Abstract:

BACKGROUND: Receptor activator of nuclear factor κ B ligand ligand (RANKL) and osteoprotegerin (OPG) play an important role in the formation of odontclasts and the root resorption. Whether the expression and changes of RANKL and OPG in gingival crevicular fluid (GCF) may be an index of root resorption in orthodontic tooth movement remains unclear.
OBJECTIVE: To investigate the changes and significance of the receptor activator for RANKL and OPG in GCF of the rats with orthodontic appliances.
METHODS: An animal model of orthodontic tooth movement was established in male SD rat. The rats were randomly divided into 0.49 N, 0.98 N, and 1.47 N groups, which assigned into 0, 3, 7, 10, 14, 21 and 28 days subgroups. Following careful sampling of GCF with absorbed paper points in the rats, the levels of RANKL and OPG were determined by ELISA. The effect of loading duration on RANKL and OPG ratio was observed.
RESULTS AND CONCLUSION: There were obviously differences in RANKL/OPG in different groups (P < 0.01). The RANKL/OPG was increased as the force increased. In the 0.49 N-force application group, the level of RANKL/OPG increased significantly during the first 21 days (P < 0.01), but the changes were not significant at 28 days. In the 0.98 N and 1.47 N-force application groups, the level of RANKL/OPG increased significantly between different orthodontic force application days (P < 0.01). RANKL and OPG in GCF play an important role in the root resorption in the rats with orthodontic appliances, which can be served as an clinical index for testing root resorption.