The oral cavity contains some of the varied and vast flora in the entire human body and is the main entrance for two systems vital to human function and physiology, gastrointestinal and respiratory systems. The mouth harbors a diverse, abundant and complex microbial community. This highly diverse microflora inhabits the various surfaces of the normal mouth. Bacteria accumulate on both the hard and soft oral tissues in biofilms. Bacterial adhesion is particularly important for oral bacteria. Some bacterial population causes the oral disease like dental caries, gingivitis, periodontitis etc. (Seymour et al.,2007)
The periodontal diseases are a diverse group of clinical entities in which induction of an inflammatory process results in destruction of the attachment apparatus, loss of supporting alveolar bone, and, if untreated, tooth loss. Periodontal disease is one of the most common diseases of the oral cavity and is the major cause of tooth loss in adults. Recently, there has been increasing interest in the relationship of periodontal disease to important systemic diseases, such as cardiovascular disease. (O’Toole G et al.,2000)
The group of bacteria identified as causative organisms in periodontitis are Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forsythus, Treponema denticola, T. socranskii, and P. intermedia.
Cardiovascular disease (CVD), also called heart disease, is caused by disorders of the heart and blood vessels. It includes coronary heart disease (CHD), cerebrovascular disease, raised blood pressure, peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. Many of these conditions are related to atherosclerosis.
Fig1: Showing atherosclerosis phenomenon
Atherosclerosis is a condition that develops when a substance called plaque (atheroma) builds up in the walls of the arteries. It involves a gradual and focal accumulation of lipids, smooth muscle cells, white blood cells, cholesterol crystals, calcium, and fibrous connective tissue under the surface lining (endothelium) of the artery, ultimately forming an elevated plaque that protrudes into the vessel’s lumen and significantly reducing blood flow.
2.3 Relation between periodontal disease and atherosclerosis
Oral conditions such as gingivitis and chronic periodontitis are found worldwide and are among the most prevalent microbial diseases of mankind. The cause of these common in’ammatory conditions is the complex microbiota found as dental plaque, a complex microbial bio’lm.
The association between periodontal diseases and coronary heart disease such as atherosclerosis, has been realised. (Chun Xiao et al.,2009)
Several studies have shown bacteria in the atherosclerotic plaques. In a study by Ford et al. , real-time PCR was used to show Porphyromonas gingivalis in 100% of atherosclerotic plaques. Chlamydia pneumoniae was found in approximately 30%. Helicobacter pylori and Campylobacter rectus were both found in approximately 4% of the arteries. These results clearly show that oral organisms can and do invade blood vessel walls.
Possible explanations for the association between periodontal disease and atherosclerosis
1. It may merely reflect confounding by common risk factors that cause both periodontal disease and atherosclerosis, such as smoking, obesity, and diabetes.
2. The autoimmune theory, according to which antibodies against bacterial antigens may also react against endothelial protein, causing destruction of the artery wall and initiating the arterial lesion
3. Both atherosclerosis and periodontitis are inflammatory processes. The presence of gum inflammation enhances theory is supported by an increase in white blood cells, C-reactive protein and other markers for inflammation in patients with periodontitis.
4. Periodontal bacteria entering the bloodstream during chewing, or small cuts and tears made by dental procedures. Once in the bloodstream, bacteria can produce an enzyme that causes blood platelets to become sticky and form small blood clots which may contribute to the development of atherosclerosis. (Wong et al.,2004)
For adherence and entry into bacterial surface some surface structures are important which include:Fimbrae i.e, binding partner Fibronectin(FN) and Arg-gingipain A and Arg-gingipain B and they form the complex with tranglutaminase of the host epithlial cell.
Fig2: Showing difference in normal and atherosclerotic condition of blood vessel
The connection is indeed biologically plausible. Various epidemiological studies have shown this association in the past 20 years. There is 25% increase in the risk for CHD associated with periodontal disease. A longer follow-up period demonstrated a stronger relationship, and the risk for CHD increased gradually with the severity of periodontal disease. It is important to note that periodontitis and atherosclerosis share a number of powerful risk factors like smoking, diabetes mellitus, and low socioeconomic status, all of which can contribute to a confounded association.
2.4 Vaccine development
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body’s immune system to recognize the agent as foreign, destroy it, and keep a record of it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters. Exploration of available bioinformatics tools for epitope based vaccine design affords a thorough consideration of vaccine design without expenditure of excess time or resources.
2.5 Emerging concepts regarding vaccine development
Three emerging concepts of periodontal disease may influence the development of a sophisticated vaccine to eradicate or alleviate the disease burden. The first is that periodontal disease is a polymicrobial infection. The second is that it is a major cause of adult tooth loss worldwide. The third is that periodontal disease contributes to the perpetuation of systemic diseases of critical importance (atherosclerosis, diabetes mellitus, etc.)
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