Microbiota of periodontal pockets and root canals in induced experimental periodontal disease in dogs

Aim: To investigate the relationship between the microbiota of periodontal pockets (PP) and root canals (RC) in dogs submitted to experimental periodontal disease (ExPD). Methods: ExPD was induced by combining cotton and wire ligatures. After 125 days, microbiological samples were collected from PP and RC. Strains isolated from 19 teeth were submitted to DNA extraction, 16S rRNA gene amplification and gene sequencing. Pearson's χ²- and Fisher's exact tests and McNemar's test were used when appropriate. Results: The number of species in PP was greater than in RC, with prevalence of obligate anaerobes and Gram-negative bacteria. In the PP predominated Fusobacterium necrophorum, Porphyromonas gingivalis, Prevotella loescheii, Campylobacter gracilis and Veillonella parvula. In the RC samples, 9 had microbial growth, with predominance of the following genera: Staphylococcus, Streptococcus and Neisseria. Eight genera were common to both sites in the same tooth. PP presented a greater number of species than the RC. No significant difference was observed in the species found in PP and RC in the same tooth. Conclusion: Microbial composition of the RC could be modulated by the presence of periodontal disease, especially in cases of severe periodontal destruction. RC microbiota was less complex and diverse than the PP.