An Experimental Study on the Survival of Membranous Inlay Bone Graft on the Mandible

ABSTRACT

Bone graft is an important procedure in craniomaxillofacial reconstruction and the success of reconstruction depends on the survival of the grafted bone. In this study, the survival of the membranous inlay bone graft on the mandibles of dogs was investigated with bone scan and histologic examination. The inlay bone graft, 1x2cm critical-sized bone, was completely separated from the lower border of the mandible of dogs and then refixed to the original site. Bone scan and histologic examination were done at 1,2,3 and 4 weeks postoperatively. The bone scan after 1 week showed radioisotope uptake on the margin of the grafted bone and the isotope count was 21% compared to the uptake of the normal bone. After 2 weeks, the radioisotope uptake in the grafted bone increased to 52% of normal bone uptake. After 3 and 4 weeks, the degree of isotope uptake was 111% and 124% respectively. Histological findings after 1 week showed the absence of osteoblastic activity and 6 viable blood vessels in one 200X magnified field, which was 25% compared to the vessels of the normal bone. After 2 weeks, osteoblastic activities were noted and the number of viable blood vessels totalled 15, which was 63% of the vessels of the normal bone. After 3 weeks, osteoblastic activities increased and the number of viable blood vessels totalled 21, which was 88% of the vessels of the normal bone. After 4 weeks, there were markedly increased osteoblastic activities with a total number of 23 vessels, which was 96% of the normal bone. In summary, the revascularization of the membranous inlay bone graft began from the first week after bone graft, and then it gradually increased. After 3 weeks, the revascularization had returned to a nearly normal value compared with the value of the near-by normal mandibular bone.