Effects of icariin on orthodontic tooth movement in rats

Orthodontic tooth movement (OTM) is achieved through bone remodeling of the alveolar bone. Icariin, the active ingredient isolated from Herba Epimedii which is a traditional Chinese medicine (TCM) commonly used for osteoporosis treatment in China. The purpose of the study is to explore the effect of icariin on OTM in rats, and analyze the possible mechanism involved.

48 rats were selected and divided into 2 groups: the control group and the experimental group. Rats in the experimental group were given 20 mg/kg/day icariin by intragastric administration, while the control group received the same volume solvent. All rats were placed a closed coil spring between their upper first molar and incisor, exerting a force of about 40 g to establish animal models of OTM. As the first molar moved mesially, a space between the first and second molar was created. The rats were sacrificed in batch on the 7th, 14th, 21st and 28th days after orthodontic treatment. The amount of tooth movement was measured, and histomorphometric analysis based on slices from periodontium adjacent to the maxillary first molars were used to observe new bone formation, bone resorption and quantify osteoclasts.

Icariin increased OTM (P<0.05) by 65.2%, 35.3%, 11.7% and 16.7% on day 7, 14, 21, 28 respectively compared with the control group. The number of osteoclasts in the icariin group showed a transient but sudden increase and then a persistent decrease.

Icariin could accelerate OTM in rats through promoting bone remodeling of alveolar bone.