Tooth eruption into the newly generated bone induced by recombinant human bone morphogenetic protein-2.

OBJECTIVE: The purpose of this study was to observe tooth eruption pattern into the newly generated bone induced by recombinant human bone morphogenetic protein-2 (rhBMP-2).

METHOD: Three 12-week-old beagle dogs were used. Following wound healing of the extracted maxillary third deciduous incisor at the age of 13 weeks, a resection of maxillary alveolar bone (8 mm by 8 mm by 8 mm) was carried out, accompanied by extraction of the maxillary second incisor tooth germ. The rhBMP-2 (5 microgram/100 microL or 10 microgram/100 microL) was implanted in the resected area. A group that was not implanted after resection and a nonresected group were used as controls. Serial changes of the eruption pattern of the maxillary third incisor in the implanted area were observed radiographically. Oxytetracycline and calcein were employed as bone markers. Nine weeks after the implantation, the animals were sacrificed. The samples were observed histologically and analyzed using peripheral quantitative computerized tomography to acquire the bone mineral density (BMD).

RESULTS: In the rhBMP-2 (5 microgram/100 microL)-treated group, histological findings and the BMD of the newly generated bone were almost same as in the nonresected group. The maxillary third incisor erupted through the implanted area. However, in the rhBMP-2 (10 microgram/100 microL)-treated group, more osteoinductive activity and significantly higher BMD were observed in the newly generated bone. The maxillary third incisor erupted mesially so as to avoid this implanted area.

CONCLUSION: Results showed that bone remodeling and tooth eruption through the newly generated bone appear to be dose dependent. Accordingly, proper dosage of rhBMP-2 should be determined for successful clinical application.