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Updated: Aug 24, 2026
Inducing Apical Periodontitis in Mice
Published on: August 6, 2019
Apical periodontitis development and bacterial response to endodontic treatment. Experimental root canal infections
Ake J R Möller1, Lars Fabricius, Gunnar Dahlén
1Department of Oral Microbiology, Sahlgrenska Academy at Göteborg University, Gothenburg, Sweden. ake.moller@odontologi.gu.se
Abstract:
In six monkeys, 160 root canals were inoculated with a combination of four bacterial strains belonging to species Streptococcus milleri, Peptostreptococcus anaerobius, Prevotella oralis, and Fusobacterium nucleatum. In two other monkeys, 24 root canals were inoculated with a five-strain combination consisting of these strains and a strain of Enterococcus faecalis. All strains were previously isolated from an infected monkey root canal. After 8-12 months, survival of the strains was recorded bacteriologically, and the reaction in the periapical region was radiographed. From 180 of 184 root canals, one or more of the bacterial strains were reisolated. The two facultative strains were more frequently reisolated than the anaerobic strains. Apical periodontitis was registered in the periapical region of more than 96% of root canals with reisolated bacteria but in none of those without reisolated bacteria. Endodontic treatment was carried out in two sessions with an interval of 14 d without interappointment dressings, and the effect was evaluated bacteriologically before and after each treatment. The chemo-mechanical treatment reduced significantly the number of strains and bacterial cells. The facultative bacteria were more resistant to the treatment than the anaerobic bacteria. The five-strain combination had a higher survival rate than the four-strain combination.
Insights
Bacterial strains from infected root canals frequently survived and caused apical periodontitis in monkeys. Chemo-mechanical endodontic treatment significantly reduced bacteria but facultative strains showed higher resistance.
Area of Science:
- Microbiology
- Endodontics
- Veterinary Dentistry
Background:
- Root canal infections are often polymicrobial, involving both facultative and anaerobic bacteria.
- Enterococcus faecalis is a common pathogen in persistent endodontic infections.
- Understanding the survival and pathogenicity of specific bacterial consortia is crucial for effective treatment.
Purpose of the Study:
- To investigate the survival and pathogenicity of specific combinations of root canal bacteria in vivo.
- To evaluate the efficacy of chemo-mechanical endodontic treatment against these bacterial consortia.
Main Methods:
- Inoculation of monkey root canals with four or five specific bacterial strains (Streptococcus milleri, Peptostreptococcus anaerobius, Prevotella oralis, Fusobacterium nucleatum, and Enterococcus faecalis).
- Bacteriological monitoring for strain survival and radiographic assessment of periapical reactions over 8-12 months.
- Evaluation of chemo-mechanical endodontic treatment efficacy through pre- and post-treatment bacterial sampling.
Main Results:
- High rates of bacterial reisolation (over 96%) from root canals with observed apical periodontitis.
- Facultative strains demonstrated higher survival and resistance to chemo-mechanical treatment compared to anaerobic strains.
- The five-strain combination showed a higher survival rate than the four-strain combination.
Conclusions:
- Polymicrobial infections involving these specific bacteria can lead to significant apical periodontitis.
- Chemo-mechanical endodontic treatment effectively reduces bacterial load but exhibits differential efficacy against facultative and anaerobic bacteria.
- The complexity of the bacterial consortium influences treatment outcomes and bacterial survival.
