Periodontal Regeneration by Application of Recombinant Human Bone Morphogenetic Protein‐2 to Horizontal Circumferential Defects Created by Experimental Periodontitis in Beagle Dogs

The purpose of this study was to examine the regeneration of periodontal tissue after the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) to horizontal circumferential defects created by experimental periodontitis. Twelve mandibular second premolars in 6 adult beagle dogs were subjected to experimental periodontal breakdown by placing silk ligatures around the teeth until the bone loss exceeded half of the root length. Flap surgery was then performed and the exposed cementum removed. The distance between the bone crest and cemento-enamel junction (CEJ) was about 5 mm. RhBMP-2 (40 micrograms/100 microliters) with a sponge-type carrier material made of gelatin and polylactic acid polyglycolic acid copolymer was placed in the furcation area (5 mm x 5 mm x 5 mm) and around the roots (10 mm x 5 mm x 2.5 mm x 2 pieces). In the control group, the same carrier material without rhBMP-2 was placed in the same manner. The flaps were replaced and sutured to cover these materials completely. Twelve weeks after surgery, the animals were sacrificed and serial sections were prepared in a bucco-lingual plane. Considerable new bone formation was observed in the rhBMP-2-treated sites. New cementum with Sharpey's fibers was observed on the instrumented root surface. On histometric analysis, the amount of new bone, new cementum, and connective tissue attachment was significantly greater in the rhBMP-2-treated group (paired t test; P < 0.01). These results indicate that suitable application of rhBMP-2 can produce considerable periodontal tissue regeneration, even in cases of horizontal circumferential defects.