Longitudinal changes in the dental arches and soft tissue profile of untreated subjects with normal occlusion

The aim of this study was to analyze dental and soft tissue profile development in children with normal occlusions to establish age- and gender-specific reference intervals for German children during their active growth period.

The study group consisted of a sample of 31 untreated Caucasian subjects with normal occlusions. Dental casts were analyzed at four different stages of dentitional development. Extraoral profile photographs were available for 19 subjects at stages T2-T4. In these subjects 11 angular measurements and 14 indices were analyzed. Statistical comparisons of gender-specific differences were performed by Mann-Whitney U tests (p ≤ 0.05).

Upper and lower posterior and total arch perimeters were recorded to be significantly larger in male subjects until the late mixed dentition. Subsequently, there was a tendency toward larger dimensions in males for those parameters. Upper and lower intercanine, interpremolar and intermolar widths were significantly larger in males throughout the entire observation period. There were no statistically significant gender differences with regard to most angular measurements in the dental arches, including molar rotation, palatal volume, overbite, overjet and molar relationship at later dental stages.

In untreated subjects with normal occlusion, dental arch and soft tissue parameters can be considered age-dependent. For some dental parameters, gender-specific differences were found that should be taken into consideration during diagnosis and treatment planning of growing children. The obtained longitudinal data of untreated children provide useful information for orthodontic diagnosis, treatment planning and future research projects.