OLYMPIA — A year after voters in Olympia rejected fluoridation of water supplies for the third time, a statewide dental group is at the Capitol, pushing for legislation to make fluoridation mandatory throughout the state.

The Washington State Dental Association proposal would require public water systems with more than 1,000 hookups to fluoridate water supplies over a five- to 10-year period, said Dan Davidson, a pediatric dentist based in Olympia.

Fluoride should be put in public water supplies because it effectively cuts dental disease by as much as 65 percent, Davidson and dental association representatives told The Olympian’s editorial board Wednesday.

Opponents who narrowly won the November 1998 vote against fluoridating Olympia’s water supplies said they also would oppose any push to require fluoridation statewide.

“It should be up to a community. It should be up to an individual,” said Chris Carson of Olympia, co-chairwoman of the Citizens for Pure Water group, which is against putting any nonessential material into water supplies. “Once it’s in the water, you can’t take it out.”

A fluoridation proposal will get consideration next year in the Legislature. State Sen. Pat Thibaudeau, D-Seattle and chairwoman of the Senate Health and Long-term Care Committee, said in an interview that she will sponsor a bill promoting fluoridation statewide.

“Fluoride has been proven to be preventive of dental disease,” Thibaudeau said. “We have a horrible problem of dental disease around the state.”

The dental association defended use of a statewide mandate on grounds that a greater public good would be served — even though voters in some communities oppose fluoride.

Going community to community to win votes for fluoridation is a long-term alternative, and Washington needs to deal with rampant tooth decay among children, said Alice Kaderlan, director of communications for the dental association.”I see on average three to five kids a week at (Providence) St. Peter Hospital in the operating room with rampant dental disease,” Davidson said, adding that fluoride has proved effective in fighting tooth decay for 50 years.

“It’s the most cost-effective, successful medical treatment ever. … It will save, for every $1 spent by a city, $80 in dental treatment,” he said.

Olympia dentist Bruce Cooper said parents who give their children fluoride tablets as directed cannot improve upon the protection offered by fluoridated water.

But Carson said fluoride is a toxic chemical that poses health risks to people with brittle bones, kidney problems, diabetes and heart problems.

Kaderlan of the dental association quickly dismissed those claims, arguing they have no credible, scientific basis.