The New Zealand Dental Association has dismissed a recent study that claims fluoridation can lead to hypothyroidism, a condition that slows the body's metabolism.
The study of underactive thyroid conditions diagnosed by family doctors in Britain found a correlation between higher levels of fluoridation and an underactive thyroid.
But the association's chief executive, David Crum, said the paper failed to highlight that iodine deficiency was a major cause of hypothyroidism.
He said the research was flawed because fluoridated areas of Britain were also the areas with high iodine deficiency.