하악두연골 절제후 악간고정 및 조기운동이 하악두 치유에 미치는 영향에 관한 실험적 연구

The effects of immobilization and early movement on the condylar repair after condylar shaving of the rabbits

The present study was designed to compare the effects of the immobilization with those of early movement on the condylar repair after condylar shaving of the rabbits. In order to carry out this experiment, 20 rabbits weighing about 3. 0㎏ were selected and were randomly assigned to one of two different postoperative treatment groups: early active motion in the cage or immobilization with intermaxillary fixation. Additional two rabbits were used as normal controls. Under the general anesthesia with sodium thiopental, superior aspect of the left condyle of all experimental animals was shaved with a fissure bur about 1㎜ in depth until bleeding bone was encountered and in the group 1 animals normal diet was permitted postoperatively and group 2 animals were immobilized with intermaxillary fixation and feed with liquid diet through intraoral tubing. The experimental animals were sacrified consecutively on the third day, first week, second week, third week, and forth week after condylar shaving and the mandibles were dissected out carefully to produce tissue specimen. The specimens were fixed with 10% formaline solution for 24 hours and rinsed with phosphate buffer solution. It was decalcified with 5% nitric acid for 15 days. Thereafter the specimens were dehydrated in alcohol series, and embedded paraffin as usual manner. The embedded specimens were sectioned in 4-6㎛ with microtome. stained with hematoxylin-eosin stain, Masson s trichrome stain and Koneff stain and observed through microscopic study. The results were as follows. 1. Early movement stimulated histological repair than did immobilization with intermaxillary fixation. 2. All experimental groups revealed the differentiation of chondrocytes at the second week and it was more remarkable in the early movement group. 3. The repaired cartilaginous layer of early movement group was thicker than that of immobilization group. 4. In the whole experimental period, bone marrow was intact in early movement group, however, it was degenerated in immobilization group. 5. All experimental groups revealed the cartilagious covering and endochondral ossification.