MORPHOLOGICAL ALTERATIONS IN THE ELASTIC FIBERS OF THE RABBIT CRANIOMANDIBULAR JOINT FOLLOWING EXPERIMENTALLY-INDUCED ANTERIOR DISK DISPLACEMENT

Elastic fibers are important components of the connective tissue that attaches the articular disk of the craniomandibular joint (CMJ) to the skull and mandible. Biopsies of the articular disk proper and bilamin ar zone (BZ) tissues from patients with anterior disk displacement (AD D) have shown previously that there is a marked loss of elastic fibers . In the present study, the effects of inducing ADD on the elastic fib ers in the rabbit CMJ disk proper, BZ and condylar cartilage were inve stigated. The right CMJ was exposed surgically and the discal attachme nts were severed except for the BZ attachments. Then, the disk was dis placed anteriorly and sutured to the zygomatic arch. The CMJs were rem oved after 1, 2 or 6 weeks and processed for histochemical demonstrati on of elastic fibers. The results showed osteoarthritic changes follow ing ADD, and a significant decrease in the number of the elastic fiber s in the disk proper and BZ. The remaining elastic fibers were abnorma l in their appearance and orientation. In addition, ADD led to the app earance of fine elastic fibers among the chondrocytes in the hyaline c artilage of the condyle that were not present in the cartilage of the control condyle. We conclude that induced ADD can lead to a significan t loss of elastic fibers in the articular disk, and result in the appe arance of elastic fibers within the cartilage of the mandibular condyl e.