RECOMBINANT HUMAN OSTEOGENIC PROTEIN-1 (OP-1) STIMULATES PERIODONTAL WOUND-HEALING IN CLASS-III FURCATION DEFECTS

OSTEOGENIC PROTEIN-1 (OP-1) is a member of the transforming growth fac tor beta superfamily and is a potent modulator of osteogenesis and bon e cell differentiation. This preclinical study in dogs sought to asses s the effects of OP-1 on periodontal wound healing in surgically creat ed critical size Class III furcation defects. Eighteen male beagle dog s were subjected to the creation of bilateral mandibular 5 mm osseous defects. A split-mouth design was utilized which randomly assigned opp osing quadrants to control therapy (surgery alone or collagen vehicle) or 1 of 3 ascending concentrations of OP-1 in a collagen vehicle (0.7 5 mg OP-1/g collagen, 2.5 mg/g, or 7.5 mg/g). Thus, 9 quadrants per te st group received OP-1, 9 quadrants per control group received surgery alone, and 9 quadrants received collagen vehicle alone. Test articles were delivered by a surgeon masked to the treatment, and fluorogenic bone labels were injected at specified intervals post-treatment. Eight weeks after defect creation and OP-1 delivery, tissue blocks of the m andibulae were taken for masked histomorphometric analysis to assess p arameters of periodontal regeneration (e.g., bone height, bone area, n ew attachment formation, and percent of defect filled with new bone). Histomorphometry revealed Limited evidence of osteogenesis, cementogen esis, and new attachment formation in either vehicle or surgery-alone sites. In contrast, sites treated with all 3 concentrations of OP-1 sh owed pronounced stimulation of osteogenesis, regenerative cementum, an d new attachment formation. Lesions treated with 7.5 mg/g of OP-1 in c ollagen regenerated 3.9 +/- 1.7 mm and 6.1 +/- 3.4 mm(2) (mean +/- S.D .) of Linear bone height and bone area, respectively. Furthermore, the se differences were statistically different from both control therapie s for all wound healing parameters (P < 0.0001). No significant increa se in tooth root ankylosis was found among the treatment groups when c ompared to the surgery-alone group. We conclude that OP-1 offers promi se as an attractive candidate for treating severe periodontal lesions.