The relationship between parafunctional masticatory activity and arthroscopically diagnosed temporomandibular joint pathology

Purpose: The purpose of this investigation was to assess the relationship between parafunctional masticatory activity and arthroscopically visualized changes in patients with severe, unremitting symptoms caused by intra-articular temporomandibular-joint pathology. The working hypothesis was that the presence of parafunctional activity leads to increased arthroscopically diagnosed pathology. Materials and Methods: Temporomandibular joint arthroscopy was performed on 124 joints in 83 patients (female:male, 5.4:1; mean age, 35 years; mean duration of symptoms, 43 months) with severe symptoms unresponsive to nonsurgical management. Preoperatively, the presence of parafunctional habits (bruxism, clenching) was assessed, and joints were classified as either with or without parafunctional influences. Joints were diagnosed arthroscopically and assessed for the presence or absence of osteoarthritis, synovitis, and adhesions. Analyses were performed to determine significant relationships between parafunctional activity and the presence of osteoarthritis, synovitis, and adhesions. Results: Parafunctional influences were present in 82 of 124 joints: (66%). Clinically diagnosed osteoarthritis was present in 59 of 124 joints (48%) and arthroscopically diagnosed osteoarthritis was seen in 82 of 124 joints (66%). Arthroscopically, synovitis was diagnosed in 123 of 124 joints (99%) and adhesions in 93 of 124 joints (75%). Stastical analyses showed a significant relationship between parafunction and clinically diagnosed osteoarthritis, and suggested a close relationship between parafunction and arthroscopically diagnosed osteoarthritis. A significant association between clinically and arthroscopically diagnosed osteoarthritis and adhesions was also demonstrated. There also was no significant relationship detected between parafunction and the presence of synovitis or adhesions seen arthroscopically. Conclusions: It was concluded that parafunctional masticatory activity and its influence on joint loading contribute to osteoarthritis of the temporomandibular joint. Such osteoarthritis is associated with adhesions of the joint. Arthroscopically diagnosed synovitis is not specifically associated with parafunction, and it appears that numerous other causative factors may contribute to its development in the TMJ. Because abnormal joint loading is a major causative factor in cartilage degradation, biochemical and biomechanical abnormalities, and intraarticular temporomandibular pathology clinicians must identify and address parafunctional masticatory activity during nonsurgical, surgical and postsurgical treatment regimens.