Effect of distraction rates on expression of bone morphogenetic proteins in rabbit mandibular distraction osteogenesis

Background: The expression of bone morphogenetic proteins can be regarded as an indicator for biological interaction in distraction osteogenesis. It was hypothesized that different distraction rates may produce different patterns of BMP expression. Material and methods: This study compared the expression of BMP-2, -4 and -7 at routine (0.9 mm once daily) and rapid (2.7 mm once daily) distraction rates using the rabbit mandibular lengthening model. Mandibular samples were harvested at days 1, 7 and 14 of consolidation. Results: The expression of BMP-2 and BMP-4 was found throughout the experiment, their expression intensity and location being essentially similar, whereas BMP-7 had not been expressed. Expression of BMP-2 and -4 was more intense at the routine distraction rate than at the rapid distraction rate. Conclusions: BMP-7 had no expression during the consolidation period of mandibular distraction. The change in the mechanical environment created by different distraction rates led to different expression of BMP-2 and -4. In the early consolidation stage the biological environment for bone formation created by distraction at a routine rate was superior to that created by the rapid distraction rate. (C) 2006 European Association for Cranio-Maxillofacial Surgery.