IRINA ESANU, MIHAELA DEBITA, CARMEN MIHAELA DOROBAT, ALEXANDRU ANDREI ILIESCU, MADALINA NICOLETA MATEI, DRAGOS OCTAVIAN PALADE, KAMEL EARAR CHEMICAL AND BIOLOGICAL FACTORS IN INFECTIOUS DISEASES THE ORAL MICROBIAL FLORA The wide concept of health does not benefit of a single definition, but of multiple definitions and this plurality is related to the knowledge assimilated and the socio-economic dynamics. This is due to the fact that health is an ongoing process, its notion changing with the passage of time. Thus, at international level, health is nowadays defined considering multiple criteria. In the last decade, the analysis of relevant statistical data presents an unfavourable evolution for the three major components of population dynamics: natality, mortality and external migration, accompanied by the deterioration of the entire demographic construction and tendencies of heading towards an imminent demographic drift. Humans protect themselves against the microbial aggression by using their inborn barriers and mechanisms that are completed and modulated by acquired barriers and mechanisms. For a microorganism to reach the internal environment and generate an infectious process, it must get through and overcome these barriers. In order to overcome these barriers, the infectious agent must first adhere to the surface of epithelial cells and then pass through the epithelium. Local defence mechanisms help limit the infection and present the antigen to the regional lymphatic ganglions, contributing at the initiation of the immune response. On the other hand, the infectious agent present in the lymphatic system causes lymphangitis and satellite adenitis, which stand as a filter in the infections’ way. The study included 127 patients with bacterial infections that were studied from 2014 to 2018. Infection can be caused by certain species of germs whose main feature is pathogenicity. Specific infections are caused by a foreign infectious agent that has accidentally reached the oral cavity causing oral lesions (appear in the secondary phase of the general infection). Specific infections are individualized, caused by a single microbe (monomicrobial) while the non-specific ones are associated (polymicrobial).