Effect of Chewing Upon Disc Reduction in the Temporomandibular Joint

Aims: To test whether an intensive chewing exercise influences the moment of disc reduction in subjects with or without reports of intermittent locking of the jaw. Methods: This experimental study included 15 subjects with a reducing anteriorly displaced disc (ADD) and with symptoms of intermittent locking and 15 subjects with a reducing ADD without such symptoms. The moment of disc reduction (MDR), quantified using mandibular movement recordings, was recorded at baseline, and after maximally 60 minutes of chewing. Thereafter, MDR was recorded again after 20 minutes of rest, and if necessary after 72 hours, in order to document return of MDR to baseline values. Results: In subjects without intermittent locking, the MDR after chewing was not different from baseline (P = .25). However, in the subjects with intermittent locking, the MDR value had increased significantly after chewing (P = .008); two subjects showed a later moment of disc reduction, and four showed a temporary loss of disc reduction. Conclusion: While intensive chewing did not influence disc reduction in subjects without intermittent locking, it caused a delay or even hampered disc reduction in approximately half of the subjects reporting intermittent locking. Keywords: anterior disc displacement, human, internal derangement, mandibular movement recordings, parafunctional activities