[The mechanism of corticotomy accelerating orthodontic tooth movement in SD rats].

PURPOSE: To study the influences of corticotomy on orthodontic tooth movement (OTM) and the underlying mechanism in rats.

METHODS: Forty-eight female Sprague-Dawley rats were randomly assigned to corticotomy group (Cort, 24 rats) or sham-corticotomy group (Sham, 24 rats). All rats were subjected OTM after corticotomy or sham surgery. 6 rats of each group were sacrificed at 0, 1, 3 and 7 day of OTM. OTM were measured with an electronic digital caliper. Osteoclasts were counted in pressure side with TRAP. RANKL were measure by IHC at pressure side. The data were analyzed with SPSS 16.0 software package.

RESULTS: OTM at the 1 and 7 day in Cort group increased compared with sham group. Number of TRAP positive osteoclasts in pressure side increased in Cort group at the 3 and 7 day. Expression of RANKL in pressure side also increased in Cort group at the 3 and 7 day.

CONCLUSIONS: Corticotomy accelerates OTM in rats and it may result from promoted bone resorption via increased RANKL expression in periodontal tissue.