Abstract:

BACKGROUND: Recently, microscrew anchorage implant has been widely used in the orthodontics due to its simple operation, little trauma and strong anchorage, but it is rarely used in type Ⅱ intermaxillary extraction.
OBJECTIVE: To establish the animal experiment model of orthodontic microimplant, to investigate the effects of orthodontic forces on the expression of core binding factor a1 (Cbfa1) in condylar cartilage and on condylar process modification.
METHODS: Thirty 8-week-old healthy New Zealand rabbits were randomly divided into experimental group (n=24) and control group (n=6). According to different forces, the experimental group was randomly subdivided into four groups: 100 g, 200 g, 300 g, and 400 g. Rabbits from the experimental group were performed type Ⅱ intermaxillary extraction taking microscrew implants as anchorages. At 4 weeks after surgery, Cbfa1 expression in the condylar cartilage was detected.
RESULTS AND CONCLUSION: Different orthodontic forces resulted in different Cbfa1 expression in the condylar cartilage. When orthodontic force was 100 g and 200 g, Cbfa1 expression was significantly higher compared with the control group and orthodontic force of 200 g lead to highest Cbfa1 expression. When the orthodontic force was 300 g, there was no significant difference between the experimental and control groups (P > 0.05). When orthodontic force was 400 g, Cbfa1 expression was significantly greater in the experimental group than in the control group (P < 0.05). Orthodontic force can influence the expression of Cbfa1 in the condylar cartilage, suggesting that appropriate orthodontic forces have good effects on remodeling condylar cartilage.