There is a significant prevalence of subjects with periodontitis presenting with other inflammatory conditions
such as coronary heart disease, insulin resistance and arthritis. This pattern of disease presentation underscores the
importance of inflammatory loading from chronic diseases, in driving their pathogeneses in a multidirectional manner.
Pro-inflammatory cytokines and other agents play an important role in this process; for example, a single nucleotide
polymorphism of the TNFα- gene is associated with significant periodontal attachment loss in patients with coronary
heart disease. Changes in gene expression associated with inflammation and lipid metabolism in response to oral infection
with the periodontal pathogen Porphyromonas gingivalis (Pg) have been demonstrated in mouse models, independent of
the demonstration of atherosclerotic lesions. Insulin resistance is considered to be a chronic low-grade inflammatory
condition, associated with altered glucose tolerance, hypertriglyceridemia, central obesity and coronary heart disease. It is
accompanied by elevated levels of IL-1, IL-6 and TNFα- also relevant to the progression of periodontitis. There is
evidence that uncontrolled periodontal disease contributes to maintenance of systemic diseases, including rheumatoid
arthritis (RA), with increased risk of periodontitis in subjects with RA. The periodontal pathogen Pg is significant in
contributing to citrullination of proteins resulting in immune dysregulation and autoimmune responses, seen in RA.
However, they are both multifactorial chronic diseases with complex etiopathogeneses that affect their presentation.
Consistent but weak associations are seen for surrogate markers of periodontitis such as tooth loss, with multiple systemic
conditions. Effective treatment of periodontitis would be important in reducing systemic inflammatory loading from
chronic local inflammation and in achieving systemic health. Lack of a consistent cause and effect relationship in all subjects
would be influenced by genetic, epigenetic and other subject variables, although there are clear mechanisms that link
the associations. This article includes an appraisal of patents and their applications.