NHS dentists treat 500,000 fewer patients after Labour's controversial new contract

It means an extra 500,000 patients have been forced to either pay for expensive private care or go without treatment and risk agonising toothache and gum disease.

Ministers promised the new contract, introduced in 2006, would give more patients the chance to register with an NHS dentist and encourage preventive care.

But there is mounting concern that it has led to a worse service.

Many dentists have rejected NHS patients, are providing less complex treatment amid fears their income will be hit, or have left the NHS because they are not paid well enough for the amount of work done.

In the two years to last October, a total of 27.6million saw an NHS dentist, according to official figures.

It compares to 28.1million in the two years to April 2006, when the old dental contract was scrapped.

The figures from the NHS Information Centre for Health and Social Care will be an embarrassment for the Government.

In 1999, then-prime minister Tony Blair pledged everybody would have easy access to an NHS dentist within two years.

Dentists, MPs and patients' groups branded the situation a "disgrace" and a "milestone of failure" for the Government's dental policy.

Norman Lamb, the Liberal Democrat health spokesman, said: "The crisis in NHS dentistry is this Government's hidden legacy.

"When will the Government bow to the inevitable and admit that the dental contract has failed?"

Tory health spokesman Mike Penning said: "These figures are a disgrace, considering Labour's promises that everyone would have access to an NHS dentist."

Susie Sanderson, chairman of the British Dental Association's executive board, said: "The Government's reforms have failed to achieve the stated aim of improving access to care for patients.

"They have also failed to allow dentists to deliver the kind of modern, preventive care they believe their patients deserve.

"The loss of access to NHS dental care for half a million patients is a milestone in the failure of these reforms."

Last month, a British Dental Association survey revealed that more than 1,000 dentists had stopped providing state-funded care since the introduction of the unpopular contract, even though their earnings had risen to as much as £128,000 a year.

It followed a survey by Citizens' Advice which found at least seven million patients, including children, had been unable to see an NHS dentist for almost two years.

And in October last year, a survey by the Patient and Public Involvement Forums revealed that one in 20 patients had resorted to DIY treatment – in some cases pulling out their own teeth.

One in five has gone without treatment because of the cost.

Official figures also show a drop in the amount of complex work being carried out.

Critics have claimed this is because the contract allows dentists to earn more from cheaper procedures.