An undercover investigation has revealed that some dentists are overcharging patients for treatment that should be available on the NHS.

Channel 4’s Dispatches programme sent seven members of the public into surgeries that do both NHS and private treatment.

They all went in as NHS patients, but six out of the seven were recommended private treatment - the most common being hygiene work - despite a scale and polish being available on the NHS for £17.

An undercover reporter was also sent to three surgeries as an NHS patient in need of root canal treatment and a crown.

This would have cost £198 on the NHS, but he received quotes of £598, £678 and £725.

Leading dentist Dr Anthony Halperin told the programme: “I have felt with all the pictures of these dentists that you’ve shown me that they should have been accepted as NHS patients.”

He added: “If the patients go in as NHS patients, and are told work is not available under the NHS which is available under the NHS, then they are in breach of their contract.”

Danny Pretorius left the NHS last year and has called for an overhaul of the system.

“I believe that the government should say ‘right, we’re going to provide an NHS service’.

“They should then employ every dentist they want to on a set salary which is paid to them by the government or the NHS… those dentists should not be allowed to do any private treatment at all,” he said.

A Department of Health spokeswoman said: “We are committed to improving dental access, and we will achieve this sustainably by replacing the existing dental contract with one that pays dentists for the number of patients registered and the quality of the care they provide, rather than the number of treatments carried out.”