Health advocates say a Hamilton City Council decision to drop fluoride from its water supply will mean a costly decline in oral health in which the poor will suffer most.

A special tribunal yesterday voted 7 to 1 in favour of removing fluoride from the city's water supply following four days of submissions.

Dr Felicity Dumble, Waikato District Health Board's medical officer of health, said the decision discounted the opinion of the vast majority of dentists and doctors locally and in New Zealand.

"They instead listened to a highly vocal minority and as a result the oral health of Hamilton residents will suffer, dental decay will increase and DHB dental services will be stretched and resources will need to be reallocated."


She said associated oral health inequities based on ethnicity and socio-economic status would also increase.

Principal dental officer for community oral health Dr Rob Aitken said a study of 16,500 children in Australia showed there was a big reduction in tooth decay for those who drank sugar-sweetened drinks but had access to fluoridated water.

"Given we consume more sugar per capita than Australia, the US or Great Britain then if you take fluoride out of the water and fluoride reduces decay - the logical outcome is decay is going to increase," he said.

"We can't access everyone to teach them how to brush their teeth and that's the biggest problem ... it's the children in the lower socio-economic groups that don't even have toothbrushes, it's those kids who are hardest hit."

Mayor Julie Hardaker, who tabled the motion to remove fluoride, said the issue was a public health matter that central government needed to determine.

But deputy mayor Gordon Chesterman said there was "a lack of clear proof" of benefits in fluoridation as well as a continuing reduction in support for it with just 23 of New Zealand's 67 local authorities using it in their water supplies.

A $160,000 referendum of Hamilton City voters in 2006 drew 38 per cent of voters - 70 per cent of whom voted to keep fluoridation. But during a campaign for public input the tribunal received 1560 submissions - with 89 per cent (1386) opposed to fluoridation.