The vote follows a nearly seven-hour public meeting last week in which proponents and opponents traded statistics and made their best arguments for why Portland should or should not use fluoride to combat tooth decay.
"This is the right thing to do, and I'm pleased to vote aye," Commissioner Dan Saltzman said first, drawing boos from the crowd.
Commissioner Amanda Fritz, a former nurse, parted ways with colleagues and declined to say before Wednesday's vote how she would come down. Before voting yes, she gave a lengthy speech noting that fluoride was not a silver bullet. "We cannot simply add fluoride and expect all children and adults to have cavity-free teeth," Fritz said. "Clearly, more education is needed."
Commissioner Nick Fish, who missed much of the public testimony at last week's meeting, said he was "proud" to vote aye.
Mayor Sam Adams was the final yes vote.
Adams ejected several members of the audience who heckled members of the City Council during Wednesday's vote.
-- Beth Slovic