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 induction of anterior disk displacement (ADD) on fibronectin amount and distribution 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 attachment. The disk was then repositioned anteriorly and sutured to the zygomatic arch. The left CMJ served as a sham-operated control. Ten additional joints were used as nonoperated controls. Deeply anesthetized rabbits were perfused with 2% buffered formalin 2 weeks (10 rabbits) or 6 weeks (10 rabbits) following surgery. Disks, bilaminar zones, condyles and articular eminences were excised. Condyles and articular eminences were decalcified in EDTA. All tissues were sectioned at 10 μm in a cryostat. Sections were incubated with monoclonal antibodies directed against fibronectin. Following incubation in the appropriate FITC-labeled secondary antibodies, tissue sections were studied under the fluorescence microscope. The results showed that at 2 weeks following induction of ADD, there was a reduction in fibronectin immunostaining in the condyle, articular eminence and articular disk. Depletion of fibronectin in these tissues was followed by restoration of its immunostaining at 6 weeks. Also, there was a progressive increase in fibronectin immunostaining in the bilaminar zone at 2 and 6 weeks. It was concluded that surgical induction of ADD in rabbit CMJ leads to alteration in the amount and distribution of fibronectin.