Effect of recombinant human bone morphogenetic protein-2 on bone formation in the acute distraction osteogenesis of rat mandibles.

Background: Distraction osteogenesis (DO) is a method of producing new bone directly from the osteotomy site by gradual traction of the divided bone fragments.

Aim: The purpose of the present study was to evaluate histomorphometrically whether acute DO would constitute a viable alternative to the conventional continuous distraction treatment and also to verify the capacity of a recombinant human BMP (rhBMP-2) associated with monoolein gel to stimulate bone formation in the acute distraction process.

Materials And Methods: Forty-eight Wistar rats were assigned to three groups: Group 1, treated at a conventional continuous distraction rate (0.5 mm/day), Group 2, treated with acute distraction of 2.5 mm at the time of the surgical procedure, and Group 3, subjected to acute distraction associated with rhBMP-2. The animals from each experimental group were killed at the end of the second or fourth post-operative weeks and the volume fraction of newly formed bone trabeculae was estimated in histological images by a differential point-counting method.

Results: The results showed that after 2 and 4 weeks, bone volumes in the rhBMP-2 group were significantly higher than in the other groups (P<0.05), but no significant difference was observed in the volume fraction of newly formed bone between the continuous and acute DO groups.

Conclusion: In conclusion, the study indicates that rhBMP-2 can enhance the bone formation at acute DO, which may potentially reduce the treatment period and complications related to the distraction procedure.