[Expression of BMP/Smads in rabbit condylar cartilage during mandibular forward positioning].

Objective: To identify the relationship between the expression of BMP/Smads in condylar cartilage and condylar growth modifications in rabbits during mandibular forward positioning.
Methods: Sixty male rabbits with 8 weeks of age were randomly divided into the experimental group (n=36) and control group (n=24). The mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance. The rabbits in the experimental group and control group were sacrificed after 3 days and 1, 2, 4, 8, 12 weeks, respectively. The expression of BMP-2, Smad1/5, 4 and 6 in condylar cartilage was examined by immunohistochemical staining.
Result: The expression of BMP-2, Smad1/5, 4 and 6 was mainly found in the chondrocytes from the transitional zone and hypertrophic zone, and was also found in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for BMP-2, Smad1/5, 4 and 6 in the experimental animals were stronger at early stage (P<0.05), coinciding with the remodeling in condylar cartilage after functional appliance.
Conclusion: The expression of BMP-2, Smad1/5, 4 and 6 is associated with the adaptive remodeling of the condylar cartilage after functional appliance.