Investigation of Microbicidal Activity of MTAD® Against Endodontic Pathogens in-vitro

The presence of bacteria in root canal systems leads to the development of periapical periodontitis. Several studies showed an association between painful exacerbation of periapical lesions and the presence in the root canal of specific bacteria. Black-pigmented bacteria belonging to the genera Porphyromonas, Prevotella, and Bacteroides have been cultured from root canals in a significant proportion of cases. MTAD®,a mixture of an antibiotic (doxycycline), acid (citric acid) and detergent, has been demonstrated to have antimicrobial activity. Objective: Compare how effectively bacteria are eliminated from root canal systems using MTAD® as an irrigating solution, and contrasting these results with sodium hypochlorite and saline. Methods: Extracted teeth were prepared for endodontic therapy, cleaned and shaped using traditional methods. The teeth were inoculated (10⁷ bacterial cells) and allowed to colonize with Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Eikenella corrodens. The root canal systems of these teeth were irrigated with the three agents. Additional in-vitro studies were focused on determining the antimicrobial activity of MTAD® against a battery of oral pathogens, by treating the bacteria with irrigating solutions for various time intervals. The bacteria were plated on appropriate agar media, incubated for 48 hours under anaerobic conditions. Results: MTAD® was found to be as effective as sodium hypochlorite in its antimicrobial activity. Irrigation of infected root canals with MTAD® or hypochlorite killed 97% of the colonized periodontal pathogens, with in 5 minutes. MTAD® and hypochlorite also exhibited antimicrobial activity against other oral microorganisms, killing more than 97% of the bacteria in less than 5 minutes. Conclusion: Irrigation of the root canals with MTAD® appears to be equally effective as the hypochlorite in killing periodontal and endodontic pathogens. Unlike hypochlorite, MTAD® has been reported to be less toxic to the soft tissue, even when expelled into the periapical bone.