Thomas Patterson for The New York TimesProtesters’ signs outside City Hall in Portland, Oregon.

Portland, Oregon, has once again voted against adding fluoride to the city water supply — not, it seems, out of any love of cavities, but in response to a perceived threat to the city’s anti-establishment culture. At least that’s the view of one of those handy political science professors inevitably called upon to explain the inexplicable.

Fifty years ago, fluoridation was first taken up by the nation’s major cities as a serious civic issue. There were angry all-night hearings in New York and other locales and warnings of a Commie plot to despoil vital bodily fluids. The debates were loud and sprawling, tailor-made for cable news and Internet aggregators nowhere in sight back then. It seems an open question whether fluoridation would have made the grade in the cut-and-thrust of today’s politics.

Twenty-nine of the nation’s 30 most populous cities eventually decided to fluoridate their water. But Portland has remained the nay-saying standout among the 30, rejecting fluoridation four times since 1956 despite repeated pleas from government and health officials and well organized voter drives.

The vote this time was by a 60-to-40 margin after what The Oregonian newspaper called “stark and heated divisions” among the city’s heavily liberal, mainly Democratic electorate. No hangings in effigy, but the two sides complained of vandalized lawn signs and onslaughts of misleading propaganda.

Opponents, as ever, warned that fluoride would unnecessarily, even dangerously pollute good water. Proponents cited sundry studies by the nation’s major health and government research institutions pronouncing fluoridation an indisputable success in reducing tooth decay. Some losers uncharitably attributed the result to a strain of self-centered contrarianism in the city — solipsistic stoners and others reducing politics to entertainment.

“The issue doesn’t go away at the end of the election,” cautioned a leader from the losing side who probably only galvanized the victors for a fifth go.

Comment by James to the New York Times: