The effect of orthodontic force on the inflammatory periodontal tissue and alveolar bone remodeling in rats

Objective To study the combined effect of orthodontic force and inflammation on the periodontal tissue remodeling by evaluating the change of alveolar bone of rats.Methods 60 SD rats were randomly divided into orthodontic tooth movement group(P1)and periodontitis group(P2).Fifty gram orthodontic force was loaded on the maxillary left first molars of rats in P1.Meanwhile,experimental periodontitis was established to the other 30 rats.Inflammatory stimulus was removed after two weeks when the experimental periodontitis was established.We considered the maxillary right first molars as self-controlled periodontitis group(P2)and loaded 50 gram orthodontic force on the maxillary left first molars to be orthodontic tooth movement with periodontitis group(P3).Histomorphometric analysis was performed to measure the loss of alveolar bone of 3 groups at different time after the application of orthodontic force.Results Obvious alveolar bone loss can be detected in P2 and P3 but not in the mesial side of P1.But after the inflammatory stimulus was removed,further alveolar bone loss can not be observed in the mesial side of P3.Conclusion Orthodontic force can not cause severe alveolar bone loss as long as the local inflammatory stimulus was eliminated.