Treatment of experimental periodontitis with chlorhexidine as adjuvant to scaling and root planing

•Chlorhexidine 0.12 % or 0.2 % presented the same effect on periodontitis healing.•Chlorhexidine should be considered an antimicrobial and anti-inflammatory agent.•Chlorhexidine seems to modulate the bone remodeling process. To assess whether subgingival irrigation with 0.12 % or 0.2 % chlorhexidine (CHX) immediately after scaling and root planing (SRP) enhances periodontal tissue repair compared to irrigation with saline solution (control). Periodontitis was ligature-induced in rat molars for 7 days. Animals were distributed into three groups: 1) SRP group, SRP and irrigation with 0.9 % saline (n = 30); 2) SRP + 0.12 % CHX group, SRP and irrigation with 0.12 % CHX (n = 30); 3) SRP + 0.2 % CHX group, SRP and irrigation with 0.2 % CHX (n = 30). Animals were killed at 7, 15, and 30 days after treatment. Furcation region was histometrically analyzed to determine the bone area. Immunohistochemical reactions were performed for receptor activator of nuclear factor-kB ligand (RANKL), osteoprotegerin (OPG) and tartrate-resistant acid phosphatase (TRAP). Both chlorhexidine groups presented less inflammation and improved tissue repair along the entire experiment when compared with the SRP group. In the histometric analysis at 7, 15 and 30 days, SRP group (4.58 ± 2.51 mm2, 4.21 ± 1.25 mm2, 3.49 ± 1.48 mm2), showed statistically less bone area than groups SRP + 0.12 % CHX (1.86 ± 1.11 mm2; 0.79 ± 0.27 mm2; 0.34 ± 0.14 mm2) and SRP + 0.2 % CHX (1.14 ± 0.51 mm2; 0.98 ± 0.40 mm2; 0.41 ± 0.21 mm2). Both chlorhexidine concentrations modulated the expression of TRAP, RANKL and OPG. Subgingival irrigation with chlorhexidine contributed for a quicker shift from a proinflammatory destructive profile to healing of periodontal tissues.