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