Induced growth of the mandibular condyle in the rat.

Advancement of the calcification front in the cartilage, which is a measure of the growth of the cartilage, can be determined by the administration of two dose bone-markers at specific intervals. It appears that growth still takes place in animals of 12-18 months. This growth is possible by the persistence of chondrogenic cells. The overall growth of the central part of the condyle amounts to about 2 mm over the period from 2 to 18 months. Raising of the bite in the rat has an obvious influence on the temporomandibular joint, and on the condyle in particular. Within a few days an increase of growth-rate of cartilage can be demonstrated. This extra growth is temporary, and the intensity and duration of the response is determined by the age of the animal. This adaptation is related to the presence of chondrogenic cells in the cartilaginous layer in the condyle.