Effects of antigen-induced arthritis and compressive mechanical stress on condylar head of mandible.

OBJECTIVE: Compressive mechanical stress was applied to the temporomandibular joints (TMJ) affected by antigen-induced arthritis to assess the etiological factors of idiopathic condylar resorption.

METHODS: Following ovariectomy in 27 female rabbits, 12 received ovalbumin (OVA), 12 received phosphate-buffered saline, and three formed the control group. Each treated rabbit underwent an osteotomy, and a custom device was employed for one week postoperatively, with the length increased by 0.25 mm every 12 h to provide compressive mechanical stress to the TMJ. Thereafter, samples were obtained from the treated groups, subjected to histological staining and immunohistochemistry, and examined using micro-computed tomography.

RESULTS: At each examination, the OVA group showed a greater area and depth of bone resorption, with bone resorption continuing for three weeks following distraction. Additionally, subcondylar bone resorption was noted significantly earlier and had a greater prevalence in the OVA group and greater numbers of tartrate-resistant acid phosphatase-positive cells. Immunostaining for metalloproteinase (MMP)-3 and MMP-13 of the anterior condylar head in the OVA group after two and three weeks revealed high levels of both proteins from the surface to the deep cartilage layer.

CONCLUSION: Therefore, coexisting TMJ pathology factors, such as antigen-induced arthritis, promote a significantly greater amount of condylar head anterior surface bone resorption.