Experimental Study of Remodeling in Periodontal Tissues during Orthodontic Tooth Movement in Rats with Periodontitis

Objective To evaluate the periodontal responses and bone remodeling to orthodontic tooth movement in rats with periodontitis. Methods 40 adult male Sprague-Dawley rats were randomly divided into two groups: non-periodontitis and periodontitis. The experimental group was induod for periodentitis by placing a cotton ligature around the cervix of the first upper molars for 4 weeks. Then all rats were treated with the fixed orthodontic appliance by 50 g forces that moved mesially the maxillary first molars and the animals were sacrificed at the corresponding treatment time. The distance of tooth movement were measured and periodontal tissues were studies histologically. Results Statistical analysis by Student's paired t test showed that the speed of tooth movement in rats with periodontitis was faster than in controls (P0.05). In the histologically examination, the bone formation and the number of the osteoblast were suppressive in rats with periodontitis, whereas the bone resorption increased significantly. Conclusion The present study shows that the risk of deficiency of bone formation in patients with periodontitis submitted to orthodontic treatment, and treatment were delayed until the inflammatory signs have subsided.