In vivo investigation of the bacterial diversity of endodontic microbiota in primary endodontic infections and evaluation of antimicrobial effects of endodontic treatment procedures by Next Generation Sequencing and a metagenomic approach

Abstract

The role of polymicrobial infection of the root canal system in apical periodontitis is well established but deep insight into the ecology and physiology of the bacterial colonization remain elusive. Although the bacterial community in the oral cavity may comprise over 700 species or taxa, only a limited number find proper conditions to colonize root canal system. Most data on the endodontic microbiota were obtained by culture approaches, but culture-dependent methods grossly underestimate the extent of the bacterial diversity in polymicrobial infections. Furthermore phenotypic profile variations and methodological bias also limit the conclusions drawn from culture studies. newlineIn the last two decades, 16SrRNA analysis became a powerful phylogenetic framework for the identification of fastidious, slow-growing, or not-yet-cultivable bacteria which makes a high proportion of the microorganisms in the oral cavity. Therefore it is likely that currently unknown species are present in disease infections which have led to emerging of new concepts in the pathogenesis of several human infections and redirecting therapeutic strategies. newlineThe assessment of human microbiota by metagenomic approaches revealed that these techniques are sensitive and specific to evaluate the bacterial diversity of root canal infections. These studies have shown that the prevalence of yet non-cultivable bacteria remarks over 50% of the microbiota in all sorts of endodontic infections. Previous data suggested that endodontic infections are characterized by a consortium of microorganisms, more restricted than observed in other sites of oral cavity, evidencing a selection within this niche, which may lead to a specific microbiota able to induce periradicular inflammation.The great majority of clinical studies evaluating the antibacterial effects of endodontic treatment procedures have been based on culture techniques.