Development of the rabbit craniomandibular joint in association with tooth eruption.

The adult rabbit craniomandibular joints (CMJs) are stress-bearing joints. The two CMJs and the teeth form an articular triad. In early fetal life the developing triad consists of the CMJ primordia, the tooth germs for the entire set of deciduous teeth, as well as the posterior extensions of the dental lamina, which will give rise to the permanent teeth with no deciduous predecessors. During postnatal life, before occlusion is established, there is a remodelling stage in which the CMJ builds up its matrix components such as collagenous and elastic fibres, proteoglycans and type II collagen. Remodelling gradually diminishes into the maintenance stage once occlusion is fully established and after eruption of the first and second molars. Chondrocytes first appear in the CMJ articular disc during the second week of postnatal development. These cells localize in the band areas of the disc and establish an extensive cartilaginous matrix 3-4 weeks postnatally. This study supports the concept that the full development of a fibrocartilaginous articular disc, rich in proteoglycans, occurs as adult occlusion is established.