LONGITUDINAL DENTAL ARCH CHANGES IN ADULTS

This study examined changes in the dental arches that occur in untreat ed persons between late adolescence and the fifth or sixth decade of l ife. Longitudinal dental casts from 82 subjects were obtained as part of a recall study of subjects from the University of Michigan Elementa ry and Secondary School Growth Study. From the parent sample, three gr oups were identified. The untreated sample comprised 53 subjects (27 m ales and 26 females). A midadult sample of 10 persons, who had an addi tional set of records taken on average during their fourth decade of l ife also was analyzed, as was a sample of 13 subjects who received ort hodontic treatment as adolescents and were about 30 years posttreatmen t. Measures of dental arch width, arch depth, and arch perimeter were evaluated with the aid of digital-imaging hardware and software. Incis or irregularity, curve of Spee, overjet, and overbite were measured di rectly from the dental casts. Statistically significant decrements occ urred in arch width, depth, and perimeter. The mean decrement in any o ne dimension was less than 3 mm, At all times, males displayed signifi cantly more mandibular incisor irregularity than females. In addition, the increase in mandibular incisor irregularity that occurred in male and female subjects was the same. However, irregularity did not incre ase in all subjects; it decreased in 3% of the males and 7% of the fem ales. In general, overbite, overjet, and curve of Spee were stable dur ing adulthood. Statistically significant correlations between the chan ges in dental arch measures could not be established.