Condylar movements during mastication.

To investigate the relationship between mastication and TMJ abnormalities, the incisal point and condylar movements during mastication were analysed in two normal subjects and six patients with stomatognathic dysfunction. The patients with stomatognathic dysfunction were two patients with unilateral anterior disk displacement with reduction, two with unilateral anterior disk displacement without reduction, and two with unilateral osteoarthritis. The incisal point movement was recorded using Sirognathograph Analysing System, and condylar movement was recorded with a pantograph. The movement path of the non-working condyle was shorter than that of the working condyle when patients with unilateral TMJ abnormalities used their non-abnormal side to chew, which resulted in deviation of the turning point (the point where the mouth changes from opening to closing) to the non-chewing side. Also, the convexity of the opening path was influenced by the condylar mobility of the abnormal side TMJ. Posterior dislocation of the condyle of the abnormal side TMJ resulted in a crossover chewing pattern of incisal point movement in the frontal or horizontal planes.