하악골 절단부의 고정방법이 치유에 미치는 영향에 관한 조직화학적 및 생물계측학적 연구

A histochemical and biometric study on bone healing fater girid fixation and non-fixation on mandibular osteotomy

The purpose of this study was to investigate the influence of fragmental movements on healing process after mandibular osteotomy in dog. In order to carry out this experiments, 6 Korean dogs weighting about 10-12Kg were selected. Under the general anesthesia with Entobar, osteotomy was performed on both side of the mandibular body area, pay attention not to occur compound fracture into the oral cavity and not to damage the inferior alveolar nerve and vessels. In the osteotomized left sides were fixed with non-compression plates and screws and in the right sides, bone fragments were left without fixation. The experimental animals were sacrificed at 4, 6 and 8 weeks after surgery and the mandibles were 4 extirpated after dissection of soft tissue. The operated sites of 3 mandibles were examined under the light micorscope to observe the bony repair process histochemically, and another 3 mandibles were selected for measuring the strength of bony union. The results obtained from this study were as follows; 1. In the non-fixation parts of the 6 weeks experimental groups, there were marked periosteal bone formation on the outer surfaces of fractured fragments. And in the rigid fixation part, closely united trabeculae between bony fragments were observed. 2. In the rigid fixation parts of the 8 weeks experimental groups, fractured bone fragments were united with compact bone but in the non-fixation part tiny bone trabeculae were scattered in the large amount of fibrous connective tissue. 3. The size of cross-sectional area was 555㎟ at the non-fixation part and 270㎟ at the rigid fixation part and so a large amount of the external callus were formed in the non-fixation part. 4. The rigid fixation part (6.11KgㆍF/㎟) showed more united strength than the non-fixation part (2.69KgㆍF/㎟) after 8 weeks. 5. The tensile strength recovered 20% at the non-fixation part and 47% at the rigid fixation part after 8 weeks. 6. The tensile strength increased according to duration in the rigid fixation part but no significant changes in the non-rigid fixation part.