MPs are debating whether health authorities and local communities should be able to sanction the addition of fluoride to the water supply.
Would fluoridation tackle tooth decay
Here two experts on either side of the argument explain the issues to be debated to BBC News Online.
Professor Liz Kay is scientific advisor to the British Dental Association.
"All the scientific research that has been done has shown that fluoridation has a beneficial effect on children's health.
"I spend all day taking children's teeth out, and it's not a pleasant thing to do, especially when they are very young.
"Fluoridation does make a difference.
"Birmingham - where the water supply does have fluoride added to it - and Manchester - where it isn't - are very similar in terms of social demographics.
"But Manchester has three times the amount of decay.
"The evidence is absolutely overwhelming, with a 50% reduction in tooth decay where there is fluoridation.
"What the BDA is advocating is that fluoridation is targeted at areas that need it most, areas with high levels of tooth decay, which tend to be the more northern, urban conurbations.
"Fluoridation is for the greater good, particularly for the most vulnerable in society.
"The science does not support the view that fluoridation is harmful to health.
"The Medical Research Council carried out a review and found there was no evidence of health risks.
"Sugar is one of the causes of tooth decay. But people can't fight the overwhelming push from manufacturers to eat sweet things.
"We should be educating them of the dangers of tooth decay but they are not going to stop eating sweet things - it's just not going to happen."
Spencer Fitzgibbon is a member of the executive council of the Green Party, who wrote 'Truth Decay', a report into the dangers of adding fluoride to water supplies.
"Studies from around the world have shown there is no significant difference in rates of tooth decay between fluorided and non-fluorided areas.
"If you look at Gateshead - where fluoride is added to the water - it has the same level of tooth decay as Liverpool, which isn't fluorided.
"We all know that poor diet, eating too much unrefined sugar and not brushing our teeth are causes of tooth decay.
"Fluoridation doesn't address any of those issues.
"Health education for parents and children would.
"The York Review on fluoridation, commissioned by the government, said there was 'little evidence' it would be beneficial.
"There have been scientific papers that have made some sort of link between fluoridation and problems ranging from bone cancer and brittle bones to Irritable Bowel Syndrome and thyroid problems.
"The York Review found no conclusive evidence, at the concentrations it was talking about being added to water, that that would be a problem.
"But fluoride is a cumulative poison. What counts is how much you have in your body.
"Tea is high in fluoride. If you add fluoride to water, swallow fluoride toothpaste as well as drinking lots of tea, no one's going to be testing to see how much fluoride you've got in your body."