Forward mandibular positioning enhances the expression of Ang-1 and Ang-2 in rabbit condylar chondrocytes

Functional appliances correct dental malocclusion, partly by exerting an indirect mechanical stimulus on the condylar cartilage, initiating novel bone formation in the condyle. Angiopoietin is involved in the angiogenesis associated with novel bone formation. This study aimed to determine the expression of angiopoietin (Ang)-1 and -2 following forward mandibular positioning (FMP) in the condylar chondrocytes of rabbits. Sixty rabbits (age, 8 weeks) were randomly allocated to the experimental and control groups (n=30 per group). In the experimental group, FMP was induced by a functional appliance. Five rabbits from the experimental group and the control group were sacrificed following 3 days and 1, 2, 4, 8 and 12 weeks, respectively. The right temporomandibular joints (TMJs) were collected and the expression of Ang-1 and -2 was evaluated by immunohistochemical staining. The expression of Ang-1 increased at day 3 and reached a peak at 2 weeks, whereas Ang-2 reached maximal expression 4 weeks after FMP. Subsequently, the expression of Ang-1 and -2 gradually decreased. Thus, FMP enhanced the expression of Ang-1 and Ang-2 in condylar cartilage, which is related to angiogenesis in the process of endochondral ossification.