To study structural changes which occur following bone transplantation along with internal remodelling of a transplanted bone, its surrounding alveolar bone and thejaw bone in the remote area, autogenous iliac bone and kiel bone were transplanted into theleft and right lower jaw, respectively, of adult dogs. Time tracing was performed by using three labelling agents (tetracycline, calcein, alizarin complexone) during the experiment (6 to 184 days after bone transplantation). Angiography was also conducted prior to the animals' sacrifice. Microradiograms, labelling findings and angiograms obtained from large ground sections prepared from the lower jaw were compared. The following results were obtained.
In both the left and right transplantation beds, capillary blood vessels newly developed at the transplantation site showed d network-like proliferation and developed in the transplanted bone prior to new bone formation around the transplanted bone. Almost simultaneously with this change, absorption of the existing bone and new bone formation became active in the interior of the alveolar bone around the transplantation bed.
The new bone in the transplantation beds showed compact proliferation 10 days and 30 days after transplantation of the iliac bone and the kiel bone, respectively. The degree of calcification became almost the same as that for the surrounding alveolar bone 60 days and 120days, respectively, after transplantation.
With the new bone formation in the transplantation bed that received the kiel bone, addition of bone proceeded actively around the bed, in the interior of the alveolar bone on the surface layer of the remote region and in the compact bone facing the mandibular canal in the lower margin (lining phenomenon).
The patterns of new bone formation in the bed that received the iliac bone included a new bone proliferation from the base toward the apex of the transplantation bed inone case, and gradual replacement of the transplanted bone by new bone originating in the surrounding area of the transplanted bone in another case. By contrast, the kiel bone was replaced almostentirely by new bone developing around the transplanted bone. The iliac bone and kid bone were absorbed and had disappeared by about 30 days and 140 days, respectively, after transplantation.
These changes in the kiel bone transplantation group were observed later than those in the iliac bone transplantation group. The process of their appearance was influenced by individual differences, age, transplantation material, etc.
Absorption of new bone in the transplantation bed began about 60 days after transplantation, and it continued even up to 184 days after transplantation. Therefore on the side that received the iliac bone, the site around the apex of the transplantation bed and its vicinity became compact, while the base became porous. On the side that received the kiel bone, bone absorption and addition were repeated, with the result that the base of the transplantation bed was occupied by bone trabeculae which were highly calcified.