ALTERATION IN FIBRONECTIN OF THE RABBIT CRANIOMANDIBULAR JOINT TISSUES FOLLOWING SURGICAL INDUCTION OF ANTERIOR DISK DISPLACEMENT - IMMUNOHISTOCHEMICAL STUDY

The purpose of this study was to determine the effect of surgical indu ction of anterior disk displacement (ADD) on fibronectin amount and di stribution in the rabbit craniomandibular joint (CMJ) tissues using an immunohistochemical technique. The right CMJ was exposed surgically, and all discal attachments were severed except for the posterior attac hment. The disk was then repositioned anteriorly and sutured to the zy gomatic arch. The left CMJ served as a sham-operated control. Ten addi tional joints were used as nonoperated controls. Deeply anesthetized r abbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits) following surgery. Disks, bilaminar zones, condy les and articular eminences were excised. Condyles and articular emine nces were decalcified in EDTA. All tissues were sectioned at 10 mu m i n a cryostat. Sections were incubated with monoclonal antibodies direc ted against fibronectin. Following incubation in the appropriate FITC- labeled secondary antibodies, tissue sections were studied under the f luorescence microscope. The results showed that at 2 weeks following i nduction of ADD, there was a reduction in fibronectin immunostaining i n the condyle, articular eminence and articular disk. Depletion of fib ronectin in these tissues was followed by restoration of its immunosta ining at 6 weeks. Also, there was a progressive increase in fibronecti n immunostaining in the bilaminar zone at 2 and 6 weeks. It was conclu ded that surgical induction of ADD in rabbit CMJ leads to alteration i n the amount and distribution of fibronectin.