The role of the disk in sheep temporomandibular joint ankylosis

Objective. The purpose of this study was to determine the role of the disk in intraarticular ankylosis of the temporomandibular joint. Study design. Twelve adult sheep were divided into 2 groups. In group 1 rem oval of the temporal and condylar articular surfaces was performed on the r ight temporomandibular joint and the disk was maintained; in group 2, remov al of the articular surfaces and diskectomy were performed on the right tem poromandibular joint. One sheep from each group was killed just after surge ry acid 5 sheep from each group were killed at 3 months. The joints were ex amined radiologically, macroscopically, and histologically. The range of ja w movements was recorded preoperatively and at sacrifice. Results. Each of 2 sheep in group 2 had lost 4% of their body weight by 3 m onths; all of the other sheep maintained or increased their weight. The ran ge of jaw motion to the right was significantly lower in group 2 than in gr oup 1 (P <.01). In group 1, fibrous repair of the articular surface and reg eneration of the condylar head was seen. In group 2, each of the joints sho wed a total fibrous ankylosis with some calcification. There was a statisti cally significant difference in radiologic score between the groups (P<.000 1). Histologic scores for group 1 demonstrated significantly lower scores o n the degree of ankylosis scale and degree of calcification scale (P <.0001 ). Conclusions. This study showed that the presence of the disk prevented the development of fibrous intraarticular ankylosis of the temporomandibular jo int.