Gingival disease, or periodontitis, is an infectious gum disease that affects soft tissue and degrades the bone that supports the teeth.
In order to explore the protective factors of gum tissue in rheumatoid arthritis patients, the researchers assessed 754 patients from the Centers for Disease Control and Prevention’s (CDC) 1999 — 2004 National Health and Nutrition Examination Survey (NHANES) database.
They found that 173 of the patients had gingival disease, but "a significantly higher percentage of patients with no gingival disease were older subjects (42.4% vs. 28.1%), female (61.1% vs. 51.1%), and non-smokers (73.3% vs. 57.5%)".
At the same time, the odds of gingival disease were greater in male rheumatoid arthritis patients between the ages of 60 and 85.
Upon analysing their dietary characteristics, the researchers observed that patients who did not suffer from gingival disease had a considerably higher vitamin C and beta-cryptoxanthin intake than gingival disease patients (152.33mcg vs. 91.15mcg).
Additionally, the odds of gingival disease were lower in those with higher serum vitamin D levels.
Vitamin C's effect on gingival disease risk is attributed to its antioxidant and wound-healing properties; the paper stated that "vitamin C intake above the recommended daily allowance was shown to be beneficial in gingival disease treatment".
Vitamin D, on the other hand, is believed to fight gingival disease through its antimicrobial and immunomodulatory qualities, as well as its calcium absorption and effects on bone metabolism.
High serum levels of vitamin D help to regulate the immune response in inflamed areas of the body, encouraging wound-healing and bone resorption.
According to the paper, the relationship between gingival disease and rheumatoid arthritis can be explained by two different hypotheses.
One is the 'two-hit' model, whereby a primary 'hit' of gingival disease causes chronic inflammation, followed by a secondary arthritogenic ‘hit’ that leads to a rise in inflammation mediators, including cytokines and TNFα.
The other hypothesis involves the bacterium Porphyromonas gingivalis activating deamination enzymes (enzymes that remove amino groups from molecules). This results in the production of peptide autoantibodies complicit in the development of rheumatoid arthritis.
The researchers noted the association between the prevalence of gingival disease and rheumatoid arthritis, as well as the significantly decreased odds of gingival disease with increased vitamin C intake and higher serum vitamin D levels.
They concluded: "Given the significant association between the prevalence of gingival disease and RA, identification of risk factors of gingival disease will be useful as a screening tool in national health surveys to improve the management of periodontal disease as well as RA."
Source: PLOS ONE
"Factors associated with the risk of gingival disease in patients with rheumatoid arthritis"
Authors: Liang-Gie Huang, et al.