This study was performed to investigate the change of chewing pattern affected by internal derangement of temporomandibular joint(TMJ). Thirty-three patients who were involved with internal derangement of temporomandibular joint unilaterally took part in this study. The subjects were classified into three groups according to clinical examination and radiographic image. First group was composed of patients with disc displacement with reduction(DDR), second group was composed of patients with disc displacement without reduction(non-DDR), and third group was composed of patients with degenerative joint disease of TMJ(DJD).
BioEGN and BioEMG of the Biopak` (BioResearch Inc. USA) was used to record electromyographic activity in anterior temporalis and masseter muscle on clenching, and to observe chewing pattern as to velocity and three dimensional range of movements, respectively.
The data obtained were analyzed with SAS/stat program and the results of this study were as follows
1. Frontal lateral distance and horizontal ipsilateral distance in ipsilateral chewing were longer than those in contralateral chewing in DDR group, but there were no difference between the two chewing movement as to the variables in both non-DDR group and DJD group.
2. In comparison of muscle activity, activity of contralateral anterior temporalis was higher than that of ipsilateral anterior temporalis, however, there were also no difference between the two side muscles in both non-DDR group and DJD group. Activity of contralateral muscles were positively correlated with frontal lateral distance and horizontal ipsilateral distance in ipsilateral chewing to affected side.
3. Sagittal slant distance and frontal lateral distance in ipsilateral chewing in DDR group and in non-DDR group were longer than those in DJD group, and horizontal ipsilateral distance in ipsilateral chewing and frontal lateral distance in contralateral chewing in DDR group were longer than those in DJD group. Clinical mouth opening range was larger in DDR group than that in the other two groups, but was not significantly correlated with any other variables in chewing movement.
|