Histological and immunohistochemical studies on the articular cartilage after experimental discectomy of the temporomandibular joint in rabbits.

Total discectomy was performed experimentally in the rabbit temporomandibular joint (TMJ). In order to evaluate the injury and repair of the articular cartilage of the mandibular condyle after discectomy, both histologic and immunohistochemical observations were made. Immunohistochemical observation by using bromodeoxyuridine (BrdU) and its monoclonal antibody in vivo labelling method was used. The present study demonstrated that the cartilage on the articular surface of the condyle disappeared at 1 week post-operatively. This defect in the injured articular cartilage was not repaired by the cartilage, but was covered by a fibrous connective tissue at 6 weeks post-operatively, where the condylar recontouring by the adjacent articular cartilage, and flattening and hyperplasia of the condyle were observed. Thus, the cartilaginous repair following discectomy was characterized by the proliferation of the adjacent cartilage to the injured site and osteoblastic formation in the bone marrow at the exposed subchondral bone.