontal disease and systemic health. When it comes to oral health and rheumatoid arthritis, dentists and their patients are primarily concerned with two areas: the oral manifestation of RA, and the mechanistic link with periodontal disease.

Oral manifestations of rheumatoid arthritis

Oral manifestations of rheumatic diseases can include, but are not limited to:

• Hyposalivation
• Xerostomia
• Temporomandibular joint disorders
• Periodontal disease
• Dysphagia

“Oral alterations in rheumatic diseases are frequently overlooked in clinical practice, but their prompt recognition not only allows the local lesions to be appropriately treated, but also makes it possible to identify an underlying systemic disease,” explained Gualtierotti et al (2019).

Mechanistic link between periodontal disease and rheumatoid arthritis

A great deal of research on the relationship between these chronic inflammatory diseases has centred on bacterial periodontal pathogens such as Porphyromonas gingivalis in the citrullination process. Here a few examples of the noteworthy findings worth highlighting:

• Research conducted on mice has shown that P. gingivalis plays a harmful role in triggering or worsening arthritis. Not only can the bacteria cause the conversion of certain proteins in the body, but it also leads to other negative effects such as increased bone damage and inflammation throughout the body.
• High levels of citrullinated proteins have been found in the gum tissues of patients with chronic gum disease, and studies in rats have shown a positive relationship between gum disease caused by P. gingivalis and the presence of ACPA antibodies.
• Rheumatoid arthritis is often accompanied by the presence of an immune response against P. gingivalis. The significantly higher antibody response to P. gingivalis in comparison to systemically healthy individuals further supports this link.

Impact of periodontal treatment on rheumatoid arthritis

In a study, researchers looked at how periodontal disease relates to the presence and levels of certain antibodies in rheumatoid arthritis patients. They found that the severity of gum disease, measured by parameters like CAL (clinical attachment loss) and periodontal pockets of 5 millimetres or more, is linked to the levels of ACPAs. This connection was stronger in patients with higher levels of the antibodies.

In light of this information, there is potential that effective periodontal treatment – and especially prevention – can have a positive impact against rheumatoid arthritis and its severity.

One feasibility study of patients with rheumatoid arthritis and periodontitis found that “periodontal treatment resulted in significant improvements in periodontal disease outcomes and overall RA disease activity, although complete resolution of periodontal inflammation was difficult to achieve in some cases.”

Patient compliance has been demonstrably difficult to achieve in clinical trials for those who experience both of these diseases, suggesting that patient motivation is a key priority.

Researchers from Spain and Colombia conducted a study to understand how oral health impacts the quality of life of people with rheumatoid arthritis, hoping to encourage collaborative research. The study revealed that physical pain, disability, and emotional distress had the biggest impact on the oral health-related quality of life (OHRQoL) of patients with rheumatoid arthritis, regardless of whether or not they had periodontal disease. However, the researchers also found that periodontal disease added significantly to the disability and distress experienced by these patients.

Growing evidence suggests that pathogenic oral bacteria may contribute to immune problems in rheumatoid arthritis. Imbalances in gut and oral bacteria can trigger chronic inflammation, leading to autoimmunity.

Preventing these imbalances through a healthy diet and excellent oral care rituals may help patients with rheumatoid arthritis slow down the development and reduce the severity of this chronic inflammatory disease.