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Influence of combinations of oral bacteria on periapical tissues of monkeys
Abstract:
The present study deals with the ability of 11 bacterial strains, in various combinations, to induce periapical reactions. The indigenous oral bacteria were originally isolated from an experimental apical periodontitis in monkey. Eight of the strains were complete collection isolated from one root canal. These strains were inoculated together, in equal proportions, into 12 root canals. In addition, 63 canals were inoculated with other combination or separate strains. At the end of the experimental period it was found that in the mixed infections the Bacteroides oralis strain predominated in most root canals. In contrast, this Bacteroides strain was not reisolated in any of nine root canals when inoculated in a pure culture. Enterococci, however, survived as pure cultures in all canals. The mixed infections showed the greatest capacity of inducing apical periodontitis, as revealed by radiography, and most pronounced was the "eight-strain collection". The facultatively anaerobic streptococci induced only weak periapical reactions.
Insights
Mixed bacterial infections, particularly an eight-strain collection, significantly induced apical periodontitis in experimental models. Pure cultures showed limited ability to cause these reactions, highlighting the role of polymicrobial communities in disease.
Area of Science:
- Microbiology
- Oral Biology
- Infectious Diseases
Background:
- Apical periodontitis is an inflammatory condition often linked to endodontic infections.
- The polymicrobial nature of root canal infections complicates understanding disease pathogenesis.
- Indigenous oral bacteria play a crucial role in initiating and perpetuating periapical lesions.
Purpose of the Study:
- To investigate the periapical inflammatory potential of indigenous oral bacterial strains, both individually and in combinations.
- To determine the predominant bacterial species in experimentally induced apical periodontitis.
- To compare the pathogenicity of pure bacterial cultures versus mixed infections in inducing periapical reactions.
Main Methods:
- Isolation of 11 indigenous oral bacterial strains from experimental monkey apical periodontitis models.
- Inoculation of bacterial strains, individually and in various combinations (including an eight-strain collection), into monkey root canals.
- Radiographic assessment of periapical reactions and bacterial reisolation at the end of the experimental period.
Main Results:
- Mixed infections demonstrated the highest capacity to induce apical periodontitis, with the eight-strain collection showing the most pronounced effect.
- Bacteroides oralis predominated in most mixed infections but was not reisolated from pure cultures.
- Enterococci survived as pure cultures in all canals, while facultatively anaerobic streptococci induced only weak reactions.
Conclusions:
- Polymicrobial communities, especially complex mixtures like the eight-strain collection, are more potent inducers of apical periodontitis than pure bacterial cultures.
- Bacteroides oralis appears to thrive and dominate in mixed endodontic infections.
- Understanding bacterial interactions is critical for managing apical periodontitis.