STUART — On one side were the blue-shirted activists, those convinced that fluoride is hazardous to the health of most anyone who drinks it out of the tap.

On the other side were those dressed in white: dentists and nurses who desperately wanted the chemical compound added to Martin County’s water supply to help strengthen teeth and prevent decay.

On Tuesday, the blue shirts won.

After a five-hour, often-testy debate, Martin County commissioners voted 3-2 against fluoridating water the department serves to more than 20,000 customers.

The vote reverses a 4-1 decision commissioners made in 2003 to start adding fluoride to improve the county’s oral health – a process that was supposed to begin early next year.

“To me it’s medicine and I’m not licensed to prescribe medicine,” said Commissioner Susan Valliere, who voted against fluoride in 2003 and Tuesday.

Anti-fluoride activist Glenn Burdge echoed the thoughts of many.

“I don’t want fluoride in my water,” he said. “If you want fluoride, go get drops from your dentist and then drink it. Leave us to our choices.”

Commissioners earlier decided to reconsider the fluoride issue after Jensen Beach engineer Pat Arena began a prolific campaign, which attracted a throng of supporters claiming that the chemical can cause problems with teeth, bones and thyroid glands.

More than two dozen fluoride opponents, who also claimed the chemical can cause cancer and mental illness, flocked to the commission chambers Tuesday to join Arena’s fight.

“I am appalled at the prospect of using water as a vehicle for drugs,” said Lynne Pine of Stuart, who is well-known for her fight against jet noise at the county’s airport. “In today’s world, mass medication through water is not a good idea. It’s about more than teeth.”

Commissioners Lee Weberman and Sarah Heard said they voted against adding fluoride because studies on the issue raise too many questions about negative impacts. They also said they have not seen a demonstrated oral health problem in the county.

Commissioner Doug Smith and Chairman Michael DiTerlizzi voted to stick with the plan to fluoridate the water.

“This will be an enormous letdown for a community that deserves better,” Smith said.

Michael Easley, dental coordinator for the state Department of Health, said fluoridating water was not dangerous in controlled amounts and was not medicating the public.

“It’s not a prescription medicine,” he said. “It’s a nutritional supplement.”

That elicited laughs and shouts of derision from fluoride opponents.

Dentists and health officials from as far away as Rockledge endorsed fluoridation, citing national research showing drinking fluoridated water prevents tooth decay. Dentists and hygienists said poorer residents do not have as much access to dentists and that a progressive area like Martin County should do something to help them.

“I am taking out an inordinate number of decayed, bombed-out, abscessed, pus-ridden teeth in children ages 3 to 6 and teens ages 13 to 16,” said Inge Ford, a doctor with the Martin County Health Department. “Can you say ‘Third World developing country?’ This is unreal.”

Dentist David Boden said adding fluoride to the county’s water would keep children from becoming what he called “dental cripples.”

Pat Austin, with the county’s health care coordinating board, said the use of fluoride is “a historically proven method.”

Opponents called the claims of fluoride’s benefits a conspiracy by companies that want to make a profit selling the chemical, which is a byproduct of the manufacturing of aluminum and nuclear material.

“They found a way to sell this radioactive elixir to municipalities,” said Monte Perini. “It’s all about big bucks.”

But dentists dismissed that conspiracy theory.

“The belief in a conspiracy to force fluoridation is at best ludicrous,” Jensen Beach dentist Rad Orlandi said.

Before the meeting, opponents held signs in front of the county administrative complex that labeled fluoride a poison. Some brought their children, and one opponent put his dog in a blue shirt.

Stuart Mayor Mary Hutchinson was in the audience watching the debate. The city plans to start fluoridating its water next year, but Hutchinson said the city council probably would discuss the issue next month based on the opposition the county has encountered.