Early Revascularization of membranous inlay bone graft in canine mandible model

The early revascularization of a membranous inlay bone graft in a canine mandible was investigated using bone scans and histological examinations. Eight 5-month-old mongrel dogs were used as the subjects. The inlay bone graft, a 1- x 2-cm critically sized bone, was completely separated from the lower border of the canine mandible and then refixed to the original site. Bone scans and histological examinations were performed in the first, second, third, and fourth postoperative weeks. The bone scan in the first postoperative week revealed radioisotope uptake on the margin of the grafted bone with an isotope count that was 21% of the normal bone uptake. In the second postoperative week, the radioisotope uptake in the grafted bone increased to 52% of the normal bone uptake. In the third and fourth postoperative weeks, the isotope uptakes were 111% and 124%, respectively. The histological findings in the first postoperative week showed an absence of osteoblastic activity and 6 viable blood vessels in a field magnified x200, which was the equivalent of 25% of the vessels of the normal bone. In the second postoperative week, osteoblastic activity was noted, and the number of viable blood vessels increased to 15, that is, 63% of the vessels of the normal bone. In the third postoperative week, there was an increase in osteoblastic activity, and the number of viable blood vessels was 21, that is, 88% of the vessels of the normal bone. In the fourth postoperative week, there was a marked increase in osteoblastic activity with the number of vessels reaching 23, that is, 96% of the normal bone. In summary, revascularization of the membranous inlay bone graft began within the first week after the bone graft and thereafter gradually increased. In the third postoperative week, revascularization returned to a near-normal value compared with the value of the adjacent normal mandibular bone.