Calcification patterns of rat condylar cartilage after induced unilateral malocclusion.

Occlusal interferences on right upper molars in rats produced ultrastructural changes in the calcification of ipsilateral condylar cartilage. This was characterized by premature appearance of apatite crystals within extracellular matrix vesicles present in the proliferative cell zone. The normal proliferative cell zone in the rat condyle manifested noncalcifying vesicles. The zone of calcification in rats with an occlusal splint revealed longitudinal calcifying fronts in the vicinity of the chondrocytes. These fronts were composed of haphazardly distributed apatite crystals. These ultrastructural alterations support the generally accepted view that mechanical stimuli induce changes in the process of primary mineralization.