Objectives: The objectives were to find specific factors that are mathematically distinct between the chewing timings, movement pattern shapes, variability and movement velocities of normal asymptomatic subjects and a group of subjects with verified TMJ internal derangements.
The chewing movement recordings of 29 subjects (34.2 + 16.8 yrs) were randomly selected from a large database of patients exhibiting unilateral or bilateral temporomandibular joint internal derangements. The chewing movements of a control group of 29 asymptomatic subjects (32.9 +11.7 yrs, p > 0.78) with verified normal TM joint function were also recorded. Means and standard deviations of the opening, closing, turning point, terminal chewing position and velocity patterns were calculated. A two-tailed Student’s t test with unequal variances was used to compare several parameters of the two groups (alpha = 0.05).
With respect to the timing of opening and closing the control group functioned faster and with less variability (p < 0.0002). With respect to the movement pattern the vertical dimension was consistently larger in the control group chewing an identical bolus (p < 0.0001). The consistency of the terminal chewing position was also significantly less variable (Vertical - p < 0.0041, A/P p < 0.029, Lateral P < 0.028) in the control group. The maximum lateral width was significantly greater (p < 0.0075) and both the peak and average velocities were significantly greater (p < 0.0001 for both) in the control group.
This group of subjects with verified TMJ internal derangements exhibited significantly slower, smaller and more variable chewing patterns than the age-matched control group.
Keywords: Anatomy, Evaluation, Human, Joint dysfunction and Mastication