The Effect Of Two Tetracyclines In The Ligature-Induced Periodontal Disease

Objective: To evaluate the effect of doxycycline (Dx) and minocycline (Mn) on periodontal disease induced by ligature (LIPD) in rats. Methods: Forty male rats were divided into 4 groups (n=10): G1 – Control, no LIPD; G2 – LIPD; G3 – LIPD + Dx (6mg/kg/p.o.); G4 – LIPD + Mn (6mg/kg/p.o.). Treatments were kept for 30 days. After this period, the animals were killed and the following parameters were analyzed: distance between alveolar bone crest and enamel cementum junction (ABC-ENJ), polimorfonuclear cells (PMN), mononuclear cells (MN) and fibroblasts (F) counts, junctional epithelium, connective tissue, root-cement resorption, bone resorption, and osteoclast activity through tartrate resistant acid phosphatase enzyme (TRAP). Data were analyzed by ANOVA (alpha=5%). Results: G2 (0.73±0.22mm) showed higher (p<0.001) ABC-ENJ than G1 (0.29±0.09mm), G3 (0.46±0.17mm) and G4 (0.49±0.17mm), which did not showed statistically significant differences among them. PMN counts were lower (p<0.05) for G1 (3.8±3.0%) than G2 (19.9±4.9%), G3 (14.0±8.3%) and G4 (10.7±5.9%). No differences were observed among PMN of G2, G3 and G4. In addition, none statistically significant differences (p>0.05) were observed among groups regarding MN and F counts. Osteoclast activity was higher (p<0.05) in G2 (6.4±1.9%) and G4 (5.2±1.6%) than G1 (2.7±1.2%) and G3 (3.8±2.2%). G1 showed intact junctional epithelium and mild inflammatory infiltrate. G2 exhibited periodontal attachment loss with alveolar bone resorption. Similar characteristics were observed in both G3 and G4, but with reduced inflammatory intensity. Conclusion: Both doxycicline and minocycline were able to reduce the inflammatory response and alveolar bone resorption in rat LIPD. Support: FAPESP #2006/06440-9.