Background: This study evaluates effects of topical administration of probiotic bacteria of the genus Bifidobacterium on experimental periodontitis (EP) in rats.Methods: Thirty‐two rats were divided into groups C (control; without EP), EP (EP only), C‐HN019 (control+probiotic), and EP‐HN019 (EP+probiotic). On day 0 of the experiment, animals of groups EP and EP‐HN019 received cotton ligatures around mandibular first molars (MFMs). In groups C‐HN019 and EP‐HN019, 1 mL of suspensions containing Bifidobacterium animalis subsp. lactis (B. lactis) HN019 was topically administered in the subgingival region of MFMs on days 0, 3, and 7. In groups C and EP, topical administrations were performed using a sham suspension (without probiotic). All animals were euthanized at day 14. Gingival tissue, hemimandibles, and oral biofilm were collected. Data were statistically analyzed (P <0.05).Results: Group EP presented greater bone porosity, trabecular separation, and connective tissue attachment loss (CTAL) as well as reduced bone volume than all other groups (P <0.05). In group EP‐HN019, there were greater proportions of Actinomyces and Streptococcus‐like species and lower proportions of Veillonella parvula, Capnocytophaga sputigena, Eikenella corrodens, and Prevotella intermedia‐like species than group EP. Group EP‐HN019 presented greater expressions of osteoprotegerin and β‐defensins than group EP (P <0.05). Group EP presented greater levels of interleukin‐1β and receptor activator of nuclear factor‐kappa B ligand than group EP‐HN019 (P <0.05).Conclusion: Topical use of B. lactis HN019 promotes a protective effect against alveolar bone loss and CTALs attributable to EP in rats, modifying immunoinflammatory and microbiologic parameters.

Lactobacillus probiotics have been investigated in periodontitis. However, the effects of the genus Bifidobacterium on periodontitis are hardly known. This study evaluated the effects of the probiotic (PROB) Bifidobacterium animalis subsp. lactis (B. lactis) HN019 as an adjunct to scaling and root planing (SRP) in rats with experimental periodontitis (EP). At baseline, 32 rats were assigned to 4 groups: C (control), PROB, EP-SRP and EP-SRP-PROB. In groups EP-SRP and EP-SRP-PROB, the mandibular first molars of the animals received a ligature. At day 14, the ligatures were removed and SRP was performed. Animals of groups PROB and EP-SRP-PROB were orally administered with 10 mL/day of 10⁹ colony forming units of B. lactis HN019 for 15 days, starting at day 14. Animals were euthanized at day 29. Histomorphometric, microtomographic and immunohistochemical analyses were performed. Microbiological effects of B. lactis on biofilm were also evaluated. Data were statistically analyzed (ANOVA, Tukey; Kruskal-Wallis, Dunn’s; Two-tailed t-test; p<0.05). Group EP-SRP-PROB presented reduced alveolar bone resorption and attachment loss when compared with Group EP-SRP (p<0.05). Group EP-SRP-PROB showed significantly fewer osteoclasts, increased expression of anti-inflammatory cytokines and reduced expression of proinflammatory cytokines compared with Group EP-SRP (p<0.05). B. lactis promoted a higher ratio between aerobic and anaerobic bacteria in biofilm samples (p<0.05). B. lactis HN019 may have a role in the treatment of EP in rats, as an adjunct to SRP.