The microbiota of periodontitis is usually complex consisting of Gram-negative anaerobic bacteria such as Porphyromonas gingivalis, Treponema denticola, Prevotella intermedia, Tannerella forsythia and Agregatibacter actinomycetemcomitans. For a long time, the analysis of the oral microbiota was dependent on conventional culture techniques, however molecular diagnostic techniques have identified about 1,200 species of bacteria in the oral cavity, including indigenous and transient species. Usually, 620 species are most prevalent and around 35% of these have not been cultivated. Thus, new information about the role of 'unusual' species or species not yet cultivated in the aetiology of periodontitis see the light of knowledge gained from the advances in molecular techniques. Desulfobulbus sp. R004, Deferribacteres sp. D084, Eubacterium sp BB142, Prevotella sp AH125, Megasphaera sp. CS025, TM7 sp. AH040, Selenomonas sp. CS002, Eubacterium sp. BB142, Tannerella sp. BU063 and Porphyromonas sp. BB136 are examples of species that have not yet cultivated and may be involved in the aetiology of periodontitis. However, lack of data regarding the role of these species in the etiological process of periodontal diseases. Therefore, the objective of this study is to evaluate the participation of certain species of bacteria not yet cultivated in the aetiology of periodontitis. 30 subjects with chronic periodontitis (CP), 30 with aggressive periodontitis (AP) and 30 with periodontal health (SP) will be selected. All subjects will undergo a clinical examination and microbiological evaluation. Subgingival biofilm samples will be collected from 9 sites (shallow, moderate and deep) in each of the volunteers and the prevalence, levels and proportions of 20 bacterial not yet cultivated bacterial species will be evaluate by RNA oligonucleotide Quantification technique (ROQT). Differences in clinical and microbiological parameters among groups will be evaluated using the Kruskal-Wallis test. Correlation tests will be conducted between levels, proportions and prevalence of the species studied and the clinical parameters of periodontal disease. Statistical significance will be set at 5%.
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