Analysis of the vertical facial form in patients with severe hypodontia

Abstract

We examined the lateral cephalograms of Russian patients in the following categories: control with acceptable occlusions (group 1); severe hypodontia with absence of six or more teeth (group 2); and severe hypodontia associated with hypohidrotic ectodermal dysplasia (HED) (group 3). Analysis was in a cross-sectional manner, comparing dimensions at the start of the mixed dentition phase (age 6-10) and in the permanent dentition (age 12-18). The groups were matched for age and sex. Thirty-one hard- and soft-tissue landmarks were traced, and 35 linear, 19 angular, and 7 ratioed measurements were taken and compared, using analysis of variance to compare the means of each group. A reduced anterior face height was found in groups 2 and 3 as a consequence of a reduced anterior lower face height. In group 2 in the mixed dentition, the posterior face height was also reduced. The inclination of the mandible (<Se S Go Gn) was significantly reduced to 28.22 degrees +/- 0.71 degrees in group 2 and to 24.07 degrees +/- 0.97 degrees in group 3. The facial profile appeared flat or concave (<se pn pg was increased up to 8.42 degrees +/- 1.56 degrees in children and 16.81 degrees +/- 2.18 degrees in adolescents). The subnasion point was behind the aesthetic line (EL), and in group 2 patients the naso-labial angle was obtuse when compared to nonaffected patients. In group 3 patients, the naso-labial angle became acute and lips were protuberant and everted as a consequence of the reduced vertical height. Groups 2 and 3 have the typical facial characteristics unique to hypodontia, with reduced vertical dimensions as a consequence of limited alveolar bone growth. However, group 3 patients have a unique abnormal craniofacial development.