Investigation of the microbiological content, matrix metalloproteinase expression and antimicrobial susceptibility of specific bacteria in endodontic failure cases

Abstract

The main cause of the post-treatment periapical lesion, that is, the endodontic treatment failure, is the presence of microorganisms in the root canal system. In periapical periodontitis, certain components of the bacterial structure, known as virulence factors, can act by stimulating inflammatory responses with consequent bone destruction in the periapical region. Knowledge of the microbial community, pathogenicity mechanisms, and bacterial resistance to antimicrobial agents allows the development of more effective and long-lasting treatment protocols. Thus, the objectives of the present study will be: a) to characterize the cultivable microbiota present in the initial root canal collections with endodontic treatment failure, through next generation sequencing; b) to verify the microbiota susceptibility of infected root canals to the chemical-mechanical preparation and the use of intracanal medication for 30 days, through the counting of colony-forming units; c) to study the changes in the microbiota composition of the root canals infections from endodontic failure during endodontic therapy, using the checkerboard technique; d) to evaluate and correlate the effect of the chemical-mechanical preparation or intracanal medication on the reduction of LPS/LTA and MMPs (MMP-2, MMP-3, MMP-8, MMP-9 and MMP-13) by the ELISA method; e) to investigate the antimicrobial susceptibility of Enterococcus faecalis and Streptococcus mutans strains that are isolated from root canals against different antibiotics by the Etest method; and f) to correlate the findings with each other and with clinical signs and symptoms. Twenty teeth with periapical lesion and need for endodontic retreatment will be selected, and collections will be performed before and after the chemical-mechanical preparation and after intracanal medication for 30 days. After the laboratory processing of the samples, the obtained data will be tabulated and statistically analyzed by SPSS for Windows. (AU)