Histopathology of temporomandibular joint osteoarthritis in rats under abnormal mechanical load

Abstract:

Objective To investigate the impact of abnormal mechanical load on cartilage degeneration of the temporomandibular joint （TMJ） in rats.Methods A total of 36 female Sprague-Dawley rats，aged 8 weeks，were randomly divided into control group（Con group），collagenase type Ⅱ group（CⅡ group），wide mouth opening group（MS group），and collagenase type Ⅱ+wide mouth opening group （CII+MS group）. HE staining and safranin O-fast green staining were used to observe the histopathological changes of cartilage， and immunohistochemistry was used to measure the expression levels of the inflammatory factors matrix metalloproteinase 3（MMP3） and A disintegrin and metalloproteinase with thrombospondin motifs 5（ADAMTS5）.Results Compared with the Con group，the CII，MS， and CII+MS groups had significant reductions in the total thickness，calcified layer thickness， and safranin O-positive area ratio of the TMJ posterior zone（P<0.05） and significant increases in the positive expression of MMP3 and ADAMTS5（P=0.000）. Compared with the CⅡ and MS groups，the CⅡ+MS group had a significant reduction in the calcified layer thickness of cartilage（P=0.000） and a significant increase in the expression of ADAMTS5（P=0.000）. The MS and CII+MS groups had a wavy tidal line in the posterior zone of cartilage.Conclusion Abnormal mechanical load promotes the degeneration and reconstruction of the posterior zone of condylar cartilage，which may help with the research on the mechanism of TMJ osteoarthritis caused by abnormal mechanical load.