This study evaluated the influence of Doxycycline (DOX) and Low-Intensity Laser (LIL) (InGaAlP diode laser) as scaling and root planing (SRP) adjuvants in the treatment of periodontitis induced in rats. The rats received periodontal disease induction, and after 7 days, the ligature was removed, and the animals were divided into groups/treatments: NTreceive no treatment; SRP-

Purpose This study evaluated the systemic and local effects of doxycycline (DOX) and low-intensity laser (LIL) treatment as adjuvants to scaling and root planing (SRP) in the treatment of experimental periodontitis in rats. Methods The sample consisted of 180 male rats ( Rattus norvegicus albinus , Wistar), of which 30 did not receive induction of periodontal disease (negative control [NC] group) and 150 received induction of periodontal disease in the lower first molar. After 7 days, the ligature was removed, and the animals were divided into the following groups: NT (no treatment), SRP (SRP), DOX (SRP and DOX irrigation), LIL (SRP and laser irradiation), and DOX+LIL (SRP, DOX, and LIL). The animals were euthanized at 7, 15, and 30 days; thereafter, biochemical, radiographic, histological, and immunohistochemical analyses were performed. Results In the intragroup analysis, lower concentrations of α-1-glycoprotein acid (α-1-Ga) and complement 3 (C3) were observed in the DOX+LIL group than in all other groups at all time points, as well as lower levels of complement 4 (C4) at 15 and 30 days ( P <0.001). Less bone loss was observed in the DOX, LIL, and DOX+LIL groups than in the NC and SRP groups at all time points ( P <0.001). There was a smaller number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the DOX+LIL group than in the other groups at all time points ( P <0.001). Positive correlations were observed between the systemic levels of α-1-Ga, C3, and C4 and the number of TRAP-positive cells. Conclusions The combination of DOX with LIL as SRP adjuvants was effective both systemically and locally for the treatment of experimental periodontitis in rats.