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

Purpose: This study investigated whether surgically induced disc displacement (DD) in the rabbit temporomandibular joint leads to joint dysfunction. Materials and Methods: Fourteen adult Japanese white rabbits were divided into two groups. Eight animals had surgically induced DD, and 6 were used as a sham operation group, Jaw movement trajectories during chewing were recorded preoperatively and 2 weeks after induction of DD. Postoperative recordings after administration of a nonsteroidal anti-inflammatory drug (NSAID) were also performed to eliminate any influence of joint pain on chewing. Vertical and horizontal ranges of chewing movement, duration of the opening and 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 the same as preoperatively. In the experimental group, increase in the cycle duration and decrease in the vertical and horizontal ranges of movement were 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 group. AU of the experimental animals had total anterior DD histologically. Conclusion: Changes in the chewing pattern of the experimental animals occurred from mechanical interference of the displaced disc. This animal model can be used as a model for human internal derangement.