Abstract
The purpose of this study was to evaluate the longitudinal changes in arch width from childhood to adolescence. The subjects in this study were 28 persons (13 male and 15 female) with untreated normal occlusion. Dental casts were taken at bimonthly intervals from childhood to adolescence. These series of materials were measured and the changes in the dental arch were observed on the basis of the status of tooth emergence certain permanent teeth and also on the chronological age from 3 years to 20 years of age. The arch width measurements of the distance between the lowest curvature of the lingual gingival margins were obtained on each set of models at each stage, for the primary canine, first primary molar, second primary molar, and after the transition from deciduous teeth to the permanent teeth, for the canine, first premolars and second premolars. The width of the deciduous canines, the deciduous first molars and the deciduous second molars were nearly stable or increased slightly until 6 years of age.
The width of the maxillary deciduous second molars increased the most among these. After that, all of the widths of the deciduous teeth gradually increased, specially at emergence of the permanent incisors in deciduous canines width. For all of the width of the deciduous teeth, changes in the maxilla were greater than in the mandible. The width of the canines decreased until 13 years of age in the maxilla, and until 15 years of age in the mandibular. After that the widths of the canines were nearly stable. Until 1 year after the emergence, width of the canines decreased in particular during transition to the canines based on dental age observation.
The width of the maxillary first premolars decreased until 6 months after emergence based on dental age observation. After that the width of the maxillary first premolars showed no clear change. The width of the mandibular first premolars and the second premolars width increased until several years after emergence, but after that they showed no clear changes. The width of the maxillary first molars gradually increased until 15 years of age, but after that there was no clear change. The width of the mandiblar first molars was nearly stable throughout the observation period. The width of the maxillary second molars decreased until 2 years after emergence, after that no clear change were observed. The width of the mandiblar second molars was unstable until severalyears after emergence, and then became nearly stable.
