A forum meant to showcase both sides in the debate over the safety of water fluoridation turned lopsided Thursday night, when the dentist representing the pro-fluoride side initially declined to participate, saying the role he was supposed to play had been misrepresented to him.

Dentist Gary Brooks of Willamina said he had not been asked to give a presentation, let alone a keynote presentation in a pro-con format. He said he thought he’d merely been invited to attend.

The forum grew contentious even before it began, and turned more so as it progressed.

The dentist, anti-fluoride activist Bill Osmunson of Lake Oswego, came prepared with a detailed slide presentation.

However, he ran into problems of his own when his computer was unable to interact with the system in the Carnegie Room of the McMinnville Public Library.

Meanwhile, audience member Denise Murphy raised an objection, saying the presentation shouldn’t go forward if it wasn’t going to be balanced. She said both sides should be fairly represented, as the meeting was taking place in a city-owned and tax-payer-funded building.

That led to shouting between Murphy and forum organizer Jo McIntyre, an anti-fluoride activist, who accused Murphy of representing a dental hygienist organization.

Murphy, a friend of Library Director Jill Poyer, later contacted the News-Register to deny the allegation.

In fact, she said, she works at the county courthouse and attended the meeting solely on her own behalf.

“I am not a shill for anyone even remotely connected to dentists or the fluoride industry,” Murphy said.

Poyer also contacted the News-Register, complaining that McIntyre had misled her.

“I was assured by Jo McIntyre that both sides would be represented in a fair and equal manner, and moderated accordingly. That clearly did not happen,” Poyer wrote.

“It was clearly a misuse of our meeting room guidelines and I am personally responsible for the error in judgment. … I was actually there for most of the meeting and was able to observe the imbalance first-hand.”

Brooks eventually agreed to improvise a presentation, to satisfy the audience.

During the evening, moderator Larry Bohnsack of KLYC Radio tried to diffuse the tension — and occasional shouting — with jokes about bourbon-flavored toothpaste and confusing formaldehyde with fluoride.

When a woman who identified herself as a dentist angrily told Osumson that he was counteracting the efforts of dentists who have “worked like dogs” to improve the public’s dental hygiene, Bohnsack noted his golden retriever doesn’t work at all hard.

“Well, I have toy poodles, and they are very energetic,” the woman responded.

Osmunson told the audience that dental cavities have been declining steadily and substantially worldwide since 1930, well before water fluoridation began. He said it has not been limited to countries where water is fluoridated.

Fluoridating water is actually illegal under the federal Safe Drinking Water Act, passed in 1974, because the act prohibits adding anything to public water systems other than agents intended for disinfection. Osmunson said federal agencies “are deferring regulatory action” on the issue of water fluoridation, which is widespread throughout the United States.

He said the artificial fluoride added to drinking water, a by-product of phosphate fertilizer, is known to be toxic. He told the audience that a tube of fluoridated toothpaste contains instructions to use a pea-sized amount, which contains a quarter milligram of fluoride, to avoid swallowing it, and to contact the Poison Control Center if it is swallowed.

“That’s the same amount of fluoride as there is in one glass of McMinnville water,” he said.

Brooks told the audience he grew up in McMinnville and practiced dentistry in the community for several years before moving to Willamina. He said McMinnville and Sheridan fluoridate their water, while Willamina does not.

“It is obviously anecdotal evidence, which means there’s no scientific basis to it, but I am here to tell you that the kids in McMinnville and Sheridan have much better teeth than the kids in Willamina,” he said.

Brooks said he believes “the preponderance of evidence” shows that fluoride in effective in reducing tooth decay.

“The difference between a poison and a drug is in the dose,” he said.

He went on to note that McMinnville’s population has roughly doubled since 1982, when it had 19 full-time dentists, but it now gets by with 18.

“This tells me that the people in McMinnville are not needing the care,” Brooks said. “I believe that is due to fluoride.”

He said, “Seventy-six percent of people in the nation are drinking fluoridated water. I don’t think that would be the case if it were dangerous.”

Both dentists agreed that fluoride is absorbed by the teeth up to age 8, after which it becomes a topical treatment only.

People living in areas with naturally fluoridated water have much lower rates of tooth decay, even though in areas where the dose is high, they often suffer discoloration from a condition called dental fluorisis, Brooks said.

Osmunson argued that people today receive higher doses of fluoride than originally intended, because it is added to toothpaste and mouthwash, as well as drinking water.

In addition, he said, there is a significant difference between natural fluoride, which is calcium-based, and artificial fluoride, which is not. The calcium prevents the fluoride from being readily absorbed by the body, he said.

Brooks told the audience, “Fluoride is fluoride. Once it’s ionized — that means dissolved — that’s the stuff that gets in your teeth.”

The McMinnville City Council will hold a public hearing Tuesday evening at 7 p.m. on whether to put a measure on the ballot allowing residents to vote whether they want to continue fluoridating the city’s water. The meeting will be held in the Civic Hall, 200 N.E. Second St.