Oral Surgery in the Human Microbiota Era, the role of Periodontal Bacteria

Recent studies have highlighted the oral cavity as a complex biological system organized into several micro and nanoscopic scales, as described by an interdisciplinary field of study using a holistic approach. In this context the recent introduction of the technology of Next Generation Sequencing (NGS) has shed new light on human genomics, but,more especially, has increased the knowledge of the bacterial populations normally resident in the human tissues and called microbiota. NGS, also known as high-throughput sequencing, is a procedure that is able to perform the sequencing in a few hours of both the entire human genome and also the complete profile of the ribosomal gene set or certain genes of interest related to a specific microbiota (metagenomics). Many human tissues, such as the skin, oral cavity, nose, upper air-ways, stomach, lower intestine, and the genito-urinary tract, are colonized by resident populations of bacteria. This complex microbial community performs many essential functions, including a protective effect in preventing opportunistic infections through the competitive exclusion of pathogenic species or by modulating the immune response in the host. In other cases it provides a fundamental contribution to normal functioning in its ecological area (tissue) i.e.in the digestive function in the gastro intestinal tract. The microbiotas in the healthy subjects must be in a strict range of homeostasis with the tissues in which they exist. In fact, the reasons why these bacterial communities could be harmful in humans is that a group of some opportunistic bacteria can infect body areas, normally free from microbial colonization, as a result of normal host defenses being compromised. In particular, in oral microbiota we find a group of anaerobic bacteria that are historically related to periodontal disease, which according to the latest research, are able to invade other body regions or organs from the oral district. The latest evidence shows that these severe infections were most likely a consequence of a bacteremia from oral tissues due to surgical acts or caused in patients after oral hygiene procedures, such as tongue scraping .