Secular change in dental development in New Mexican females

Abstract

Recent research has indicated a dramatic acceleration of dental development in 20th century European Americans in Tennessee and Arizona, resulting in developmental stages being reached at earlier calendar ages. In order to determine whether this rate change is also observed in New Mexico, radiographs from two cohorts of European American female orthodontic patients with known ages were used to compare age by stage of development. The cohorts date to the 1970's (n=101) and the 1990's (n=93) and were between 5-11 years of age. Dental developmental stages were recorded for five mandibular teeth.
The average calendar age difference between cohorts per tooth and developmental stage combination was less than one month, but varies among tooth/stage combinations by up to 13 months. A Pearson's chi square test found no significant difference between the two cohorts for the 22 tooth/stage combinations. However, Cox Hazards Analysis demonstrated significant differences between the cohorts for five of the 22 tooth and stage combinations. Contrary to previous findings, the calendar age of the 1990's cohort is older for 16 of the 22 tooth/stage combinations than the 1970's cohort. This runs counter to the general trend of acceleration in development observed in multiple systems.