The effect of articular function on the mandibular condyle of the rat

It has been suggested by Duterloo (1967) that growth of the mandibular condyle is dependent on articular function. This has been investigated by removing the zygomatic process of the squamosal bone with which the mandibular condyle articulates in rats. In the first group of 57 animals the disc was left intact whilst in the second procedure performed on 12 rats the disc was removed electively. 30 animals were used for autoradiography. Both control and experimental condyles were sectioned at 0.5 mm. intervals in the coronal plane and stained with Haematoxylin and Eosin, Van Gieson and Toluidine Blue. The labelling index for the whole condylar was determined. Overall there was a statistically significant difference in labelling index between control and experimental condyles. When examining the results with respect to age they appeared to suggest that the condylar cartilage is a local modification of periosteum dependent on articular function for its maintenance. The second study confirmed that the articular disc and capsule appear to act as a restraint on condylar form.