| It has been proved that gradually occlusal disorder led to degenerative changes of TMJ, primarily focused on the fibrous cartilage, and then if the degenerative changes would be reversible? There is proliferative zone in the fibrous cartilage, a lot of undifferentiated cells in it, provided the proliferative and differentiative ability to the condyle, basis of remodling. There remain a certain quantity of proliferative cells in the degenerative condyle, and then it is necessary to investigate the recuberative recuperation of the degenerative cartilage. And this may offer experimental basis for the clinic. This study consisted of two parts and 5 months old new Zealand rabbits were divided in 3 groups of 9 animals each:Part I: An orthodontic string was fixed on the upper incisors and the 1 st premolar on one side while the other side was applied on the lower side,and the premolar was pulled forward half tooth for 2 months. Then, in one group the othodontic instrument was removed (removing group), and in the other group the over-erupted premolars were extracted (extracting group), and blank control was set. Histological examination showed the followings.l.TMJ of New Zealand rabbits blank controls aged 7-10 months, the structure was relatively stable but the thickness of condyle cartilage declined, and the trabecular of subarticula bone became thicker, and the area of cartilage of temporal bone decreased, while the thicknss of the articular disc increased a little with the age.2.We found that obvious degenerative changes were common in the TMJs of the experimental rabbits. The changes of 1-3 months of extracting group as well as removing group after 1-3 months were that: the layers of condyle cartilage was thinner than the blank contol group and the trabecular were thinner than the blank control, and the fibrous tissue was proliferated between the trabeculars and hyaline thrombus was found in the condyles; the thickness of temporal cartilage decreased while that of the disc increased. The difference were that: the PZ of extracting groups formed mastoid structure in some places and the cells of HZ and CCZ were well-arranged; the PZ of removing group didn't form that structure, and cells of HZ and CCZ ill-arranged and formed cell cluster.Part II: The TMJs of three groups were investigated the representation of PCNA and PG-C4S and DS. The result as followings:1 PCNA positive cells distributed on the PZ and superficial layer of HZ. The number of positive cells was lower in the removing group than that in the blank group, but the rate of positive cell was higher, related to the thinner of the cartilage. The extracting group was similar to the removing group, but the two markers of extracting group were slightly higher than the removing group. It is suggested that proliferation state of the extracting group was better than the latter. During the 1-3 months of experiment, the proliferation state of removing group decreased while the extracting group kept a relatively high state.2 DS positive staining was found in the FZ and extracellular matrix of PZ and HZ, and the pericellular matrix of the fibrocyte, and a small quantity of the temporal cartilage. It was relatively stable in the blank contol and the aging changes were not notable. The extracting group maintained steady while theremoving group increased from 1 to 3 months. The distribution of blank control was that the central part was higer than the anterior and posterior parts. The first month removing group the central part was lower than the anterior and the posterior parts, and the second month inclined to the blank control, and the third month was similar to that of the first month group. The DS staining of extracting group was higher man the blank control, but its distribution order was similar to the latter. The DS levels of the disc and the temporal bone were higher than that of the blank control. It suggested that the load of parts of TMJ remarkably changed.3 Staining for C4S was intense in the FZ PZ and HZ of condyle, perice...
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