Inhibition of Orthodontic Relapse by Local Application of Simvastatin-Loaded Gelatin Hydrogel in a Rabbit Model.

Objectives: This study aims to determine the effect of gelatin-simvastatin hydrogel application on bone remodelling during relapse.
Materials and Methods: Twenty-four rabbits (Oryctolagus cuniculus) were divided into a control group (n = 12) and a treatment group (n = 12). The lower incisors were subjected to orthodontic force and moved distally by an open coil spring. The force (50 cN) was extended for 1 week and retained in a new position for 2 weeks (stabilisation period). The treatment group received a local gelatin-simvastatin hydrogel administration during stabilisation, and the control group received only gelatin hydrogel. The springs were debonded after the stabilisation phase from both groups to facilitate a relapse. The percentage of relapse was measured in a model study using digital callipers. Levels of OPG and RANKL were analysed using ELISA.
Results: The local application of gelatin-simvastatin hydrogel in the treatment group significantly decreases the relapse percentage and RANKL level. Additionally, the gelatin-simvastatin hydrogel significantly increases the level of OPG and ratio of OPG/RANKL.
Conclusions: Applying gelatin-simvastatin hydrogel in the retention period can induce bone formation, inhibit orthodontic relapse and increase tooth stability (in vivo).
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