The Cochrane 2015 Review on Water Fluoridation: their conclusions? The current available studies are of poor quality and don't prove anything ... the studies don't prove it helps the poor or even that fluoride helps adults!
The Cochrane Review is a highly regarded group of scientists and researchers who periodically publish their systematic review of available scientific studies. They just published their findings recently on water fluoridation. To paraphrase their conclusions: the science shows nothing of importance: there is no proof of efficacy for adults or those with lower income:
“There is very little contemporary evidence … that has evaluated the effectiveness of water fluoridation for the prevention of caries."
"There is insufficient evidence to determine whether water fluoridation results in a change in disparities in caries levels across SES (Social Economic Status)."
"We did not identify any evidence ... to determine the effectiveness of water fluoridation for preventing caries in adults."
"There is insufficient information to determine the effect on caries levels of stopping water fluoridation programmes.e. There is a significant association between dental fluorosis (of aesthetic concern or all levels of dental fluorosis) and fluoride level. The evidence is limited due to high risk of bias within the studies and substantial between-study variation.”