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Updated: Jul 4, 2026
Using Coculture to Detect Chemically Mediated Interspecies Interactions
Published on: October 31, 2013
Comparative analysis of endodontic pathogens using checkerboard hybridization in relation to culture
M E Vianna1, H-P Horz, G Conrads
1Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas - UNICAMP, Piracicaba, SP, Brazil.
Background/Aim:
The purpose of this study was to detect bacterial species and to quantify the total number of bacteria from samples of infected root canals before (S1) and after chemo-mechanical preparation using 2% chlorhexidine (CHX) gel as auxiliary chemical substance (S2) and after 7 days of intracanal dressing (S3) to compare microbial changes.
Method:
Twenty-four teeth were selected for this study. Chemo-mechanical preparation was performed using 2% CHX gel, then three different intracanal medicaments [M1: Ca(OH)(2) paste; M2: 2% CHX gel; and M3: Ca(OH)(2) paste plus 2% CHX gel] were used for 7 days. Checkerboard DNA-DNA hybridization was performed to detect 40 bacterial species. Aerobic and anaerobic culture techniques were used to determine the bacterial community by counting the colony-forming units (CFU).
Results:
The species most frequently identified by checkerboard in S1 were: Fusobacterium nucleatum ssp. polymorphum, Treponema socranskii ssp. socranskii, Parvimonas micra and Enterococcus faecalis. In S2 and S3 a total of eight different species were identified; and only one of them was gram-positive (E. faecalis). Microorganisms were not identified after use of M2 for 7 days. The quantification obtained on agar plates ranged from 4 x 10(5) to 2.6 x 10(6) CFU/ml in S1, mean CFU was reduced by 99.96% in S2, and there was no statistical difference between the CFU in S2 and S3.
Conclusion:
The antibacterial effect of the mechanical preparation supplemented by the use of an antibacterial auxiliary substance greatly reduced the microorganisms in the main root canal.
