Influence of two masticating conditions on assessment of movement path stability

The purpose of this study was to clarify whether differences in masticating conditions affected masticatory path stabilities of healthy subjects and TMD patients.

Twenty healthy female subjects as the healthy group, and 20 female Temporomandibular Disorders (TMD) patients as the TMD group, were selected. Incisal point movement of during mastication of both masticating condition 1 (mc1; crispy bread chewed until swallowing on the free side) and masticating condition 2 (mc2; softened chewing-gum chewed for 20s on the habitual side) were recorded by MKG. As for mc1, out of all cycles during mastication only those cycles on the habitual chewing side were analyzed. As for mc2, the ten cycles from the fifth cycle were analyzed. For these analyzed sections, the indicators representing movement path stability were calculated and compared between the two groups.

As for mc1, though the values of the indicators representing path stability were larger for the TMD group, there were cases where no significant differences were found between the two groups. As for mc2, the values were significantly larger for the TMD group (SDs; P<0.05, SD/ODs; P<0.01).

From these results, it was suggested that the differences in masticating conditions affected the assessment of masticatory path stabilities of healthy subjects and TMD patients and the conditions should be considered for analyzing masticatory movement.