Associations between longitudinal fluoride intakes from birth to age 23 and multi-detector computed tomography (MDCT) bone densitometry outcomes at age 23
Creators: name: Bhatia, Gurjot Kaur
Publisher: name: University of Iowa
Year: 2025
Subjects: Bone Densitometry Outcomes
Fluoride
MDCT
public abstract

description: While fluoride is widely used as an anti-cavity agent, there have been conflicting findings on its impact on bone health. Given the widespread use of community water fluoridation in the U.S. and increased access to fluoride from other sources (dietary and non-dietary), there have been concerns about the possible greater accumulation of fluoride in developing skeletons of children, adolescents, and young adults. Therefore, there is a need for studies relating bone outcomes to detailed fluoride exposure assessment among children, adolescents, and young adults.
description: Most previous studies which assessed the effects of water fluoridation on fracture risk or bone mineral density in adults were based on community level data instead of individual level data. Conflicting results, in terms of the effects of fluoride on bone, were obtained from these studies. In the few longitudinal studies that assessed relationships between fluoride intake and bone development in children, adolescents, or young adults, most had small sample sizes and/or utilized less refined densitometry methods. Hence, there is a need for more individual- level fluoride exposure and longitudinal studies to assess the relationships between fluoride intake and bone development. There are especially important gaps in our understanding about the relationships between fluoride and bone development during the adolescent-adult transition period. Thus, analysis of relationships between fluoride intake from birth to age 23 and bone outcomes at age 23 can help to address these gaps.
description: The aim of this thesis was to assess the relationships between period-specific and cumulative daily fluoride intakes from birth to age 23 and bone densitometry outcomes of the 23-year-old young adults. This thesis project is a secondary data analysis of the previously-collected and de-identified data from the Iowa Fluoride Study (IFS) and the Iowa Bone Development Study (IBDS).
description: The IBDS is an offshoot of the IFS, a study that tracked the effects of fluoride exposures (both dietary and non-dietary sources) on dental fluorosis and dental caries over time. The IFS recruited participants between 1992 and 1995 from postpartum wards in eight Iowa hospitals. In 1998, the families that were still a part of the IFS were invited to join the IBDS.
description: Comprehensive study questionnaires were used to collect information on detailed fluoride intakes from water, beverages other than water, selected foods, dietary fluoride supplements, and fluoride dentifrice, as well as oral hygiene practices (i.e., tooth-brushing/dentifrices, mouth rinses), and professional fluoride applications. These questionnaires were sent when the child was aged 1.5, 3, 6, 9, 12, 16, 20, 24, 28, 32, and 36 months and every 6 months after that. Estimated period-specific (0-8, 8-15, and 15-23 years) and cumulative (birth to 23 years) fluoride intakes from combined sources were determined using the collected data. Additional information on dietary calcium, vitamin D and protein intakes, physical activity, and physical maturity was also obtained through specific questionnaires.
description: Age 23 multi-detector computed tomography (MDCT) scans of the distal tibia were obtained from 330 participants using a SOMATOM Force Scanner at the University of Iowa Comprehensive Lung Imaging Center. Nine cortical and four trabecular bone microstructural outcomes were computed using previously-validated methods. MDCT results of the trabecular bone (volumetric bone mineral content (vBMC), volumetric bone mineral density (vBMD), transpose bone mineral density (tBMD), plate trabecula bone mineral density (pBMD), trabecular network area density (Tb.NA), plate width (TS- PW), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), erosion index (EI)) and cortical bone (cortical bone porosity over the ROI of 0-10% peel at 4-6% of tibia length (Cb.Poro10P), cortical bone porosity over the ROI of 0- 15% peel at 4-6% of tibia length (Cb.Poro15P), cortical bone porosity (Cb.Poro), and cortical thickness (Cb.Th)) bone were related to longitudinal fluoride intakes through sex-specific bivariate and multivariable analyses, the latter adjusting for height, weight, years since peak height velocity (PHV), vertical jump, dietary calcium intake, Healthy Eating Index-2010 (HEI- 2010) scores, and Physical Activity Questionnaire (PAQ) scores. Due to the multiple statistical analyses being conducted with the same explanatory fluoride variables, p-values &lt;0.01 were considered statistically significant and those with 0.01
description: The mean daily fluoride intakes estimated using area-under-the-curve (AUC) from birth to 23 years were 0.73-1.12 mg F for males and 0.67-0.93 mg F for females, and they generally increased with age. For the unadjusted one-variable linear regression in females, Tb.vBMC was the only bone measure that had a statistically significant positive association at p&lt;0.01 with period-specific fluoride intake from 8-15 years. Also, statistically suggestive positive associations at 0.01
description: The findings of this thesis show that the longitudinal period-specific and cumulative fluoride intakes from combined sources were associated weakly and mostly positively with MDCT bone measures at age 23 years. Hence, fluoride intakes within the optimal range do not appear to have adverse impacts on bone health in young adults in the Midwest region of the United States. Thus, efforts should be continued to preserve and expand community water fluoridation.