Secular Trends in Age at Onset of Orthodontic Treatment in Adolescents

Abstract

Introduction: It was previously found that age of sexual maturity during the last two decades has declined. The purpose of this study was to investigate whether chronologic age, dental age and skeletal developmental stage at onset of orthodontic treatment have changed during the last few decades in the same manner. In addition, to find out whether correlations exist between these ages. Such changes might have implications on clinical orthodontic practice. Methods: Panoramic and lateral cephalometric radiographs of 300 adolescents (139 males, 161 females) who began their orthodontic treatment during the years 1990-1992 or 2010-2012 (152 and 148 subjects, respectively) were examined. Chronologic, dental and skeletal ages were determined and compared between the two groups and correlations between these ages were calculated. Results: Mean chronologic age was 12.26 ± 1.22 years during 1990-1992 and 12.63 ± 1.64 during 2010-2012 (p=0.028). Mean dental age was 12.27 years ± 1.88 during 1990-1992 and 13.02 ± 2.20 during 2010-2012 (p=0.002). Mean skeletal developmental stage of subjects was 2.68 ± 1.60 during 1990-1992 and 2.99 ± 1.75 during 2010-2012 (p>0.1). Significant correlations were found between chronologic, dental and skeletal ages. Conclusions: Although no significant change of skeletal developmental stage upon commencing orthodontic treatment has occurred over the last two decades, both chronologic and dental ages have increased, particularly for females. There is significant correlation between chronologic, dental and skeletal ages for the entire group, particularly for females.