Normal masticatory function of girls and young women: mandibular masticatory movements

Mandibular masticatory movements were evaluated in 10 young adult women and 12 young girls. All subjects had normal occlusion with minimal overjet. Masticatory movements of the incisors were recorded in three dimensions with an Optotrak® camera system while subjects chewed gum in a habitual manner for 20 seconds. A masticatory analysis program divided each masticatory cycle into four phases and averaged the duration, excursions, and velocities of all cycles for each subject. Duration of the total cycle was longer in women because they had longer slow opening and slow closing phases than girls. Women had a significantly larger vertical component of opening during slow opening and the power stroke than girls. Women also had a significantly larger posterior component of opening during slow opening and the power stroke than did girls. At maximum opening, women also tended to have the incisors in a more posterior position. There were no differences between the groups for the amount of maximum lateral excursion during chewing. Vertical velocity during fast opening and fast closing was slower for women, but there were no age-related differences during the slow open and slow close phases. Am. J. Human Biol. 10:53-62, 1998. © 1998 Wiley-Liss, Inc.