Histopathological and immunocytochemical studies of the effect of raised occlusal vertical dimension on the condylar cartilage of the rabbit.

The objective of this study was to evaluate the effect of raising the vertical dimension of occlusion on the condylar cartilage of young adult rabbits. Ten rabbits of approximately the same age were divided into two equal control and experimental groups. The vertical dimension of occlusion of the experimental group was raised bilaterally 1.5 mm using composite resin. No procedure was done for the control group. Animals were sacrificed during a six week period, and changes in condylar cartilage of experimental animals (compared to controls) were evaluated histomorphometrically. In addition, alterations of collagen type I and II were detected using immunohistochemical techniques. The results demonstrated an increase in the volume of the experimental condylar cartilage, which was attributed to an increase in the cartilage zone. Immunohistochemical examination of the hyperplastic cartilage showed no evidence for the production of type I collagen. These changes in condylar cartilage were considered adaptive and may lead to change in condylar shape. Further studies are needed to show if these adaptive changes would progress into osteoarthritis.