A Contemporary Examination of First and Second Permanent Molar Emergence

Abstract

The emergence of first permanent molars (FPMs) and second permanent molars (SPMs) is an important developmental milestone influencing caries risk and the timing of sealant placement. Emergence times have been shown to vary by sex and race/ethnicity, while recent reports suggest a positive association with adiposity. Amid the changing demographics of the US population and the rising rates of pediatric overweight/obesity, we sought to examine the association of body mass index (BMI) with FPM/SPM emergence in a representative sample of US children and adolescents. We used cross-sectional data from 3 consecutive cycles of the National Health and Nutrition Examination Survey (2009 to 2014). The FPM analysis included ages 4 to 8 y (n = 3,102 representing ~20 million children), and the SPM analysis included ages 9 to 13 y (n = 2,774 representing ~19 million children/adolescents). The Centers for Disease Control and Prevention’s growth chart data were used to calculate age- and sex-specific BMI percentiles, as measures of adiposity. Initial data analyses relied on descriptive statistics and stratified analyses. We used multivariate methods, including survey linear and ordinal logistic regression and marginal effects estimation to quantify the association between pediatric overweight/obesity and FPM/SPM emergence, adjusting for age, sex, and race/ethnicity. Forty-eight percent of 6-y-olds and 98% of 8-y-olds had all FPMs emerged, whereas SPM emergence varied more. Blacks (vs. whites) and females (vs. males) experienced earlier emergence of FPMs and SPMs. Overweight/obesity was associated with earlier FPM emergence, particularly among black females. Obesity but not overweight was associated with earlier SPM emergence. Overall, overweight/obesity accounted for 6 to 12 mo of dental acceleration. This study’s results emanate from the most recent US-representative data and affirm that FPM/SPM emergence varies by race/ethnicity and sex and is positively influenced by BMI. Future research should further elucidate these associations with detailed eruption data and examine the implications of this variation for clinical care.