The purpose of this study was to determine if bone morphogenetic protein (BMP) can adequately bridge alveolar clefts. Alveolar clefts were surgically created in aduly dogs. After healing, they were implanted with atelocollagen or BMP. Bone bridge formation was evaluated radiographically at 1, 2, 3, 6, 9, and 12 months. At 12 months, dogs were killed, and the specimens were examined histologically. The atelocollagen-implant cleft appeared radiolucent, with minimal new bone formation along the cleft margins, and bone bridges were not formed. The BMP-implant specimens showed almost complete filling of the clefts with bone as early as 1 month after implantation. Bone bridge formation at the clefts was completed within 3 months. The bone bridge remained stable for up to 12 months, and there was no evidence of bone resorption. The bone bridge was composed of well-mineralized lamellar bone identical to the surrounding alveolar bone. There results provide evidence that BMP can induce rapid and stable bone bridge formation in the alveolar clefts of adult dogs. The bone bridge can be expected to accomodate passive tooth eruption or orthodontic tooth movement.
