A sheep model for temporomandibular joint ankylosis.
OBJECTIVE
The purpose of this study was to develop an animal model for temporomandibular joint (TMJ) ankylosis.


METHODS
Five sheep had removal of the temporal and condylar articular surface plus discectomy in the right TMJ; the left side was used as a control. One sheep was killed just after operation and four at 3 months. The joints were examined histologically, and a scoring system was developed to evaluate the extent of the ankylosis. The range of jaw movement was compared between preoperatively and 3 months.


RESULTS
Two sheep lost 4% of their body weight by 3 months. The range of jaw movement, particularly to the left, decreased at 3 months (P < .001). The joint spaces were filled with fibrous tissue and cartilage-like tissue. Development of new bone from the damaged temporal and condylar surfaces was seen, but full bony fusion did not occur. The average histologic score of a zone was 4.9 on the degree-of-ankylosis scale and 1.7 on the degree-of-calcification scale. There were statistically significant differences between the operated and control TMJs for both changes (P < .0001).


CONCLUSIONS
Fibrous ankylosis occurs rapidly after removal of the TMJ articular surfaces and the disc. This model can be further developed to isolate relative factors in the development of ankylosis and in evaluation of different treatment methods.
Miyamoto
H
H
Department of Dentistry, The University of Adelaid, South Australia, Australia. oral_surgery@dentistry.adelaide.edu.au
Kurita
K
K
Ishimaru
J
J
Goss
A N
AN
D000818:Animals; D000844:Ankylosis / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D016723:Bone Remodeling / Q000502:physiology; D001862:Bone Resorption / Q000473:pathology; D002113:Calcification, Physiologic / Q000502:physiology; D002358:Cartilage, Articular / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D005355:Fibrosis; D005500:Follow-Up Studies; D008335:Mandibular Condyle / Q000473:pathology / Q000601:surgery; D010012:Osteogenesis / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D012756:Sheep; D013701:Temporal Bone / Q000473:pathology / Q000601:surgery; D019224:Temporomandibular Joint Disc / Q000601:surgery; D013705:Temporomandibular Joint Disorders / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D015431:Weight Loss