Expression of matrix metalloproteinase-2 and-9 in synovial fluid of the temporomandibular joint accompanied by anterior disc displacement

The purpose of this study was to determine whether or not matrix metalloproteinases (MMPs) in synovial fluid are helpful in the biochemical diagnosis of temporomandibular joint (TMJ) disorder (TMD). We examined the synovial fluid from 38 TMD patients with disc displacement and 20 volunteers by gelatin zymography and immunoblotting analysis to clarify the involvement of the joint pathology from the viewpoint of expression of MMPs. Two gelatinolytic enzymes, MMP-2 and -9, were detected in the samples. The incidences of expression, except for pro-MMP-2, in anterior disc displacement (ADD) without reduction (ADD w/o R) were significantly higher than in ADD with reduction (ADD w R) (P<0.05). Quantitative analysis showed that the degree of MMP-2 and -9 expression in ADD w/o R were higher than in ADD w R. These data suggest that the presence or absence of disc reduction is a major turning point in the process of joint destruction, and these MMPs are useful as biochemical markers for TMD diagnosis.