Phase II, proof-of-concept randomized controlled trial to evaluate dental caries preventive effects of fluoridated bottle water

Dental health benefits of fluoride in drinking water have never been tested in a randomized controlled trial (RCT). Instead, results from observational studies and a few non-randomized, community intervention studies were sufficient to justify addition of fluoride to many public water systems during the 20th century and to defend against fluoridation’s critics. However, growth in fluoridated public water systems has stalled, leaving 100 million Americans living in places that do not have fluoridated water and which probably never will. A related problem is that, nationwide, 15% of children do not drink tap water for reasons ranging from consumer preference to distrust of public water. One solution, capitalizing on consumers’ demand for bottled water, is to increase consumption of fluoridated bottled water. However, RCT evidence of dental health benefits of fluoridated bottled water will be essential if public health is to embrace it as a strategy to extend fluoridation. In the absence of a precedent, and in the face of uncertainty as to compliance and likely effect size of the intervention, a fully powered RCT is premature. We instead propose a phase II, proof-of-concept RCT to evaluate dental caries preventive effects of fluoridated bottled water in a community not served by water fluoridation. The primary recruitment population is ~470 babies born during a one-year period in Kinston, NC, the state’s community with the largest non-fluoridated public water system where caries prevalence exceeds the state average. In households where measured content of fluoride in tap water is <0.2 ppm, we will randomize 200 infant/family dyads in a 1:1 ratio to receive either fluoridated or non-fluoridated bottled water. The two types of commercially water in 5-gallon bottles will be relabeled to mask infants, families and researchers as to the fluoride content. For 3½ years after randomization, each household will be provided with water, dispensers and other supplies to encourage water consumption consistent with nutritional recommendations. Bottled water consumption will be monitored and fingernail clippings collected to provide a biomarker-measure of fluoride intake. A dental examination conducted when children are aged 48?3 months will measure caries experience using the index of decayed, missing and filled tooth surfaces (dmfs). Statistical analysis will compare mean dmfs between study-groups to generate effect size estimates and standard errors needed to calculate sample size requirement for a future, multi-site, Phase III RCT. The investigative team has a strong record of accomplishment in observational and interventional studies of dental caries in children, and is experienced in work needed to plan (during the UG3 phase) and conduct (during the 5-year UH3 phase) the study as required by PAR-18-547. Local, state and national stakeholders have expressed support for the proposed study, noting its potential to improve oral health in underserved communities. By applying the rigor of a placebo-controlled RCT design, the study will address a serious shortfall in the evidence that hampers the nation’s primary public health strategy for dental caries prevention.