Preventive effects of thymoquinone in a rat periodontitis model: a morphometric and histopathological study

Thymoquinone has a variety of pharmacologic properties, including antihistaminic, antibacterial, antihypertensive, hypoglycemic, anti-inflammatory and anti-oxidative activities. Through its anti-inflammatory and antioxidant properties, thymoquinone may play an important role in preventing periodontal diseases. The aim of this study was to evaluate the effectiveness of thymoquinone in preventing the initiation and progression of periodontitis in a rat periodontitis model.

Twenty-four rats were randomly divided into three experimental groups: a nonligated (NL) treatment group (n = 8), a ligature-only (LO) treatment group (n = 8) and a ligature plus thymoquinone (10 mg/kg, daily for 11 d) (TQ) treatment group. In order to induce experimental periodontitis, a 4/0 silk suture was placed at the gingival margin of the right-mandibular first molars of the rats. Thymoquinone was administered by gastric feeding until the animals were killed on day 11. Changes in the alveolar bone levels of rats in each group were measured clinically, and tissues of rats in each group were examined histopathologically to determine inflammatory cell infiltration (ICI), osteoblast and osteoclast activities, and osteoclast morphology.

Alveolar bone loss around the mandibular molar tooth was significantly higher in the LO group compared with NL and TQ groups (p < 0.05). The ratio of the presence of ICI and osteoclast numbers was significantly higher in the LO group than in the NL and TQ groups (p < 0.05). Osteoblastic activity was significantly lower in the LO group than in the NL and TQ groups (p < 0.05).

The present study showed that the oral administration of thymoquinone diminishes alveolar bone resorption in a rat periodontitis model.