Trends in the Emergence of Permanent Dentition: A Retrospective Analysis of Adolescents From 1980 to 2020

Purpose: This study investigated whether the age of permanent tooth emergence in US adolescents has shifted over the past 40 years and whether these changes vary by gender or race. Methods: A retrospective review of clinical records from 751 patients aged 9 to 16 years was conducted across three cohorts: 1978 to 1982, 1998 to 2002, and 2018 to 2022. Intraoral photographs were analyzed to assess the presence of maxillary and mandibular canines, premolars, and second molars at half-year intervals. Logistic regression modeled the probability of tooth presence based on age, cohort, gender, and race. Results: Median age of tooth emergence was found to be earlier by 0.5 to 0.9 years for most teeth. Compared to 1980, the odds of tooth presence were significantly higher in 2000 (odds ratio [OR]=1.75) and 2020 (OR=3.01), indicating a consistent trend toward earlier emergence. Females demonstrated significantly earlier emergence than males (OR equals 0.63), and Black children exhibited higher odds of tooth presence compared to White and Hispanic peers. Conclusions: This study provides evidence of a trend toward earlier emergence of permanent dentition in a US adolescent population. Gender and racial differences suggest that emergence timing is influenced by both biological and environmental factors.