An experimental study of the remodeling mechanism of the retrodiscal tissues by traction of the mandibular ramus and zygomatic arch in rabbits / 实用口腔医学杂志

ABSTRACT

Objective; To investigate the remodeling mechanism of the retrodiscal tissues of temporomandibular joint after mechanical loading. Methods; 15 adult New Zealand rabbits were subjected to traction between the mandibular ramus and zygomatic arch in the postero-superior direction unilaterally using elastic force. The animals were killed respectively at 2, 4 and 6 weeks. The histologic features were observed by Hematoxylin & Eosin and Alcian blue staining. The expressions of aggre can and collagen II antigen in the articular disc of temporomandibular joint were observed by immunohistochemical staining. Results: The articular disc of the traction side in temporomandibular joint was characterized by an early phase (2 weeks postoperatively) with partial anterior disc displacement and disc deformity and subsequently in deposition of fibrous material in the matrix of the retrodiscal tissues. With time going on, fibroblasts significantly decreased and connective tissues increased. A small quantity of cartilage-like cells were also investigated in that area. However, no obvious histological change was observed in the control group. Compared with the control group, glycosaminoglycan, ag-grecan and collagen II were weakly positive in the intermediate zone of articular disc in experimental group. Aggrecan was stronger positive in the intermediate zone of articular disc after two weeks in experimental group. When traction period prolonged, glycosaminoglycan, aggrecan and collagen II were strong positive in the retrodiscal tissue of articular disc in experimental group. Conclusion; These investigations reveal that distracting mandibule towards rear and top through ansa capitis, the synthesis of cartilage matrix increase and a small quantity of cartilage cells appear to adjust to its functions.