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The use of fluoride is effective in preventing dental caries. However, an excessive intake of fluoride leads to dental fluorosis, making it necessary to regularly monitor the fluoride intake especially for infants. There is hitherto a lack of information on fluoride content in infant foods from an Australian perspective. Therefore, this study aims to estimate the amount of fluoride content from a range of commercially available ready-to-eat (RTE) infant foods and drinks available in Australia. Based on an external calibration method, potentiometry involving a fluoride ion selective electrode and a silver|silver chloride reference electrode was conducted to analyse the fluoride content of a total of 326 solid food samples and 49 liquid food samples in this work. Our results showed an overall median (range) fluoride content of 0.16 (0.001–2.8) µg F/g of solid food samples, and 0.020 (0.002–1.2) µg F/mL of liquid food samples. In addition, ~77.5% of the liquid samples revealed a fluoride content < 0.05% µg F/mL. The highest variation of fluoride concentration (0.014–0.92 µg F/g) was found in formulas for ≥6 month-old infants. We have attributed the wide fluoride content variations in ready-to-eat infant foods and drinks to the processing steps, different ingredients and their origins, including water. In general, we found the fluoride content in most of the collected samples from Australian markets to be high and may therefore carry a risk of dental fluorosis. These results highlight the need for parents to receive appropriate information on the fluoride content of ready-to-eat infant food and drinks.

BACKGROUND Associations among body composition measures have been limited to cross-sectional analyses of different subjects. We identified cross-sectional relationships between body mass index (BMI) and other body composition measures and predicted body composition measures from BMI throughout childhood and adolescence. METHODS BMI was calculated and % body fat (%BF), fat mass index (FMI), and fat-free mass index (FFMI) were measured using dual-energy x-ray absorptiometry at ages 5, 9, 11, 13, 15, and 17 years in a birth cohort (n = 629). Sex-specific body composition measures were calculated for BMI-for-age percentiles; associations between BMI and body composition measures were characterized; and body composition measures were predicted from BMI. RESULTS %BF, FMI, and FFMI generally increased with BMI-for-age percentiles at each age. Correlations between BMI and %BF or FMI were generally higher at BMI-for-age percentiles ≥95% than for lower BMI-for-age percentiles. Correlations between BMI and FFMI were generally higher for participants at very low and very high BMI-for-age percentiles than at moderate BMI-for-age percentiles. Age- and sex-specific predictions from BMI are provided for %BF, FM, and FFMI. CONCLUSIONS Sex-specific body composition measures throughout childhood and adolescence are presented. BMI is a better indicator of adiposity at higher than at lower BMI values. IMPACT Sex-specific body composition measures throughout childhood and adolescence are described. % BF, FMI, and FFMI generally increased with BMI-for-age percentiles for both sexes throughout childhood and adolescence. BMI is a better indicator of adiposity at higher BMI levels than at lower BMI values throughout childhood and adolescence.

Biological and medical researchers often collect count data in clusters at multiple time points. The data can exhibit excessive zeros and a wide range of dispersion levels. In particular, our research was motivated by a dental dataset with such complex data features: the Iowa Fluoride Study (IFS). The study was designed to investigate the effects of various dietary and nondietary factors on the caries development of a cohort of Iowa school children at the ages of 5, 9, and 13. To analyze the multiyear IFS data, we propose a novel longitudinal method of a generalized estimating equations based marginal regression model. We use a zero-inflated model with a Conway-Maxwell-Poisson (CMP) distribution, which has the flexibility to account for all levels of dispersion. The parameters of interest are estimated through a modified expectation-solution algorithm to account for the clustered and temporal correlation structure. We fit the proposed zero-inflated CMP model and perform a comprehensive secondary analysis of the IFS dataset. It resulted in a number of notable conclusions that also make clinical sense. Additionally, we demonstrated the superiority of this modeling approach over two other popular competing models: the zero-inflated Poisson and negative binomial models. In the simulation studies, we further evaluate the performance of our point estimators, the variance estimators, and that of the large sample confidence intervals for the parameters of interest. It is also demonstrated that our longitudinal CMP model can correctly identify the time-varying dispersion patterns.

The foundation for osteoporosis risk is, in part, established during childhood, adolescence, and young adulthood, all periods of development when bone mass is acquired rapidly. The relative quantity of bone mass accrued is influenced by both lifestyle and genetic factors, although the genetic component is not yet well understood. The purpose of this study was to use a genome-wide association (GWA) analysis to discover single nucleotide polymorphisms (SNPs) associated with: (1) the sex-specific hip bone mineral content (BMC) at approximately the age of 19 when the amount of bone accrued is near its peak; and (2) the sex-specific rate of hip BMC accrual during the adolescent growth spurt. The Iowa Bone Development Study, a longitudinal cohort study exploring bone health in children, adolescents, and young adults was the source of data. From this cohort, n = 364 (190 females, 174 males) participants were included in GWA analyses to address (1) and n = 258 participants (125 females and 133 males) were included in GWA analyses to address (2). Twenty SNPS were detected having p < 1.0×10(−5). Of most biologic relevance were two suggestive SNPs (rs2051756 and rs2866908) detected in an intron of the DKK2 gene through the GWA analysis that explored peak bone mass in females.

Dental caries (i.e., cavities) is one of the most common chronic childhood diseases and may continue to progress throughout a person's lifetime. The Iowa Fluoride Study (IFS) was designed to investigate the effects of various fluoride, dietary and nondietary factors on the progression of dental caries among a cohort of Iowa school children. We develop a mixed effects model to perform a comprehensive analysis of the longitudinal clustered data of IFS at ages 5, 9, 13, and 17. We combine a Bayesian hurdle framework with the Conway-Maxwell-Poisson regression model, which can account for both excessive zeros and various levels of dispersion. A hierarchical shrinkage prior distribution is used to share the temporal information for predictors in the fixed-effects model. The dependence among teeth of each individual child is modeled through a sparse covariance structure of the random effects across time. Moreover, we obtain the parameter estimates and credible intervals from a Gibbs sampler. Simulation studies are conducted to assess the accuracy and effectiveness of our statistical methodology. The results of this article provide novel tools to statistical practitioners and offer fresh insights to dental researchers on effects of various risk and protective factors on caries progression.

Osteoporosis causes bone fragility and elevates fracture risk. Applications of finite element (FE) analysis (FEA) for assessment of trabecular bone (Tb) microstructural strength at whole-body computed tomography (CT) imaging are limited due to challenges with Tb microstructural segmentation. We present a nonlinear FEA method for distal tibia CT scans evading binary segmentation of Tb microstructure, while accounting for bone microstructural distribution. First, the tibial axis in a CT scan was aligned with the FE loading axis. FE cubic mesh elements were modeled using image voxels, and CT intensity values were calibrated to ash density defining mechanical properties at individual elements. For FEA of an upright volume of interest (VOI), the bottom surface was fixed, and a constant displacement was applied at each vertex on the top surface simulating different loading conditions. The method was implemented and optimized using the ANSYS software. CT-derived computational modulus values were repeat scan reproducible (intraclass correlation coefficient [ICC] ≥ 0.97) and highly correlated (

Some non-cavitated caries lesions (DThe Iowa Fluoride Study (IFS) participants were followed longitudinally; all permanent tooth surfaces were examined clinically for caries at ages 9, 13, 17, and 23 using standardized criteria for sound (S), questionable (DThe sample had relatively high socioeconomic status (SES), with about 52%-55% high SES, 32-35% middle SES, and 12-13% low SES. Person-level prevalences of DNon-cavitated lesions were more prevalent at age 17 than at ages 9, 13, and 23. The high rates of regression compared to progression or no change suggest that many non-cavitated lesions do not progress to cavitated lesions and could be reversed; therefore, surgical intervention should not be the treatment of choice for incipient lesions.

Fragility of trabecular bone (Tb) microstructure is increased in osteoporosis, which is associated with rapid bone loss and enhanced fracture-risk. Accurate assessment of Tb strength using in vivo imaging available in clinical settings will be significant for management of osteoporosis and understanding its pathogenesis. Emerging CT technology, featured with high image resolution, fast scan-speed, and wide clinical access, is a promising alternative for in vivo Tb imaging. However, variation in image resolution among different CT scanners pose a major hurdle in CT-based bone studies. This paper presents nonlinear continuum finite element (FE) methods for computation of Tb strength from in vivo CT imaging and evaluates their generalizability between two scanners with different image resolution. Continuum FE-based measures of Tb strength under different loading conditions were found to be highly reproducible (ICC ≥ 0.93) using ankle images of twenty healthy volunteers acquired on low- and high-resolution CT scanners 44.6 ± 2.7 days apart. FE stress propagation was mostly confined to Tb micro-network (2.3 ± 1.7 MPa) with nominal leakages over the marrow space (0.4 ± 0.5 MPa) complying with the fundamental principle of mechanics at in vivo imaging. In summary, nonlinear continuum FE-based Tb strength measures are reproducible among different CT scanners and suitable for multi-site longitudinal human studies.

Although genetics affects early childhood caries (ECC) risk, few studies have focused on finding its specific genetic determinants. Here, we performed genome-wide association studies (GWAS) in five cohorts of children (aged up to 5 years, total N = 2974, cohorts: Center for Oral Health Research in Appalachia cohorts one and two [COHRA1, COHRA2], Iowa Fluoride Study, Iowa Head Start, Avon Longitudinal Study of Parents and Children [ALSPAC]) aiming to identify genes with potential roles in ECC biology. We meta-analyzed the GWASs testing ~3.9 million genetic variants and found suggestive evidence for association at genetic regions previously associated with caries in primary and permanent dentition, including the β-defensin anti-microbial proteins. We then integrated the meta-analysis results with gene expression data in a transcriptome-wide association study (TWAS). This approach identified four genes whose genetically predicted expression was associated with ECC (p-values < 3.09 × 10−6; CDH17, TAS2R43, SMIM10L1, TAS2R14). Some of the strongest associations were with genes encoding members of the bitter taste receptor family (TAS2R); other members of this family have previously been associated with caries. Of note, we identified the receptor encoded by TAS2R14, which stimulates innate immunity and anti-microbial defense in response to molecules released by the cariogenic bacteria, Streptococcus mutans and Staphylococcus aureus. These findings provide insight into ECC genetic architecture, underscore the importance of host-microbial interaction in caries risk, and identify novel risk genes.

Background:. The purpose of this study was to evaluate the influence of the volume and type of sport on the development of cam-type femoroacetabular impingement and acetabular dysplasia. Methods:. The Physical Activity Questionnaire for Adolescents (PAQ-A) was administered to Iowa Bone Development Study participants at the age of 17 years to identify those who had participated in at least 2 seasons of high school interscholastic sports. Based on relative peak strain and ground reaction forces, subjects were grouped as power sport athletes (basketball, cheerleading, football, gymnastics, soccer, and volleyball), non-power sport athletes (wrestling, baseball, cross-country or track and field, softball, or tennis), or non-athletes. Using anteroposterior views of the left hip formatted from dual x-ray absorptiometry (DXA) scans, the alpha angle, head-neck offset ratio (HNOR), and lateral center-edge angle (LCEA) were evaluated longitudinally at the ages of 17, 19, and 23 years. Logistic regression was used to evaluate the odds of hip cam morphology (alpha angle >55° and/or HNOR 0.05). There were no significant differences in the odds of cam morphology or acetabular dysplasia in non-power sport athletes compared with non-athletes (all p > 0.05). Higher physical activity levels were significantly associated with an increase in the alpha angle (beta and standard error, 0.77° ± 0.30°; p = 0.011) and a decrease in the HNOR (−0.003 ± 0.001; p = 0.003), but not the LCEA (−0.05 ± 0.15; p = 0.744). Conclusions:. A higher volume of physical activity and participation in sports with higher peak strain and ground reaction forces during the process of skeletal maturation may increase the risk of developing cam morphology during late adolescence. Level of Evidence:. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

OBJECTIVES: This study assessed the relationship between the number of teeth present at 12 months and dmfs at 30 and 48 months. METHODS: Data are from a longitudinal, multi-site study with clinical dental examinations conducted at 12, 30 and 48 months of age. Spearman correlation, and chi-square tests assessed relationships between teeth present at 12 months and decayed, missing or filled surfaces (dmfs) at 30 (n=1,062) and 48 months (n=985). RESULTS: Spearman correlations were weak but significant for both 30- and 48-month time points (R= 0.066; p=0.032, R= 0.093; p=0.004, respectively). Mantel-Haenszel chi-square analyses of categories of teeth present at 12 months (0, 1–4, 5–8, and 9+) and categories of dmfs at 30 and 48 months (0, 1–2, 3–5, 6–15 and 16+), revealed non-significant (p=0.326) relationship with 30-month dmfs, but a significant (p=0.013) relationship with 48-month dmfs. CONCLUSION: Results suggest that early tooth eruption is weakly associated with occurrence of early childhood caries.

Introduction Nearly 8 million American adolescents participate in sports. Participation declines in young adulthood. Purpose This study assessed longitudinal effects of high school sport participation and muscle power on young adult bone strength. Methods Two hundred twenty-eight young adults from the Iowa Bone Development Study completed an interscholastic sport participation questionnaire. Current physical activity (PA) behaviors were assessed via questionnaire. Dual x-ray absorptiometry assessed hip areal bone mineral density and was used with hip structure analysis to estimate femoral neck section modulus and hip cross-sectional area. Peripheral quantitative computed tomography provided strength-strain index and bone strength index at 38% and 4% midshaft tibial sites, respectively. Vertical jump estimated muscle power at 17 yr. Sex-specific multiple linear regression predicted young adult bone outcomes based on sport participation groups. Mediation analysis analyzed the effects of muscle power on relationships between sport participation and bone strength. Results At follow-up, males participating in any interscholastic sport had greater bone strength than males who did not participate in sport. The explained variability in bone outcomes was 2% to 16%. Females who participated in sports requiring muscle power had greater bone strength than females who did not participate in sports or females who participated in nonpower sports (explained variability was 4%-10%). Muscle power mediated 24.7% to 41% of the effect of sport participation on bone outcomes in males and 19.4% to 30% in females. Conclusions Former male interscholastic sport participants and female interscholastic power sport participants have stronger bones than peers even when adjusting for current PA. Muscle power did not fully explain differences in all bone outcomes, suggesting that sport participation has additional bone health benefits.

Purpose This study analyzed prospective associations between distinct trajectories of objectively measured physical activity (PA) and late adolescent bone parameters and explored the mediating effects of lean soft tissue, a surrogate of muscle mass to associations. Methods Physical activity was measured by accelerometry starting at age 5 yr and continuing at 8, 11, 13, 15, and 17 yr in approximately 524 participants from the Iowa Bone Development Study. Sex-specific group-based trajectory modeling was used to construct developmental trajectories of moderate- and vigorous-intensity PA (MVPA) from childhood to late adolescence. At age 17 yr, proximal femur bone mineral density (aBMD) was assessed by dual X-ray energy absorptiometry, and its distribution was calculated by aBMD ratios. Specific geometric measures of the proximal femur were assessed using hip structural analysis. Results A significant portion of the total effect of MVPA from age 5 to 17 yr on bone parameters at age 17 yr was explained by an increase in leg lean soft tissue in both sexes. For males and females, indirect effects were observed on the total and all regional proximal femur aBMD, and on the ratio between the inferomedial and superolateral neck aBMD. The effect on the ratio between the trochanter and the total proximal femur was specific to females, whereas the effect on the hip axis length was specific to males. Direct effects of MVPA on aBMD were identified only in males. Conclusions Using robust mediation analysis, this is the first study addressing the indirect effect (through muscle) of PA across childhood and adolescence on proximal femur bone parameters. To improve bone health at the proximal femur, the results suggest PA interventions during growth that increase muscle mass, particularly in females.

Associations among body composition measures have been limited to cross-sectional analyses of different subjects. We identified cross-sectional relationships between body mass index (BMI) and other body composition measures and predicted body composition measures from BMI throughout childhood and adolescence.BMI was calculated and % body fat (%BF), fat mass index (FMI), and fat-free mass index (FFMI) were measured using dual-energy x-ray absorptiometry at ages 5, 9, 11, 13, 15, and 17 years in a birth cohort (n = 629). Sex-specific body composition measures were calculated for BMI-for-age percentiles; associations between BMI and body composition measures were characterized; and body composition measures were predicted from BMI.%BF, FMI, and FFMI generally increased with BMI-for-age percentiles at each age. Correlations between BMI and %BF or FMI were generally higher at BMI-for-age percentiles ≥95% than for lower BMI-for-age percentiles. Correlations between BMI and FFMI were generally higher for participants at very low and very high BMI-for-age percentiles than at moderate BMI-for-age percentiles. Age- and sex-specific predictions from BMI are provided for %BF, FM, and FFMI.Sex-specific body composition measures throughout childhood and adolescence are presented. BMI is a better indicator of adiposity at higher than at lower BMI values.Sex-specific body composition measures throughout childhood and adolescence are described. % BF, FMI, and FFMI generally increased with BMI-for-age percentiles for both sexes throughout childhood and adolescence. BMI is a better indicator of adiposity at higher BMI levels than at lower BMI values throughout childhood and adolescence.

Our objective was to identify sex-specific age 5- to 17-year body composition (body mass index (BMI), % body fat, fat mass index, fat-free mass index) trajectories, compare trajectories assigned using age 5 (AGE5) data to those assigned using all available (ALL) data, and compare BMI assignments to other body composition assignments. Cluster analysis was used to identify low, medium, and high trajectories from body composition measures obtained from dual energy x-ray absorptiometry (DXA) scans at 5, 9, 11, 13, 15, and 17 years in a birth cohort followed longitudinally (n = 469). Moderate agreement was observed for comparisons between AGE5 data and ALL data cluster assignments for each body composition measure. Agreement between cluster assignments for BMI and other body composition measures was stronger using ALL data than using AGE5 data. Our results suggest that BMI, % body fat, fat mass index, and fat free mass index trajectories are established during early childhood, and that BMI is a reasonable predictor of body composition appropriate to track obesity in public health and clinical settings.

This study examined the associations of moderate-to-vigorous intensity physical activity (MVPA) trajectories in adolescence through young adulthood with adiposity in young adults. Participants from The Iowa Bone Development Study cohort were longitudinally assessed (N = 297; 57% female). Accelerometry-measured MVPA (min/day) at ages 15 through 23 years, and fat mass and visceral adipose tissue mass indices (kg/m(2), g/m(2)) derived from dual-energy X-ray absorptiometry scans at age 23 years were analyzed. Latent trajectory analyses classified MVPA into two patterns. Multivariable linear regression analyses showed that being in the high MVPA trajectory group was associated with lower fat mass index z-scores. Individuals who were consistently active with high MVPA (vs. moderately active with decreasing MVPA) during adolescence up until early young adulthood had less accumulation of total body adiposity in young adulthood. This study suggests that adopting a consistently active lifestyle throughout adolescence can result in healthier body composition in young adulthood.

Background Sugar-sweetened beverages (SSBs) have been associated with childhood caries; however, associations among lifelong beverage intakes and adolescent caries have received less attention. Objective To investigate associations between beverage intakes during childhood and adolescence and caries experience at 17 years of age, while adjusting for fluoride intakes and toothbrushing. Design Descriptive model analyses were conducted on data collected from a longitudinal birth cohort study. Participants/setting Participants included Iowa Fluoride Study members (n = 318) recruited at birth between 1992 and 1995 with at least 6 beverage questionnaires completed from ages 1 to 17 years and a caries examination at age 17. Exposure Predictors included mean daily milk, juice (100% juice and juice drinks before age 9), SSB (including juice drinks after age 9), and water/sugar-free beverage (SFB) intakes; daily fluoride intakes; and daily toothbrushing frequencies for ages 1 to 17. Main outcome measures The outcome was dental caries count at age 17, adjusted for the number of scored tooth surfaces (decayed and filled surfaces attack rate [DFSAR]). Statistical analyses performed Univariable generalized linear models were fit for each predictor and the outcome DFSAR. Multivariable models assessed combined effects of beverage types, fluoride variables, toothbrushing, sex, and baseline socioeconomic status. Results Based on multivariable models, each 8 oz of additional daily juice and water/SFB decreased expected DFSAR by 53% (95% confidence interval [CI]: 17%-73%) and 29% (95% CI: 7%-46%), respectively, and 8 additional oz SSBs increased expected DFSAR by 42% (95% CI: 5%-92%), after adjustment for other beverage intakes, toothbrushing, total fluoride intake excluding SSB fluoride (non-SSB total fluoride), sex, and baseline socioeconomic status. Each additional daily toothbrushing event decreased expected DFSAR by 43% (95% CI: 14%-62%) after adjustment for beverage intakes, non-SSB total fluoride intake, sex, and baseline SES. Conclusions Higher juice and water/SFB intakes and more toothbrushing were associated with lower caries at age 17, while higher SSB intakes were associated with higher caries.

Osteoporosis is a common age-related disease characterized by reduced bone density and increased fracture-risk. Microstructural quality of trabecular bone (Tb), commonly found at axial skeletal sites and at the end of long bones, is an important determinant of bone-strength and fracture-risk. High-resolution emerging CT scanners enable in vivo measurement of Tb microstructures at peripheral sites. However, resolution-dependence of microstructural measures and wide resolution-discrepancies among various CT scanners together with rapid upgrades in technology warrant data harmonization in CT-based cross-sectional and longitudinal bone studies. This paper presents a deep learning-based method for high-resolution reconstruction of Tb microstructures from low-resolution CT scans using GAN-CIRCLE. A network was developed and evaluated using post-registered ankle CT scans of nineteen volunteers on both low- and high-resolution CT scanners. 9,000 matching pairs of low- and high-resolution patches of size 64×64 were randomly harvested from ten volunteers for training and validation. Another 5,000 matching pairs of patches from nine other volunteers were used for evaluation. Quantitative comparison shows that predicted high-resolution scans have significantly improved structural similarity index (p < 0.01) with true high-resolution scans as compared to the same metric for low-resolution data. Different Tb microstructural measures such as thickness, spacing, and network area density are also computed from low- and predicted high-resolution images, and compared with the values derived from true high-resolution scans. Thickness and network area measures from predicted images showed higher agreement with true high-resolution CT (CCC = [0.95, 0.91]) derived values than the same measures from low-resolution images (CCC = [0.72, 0.88]).

Osteoporosis is a common age-related disease characterized by reduced bone mineral density (BMD), micro-structural deterioration, and enhanced fracture-risk. Although, BMD is clinically used to define osteoporosis, there are compelling evidences that bone micro-structural properties are strong determinants of bone strength and fracture-risk. Reliable measures of effective trabecular bone (Tb) micro-structural features are of paramount clinical significance. Tb consists of transverse and longitudinal micro-structures, and there is a hypothesis that transverse trabeculae improve bone strength by arresting buckling of longitudinal trabeculae. In this paper, we present an emerging clinical CT-based new method for characterizing transverse and longitudinal trabeculae, validate the method, and examine its application in human studies. Specifically, we examine repeat CT scan reproducibility, and evaluate the relationships of these measures with gender and body size using human CT data from the Iowa Bone Development Study (IBDS) (n = 99; 49 female). Based on a cadaveric ankle study (n = 12), both transverse and longitudinal Tb measures are found reproducible (ICC > 0.94). It was observed in the IBDS human data that males have significantly higher trabecular bone measures than females for both inner (p < 0.05) and outer (p < 0.01) regions of interest (ROIs). For weight, Spearman correlations ranged 0.43-0.48 for inner ROI measures and 0.50-0.52 for outer ROI measures for females versus 0.30-0.34 and 0.23-0.25 for males. Correlation with height was lower (0.36-0.39), but still mostly significant for females. No association of trabecular measures with height was found for males.

Objectives There is strong affinity between fluoride and calcium, and mineralized tissues. Investigations of fluoride and bone health during childhood and adolescence show inconsistent results. This analysis assessed associations between period-specific and cumulative fluoride intakes from birth to age 11, and age 11 cortical bone measures obtained using peripheral quantitative computed tomography (pQCT) of the radius and tibia (n = 424). Methods Participants were a cohort recruited from eight Iowa hospitals at birth. Fluoride intakes from water, other beverages, selected foods, dietary supplements, and dentifrice were recorded every 1.5-6 months using detailed questionnaires. Correlations between bone measures (cortical bone mineral content, density, area, and strength) and fluoride intake were determined in bivariate and multivariable analyses adjusting for Tanner stage, weight and height. Results The majority of associations were weak. For boys, only the positive associations between daily fluoride intakes for 0-3 years and radius and tibia bone mineral content were statistically significant. For girls, the negative correlations of recent daily fluoride intake per kg of body weight from 8.5 to 11 years with radius bone mineral content, area, and strength and tibia strength were statistically significant. No associations between cumulative daily fluoride intakes from birth to 11 years and bone measures were statistically significant. Conclusions In this cohort of 11-year-old children, mostly living in optimally fluoridated areas, life-long fluoride intakes from combined sources were weakly associated with tibia and radius cortical pQCT measures.

BACKGROUND: Height is an indicator of nutritional status; linear growth faltering has recognized consequences for cognitive, emotional, and chronic disease risk. Although height is routinely studied in developing countries, less attention is given to height in the United States. OBJECTIVE: The objective of this study was to identify longitudinal associations between childhood and adolescent beverage intakes, nutrient adequacy, or energy intake and height in a birth cohort. METHODS: Data for participants through ages 2–17 y (n = 717; 353 males, 364 females) recruited at birth for the longitudinal Iowa Fluoride Study (IFS) were used in the current cohort analyses. Beverage intakes (n = 708) were collected by beverage-frequency questionnaires at 3- to 6-mo intervals, whereas nutrient data (n = 652) were obtained from 3-d food diaries completed at 3- to 6-mo intervals through age 8.5 y and from Block Kids’ food-frequency questionnaires at 2-y intervals after age 8.5 y. Nutrient adequacy ratios were calculated with the use of age- and sex-specific Estimated Average Requirements. Height was measured at clinic visits when the participants were approximately ages 5, 9, 11, 13, 15, and 17 y. Linear mixed models were used to identify longitudinal associations between dietary variables and height. A baseline model that adjusted for changing growth patterns during adolescence was established. Dietary and potential confounding variables were added to this baseline model. RESULTS: Milk intake adjusted for mean adequacy ratio, energy intake, and baseline socioeconomic status was associated with height; for each additional 8 ounces (236 mL) of milk consumed per day throughout childhood and adolescence, height increased, on average, by 0.39 cm (95% CI: 0.18, 0.60 cm; P

Objectives To assess longitudinal associations between permanent tooth caries increment and both modifiable and non-modifiable risk factors, using best subsets model selection. Methods The Iowa Fluoride Study has followed a birth cohort with standardized caries exams without radiographs of the permanent dentition conducted at about ages 9, 13, and 17 years. Questionnaires were sent semi-annually to assess fluoride exposures and intakes, select food and beverage intakes, and tooth brushing frequency. Exposure variables were averaged over ages 7-9, 11-13, and 15-17, reflecting exposure 2 years prior to the caries exam. Longitudinal models were used to relate period-specific averaged exposures and demographic variables to adjusted decayed and filled surface increments (ADJCI) (n = 392). The Akaike Information Criterion (AIC) was used to assess optimal explanatory variable combinations. Results From birth to age 9, 9-13, and 13-17 years, 24, 30, and 55 percent of subjects had positive permanent ADJCI, respectively. Ten models had AIC values within two units of the lowest AIC model and were deemed optimal based on AIC. Younger age, being male, higher mother's education, and higher brushing frequency were associated with lower caries increment in all 10 models, while milk intake was included in 3 of 10 models. Higher milk intakes were slightly associated with lower ADJCI. Conclusions With the exception of brushing frequency, modifiable risk factors under study were not significantly associated with ADJCI. When possible, researchers should consider presenting multiple models if fit criteria cannot discern among a group of optimal models.

Objectives To examine the relationships between fluoride intake levels and fluorosis of late-erupting permanent teeth. Methods The current study used information collected from 437 children in the longitudinal Iowa Fluoride Study. Participants' fluoride intake information was collected using questionnaires from birth to age 10 years. Estimated mean daily fluoride intake was categorized into low, moderate, and high intake tertiles for each age interval (2-5, 5-8, and 2-8 years). Bivariate analyses were performed to study the relationships between self-reported fluoride intake levels during three age intervals and dental fluorosis. Results For canines and second molars, the prevalence of mostly mild fluorosis was less than 10% in the lowest fluoride intake tertile and more than 25% in the highest intake tertile. For both first and second premolars, the prevalence in the low and high intake tertiles was approximately 10-15% and 25-40%, respectively. When estimated total daily fluoride intake was 0.04 mg/kg BW during ages 2-8 years, the predicted probability of fluorosis was 16.0%, 20.5%, 21.8%, and 15.4% for canines, 1st and 2nd and premolars and 2nd molars, respectively. We found that an incremental increase in fluoride intake during the age 5- to 8-year interval led to greater odds for development of mostly mild dental fluorosis in late-erupting teeth compared to increases in fluoride intake during other age intervals. Conclusions Our results clearly show that dental fluorosis prevalence is closely related to fluoride intake levels and that teeth have greater susceptibility to fluoride intake during certain age intervals.

OBJECTIVES: This analysis examines the etiology of caries development in adolescents by using structural equation modeling to identify behavioral mediators of the relationship between socioeconomic status (SES) and caries incidence, and to investigate the role of sex on caries preventive behavior and caries. METHODS: This analysis was based on data from the Iowa Fluoride Study, a longitudinal study of a birth cohort. We hypothesized that socioeconomic status earlier in life has a direct effect on caries development and an indirect effect from improved behavioral variables – dental visit attendance, tooth brushing frequency, and percentage of beverage intake consisting of sugar-sweetened beverages – and that sex also plays a role in behavioral variables, as well as caries. A structural equation model was developed based on these hypotheses and direct and indirect standardized path coefficients were calculated, as well as their standard errors. RESULTS: Based on our proposed model, SES at birth significantly influences SES during adolescence, but not adolescent behaviors. The effect of SES during adolescence on caries in the permanent dentition is mediated by adolescent behaviors. Female participants have worse caries than male participants, despite lower self-reported percentages of sugar-sweetened beverage intake and more frequent brushing and dental attendance. CONCLUSIONS: This analysis models the relationships among known causal factors for caries and suggests that the role of SES in caries may not be as important as previously thought and different behaviors that affect oral health between males and females as well as differences in caries between the sexes could begin during adolescence. These findings could help improve caries prevention programs for adolescents.

This study evaluated the longitudinal relationships among visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and peripheral bone strength during adolescence. Fat and lean mass, VAT and SAT area, and android/gynoid (A/G) ratio were estimated with DXA. Our main outcome was strength-strain index (SSI), an indicator of peripheral bone strength estimated by pQCT at the radius and tibia. Sex-specific analyses evaluated the longitudinal bone-fat relationship from ages 11 to 19 years with linear mixed models using biological age as the time variable and adjusted for limb length and lean mass in 182 girls and 167 boys. Variables were standardized (mean = 0, SD = 1) prior to model fitting and results shown are parameter estimates ± SE. Fat mass and SAT were positively associated with SSI (radius: 0.07 ± 0.02, p = 0.003 and 0.05 ± 0.02, 0.041, respectively; tibia: 0.09 ± 0.02, p

Osteoporosis associated with reduced bone mineral density (BMD) and microarchitectural changes puts patients at an elevated risk of fracture. Modern multidetector row CT (MDCT) technology, producing high spatial resolution at increasingly lower dose radiation, is emerging as a viable modality for trabecular bone (Tb) imaging. Wide variation in CT scanners raises concerns of data uniformity in multisite and longitudinal studies. A comprehensive cadaveric study was performed to evaluate MDCT-derived Tb microarchitectural measures. A human pilot study was performed comparing continuity of Tb measures estimated from two MDCT scanners with significantly different image resolution features.Micro-CT imaging of cadaveric ankle specimens (n=25) was used to examine the validity of MDCT-derived Tb microarchitectural measures. Repeat scan reproducibility of MDCT-based Tb measures and their ability to predict mechanical properties were examined. To assess multiscanner data continuity of Tb measures, the distal tibias of 20 volunteers (age:26.2±4.5Y,10F) were scanned using the Siemens SOMATOM Definition Flash and the higher resolution Siemens SOMATOM Force scanners with an average 45-day time gap between scans. The correlation of Tb measures derived from the two scanners over 30% and 60% peel regions at the 4% to 8% of distal tibia was analyzed.MDCT-based Tb measures characterizing bone network area density, plate-rod microarchitecture, and transverse trabeculae showed good correlations (r∈0.85,0.92) with the gold standard micro-CT-derived values of matching Tb measures. However, other MDCT-derived Tb measures characterizing trabecular thickness and separation, erosion index, and structure model index produced weak correlation (r0.8) with their micro-CT-derived values. Most MDCT Tb measures were found repeatable (ICC∈0.94,0.98). The Tb plate-width measure showed a strong correlation (r = 0.89) with experimental yield stress, while the transverse trabecular measure produced the highest correlation (r = 0.81) with Young's modulus. The data continuity experiment showed that, despite significant differences in image resolution between two scanners (10% MTF along xy-plane and z-direction - Flash: 16.2 and 17.9 lp/cm; Force: 24.8 and 21.0 lp/cm), most Tb measures had high Pearson correlations (r0.95) between values estimated from the two scanners. Relatively lower correlation coefficients were observed for the bone network area density (r = 0.91) and Tb separation (r = 0.93) measures.Most MDCT-derived Tb microarchitectural measures are reproducible and their values derived from two scanners strongly correlate with each other as well as with bone strength. This study has highlighted those MDCT-derived measures which show the greatest promise for characterization of bone network area density, plate-rod and transverse trabecular distributions with a good correlation (r ≥ 0.85) compared with their micro-CT-derived values. At the same time, other measures representing trabecular thickness and separation, erosion index, and structure model index produced weak correlations (r0.8) with their micro-CT-derived values, failing to accurately portray the projected trabecular microarchitectural features. Strong correlations of Tb measures estimated from two scanners suggest that image data from different scanners can be used successfully in multisite and longitudinal studies with linear calibration required for some measures. In summary, modern MDCT scanners are suitable for effective quantitative imaging of peripheral Tb microarchitecture if care is taken to focus on appropriate quantitative metrics.

In practice, count data may exhibit varying dispersion patterns and excessive zero values; additionally, they may appear in groups or clusters sharing a common source of variation. We present a novel Bayesian approach for analyzing such data. To model these features, we combine the Conway-Maxwell-Poisson distribution, which allows both overdispersion and underdispersion, with a hurdle component for the zeros and random effects for clustering. We propose an efficient Markov chain Monte Carlo sampling scheme to obtain posterior inference from our model. Through simulation studies, we compare our hurdle Conway-Maxwell-Poisson model with a hurdle Poisson model to demonstrate the effectiveness of our Conway-Maxwell-Poisson approach. Furthermore, we apply our model to analyze an illustrative dataset containing information on the number and types of carious lesions on each tooth in a population of 9-year-olds from the Iowa Fluoride Study, which is an ongoing longitudinal study on a cohort of Iowa children that began in 1991.

Objective A genetic component in early childhood caries (ECC) is theorized, but no genome-wide investigations of ECC have been conducted. This pilot study is part of a long-term research program aimed to: (1) determine the proportion of ECC variance attributable to the human genome and (2) identify ECC-associated genetic loci. Methods The study's community-based sample comprised 212 children (mean age=39 months; range = 30–52 months; males = 55%; Hispanic/Latino = 35%, African-American = 32%; American Academy of Pediatric Dentistry definition of ECC prevalence = 38%). Approximately 2.4 million single nucleotide polymorphisms (SNPs) were genotyped using DNA purified from saliva. A P

Purpose To examine the associations among physical activity (PA), sedentary time (SED), and TV viewing (TV) with fat mass (FAT) and visceral adipose tissue mass (VAT) from childhood through adolescence (5-19 yr). Methods Participants in the Iowa Bone Development Study (n = 230 males and 233 females) were examined at ages 5, 8, 11, 13, 15, 17, and 19 yr. Accelerometers measured moderate- or vigorous-intensity PA (MVPA; min·d), light-intensity PA (LPA; min·d), and SED (h·d). Parent-proxy report (5 and 8 yr) and child-report (11, 13, 15, 17, and 19 yr) measured TV (h·d). X-ray absorptiometry scans measured FAT (kg) and VAT (g). Sex-specific growth models were used to create FAT and VAT growth curves for individual participants (level 1), and to test the effect of MVPA, LPA, SED, and TV (level 2) after adjusting for weight, height, linear age, nonlinear age, and maturity. Results Growth models indicated that low levels of MVPA were associated with high levels of FAT and VAT for males and high levels of FAT for females. TV viewing was positively associated with FAT and VAT for males and females. LPA was positively associated with FAT in males. Sedentary time was not associated with FAT or VAT for males or females (P > 0.05). Conclusions This study supports current PA guidelines focusing on MVPA rather than SED. The contribution of high TV, but not high SED, to high levels of adiposity suggests that TV's contribution to obesity is not just a function of low energy expenditure.

Objectives There have been very few longitudinal studies of dental caries in adolescents, and little study of the caries risk factors in this age group. The purpose of this study was to describe different caries trajectories and associated risk factors among members of the Iowa Fluoride Study (IFS) cohort. Methods The IFS recruited a birth cohort from 1992 to 1995, and has gathered dietary, fluoride and behavioural data at least twice yearly since recruitment. Examinations for dental caries were completed when participants were ages 5, 9, 13 and 17 years. For this study, only participants with decayed and filled surface (DFS) caries data at ages 9, 13 and 17 were included (N=396). The individual DFS counts at age 13 and the DFS increment from 13 to 17 were used to identify distinct caries trajectories using Ward's hierarchical clustering algorithm. A number of multinomial logistic regression models were developed to predict trajectory membership, using longitudinal dietary, fluoride and demographic/behavioural data from 9 to 17 years. Model selection was based on the akaike information criterion (AIC). Results Several different trajectory schemes were considered, and a three-trajectory scheme—no DFS at age 17 (n=142), low DFS (n=145) and high DFS (n=109)—was chosen to balance sample sizes and interpretability. The model selection process resulted in use of an arithmetic average for dietary variables across the period from 9 to 17 years. The multinomial logistic regression model with the best fit included the variables maternal education level, 100% juice consumption, brushing frequency and sex. Other favoured models also included water and milk consumption and home water fluoride concentration. The high caries cluster was most consistently associated with lower maternal education level, lower 100% juice consumption, lower brushing frequency and being female. Conclusions The use of a clustering algorithm and use of Akaike's Information Criterion (AIC) to determine the best representation of the data were useful means in presenting longitudinal caries data. Findings suggest that high caries incidence in adolescence is associated with lower maternal educational level, less frequent tooth brushing, lower 100% juice consumption and being female.

Objectives The Akaike Information Criterion (AIC) is a well-known tool for variable selection in multivariable modeling as well as a tool to help identify the optimal representation of explanatory variables. However, it has been discussed infrequently in the dental literature. The purpose of this paper is to demonstrate the use of AIC in determining the optimal representation of dietary variables in a longitudinal dental study. Methods The Iowa Fluoride Study enrolled children at birth and dental examinations were conducted at ages 5, 9, 13, and 17. Decayed or filled surfaces (DFS) trend clusters were created based on age 13 DFS counts and age 13-17 DFS increments. Dietary intake data (water, milk, 100 percent-juice, and sugar sweetened beverages) were collected semiannually using a food frequency questionnaire. Multinomial logistic regression models were fit to predict DFS cluster membership (n=344). Multiple approaches could be used to represent the dietary data including averaging across all collected surveys or over different shorter time periods to capture age-specific trends or using the individual time points of dietary data. Results AIC helped identify the optimal representation. Averaging data for all four dietary variables for the whole period from age 9.0 to 17.0 provided a better representation in the multivariable full model (AIC=745.0) compared to other methods assessed in full models (AICs=750.6 for age 9 and 9-13 increment dietary measurements and AIC=762.3 for age 9, 13, and 17 individual measurements). The results illustrate that AIC can help researchers identify the optimal way to summarize information for inclusion in a statistical model. Conclusions The method presented here can be used by researchers performing statistical modeling in dental research. This method provides an alternative approach for assessing the propriety of variable representation to significance-based procedures, which could potentially lead to improved research in the dental community.

Background Sugar-sweetened beverages (SSB) are considered a risk factor for obesity. Objective The objective of the current study was to investigate associations between the predictors of beverage and energy intakes and mean adequacy ratios (MARs), and the outcome of body mass index (BMI) z scores, in a birth cohort using longitudinal models. Design This was a longitudinal analysis of secondary data. Participants/setting Participants in the Iowa Fluoride and Iowa Bone Development Studies with two beverage intake questionnaires completed between ages 2 and 4.7 years or 5 and 8.5 years or one questionnaire between ages 9 and 10.5, 11 and 12.5, 13 and 14.5, or 15 and 17 years (n=720); two food and beverage diaries completed between ages 2 and 4.7 years or 5 and 8.5 years or completion of the Block’s Kids’ Food Frequency Questionnaires at age 11, 13, 15, or 17 years (n=623); and anthropometric measures at the corresponding age 5-, 9-, 11-, 13-, 15-, or 17-year examination(s). Predictors Mean daily 100% juice, milk, SSB, water/sugar-free beverage, and energy intakes and MARs averaged over ages 2 to 4.7, 5 to 8.5, 9 to 10.5, 11 to 12.5, 13 to 14.5, or 15 to 17 years were predictors. Outcome BMI z score was the outcome. Statistical analyses Linear mixed models were fit for each beverage, energy, and MAR variable, with the beverage, energy, or MAR variable as the predictor and BMI z score as the outcome. Beverage models were adjusted for energy and MAR and baseline socioeconomic status. Results SSB intake adjusted for energy intake, MAR, and baseline socioeconomic status was associated with BMI z score; each additional 8 oz SSB consumed/day throughout childhood and adolescence increased the BMI z score an average 0.050 units (95% CI 0.022 to 0.079; P=0.001). Adjusted water/sugar-free beverage intake (0.026 units; 95% CI 0.006 to 0.046; P=0.013) was modestly associated with BMI z score, while 100% juice (–0.001 units; 95% CI –0.059 to 0.057; P=0.97) and milk (0.022 units; 95% CI –0.007 to 0.052; P=0.13) intakes were not associated with BMI z scores. Conclusions Higher SSB intakes were associated with increased BMI z scores throughout childhood and adolescence in Iowa Fluoride Study participants. Public health initiatives targeting SSB consumption during childhood and adolescence remain relevant.

PURPOSE: The aim of this study was to examine the effects of period-specific and cumulative fluoride (F) intake on bone at the levels of cortical and trabecular bone microstructural outcomes at early adulthood using emerging multi-row detector computed tomography (MDCT)-based novel techniques. METHODS: Ultra-high resolution MDCT distal tibia scans were collected at age 19 visits under the Iowa Bone Development Study (IBDS), and cortical and trabecular bone microstructural outcomes were computed at the distal tibia using previously validated methods. CT scans of a tissue characterization phantom were used to calibrate CT numbers (Hounsfield units) into bone mineral density (mg/cc). Period-specific and cumulative F intakes from birth up to the age of 19 years were assessed for IBDS participants through questionnaire, and their relationships with MDCT-derived bone microstructural outcomes were examined using bivariable and multivariable analyses, adjusting for height, weight, maturity offset (years since age of peak height velocity (PHV)), physical activity (questionnaire for adolescents (PAQ-A)), healthy eating index version 2010 (HEI-2010) scores, and calcium and protein intakes. RESULTS: MDCT distal tibia scans were acquired for 324 participants from among the total of 329 participants at age 19 visits. No motion artifacts were observed in any MDCT scans, and all images were successfully processed to measure cortical and trabecular bone microstructural outcomes. At early adulthood, males were observed to have stronger trabecular bone microstructural features, as well as thicker cortical bone (p < 0.01), as compared to age-similar females; however, females were found to have less cortical bone porosity as compared to males. Among participants with available F intake estimates (75 to 91% of the 324 with MDCT scans, depending on the period-specific F intake measure), no statistically significant associations were detected between any period-specific or cumulative F intake and bone microstructural outcomes of the tibia at the p < 0.01 level. Only for females, statistically suggestive associations (p < 0.05) were found between recent F intake (from 14-19 years) and trabecular mean plate width and trabecular thickness at the tibia. Those associations became somewhat weaker, but still statistically suggestive, for trabecular thickness in fully adjusted analysis with height, weight, PHV, calcium and protein intake, and HEI-2010 and PAQ-A scores as covariates. CONCLUSION: The findings show that the effects of lifelong or period-specific F intake from combined sources for adolescents typical to the United States Midwest region are not strongly associated with bone microstructural outcomes at age 19 years. These findings are generally consistent with previously reported results of IBDS analyses, which further confirms that effects of lifelong or period-specific F intake on skeletons in early adulthood are absent or weak, even at the levels of cortical and trabecular bone microstructural details.

A gender difference in youth sports and physical activity participation is well documented. However, research is limited to understand potential gender difference in the long-term effects of youth sports participation. The study aim was to compare the likelihood of meeting the aerobic Physical Activity Guidelines (PAG) in early adulthood by youth sports participation patterns among females and males. The study sample included 582 Iowa Bone Development Study participants (Iowa, USA). Participation in organized sports was assessed using a physical activity questionnaire 19 times on average between age 6 and 17 years. Accelerometer and dual-energy X-ray absorptiometry assessments were conducted at an average age of 23 years. Group-based trajectory analysis was conducted to identify youth sports participation trajectory patterns. Multivariable logistic regression analysis was conducted to examine the association between youth sports participation patterns and meeting the PAG in adulthood. We identified three youth sports participation patterns: “continuous participation,” “drop-out,” and “no participation.” Females in the continuous participation group were more likely to meet the aerobic PAG at age 23 years, compared to females in the no-participation group (OR = 2.63; 95% CI = 1.05, 6.55) or the drop-out group (OR = 2.55; 95% CI = 1.38, 4.69). However, among males, youth sports participation patterns were not significantly associated with meeting the aerobic PAG at age 23 years. In conclusion, this study suggests that youth sports participation could be more important among females than males for predicting physical activity in early adulthood.

OBJECTIVE To identify distinct body mass index (BMI) percentile trajectories during early childhood and examine adiposity levels in childhood and early adulthood according to the BMI percentile trajectories. METHODS Iowa Fluoride Study cohort parents (n = 1,093) reported their child's anthropometric data on average six times between ages 0 and 23 months. A subset of the cohort underwent DXA scans at approximately age 8 years (n = 495) and again at approximately age 19 years (n = 314). Group-based trajectory analysis was conducted to identify distinct BMI percentile trajectories from ages 0 to 23 months. Sex-specific age-adjusted linear regression analyses were conducted to compare fat mass index in childhood and early adulthood among subgroups that follow the distinct BMI percentile patterns. RESULTS Four BMI percentile patterns were identified: consistently low (group 1: 9.8%), increase in the second year (group 2: 33.7%), increase in the first year (group 3: 23.9%), and consistently high (group 4: 32.6%). Compared with group 2 females, groups 3 and 4 females had higher fat mass index in childhood and early adulthood (P

In the marginal analysis of clustered data, where the marginal distribution of interest is that of a typical observation within a typical cluster, analysis by reweighting has been introduced as a useful tool for estimating parameters of these marginal distributions. Such reweighting methods have foundation in within-cluster resampling schemes that marginalize potential informativeness due to cluster size or within-cluster covariate distribution, to which reweighting methods are asymptotically equivalent. In this paper, we introduce a reweighting scheme for the marginal analysis of clustered data that generalizes prior reweighting methods, with a particular application to measuring bivariate correlation in unpaired clustered data, in which observations of two random variables are not naturally paired at the within-cluster level. We develop unpaired clustered data analogs of well-known product moment correlation coefficients (Pearson, Spearman, phi), as well as the polyserial coefficient for measuring correlation between one discrete and one continuous variable. We evaluate the performance of these coefficients via a simulation study and demonstrate their use by finding no statistically significant association between dental caries at an early age and dental fluorosis at age 13 using a large dental dataset.

Objectives In humans, there is a large range of variation in the form of the maxillary and mandibular dental arches. This variation can manifest as either prognathism or retrognathism in either or both arches, which can cause malocclusion and lead to abnormal masticatory function. This study aims to identify aspects of variation and morphological integration existing in the dental arches of individuals with different types of malocclusion. Methods Coordinate landmark data were collected along the gingival margins of 397 scanned dental casts and then analyzed using geometric morphometric techniques to explore arch form variation and patterns of morphological integration within each malocclusion type. Results Significant differences were identified between Class II forms (increased projection of upper arch relative to the lower arch) and Class III forms (lower arch projection beyond the upper arch) in symmetrical shape variation, including anteroposterior arch discrepancies and abnormal anterior arch divergence or convergence. Partial least squares analysis demonstrated that Class III dental arches have higher levels of covariance between upper and lower arches (RV = 0.91) compared to the dental arches of Class II (RV = 0.78) and Class I (RV = 0.73). These high levels of covariance, however, are on the lower end of the overall range of possible masticatory blocks, indicating weaker than expected levels of integration. Conclusions This study provides evidence for patterns of variation in dental arch shape found in individuals with Class II and Class III malocclusions. Moreover, differences in integration found between malocclusion types have ramifications for how such conditions should be studied and treated. Am. J. Hum. Biol., 2016. © 2016 Wiley Periodicals, Inc.

Objectives To compare timing of tooth emergence among groups of American Indian (AI), Black and White children in the United States at 12 months of age. Methods Data were from two sources – a longitudinal study of a Northern Plains tribal community and a study with sites in Indiana, Iowa and North Carolina. For the Northern Plains study, all children (n = 223) were American Indian, while for the multisite study, children (n = 320) were from diverse racial groups. Analyses were limited to data from examinations conducted within 30 days of the child's first birthday. Results AI children had significantly more teeth present (Mean: 7.8, Median: 8.0) than did Whites (4.4, 4.0, P