Background: Quercetin is a flavonoid which has potent anti-inflammatory, antibacterial,
and antioxidant effect. Purpose of this study was to evaluate effects of quercetin
on alveolar bone loss and histopathological changes in ligature-induced periodontitis in rats.
Methods: Wistar rats were divided into four experimental groups: non-ligated control (C,
n=8) group; periodontitis (P, n=8) group; ligature and low dose quercetin group (75
mg/kg/day quercetin, Q75 group, n=8); ligature and high dose quercetin group (150
mg/kg/day quercetin, Q150 group, n=8). Silk ligatures were placed at gingival margin of
lower first molars of mandibular right quadrant. Study duration was 15 days, and animals
were sacrificed end of this period. Changes in alveolar bone levels were clinically measured
and tissues were immunohistochemically examined, matrix metalloproteinase 8
(MMP 8), inducible nitric oxide synthase (iNOS), tissue inhibitor of metalloproteinase 1
(TIMP 1), Cysteine-aspartic proteases 3 (Caspase 3), and tartrate-resistant acid phosphatase
(TRAP) positive osteoclast cells, osteoblast, and neutrophil counts were also determined.
Results and Discussion: Alveolar bone loss was highest in P group, and differences among
P, Q75, and Q150 groups were significant. Both doses of quercetin decreased TRAP+ osteoclast
cells and increased osteoblast cells. Inflammation in P group was also higher than
those of C, Q75, and Q150 groups indicating anti-inflammatory effect of quercetin. iNOS,
MMP-8, and caspase-3 levels were highest, and TIMP-1 expression was lowest in P group;
differences were statistically significant.
Conclusion: Within limits of this study, it can be suggested that quercetin administration
may reduce alveolar bone loss by increasing osteoblastic activity, decreasing osteoclastic
activity, apoptosis, and inflammation in an experimental model of periodontitis.