[Effect of akebiasaponin D with different concentrations on orthodontic tooth movement in rats].

Purpose: This study investigated the effect of local injection of akebiasaponin D (ASD) with different concentrations on the rate of orthodontic tooth movement in rats.

Methods: Forty 6-week-old female Wistar rats were randomly divided into 4 groups with 10 rats in each group. Animal model for orthodontic tooth movement was established. The upper first molars of the rats were moved mesially by coil springs（force=40 g）. ASD solution at the concentration of 5 mg/kg was locally injected in ASD1 group, and ASD solution at the concentration of 10 mg/kg was locally injected in ASD2 group. The rats of group PGE2 were injected PGE2 solution at the concentration of 25 μg/kg. The same amount of normal saline was injected in the control group. The rats were sacrificed in batch on the 3rd, 7th, 14th, 21st and 28th days after orthodontic treatment. The distance between upper first molar and second molar was measured. H-E straining was performed to observe the changes of periodontal tissue and the amount of osteoclast. SPSS13.0 software package was used for statistical analysis.

Results: The distance between the first and second molar was successively increased compared with the control group. On day 3, there was significant difference between PGE2 group and the control group (P＜0.05). On day 7, the distance between the first and second molar in PGE2 group and ASD2 group was significantly increased compared with the control group (P＜0.05). The amount of tooth movement was significantly increased (P＜0.05) in ASD1 group, ASD2 group and PGE2 group, compared with the control group on the 14th, 21st and 28th day. However, there was no significant difference (P＞0.05) between ASD2 group and PGE2 group. Under microscope, the number of osteoclast was increased on the tension side, reaching a peak on day 21st, and decreased later.

Conclusions: Local injection of ASD solution may accelerate orthodontic tooth movement. ASD solution at the dose of 10 mg/kg can accelerate orthodontic tooth movement efficiently similar to PGE2 solution, while ASD solution at the dose of 5 mg/kg is not as effectual as PGE2 solution.