Always start with the best/most reliable sources to establish fundamental understanding.

https://en.wikipedia.org/wiki/Sodium_fluorosilicate

That way when the health-magazine pundits make claims, you know if they are full of shit and whether they should be read.

https://www.cdc.gov/fluoridation/engineering/wfadditives.htm

https://thevaccinereaction.org/2017/11/aluminum-in-antiperspirants-linked-to-cancer-and-to-brain-damage-from-vaccines/

^^ in this link they avoid the synergy with Flouride and Aluminum.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5285601/

Here is the proof in the pudding from this link:

Results:

A significant inverse relationship was found between the fluoride concentration in drinking water and IQ (r value = −0.204; P < 0.000). It was observed that IQ level was negatively correlated with fluoride concentration in drinking water.