Bone regeneration by recombinant human bone morphogenetic protein-2 in rat mandibular defects. An experimental model of defect filling.
BACKGROUND
Bone defects and irregularities are major problems for dental implant and periodontal therapies.


METHODS
We investigated whether the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) induces bone formation in through-and-through bone defects in the rat mandible. A round through-and-through bone defect (5 mm in diameter) was created in the angle of the mandible on both sides of the jaw using a steel round bur in each of 8 Long-Evans rats. In the experimental group, polylactic acid-polyglycolic acid copolymer/gelatin sponge (PGS) containing rhBMP-2 (6 microg/60 microl) was inserted in the bone defect. In the control group, the same carrier without rhBMP-2 was applied in the bone defect on the opposite side. Four weeks after application, the rats were sacrificed. Step serial sections stained with hematoxylin and eosin at intervals of 200 microm were prepared in a bucco-lingual direction. The size of the bone defects and new bone formation were evaluated histometrically.


RESULTS
In all cases in the experimental group, a large quantity of newly formed bone was observed. The bone defects were completely filled with new bone in 4 of 8 rats in the experimental group. In the control group, small amounts of new bone formation were observed along the border of the original mandibular bone. Histometrical analysis revealed that the amount of new bone was significantly larger in the rhBMP-2 treated sites than in the control sites (P <0.0001; paired t-test).


CONCLUSIONS
These results indicate that the rhBMP-2/PGS system induced effective bone regeneration on mandibular defects in rats. This procedure may be suitable as an experimental model for bone regeneration using various growth factors and effective for alveolar ridge augmentation followed by dental implant surgery.
Higuchi
T
T
Department of Periodontology, Faculty of Dentistry, Tokyo Medical and Dental University, Japan. higumail@green.ocn.ne.jp
Kinoshita
A
A
Takahashi
K
K
Oda
S
S
Ishikawa
I
I
D000818:Animals; D001672:Biocompatible Materials; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage / Q000627:therapeutic use*; D001861:Bone Regeneration / Q000187:drug effects*; D004396:Coloring Agents; D004337:Drug Carriers; D004801:Eosine Yellowish-(YS); D005456:Fluorescent Dyes; D005780:Gelatin; D006416:Hematoxylin; D006801:Humans; D019344:Lactic Acid; D008297:Male; D008334:Mandible / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D008336:Mandibular Diseases / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D010012:Osteogenesis / Q000187:drug effects; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D051381:Rats; D020318:Rats, Long-Evans; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta / Q000008:administration & dosage / Q000627:therapeutic use*
C525718:BMP2 protein, human; D001672:Biocompatible Materials; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004396:Coloring Agents; D004337:Drug Carriers; D005456:Fluorescent Dyes; D011108:Polymers; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D005780:Gelatin; D004801:Eosine Yellowish-(YS); D006416:Hematoxylin