Chewing pattern analysis in TMD patients with unilateral and bilateral internal derangement.

In order to evaluate chewing in temporomandibular disorder (TMD) patients with unilateral and bilateral internal derangement of the temporomandibular joint (TMJ), the envelope of motion and velocity of chewing were analyzed in 103 TMD patients with unilateral internal derangement, 42 patients with bilateral internal derangement and 10 normal subjects. It was found that patients with bilateral internal derangement demonstrated a significantly restricted range of motion and reduced velocity than patients with unilateral internal derangement or normal subjects. The analysis of chewing patterns in the frontal and sagittal planes revealed that patients with bilateral internal derangement had no specific pattern while patients with unilateral internal derangement demonstrated a specific pattern. The analysis of chewing velocity pattern suggested that opening and closing patterns without any obvious peak velocity was significantly more frequent in patients with bilateral internal derangement than patients with unilateral internal derangement or normal subjects.