Dental contracts 'need reform', says OFT
29 May 2012 Last updated at 11:39 BST
It is being claimed that some dentists are misleading their patients about their right to NHS treatment, so they pay for private treatment instead.
The Office of Fair Trading says about half a million people a year may have been given the wrong information about their treatment options.
However, the British Dental Association says the research indicates most patients are happy with the care they receive.
John Fingleton is Chief Executive of the Office of Fair Trading, he told the BBC that dentists must tell patients about NHS prices.