A Study of a Novel Infected Root Canal System Model Using Porcine Extracted Teeth

Abstract

 Purpose: In this study, we examined the usefulness of a new model of infected root canals for use as an in vitro experimental system, which was prepared by bacterial infection in the root canals of porcine extracted teeth.

 Methods: Following the extraction of porcine mandibular molars, their roots were divided into mesial and distal groups. Cleaning and shaping of the root canal were performed with instrumentation up to #60, in accordance with conventional methods. Root canals were filled with a suspension of Enterococcus faecalis cells (containing an approximately consistent number of bacteria) and cultured aerobically at 37°C for 21 days. The following analyses were performed before, immediately after, and 2 days after root canal irrigation with sodium hypochlorite solution: ①comparison of the number of E. faecalis in the root canal, using the serial dilution method; and ②SEM observation of the root canal surface.

 Results: Analysis using the serial dilution method showed that the number of E. faecalis decreased below the detection limit immediately after root canal irrigation with sodium hypochlorite solution; however, it had returned to a level comparable with the saline control at 2 days after irrigation. Furthermore, SEM observation showed no biofilm-like formation on the root canal wall surface immediately after irrigation with sodium hypochlorite solution, although it was again evident on the root canal wall surface at 2 days after irrigation.

 Conclusion: It was suggested that this infected root canal system model using porcine extracted teeth has potential for use as an in vitro experimental system in the endodontic field.