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 adu lt rabbits. Ten rabbits of approximately the same age were divided int o two equal control and experimental groups. The vertical dimension of occlusion of the experimental group was raised bilaterally 1.5 mm usi ng composite resin. No procedure was done for the control group. Anima ls were sacrificed during a six week period, and changes in condylar c artilage of experimental animals (compared to controls) were evaluated histomorphometrically. In addition, alterations of collagen type I an d II were detected using immunohistochemical techniques. The results d emonstrated an increase in the volume of the experimental condylar car tilage, which was attributed to an increase in the cartilage zone. Imm unohistochemical examination of the hyperplastic cartilage showed no e vidence for the production of type I collagen. These changes in condyl ar cartilage were considered adaptive and may lead to change in condyl ar shape. Further studies are needed to show if these adaptive changes would progress into osteoarthritis.