Three-dimensional analysis of maxillary and mandibular growth increments.

Abstract

To analyze changes in the facial, maxillary, and mandibular skeleton in the vertical, sagittal, and transverse dimensions during an orthodontically relevant period of dentofacial development (i.e., between 7 and 15 years of age). This longitudinal study comprised posteroanterior (PA) and lateral cephalograms at 7, 9, 11, 13, and 15 years of 18 untreated Class I subjects with good occlusion. Transverse growth (width) was analyzed on the basis of PA cephalograms and sagittal (depth) and vertical (height) growth by means of lateral cephalograms. For each linear measurement, mean percentage increases were calculated relative to the size at 7 years of age. Between 7 and 15 years of age, in the whole facial skeleton and the maxilla, percentage increases were most pronounced in the vertical dimension when compared with the sagittal and transverse dimensions. In the mandible, the largest percentage increases were found in both sexes for vertical growth of the ramus, followed by sagittal growth (body length) and then mandibular width. In the sagittal dimension, development was more pronounced in the mandible (at pogonion more than at B point) than in the maxilla (A point). With respect to vertical growth, percentage increases in posterior face height exceeded the increases in anterior face height. When facial shape changes were analyzed between 7 and 15 years of age in both sexes, the ratio facial height/facial width increased and the ratio facial depth/ facial height decreased, which points toward an age-related increasing influence of vertical development.