Establishment of the animal model of experimental orthodontic tooth movement in the period of retention

Objective To establish an animal model of experimental tooth movement for research on the regulation of bone remodeling during retention.Methods Experimental tooth movement was performed in 36 male Wistar rats at 8 weeks of age in the animal laboratory in Dental Hospital of Jilin University in April,2008.Bilateral maxillary first molars were forced to move mesially with closed coil spring for 21 days.After remove of the closed coil spring,the left maxilla was considered as experimental side and the right maxilla as control side.The retentive appliances were placed on the molars in the experimental side and the molars in control side were untreated.Retentive appliances were maintained respectively for 1,3,7,14,21 and 28d.At the end of experimental tooth movement and retention,maxillary dental casts were made.The interdental distance between the mesial groove of the first molars and distal groove of the second molars was measured on the maxillary dental casts.The interdental distances at the end of experimental tooth movement and retention were calculated.The effectuality of retentive appliances was evaluated by comparing the tooth movement distances between the experimental side and control side.Results The relapse distance of the first molars in the experimental side was significantly smaller than that in the control side at the end of the retention(P 0.05).Conclusion Wistar rat model of retention after orthodontic tooth movement with ligature wire is applicable.