By Jane Dreaper
BBC radio health correspondent
Obtaining dental treatment on the NHS may become more difficult, when a new contract is introduced in England next month, BBC research suggests.
People may find it harder to find an NHS dentist
Three hundred out of 1,000 dentists surveyed replied to the World at One poll.
A quarter of respondents said they would not sign up to the new contract.
If those results were replicated across the country, it would mean that over 137,000 patients might have to go private, or find another NHS dentist.
Around half the dentists surveyed said they would sign - but with deep misgivings about the future.
Jim Page, a dentist in Tunbridge Wells, Kent, is among those who insist the future workload will go up, not down.
He says that, at his practice, they will probably end up introducing charges for children who stay on their books:
"When we looked at the figures that they sent us we thought 'oh that looks all right'.
"But then, when we actually looked at our appointment books and records as to how much work we had actually done the previous year, we found it was between 20-30% less than they wanted us to do the coming year.
"It doesn't tie up with what the government are saying."
Nectarios Katsikas, is a Greek dentist who's been working in Tunbridge Wells for about a year, seeing NHS patients who find it difficult to get treatment elsewhere - but he's worried about the future.
"After April 1 when people realise that 70-80% of dentists who used to do NHS don't want to do NHS any more, there will be a lot of unhappy people."
Nectarios has expanded his NHS work in recent months, and now has 1,000 families on his list.
But he won't accept new patients on the NHS after April - because he's calculated he will take home just £350 a month for what is currently 70% of his workload.
"The sums are very low - disappointingly low. If the health authority does not renegotiate the contract I won't even be able to meet my mortgage and my car loan after April 1.
NHS managers in Kent say they're confident most practices will sign up to the new contract.
But many dentists who responded to the World at One and PM programme's questionnaire said that even if they were signing, they were faced with decisions that could make life difficult for patients.
A practice manager in Swindon had this to say: "It is my belief that the government are trying to do away altogether with NHS dental care but rather than admit to this, they are making it look like the dentist is wishing to go private by choice due to financial gain.
"We have the ability and capability to take on at least 10,000 more NHS patients, but are unable to do so because there is no funding."
And a dentist in Hampshire complained about primary care trusts, who will be taking over dentistry budgets.
"My impression is one of complacent ignorance at PCT level, which is now leading to ill-considered last-minute rushing about."
It's difficult to predict the exact effects of this shake-up at the moment.
The government says the new contract will provide patients with a clearer system of fees, and dentists with a guaranteed salary of £80,000 for slightly less work.
It seems like a good deal - especially as dentists are driven by business decisions as well as by patient care.
More dentists are being recruited - and ministers say the reforms will put more power in the hands of local decision-makers.
But dentists' leaders dispute that optimism, and say the reforms are shambolic.
Health minister Rosie Winterton said: "All the indications are that the majority of dentists will sign up."
And she added that, if there was a shortfall, primary care trusts would be able to buy in dental care from other NHS dentists or other corporate bodies who were "very keen" to provide services.
Shadow Health Secretary Andrew Lansley said: "We don't know in detail what the response will be to the contract.
"But I fear that what this survey has found correlates with what dentists have been telling us."