The effect of vanillic acid on ligature-induced periodontal disease in Wistar rats

Objective: Vanillic acid, also known as 4-hydroxy-3-methoxy benzoic acid has a potent effect on bone metabolism. The purpose of the present study was to specify the effects of vanillic acid (VA) on preventing inflammation and bone destruction in experimental periodontitis as inflammatory bone disease. To evaluate the effects of VA, osteoblast, osteoclast and inflammatory cell counts, iNOS, CD68, MMP-1, and TIMP-1 levels were determined. Methods: 32 female Wistar rats were divided into four experimental groups as; Group 1: healthy control (C, n = 8), group 2: Periodontitis (P, n = 8), group 3: periodontitis and 50 mg/kg VA administered group (P + VA 50, n = 8) and group 4: periodontitis and 100 mg/kg VA delivered group (P + VA-100, n = 8). Ligature-induced experimental periodontitis was carried out at mandibular first molar teeth of the right quadrant by placing submarginal 4-0 silk ligatures. VA was administered by oral gavage for 14 days beginning from the first day. Rats were euthanized on the 15th day. Morphological changes in alveolar bone were evaluated via a stereomicroscope. Mandibles were subjected to histological procedures. Osteoblasts, tartrate-resistant acid phosphatase synthesizing osteoclasts and inflammatory cells were counted. Inducible nitric oxide synthase (iNOS), cluster of differentiation (CD)-68, Matrix metalloproteinase (MMP)-1, tissue inhibitor of MMP-1, runt-related x factor-2 (RUNX2), and cyclooxygenase (COX)-2 expressions were determined by immunohistochemistry. Results: The rats in the periodontitis group had the highest alveolar bone loss compared to the other groups. Both doses of VA significantly decreased alveolar bone loss but not the control levels. TRAP-positive osteoclast and inflammatory cell counts were also highest in the P group, and both 50 and 100 mg/kg VA reduced these counts. Control rats had the lowest osteoclast and inflammatory cell counts compared to the other groups. Similar to osteoclast counts, MMP-1, iNOS, CD68, and COX-2 expressions were the highest in the P group compared to the other groups. Both doses of VA significantly decreased these levels. Osteoblast cells were higher in the VA groups compared to the control and periodontitis groups. RUNX2 levels were lower in the periodontitis group compared to the control group. A slight increase was also observed in VA groups. However, the difference in the TIMP-1 levels was significant only between P and VA100 groups. Conclusion: VA administration successfully ameliorated periodontitis symptoms by decreasing alveolar bone and collagen destruction, periodontal inflammation, and increasing osteoblastic activity.