Guided bone regeneration using collagen membranes for sinus augmentation

We investigated the effect of guided bony regeneration using collagen membranes for sinus augmentation in the first maxillary molars of 18 adult female beagle dogs. The teeth were extracted bilaterally and the sinus floors were lifted with simultaneous implantation. The grafted material composed of a combination of autografts and Bio-oss in a 2:1 ratio. On the experimental side in each dog, collagen membrane was folded at the lateral osteotomy window, at the apex of the implants, and at a certain part of the palatal bone. On the opposite (control) side, the collagen membrane covered the osteotomy window. Six animals were killed at each of 4, 12, and 24 weeks postoperatively. Gross observation, biomechanical testing, and histological examinations were made. On the experimental side, grafted materials showed no obvious resorption or subsidence, and a new bone had formed at the apex of the implants. On the control side, the grafted materials had been shifted and absorbed. Histological examination showed increased formation of a new bone in the experimental group, which matured over time. At 4 weeks, inflammatory cells were present in the control group, which showed less maturation of the new bone. The pull-out force increased with time and, at week 24, there was a significant difference in pull-out force between the two groups (p<0.01). Guided bony regeneration with the enfolded coverage of membrane can effectively reduce resorption of grafted bone on the apical surface of implants and stimulate formation of the new bone in sinus augmentation.