In this study, effects of incision of retrodiscal tissue and unilateral occlusal reduction on temporomandibular joint of rabbit were investigated.
Twenty-seven adult New Zealand White Rabbits, weighing over 3.5kg, were utilized in this study. Temporomandibular joint surgery was performed in left temporomandibular joint of 24 rabbits to displace disc anteriorly through incising the retrodiscal tissue 1-2㎜ posterior to the disc. They were divided into two groups : twelve were left untreated after surgery, occlusal reduction was performed on left posterior teeth every 2 weeks in the other twelve rabbits. The remaining three served as the control group. The sample were sacrificed by 8, 12, and 16 weeks after surgery. Histologic examinations were performed after sacrificing them.
The results were as follows:
1. Histologic findings which was manifested by flat articular fossa, broad articular surface, generalized recession of articular cartilage and sclerosis of subchondral bone were observed. These findings were similar to internal derangement.
2. In the rabbits untreated after surgery, thin cartilagenous layer and necrotic tissue were observed in 8 weeks group, calcifying cartilagenous layer was observed in 12 weeks group, and cartilagenous layer on anterior portion was observed in 16 weeks group. So, it showed gradual healing pattern into the normal tissue except displaced disc.
3. Occlusal trauma after surgery resulted in generalized recession of upper and lower articular surface. Necrosis and vertical split on condylar process of mandible were observed in 8 weeks group. Osteoclasts, exposure of subchondral bone due to erosion on upper and lower articular surface, and degenerative changes on retrodiscal tissue were observed in 16 weeks group. So, it showed continuous progress pattern of osteoarthrosis.
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