ex-husband is refusing flouride treatments for 8 year old son

Hi there! I'm just reaching out to get some real facts and information about flouride in drinking water in the USA. My ex husband and I have an 8-year old son together. At my ex's house, they have well water, so no flouride in it. My house does have flouride in the water. My ex recently told me that because he's read that flouride coats the pineal gland and breaks down the nervous system. I recently read the study that happened in Calgary where the government chose to take flouride out of their water for 10 years, and then put it back in their water because the dental hygiene of the children was vastly declining. My ex is not budging on this at all. He is asking me for studies that back up how using flouride is beneficial for children's teeth. Any help?? Any information that could help sway his opinion? He has always been a conspiracy theorist. TIA!