Masticatory performance and areas of occlusal contact and near contact in subjects with normal occlusion and malocclusion.

This preliminary study evaluated relationships between masticatory performance and areas of interocclusal distance contact (<50 microm) and near contact (50-350 microm) of the buccal segments during maximum intercuspation. The sample included subjects with normal occlusion (n = 18) and Class I (n = 14), Class II (n = 13), and Class III (n = 6) malocclusions. Chewing performance was evaluated on the basis of the breakdown of CutterSil (Heraeus Kulze, South Bend, Ind); chewing ability was assessed by the number of chews necessary to swallow jerky and almonds. Impressions of the buccal segments, taken with Blu Mousse (Parkell Bio-Materials, Farmingdale, NY) impression material, were scanned and enlarged, and each subject's first molars and premolars were manually traced bilaterally to estimate the platform area. The areas of contact and near contact (ACNC) that measured between 0 and 350 microm thick were estimated optically on the basis of the amount of light transmitted through the impression. The results showed no significant differences in platform area between the right and left sides or between the malocclusion groups. ACNC were negatively related to median particle size and broadness of particle distribution. There were no correlations between ACNC and the number of chews necessary to swallow jerky or almonds. Subjects with normal occlusion had significantly larger ACNC than those with Class I, Class II, and Class III malocclusions, in descending order. Subjects with Class III malocclusions had the smallest areas of near contact (<350 microm). We concluded that ACNC are similar on the right and left sides; that subjects with larger ACNC are better able to break down foods; and that subjects with malocclusions have smaller ACNC than those with normal occlusions.