Corticotomy-assisted orthodontic enhancement by bone morphogenetic protein-2 administration

To determine the possibility of synergistically enhancing orthodontic tooth movement (OTM) and bone formation in vivo by administering bone morphogenetic protein type 2 (BMP-2) on the tension side or in combination with corticotomy on the pressure side.

The sample consisted of 56 Wistar rats that were subjected to experimental OTM for 32 days using a split-mouth design. The sample was divided into 4 groups: a control group, a corticotomy group, a BMP-2 group, and a corticotomy plus BMP-2 group. An OTM force of 10 cN was applied to each group. BMP-2 18 μL was administered locally on the tension side alone or in conjunction with corticotomy and then compared with the controls using fluorescence-based tartrate-resistant acid phosphatase staining for osteoclast counts, histologic bone resorption, and clinical OTM results.

Corticotomy surgery increased the OTM rate (P < .05) by more than 20%. The injection of BMP-2 alone on the tension side did not induce significant changes in the degree of OTM compared with the vehicle-treated or control group (P > .05). When BMP-2 was combined with corticotomy on the tension and pressure sides (corticotomy plus BMP-2 group), respectively, nonsignificant OTM rates were observed (P > .05) compared with the controls; however, decreased osteoclast counts, bone resorption, and clinical results were observed in the corticotomy plus BMP-2 group.

In contrast to reports published to date, the present preliminary study suggests that there are limits to OTM acceleration by bone formation on the tension side and agrees with the idea that there is a single continuous periodontal compartment in OTM, rather than a pressure side and a tension side.