Dental patients are not getting the full treatment they may need because of tight limits on NHS payments, county dentists have admitted.

In a report by health watchdogs, practices said problems with the NHS contract meant they often left fillings for up to six months, were more likely to pull out a tooth than treat it, and were unwilling to register people with poor teeth.

As a result, Oxfordshire Primary Care Trust's Patient and Public Involvement Forum has demanded NHS managers fight for better treatment by highlighting the problems to a review of dental services by the House of Commons health select committee.

The PPIF contacted all 116 dental practices in Oxfordshire. Of the 36 who replied, 97 per cent said it was more difficult for patients to get NHS treatment under the new contract, launched last year April 2006.

Almost three-quarters said the low-cost care was inferior to private treatment, and nearly two thirds said the quality of NHS care had been compromised by the new contract.

The problems, they claim, were caused by the payment system, which meant dentists were paid one fee, irrespective of the amount of work they carried out.

For example, one filling costs £43.60, but a dentist would get the same amount if they carried out several fillings on one patient - which would not cover their overheads.

They told the PPIF it was a "financial disaster" to treat people who needed a lot of care, and a patient's treatment was often staggered over months, to ensure the dentist was paid for all the work needed.

Russell Evans, of Russell & Janet Evans Dental Practice in Kidlington, opted out of NHS work because he would not sign the new contract.

He was not surprised by the survey results. He said: "It's disappointing, but it's always been the case that NHS dentists have had to make the best of a bad job.

"We felt we could no longer do that, which is why we washed our hands of it. Anyone with any foresight knew this was going to happen."

The PPIF report stated: "It is a matter of concern that fixed fees for widely differing amounts of work could potentially encourage dentists to skip essential work, due to time constraints and inadequate reimbursement for time, material costs and overheads.

"This cannot be in the interests of the public's dental health."

Report author Marion Judd suggested the PCT was not allowed to openly criticise the NHS dental contract, although its staff were aware of the problems. She said: "They can't criticise it, but we can, and we believe it is unfair to both dentists and patients.

"It seems pretty common that dentists can't afford to treat patients according to their need. They are forced to treat patients like a production line and have to run the service to their best advantage, rather than the patients'."

A PCT spokesman said dentists should not have been financially penalised under the new contract, which was based on earnings over a full year, but admitted adjustments could not be made locally.

She added: "Dentists are paid to provide a range of treatments and should do so as determined by the patient's dental need."