幼若犬における下顎骨片側切除が顎関節に及ぼす影響に関する研究

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  • An Experimental Study on Changes of Temporomandibular Joint after Hemimandibulectomy in the Young Mongrels

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<p>In case of a malignant tumor or a part of benign tumors occurring in the mandible, hemimandibulectomy might be performed. Recently autologus or artificial bone has been used for reconstruction of such cases. However, for the youngsters in their growth periods, the reconstruction used to be postponed until their development is completed, even if it is a benign case, since primary reconstruction could also be a problem for growth. On the other hand it has been reported that in those youngsters osteoanagenesis similar to the former jaw bone is feasible when the periosteum remains therein, even if hemimandibulectomy associated with great defect of the jaw bone is performed. Thus, the author studied changes of the temporomandibular joint remaining after hemimandibulectomy along the regeneration process of the jaw bone. Fourteen adult hybrid dogs about 6 months after birth were used. The right mandible was resected at the first distomolar part, detaching periosteum up to the temporomandibular joint. After that the left temporomandibular joint was observed diurnally. Observations were made 7, 14, 21, 30, 60, 90 and 180 days after the operation. After embedding the temporomandibular joint in celloidin, sections of 15μm were prepared and observed under the light microscope after staining with HE. As the result the following was known. 1. Changes of tissues at the temporomandibular joint was strongly noted at the initial stage after surgery, which was stabilized by 60 days. Characteristic changes were noted on the articular disc by 180 days after the operation. 2. Front edge of mandibular corpus showed absorption of the bone from 7 to 21 days after the operation, which was markedly strong inside compared with that outside. After that changes were not noted for a while, but absorption of the bone was again noted 90 days after the operation, and by 180 days osteoclast was not observed any more. 3. The cartilaginous zone of the mandibular head increased width of the differentiated zone markedly by 7 days after the operation, but from the 14th day onward its width decreased being irregular in convexoconvex by 21 days after the operation. After that it proceeded without changes, but 90 days after the operation again the width of the cartilaginous zone decreased to make a narrow medullary cavity by 180 days after the operation. 4. In the articular disc and tissues therearound, starting from the 7th day after the operation, changes occurred in alignment of fascicles in the posterior hypertrophied part of the articular disc, which by the 21st day of the operation showed small undulatory running on the side facing at the superior articular cavity. Furthermore, in the articular cavity, 7 days after the operation proliferation of the synovial portion was noted at the terminus, and 21 days after the operation tiny projection of the connective tissue was noted. On the other hand in the disc tissue, running of the fascicles differed between that on the mandibular head and that on the articular fossa by 90 days after the operation. In the posterior connective tissue alignment of fascicles began to be thinner, then by 180 days after the operation on the articular fossa tear of the disc tissue was noted. 5. Changes occurred on the articular fossa according to changes of the articular head. It means that, in the deepest part of the articular fossa regeneration of the bone was noted on the 14th day after the operation, while at the anterior articular fossa increase of the cartilage layer was noted initially at the anterior articular fossa, and 21 days after the operation at the posterior articular fossa. After that the course progressed without changes, and 180 days after the operation tear of the fibers was noted at a part of the fibrous covering at the posterior part of articular fossa. From the result of experiments as above, it was suggested that induction of the lower jaw after hemimandibulectomy</p><p>(View PDF for the rest of the abstract.)</p>

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