Changes in chewing pattern after surgically induced disc displacement in the rabbit temporomandibular joint

Purpose: This study investigated whether surgically induced disc displaceme nt (DD) in the rabbit temporomandibular joint leads to joint dysfunction. Materials and Methods: Fourteen adult Japanese white rabbits were divided i nto two groups. Eight animals had surgically induced DD, and 6 were used as a sham operation group, Jaw movement trajectories during chewing were reco rded preoperatively and 2 weeks after induction of DD. Postoperative record ings after administration of a nonsteroidal anti-inflammatory drug (NSAID) were also performed to eliminate any influence of joint pain on chewing. Ve rtical and horizontal ranges of chewing movement, duration of the opening a nd closing phase, and total cycle of chewing were analyzed. Thereafter, the presence of induced DD was confirmed histologically. Results: In the sham group, the rhythm and pattern of chewing were almost t he same as preoperatively. In the experimental group, increase in the cycle duration and decrease in the vertical and horizontal ranges of movement we re observed. When the sham and experimental groups were compared, there was a decreased ratio of vertical movement in the experimental animals. There was no effect of preadministration of the NSAID in either the DD or sham gr oup. AU of the experimental animals had total anterior DD histologically. Conclusion: Changes in the chewing pattern of the experimental animals occu rred from mechanical interference of the displaced disc. This animal model can be used as a model for human internal derangement.