Large UK Government funded LOTUS study 2024. This study looked at patients aged 12 years and over, attending NHS primary dental care services in England (17.8 million patients). Using recorded residential locations, individuals exposed to drinking water with fluoridated water (≥0.7 mg F/L) were matched to non-exposed individuals using propensity scores. They concluded, the same as the CATFISH study that the very slight difference in decay rates may not be cost-effective in today’s world, particularly for any new supplies where infrastructure costs would also need to be accounted for.

Large UK Government funded CATFISH study 2022. Major UK Fluoridation Study Finds Much Smaller Benefits And Much Higher Costs Than Prior Claims. This study looked at children under age 12 in two parts of Cumbria. One area with fluoridation (0.9ppm) and the other area without any fluoridation. It found only a very slight difference in tooth decay results leading the authors to conclude that fluoridation may not be cost-effective in today’s world. 

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.