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Apical periodontitis induced by selected bacterial strains in root canals of immunized and nonimmunized monkeys
Abstract:
Experimental infections in root canals with Streptococcus faecalis ss. liquefaciens (Strep-MC4). Actinomyces bovis (Act-MC6) and Bacteroides oralis (Bact-MC3) were studied in four immunized and five nonimmunized monkeys. The immunization was performed using antigens of the homologous strains. The antibody level was checked by gel diffusion. In 56 root canals of the immunized animals and 60 root canals of the nonimmunized animals, viable cells of the three bacterial strains were enclosed in equal amounts of various combinations. After 6 months, samples from the root canals were subjected to qualitative and quantitative bacteriologic analyses and the apical area was radiographically and histologically examined. The analyses revealed no significant difference between the two groups of monkeys, although the viable cell recovery was slightly higher in most of the root canals of nonimmunized monkeys. The cell proportion of the strains within the different bacterial combinations was equal in root canals of the two groups of animals. The radiographic and histologic examinations revealed no significant difference between the two groups of animals regarding the number of teeth with periapical lesions. The radiographic examination, however, showed a more distinct limitation of the process in the immunized than in the nonimmunized monkeys. Histologically the lesions were more encapsulated and had a sparser cell infiltration in immunized than in nonimmunized monkeys. In the latter, inflammatory cells had often infiltrated the bone. Mixed infections gave a more severe periapical reaction than single strain infections in both animal groups.
Insights
Immunization against root canal bacteria (Streptococcus faecalis, Actinomyces bovis, Bacteroides oralis) showed no significant difference in infection levels but improved lesion encapsulation in monkeys. Mixed infections worsened periapical reactions.
Area of Science:
- Endodontics
- Microbiology
- Immunology
Background:
- Root canal infections often involve polymicrobial communities.
- Understanding host immune response modulation is crucial for endodontic treatment success.
Purpose of the Study:
- To evaluate the effect of immunization on experimental root canal infections in a primate model.
- To assess the impact of immunization on periapical lesion development and characteristics.
Main Methods:
- Experimental root canal infections were established using Streptococcus faecalis, Actinomyces bovis, and Bacteroides oralis in immunized and non-immunized monkeys.
- Bacteriological, radiographic, and histological analyses were performed after 6 months.
- Antibody levels were assessed using gel diffusion.
Main Results:
- No significant difference in viable bacterial recovery or the number of periapical lesions between immunized and non-immunized groups.
- Radiographic and histological examinations indicated more distinct lesion limitation and encapsulation in immunized animals.
- Mixed infections resulted in more severe periapical reactions compared to single-strain infections in both groups.
Conclusions:
- While immunization did not significantly alter infection clearance or lesion incidence, it demonstrated a beneficial effect on lesion containment and host response modulation.
- The findings suggest a potential role for targeted immunization in managing endodontic infections and associated periapical pathologies.