Changes in synovial fluid N-acetyl-beta-glucosaminidase activity in the human temporomandibular joint with dysfunction.

beta-Glycosidases (N-acetyl-beta-glucosaminidase, N-acetyl-beta-galactosaminidase, beta-glucuronidase) were assayed in temporomandibular joint (TMJ) synovial fluid obtained from 23 patients with closed lock TMJ internal derangement (ID), four with closed-lock TMJ osteoarthritis (OA), and 13 with normal controls (N). Synovial fluid was collected from the upper joint space after injecting 1.5 ml of 1% lidocaine three times. The specific activity of N-acetyl-beta-glucosaminidase increased significantly both with ID (p < 0.01) and with OA (p < 0.001), along with increases in the activity of N-acetyl-beta-galactosaminidase (p < 0.05 with ID and p < 0.01 with OA) and in beta-glucuronidase (p < 0.05 both with ID and OA). The N-acetyl-beta-glucosaminidase activity with OA was also significantly higher (p < 0.001) than with ID. These findings suggest that N-acetyl-beta-glucosaminidase activity in the TMJ synovial fluid reflects the degree of TMJ dysfunction.