Fluoride is a trace element, but it is found in our daily exposure more than a "trace".
In small amounts, it appears to be okay.
The problems with fluoride appear to be in chronic use of it over long periods of time, and/or being exposed to a high dose of it in a single instance.
Apart from skeletal tissue and teeth, fluoride can cause changes in the kidneys, liver, thyroid, parathyroid, pituitary gland, testis, muscle tissues, stomach, brain, neurons, and immune system.
I have mild dental fluorosis, probably from drinking too much fluoridated water, using fluoridated toothpaste, along with taking fluoride at the dentist to protect my enamel. Read more