A Histological Study on Experimental Tooth Movement into Bone Induced by Recombinant Human Bone Morphogenetic Protein-2 in Beagle Dogs

Abstract

Objective The purpose of this preliminary study was to examine experimental tooth movement into newly generated bone induced by recombinant human bone morphogenetic protein-2 (rhBMP-2). Method After extraction of the maxillary first premolars, bone defects were surgically created in eight adult beagle dogs using a 5-mm-diameter trepan bar. According to which material was grafted into the bone defects, animals were divided into the following four groups: (1) the rhBMP-2 group in which rhBMP-2 with a poly [D,L-(lactide-co-glycolide)]/gelatin sponge complex was implanted; (2) the spongiosa group in which spongiosa from the tibia was grafted; (3) the nongrafted group in which no material was embedded; and (4) the control group in which only tooth extraction was performed. The osteoinductive activity of rhBMP-2 and tooth movement into the newly generated bone were examined by histological and morphometric comparisons of each group. Results Considerable new bone formation was observed at the grafted site both in the rhBMP-2 and in the spongiosa groups. The area of generated bone in the rhBMP-2 group was significantly greater than that in the spongiosa group. Newly generated bone, in both the rhBMP-2 and spongisosa groups, showed a similar histological response to orthodontic force as in normal alveolar bone in the control group. However, root resorption occurred on the pressure side in the rhBMP-2 group. Conclusion These results indicated that rhBMP-2 might constitute an alternative material to autogeneous bone grafting for alveolar cleft defects. Further studies regarding tooth movement into generated bone induced by rhBMP-2 are suggested.