STUDY DESIGN: In this retrospective cohort study, we included children aged 5-20 years who received regular outpatient care at a large academic medical center between January 1996 and April 2016. BMI was expressed as age- and sex-specific percentiles and BP as age-, sex-, and height-specific percentiles. Linear mixed models incorporating linear spline functions with 2 breakpoints at 9 and 12 years of age were used to estimate the changes in BMI and BP percentiles over time during age periods: <9, 9-<12, and >12 years of age.
RESULTS: Among 5703 children (24.8% black, 10.1% Hispanic), Hispanic females had an increased rate of change in BMI percentile per year relative to white females during ages 5-9 years (+2.94%; 95% CI, 0.24-5.64; P = .033). Black and Hispanic males also had an increased rate of change in BMI percentile per year relative to white males that occurred from ages 5-9 (+2.35% [95% CI, 0.76-3.94; P = .004]; +2.63% [95% CI, 0.31-4.95; P = .026], respectively). There were no significant racial differences in the rate of change of BP percentiles, although black females had higher hypertension rates compared with white females (10.0% vs 5.7%; P
AIM: To calculate age of transition of the mandibular third (M3) molar tooth stages from archived dental radiographs from sub-Saharan Africa, Malaysia, Japan and two groups from London UK (Whites and Bangladeshi).
MATERIALS AND METHODS: The number of radiographs was 4555 (2028 males, 2527 females) with an age range 10-25 years. The left M3 was staged into Moorrees stages. A probit model was fitted to calculate mean ages for transitions between stages for males and females and each ethnic group separately. The estimated age distributions given each M3 stage was calculated. To assess differences in timing of M3 between ethnic groups, three models were proposed: a separate model for each ethnic group, a joint model and a third model combining some aspects across groups. The best model fit was tested using Bayesian and Akaikes information criteria (BIC and AIC) and log likelihood ratio test.
RESULTS: Differences in mean ages of M3 root stages were found between ethnic groups, however all groups showed large standard deviation values. The AIC and log likelihood ratio test indicated that a separate model for each ethnic group was best. Small differences were also noted between timing of M3 between males and females, with the exception of the Malaysian group. These findings suggests that features of a reference data set (wide age range and uniform age distribution) and a Bayesian statistical approach are more important than population specific convenience samples to estimate age of an individual using M3.
CONCLUSION: Some group differences were evident in M3 timing, however, this has some impact on the confidence interval of estimated age in females and little impact in males because of the large variation in age.