A HISTOLOGICAL STUDY ON THE CHANCES OF THE SURROUNDING TISSUE IN MANDIBULAR JOINT BY THE ORTHOPEDIC FORCE IN RATS

ORTHOPEDIC FORCE에 의한 백서악관절 주위조직의 변화에 대한 조직학적 연구

Many different appliances have been used to move teeth or to attempt to inhibit or stimulate growth of the jaws. Especially, Orthopedic force was used to apply a constant force on the mandible. Various orthopedic forces bring the changes of surrounding tissue, growth and development on the mandibular joint. Author carried out this study to find the histological changes of the mandibular joint in rats when the mandible applied posterior displacement. For the purpose of this study, $009\times036inch$ closed coil spring and 030inch orthopedic wire were used between the post occipital region and the chin region in order to render the orthopedic forces, posteriorly. The experimental animals vu. used 1 month old (GroupI), 3 months old (Group II), and 12 months old (Group III) rats. Following results were obtained; 1. At the beginning of the experimental Group I, there were predominant increment of Cartilage layer in the posterior parts of condylar head. Especially, the mature chondrocyte zone was increased. 2. In the experimental Group II, the chondroblastic zone was decreased while it showed slightly increased mature cartilage zone. 3. In the experimental Group III, the mature chondrocyte zone was disappeared gradually and there was a tendency to reduce the endochondral bone formation in condylar head. 4. After 30 days of experimental Group I and in experimental Group II, there was a tendency to decrease the immature cellular zone in the glenoid fossa by pressure. 5. There were no histological changes in the articular disc by pressure.