Characteristic chewing parameters for specific types of temporomandibular joint internal derangements

In order to determine if there are characteristic chewing patterns for specific types of TMJ internal derangements, chewing was analyzed in 210 TMD patients with unilateral internal derangement (MDR early, 40; MDR late, 41; MD, 80; MDP, 49), and in 94 TMD patients without internal derangement, and 10 asymptomatic subjects with normal TMJ imaging. Each internal derangement subgroup demonstrated a significantly restricted envelope of motion and a reduced chewing velocity especially when they chewed on their normal TMJ side. Comparing different types of internal derangement, the MDR early group demonstrated relatively normal chewing, while the MDR late, MD and MDP groups showed severely impaired chewing movements. Among these three groups, the MD group demonstrated the most impairment, followed by the MDP and the MDR late groups. These results demonstrate that different types of internal derangement have specific impairments upon chewing, suggesting use of this analysis as a diagnostic tool.