Dissection of read-based and genome-based metagenomics of subgingival biofilms and saliva microbial communities in chronic periodontitis

Periodontal diseases (PD) comprise the mild (gingivitis) and severe (periodontitis) forms of gingival inflammation. Gingivitis is a reversible inflammation event, but chronic periodontitis is an irreversible destruction of the gum and alveolar bone in most cases. PD is one of the most common diseases of mankind nowadays, about 20-50% of the human population suffers from one or other form of PD. It has been recognized recently, that PD, and particularly chronic periodontitis (CP), is associated with oral squamous cell carcinoma and various systematic diseases such as diabetes,atherosclerosis, cardiovascular diseases, adverse pregnancy, rheumatoid arthritis, pulmonary infections, Altzheimer disease, chronic gastritis and colitis, cirrhosis, lupus erythematosus, etc. It was suggested that the basis of these conditions is the loss of proper masticatory function, which change the dietary habits, i.e. consumption of more easily chewable starch and fats and less fruits and vegetables. The relationship between oral and gut microbiota and the overall health status is multifarious, therefore having a precise picture of the oral microbiota is imperative for adequate diagnosis and therapy of numerous health threatening systemic disorders. The treatment and prevention of PD/CP is difficult because of its complex etiology. In order to obtain a more accurate picture of the CP microbiota without the potential methodological shortcomings, in this study we compared the 16S rRNA gene read-based metagenomes in samples taken from the periodontal pockets using both paper-point and curette techniques with genome-based metagenomes of the saliva collected from the same patients. The individual variations among the subjects were studied by using both sampling techniques from 4-8 separate CP pockets and one control paper-point sample of each patient.