Large UK Government funded CATFISH study 2022. Major UK Fluoridation Study Finds Much Small Benefits And Much Higher Costs Than Prior Claims
The Cochrane Collaboration Review 2015. A review of all studies on fluoridation and dental decay. The Cochrane Collaboration is touted as the top independent health science in the world and relied on by New Zealand Ministry of Health to promote fluoridation, finds no modern, reliable evidence that fluoridation reduces dental decay.
US Government funded Iowa Study looking at the relationship between total daily fluoride intake (from all sources) and several health outcomes of interest, namely: tooth decay, dental fluorosis, and bone health. First report was published in 2009. Finds no relationship between fluoride ingestion and decay rates, but does find strong evidence of fluoride ingestion and dental fluorosis rates.