Abstract Objective: To describe the dental arch changes occurring after adolescence through the sixth decade of life. Materials and Methods: Longitudinal dental casts from 40 patients (20 male and 20 female) were digitized and analyzed. Measurements were recorded after the presumed cessation of circumpubertal growth (T1), at approximately 47 years of age (T2), and at least one decade later (T3) were compared. Results: The majority of the measurements were found to have a significant time effect, demonstrating at least some level of change throughout the aging process (T1–T3). Exceptions to this observation were the posterior maxillary arch width measurements, mandibular intermolar and interpremolar (as measured at the second premolars) widths, the maxillary incisor irregularity index, overjet, overbite, and curve of Spee. The T1–T3 changes reflected for the most part the T1– T2 changes, while the T2–T3 changes affected overall modifications only for the mandibular intercanine width and maxillary depth, as measured at the second premolars. All changes reflected a decrease in arch width, depth, and perimeter, with a significant increase in the mandibular incisor irregularity index. Conclusions: The dental arches continue to change and adapt throughout life and into the sixth decade, though the degree of change decreases with time.