Almost eight out of ten dentists in Birmingham are to cut down on National Health Service work because of controversial new contracts.
Patients will find it more difficult to find a practice offering NHS treatment, Birmingham Local Dental Committee has warned.
The new contracts, which come into force on April 1, were an attempt by the Government to tackle the dentist shortage.
But it may have the opposite effect, as almost two out of ten dentists refused to sign it.
Another six out of ten say they have signed, but intend to use the next three years to cut down on their NHS work.
The Local Dental Committee surveyed all 390 dentists in Birmingham.
Eddie Crouch, secretary of the Birmingham Local Dental Committee, said: "We have had replies from half the dentists so far, and 80 per cent of those will sign the contract but 20 per cent will not.
"Around 60 per cent said they will use the period of the contact, which lasts for three years, to reduce their reliance on the NHS for work."
Birmingham MP John Hemming (Lib Dem Acocks Green) said: "What we are seeing here is NHS dentistry being phased out by the Department of Health.
"The contract guarantees the income of dentists, so this is not about greed."
Dentists have come under fire from some MPs after Ministers confirmed they could expect to earn £80,000 a year under the new contracts.
Steve McCabe (Lab Hall Green) accused them of trying to "blackmail elderly people" into buying private health insurance.
The Department of Health said the contracts offer dentists a better deal than in the past, and new dentists would be recruited to replace any who left the NHS.
The new contracts will improve dental care and allow dentists to concentrate more in preventing tooth decay, according to Ministers.
Health Minister Rosie Winterton said: "The public have every reason to be confident in the future of NHS dentistry.
"The early signs are that the vast majority of dentists will sign these contracts."
A national survey this week found more than half a million children will be removed from lists entitling them to free NHS treatment when a new pay deal comes into effect.
And another national survey yesterday warned seven out of ten dentists could eventually stop doing NHS work.
Almost half of British adults and two thirds of children are currently registered with one of the country's 19,300 NHS dentists.
The current system pays dentists for each piece of work they do, but critics say this has encouraged a "drill and fill" culture in which dentists perform as many procedures as they can, in order to make more money.
The new contract will award a lump sum. Dentists will then be expected to fulfil a certain number of procedures to earn the cash.
Dentists claim this removes incentives to perform necessary dental work.
Mr Crouch said: "One of the unfortunate aspects of this is that it has hurt relations between dentists and the primary care trusts, which administer the contracts."