Histological observations of a bilateral maxillary sinus floor elevation 6 and 12 months after grafting with osteogenic protein-1 device

OBJECTIVE: The purpose of this case study was to analyze the tissue formed in a maxillary sinus, 6 and 12 months after grafting with recombinant human osteogenic protein-1 (OP-1) linked to a collagen carrier of bovine origin. PATIENT AND METHODS: A 49-year-old woman referred for bilateral sinus floor elevation, was grafted with an OP-1 device. After 6 months, a biopsy was taken from one of the grafted areas. After 12 months, during implant placement, 5 biopsies were taken from the grafted area and the maxillary host bone. Biopsies were processed without decalcification for histological analyses. RESULTS: The biopsy taken after 6 months contained newly formed bone, fibrotic tissue and device remnants. After 12 months, however, bone was absent from all biopsies which were taken from the grafted area, while particles of the collagen carrier were still abundant. Inflammatory cells were observed between remnants of the collagen carrier in the grafted area. CONCLUSION: This study indicates that an onset of new bone formation, which was observed after 6 months, did not persist. 12 months after grafting no bone was present in the biopsies from the grafted area, while the collagen carrier had remained. Lack of mechanical loading, as a result of postponing implant placement from 6 to 12 months, may have resulted in resorption of the emerging bone which was present 6 months after grafting.