Comparative histomorphometric analysis of maxillary sinus augmentation with and without bone grafting in rabbit

The aim of this animal study was to evaluate, by histomorphometric analysis, new bone formation in rabbit maxillary sinuses with, and without, bone grafting.

Bilateral sinus augmentation procedures were performed in 20 adult male rabbits. Bony windows were made by a saw insert connected with a piezoelectric surgical device in both groups. In the experimental group, the replaceable bony window was repositioned after careful elevation of the sinus mucosa without bone grafting. In the control group, anorganic bovine graft (Bio-Oss; Geistlich AG, Wolhusen, Switzerland) was grafted in the new compartment of the maxillary sinus after elevation of the sinus membrane, and resorbable collagen membrane was used to cover over the bone graft. A mini screw was placed on the bony window to support the elevated sinus membrane. Animals were sacrificed at 1, 2, 4, 6, or 8 weeks after surgical procedure. The augmented sinuses were evaluated by histomorphometric analysis using hematoxylin-eosin and tartrate-resistant acid phosphatase stain.

Histologically, new bone was revealed along the elevated sinus membrane, but new bone was not revealed under the collagen membrane or Bio-Oss in the control group after 1 week. In the control group, new bone formation was revealed on the surface of Bio-Oss particles from 2 weeks and continued to 8 weeks. However, new bone formation began from the floor of the replaced bony window and the elevated sinus membrane in the experimental group after 1 week. New bone formation increased under the floor of the repositioned bony window and the elevated sinus membrane, and blood clots appeared in the new compartment of the maxillary sinus throughout the experimental period in the experimental group. Significant higher new bone formation was revealed in the experimental group than in the control group.

New bone formation in the experimental group was faster and denser than that in the control group. Replaceable bony window, as an autologous barrier, accelerates new bone formation early in the healing phase compared with the collagen membrane over a bone graft in the maxillary sinus. The replaceable bony window and elevated sinus membrane revealed osteoinductive potential.