OBJECTIVETo investigate the osteogenesis mechanism by analysis of the expression of insulin-like growth factor-I (IGF-1) and alkaline phosphatase (ALP) in the reconstruction of cleft palate (CP) with distraction osteogenesis (DO) in rhesus.

METHODSThe CP animal models were established surgically. 21 rhesus in experimental group underwent DO to close the soft and bony defect, followed by consolidations. Every 3 animals were killed and the specimen were taken out after consolidation of 1, 2, 4, 6, 8, 12, 24 weeks. The mRNA of IGF-1 and ALP were detected with Real-time RT-PCR technique. The expression of IGF-1 and ALP was quantitatively analyzed by ELISA. The results were compared with those in control and sham groups (each of 2 animals), respectively.

RESULTSSince consolidation, the mRNA of IGF-1 and ALP increased significantly at one week and reached the peak at two weeks, but decrease to control level after 12 weeks of consolidation. The expression of IGF-1 also increased to peak level after two weeks of consolidation. The expression of ALT increased significantly since consolidation and reach the peak value after six weeks. They all decreased to nearly control level after 8-12 weeks.

CONCLUSIONSThe palate cleft can be successfully closed with new formed bone after DO. The mechanism of bone consolidation is intramembranous bone formation.