Fluoride has long been touted as the best cavity fighter.

But some dentists and research scientists believe too much of the compound could be doing more harm than good.

For decades our children have been taught brushing prevents cavities. Fluoride in the toothpaste and tap water would protect their teeth.

But now there’s a growing movement to pressure the government to stop putting fluoride in the water supply.

A letter signed by more than 600 professionals indicates concern too much fluoride can increase bone fractures, lower IQ, damage teeth and perhaps even cause bone cancer.

At .6 parts per million, Houston tapwater has less fluoride than many cities — a level local experts said is safe for most people.

“There’s always a bell curve a certain amount,” Dr. Jarvis Chan with the UT Dental School said. “You get too much, and it’s not good.”

Dr. Chan said too much fluoride when teeth are forming can interfere with the normal formation of enamel. The result in mild cases is a chalky white color.

Severe fluorosis leaves teeth brown and pitted.

Dr. Chan said it’s rare, and water fluoridation decreases tooth decay 20 percent to 30 percent.

“Children in low socioeconomic group[s] will benefit from the water fluoridation, so if you remove fluoride from water then this group of children will really be impacted,” Dr. Chan said.

Most dentists still believe fighting cavities the old fashioned way — with the right amount of fluoride — is best.