急冷處理된 下顎骨片의 再移植에 關한 實驗的 硏究

AN EXPERIMENTAL STUDY ON THE HEALING OF REIMPLANTED FREEZE-TREATED MANDIBULAR BONE

The purpose of this experimental study was to observe and compare the healing process of reimplanted freeze-treated and saline-treated mandibular bone in healthy mongrel dogs histopathologically. The 5 animals, average weight 10 ㎏, aging 8 months to 1 year were divided into control groups and experimental groups. Under general anesthesia with sodium pentobarbital (30 ㎎ per weight ㎏), a segment of the inferior border of the mandibular body was resected, 1.5 × 1.0 × 1.0 ㎝ in size, frozen for 10 minutes in liquid nitrogen (-196℃) and thawed for 20 minutes in saline solution, and then reintroduced it into the mandibular bed. In control groups, this segment were placed in saline solution for 30 minutes. The animals were sacrificed on the 1st, 2nd, 4th, 8th and 16th weeks after experiments and all specimens were fixed in 10% neutral formalin solution, decalcified in 5% nitric acid, embedded in paraffin wax, and sectioned 5 to 7 ㎛, stained with hematoxylin-eosin stain. The following results were obtained: 1. Reimplanted freeze-treated and saline-treated bones showed favorable healing process without rejection or inflammatory reaction during whole experimental periods. 2. The lacunae in both freeze-treated and saline-treated bones showed empty spaces due to loss of osteocytes, but the Haversian canals contained minute fibrovascular cores. Although resorption of outer cortical plate by osteoclasts was noticed, there was no bone necrosis. The resorption of bone was more remarkable in freezetreated bone than in saline -treated bone. 3. In both group, the bony union resulting from direct accumulation of new bone, forming from surrounding bone, around the reimplanted bone was noted from 1st week after operation and that was more remarkable at 4th week The complete bony union was achieved at 8th weeks followed by reconstruction of cortical plate around the implanted bone. The new bone formation and its maturation were more favorable in saline-treated groups than in freezetreated groups. 4. The bony union was achieved by new bone accumulation in retiform between the implanted bone and remaining bone, the new bone progressively matured and remodeled into cortical bone plate. The implanted bone was appeared as embedded within new cortical bone.