Bactericidal activity of stabilized chlorine dioxide as an endodontic irrigant in a polymicrobial biofilm tooth model system.
BACKGROUND
The purpose of this study was to determine bactericidal efficacy of 0.04% stabilized chlorine dioxide, 3% sodium hypochlorite, 2% chlorhexidine gluconate, and sterile distilled water in a polymicrobial biofilm model.


METHODS
Roots of 35 permanent bovine incisors had pulps extirpated, and their apical size and root length were standardized. Teeth were coated with mucin, inoculated with standardized suspensions of Streptococcus sanguinis, Actinomyces viscosus, Fusobacterium nucleatum, Peptostreptococcus micros, and Prevotella nigrescens and incubated anaerobically. Teeth were randomly divided into four groups and rinsed for 3 minutes with 15 mL of irrigant. Biofilms were harvested and spiral-plated on selective media. Numbers of bacteria in the harvested biofilms was determined via the standard spiral-plating methodology. Treatment groups were evaluated using the nonparametric Kruskal-Wallis procedure. Pair-wise comparisons among the four groups and five organisms were made using the Wilcoxon-Mann-Whitney procedure. Adjustments for multiple comparisons were made using the Holm method with p < 0.05.


RESULTS
Results provide strong evidence of a significant difference in levels of bactericidal activity associated with the type of irrigant for all five bacterial species tested. Levels of bactericidal activity were significantly higher for the NaOCl group than for the stabilized chlorine dioxide (ClO₂) group for S. sanguinis, A. viscosus, and P. nigrescens. Results for F. nucleatum and P. micros were not significant after the adjustment for multiple comparisons.


CONCLUSIONS
The triple-inoculation bovine tooth model system is a robust, consistent, and reproducible model system to study polymicrobial biofilms. It should be used with the knowledge expansion of biofilm structure and function as well as the development of antimicrobial protocols.
College of Dentistry, University of Iowa, Iowa City, IA, USA.
John R
JR
Lundstrom
Anne E
AE
Williamson
Alissa L
AL
Villhauer
Deborah V
DV
Dawson
David R
DR
Drake
D016924:Actinomyces viscosus / Q000187:drug effects; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D058491:Bacterial Load; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects*; D002417:Cattle; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D017606:Chlorine Compounds / Q000494:pharmacology*; D019551:Dental Disinfectants / Q000494:pharmacology*; D003786:Dental Pulp Cavity / Q000382:microbiology*; D016967:Fusobacterium nucleatum / Q000187:drug effects; D007180:Incisor / Q000382:microbiology; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000494:pharmacology*; D010462:Peptostreptococcus / Q000187:drug effects; D045242:Prevotella nigrescens / Q000187:drug effects; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013291:Streptococcus / Q000187:drug effects; D013997:Time Factors; D014867:Water
D000891:Anti-Infective Agents, Local; D017606:Chlorine Compounds; D019551:Dental Disinfectants; D010087:Oxides; D012388:Root Canal Irrigants; D014867:Water; C025109:chlorine dioxide; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine