The purpose of this study was to observe the healing process of the autoclaved autogenous mandibles which were immediately re-implanted with rigid fixation, and to compare them with the graft of the fresh autogenous mandibles. 12 adult dogs were
used
for this experimental animals, and the mandible were divided into the control side on the left and the experimental side on the right. Partial mandibulectomies were done on both sides via extraoral approach, and the resected blocks of the
mandibles
on
the experimental sides were re-implanted with rigid fixation in their original beds after autoclaving, and the control sides were also grafted after soaking in normal saline solution.
99mtc0MDP radio0isotope bone scanning and tripple fluorescent labeling with oxytetracycline, alizarin, and calcein were done for the observation of the healing processes. Animals were sacrificed at 2, 4, 8, 12, 16 weeks of postoperative periods,
and
were examined with respect to graft incorporation(gross, radiography, histology, and histomorphometry) and bone graft metabolic activities (scintigraph). During the experiment, 7 dogs were excluded because of oral mucosal perforation and
subsequent
wound infection.
@ES The results were as follows:
@EN 1. On the gross examination of the 5 healthy experimental animals, new bone was formed on the each sides of the grafted bones, and it was much more on lingual sides than on buccal sides, and on the control sides than the experimental sides.
2. The radio-opacity of the control sides were more noticeable than the experimental sides during the entire experimental periods.
3. On the scintigraphy, the radio0isotope uptake of the experimental sides were less than the control sides during the entire experimental periods, the highest amount of uptake on the control sides was at the 4 weeks of group after grafting and
returned
nearly to the normal level at the 16 weeks of group, while, the 8 weeks of group was peak and it was less than the normal side at the 16 weeks of group(79%) on the experimental sides.
4. On the Light microscopy, the initial periods of healing were dominant by the ingrowth of bone from the adjacent periosteum to the osteotomy sites on both the control and the experimental sides, and the graft incorporation on the experimental
side
were rather delayed than the control sides.
5. On the fluorescent microscopy, the delayed remodelling o the osteotomy sites were noted on the experimental sides when were compared to that of control. One-sided invasion of fluorescence from the osteotomy site to the grafted bone were noted
on
the
experimental sides in contrast to the bone growth both from the host and the grafted bone to the osteotomy sites on the control. At the 12 weeks of group, scattered and irregular fluorescent deposits were observed on the experimental sides.
On the basis of the above results, although the autoclaved bone was not the ideal bone graft material because it showed delayed remodelling on the osteotomy site, and it needed thick soft tissue coverage to prevent the oral perforation, the
graft-hot
union was accomplished with rigid fixation which induces the bone growth from the host without the addition of cancellous bone or allogeneic bone matrix, and so, it is supposed that the autoclaved mandible can be used as one of the immediate
replacement
materials for the mandibular defects.
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