Ministers have ordered an independent inquiry into continuing problems accessing NHS dentistry in England.
New contracts for dentists were introduced in April 2006 in an attempt to widen access for NHS patients.
But figures show 1.2 million fewer patients visited a dentist in the two years to June than in the period before the reforms were introduced.
The Department of Health said access had improved in some parts, but critics said the reforms had failed.
The review team, including oral health professionals and led by Professor Jimmy Steele of Newcastle's School of Dental Sciences, will study current provision and report in the spring.
Announcing the review, Health Secretary Alan Johnson said funding for NHS dentistry had increased sharply, and the number of undergraduate training places for dentists had risen by 25%.
But he said: "It is disappointing that despite this investment there remain areas of the country in which people are unable to find an NHS dentist.
"I have appointed the independent review team to help us understand what more needs to be done to ensure that every person who wants to visit an NHS dentist can do so."
The new contract was drawn up to reform the so-called "drill and fill" culture by letting dentists spend more time with their patients.
But it has proved unpopular with dentists, with about one in ten refusing to sign it.
There has also been criticism that because dentists now receive a flat salary, they no longer have any financial incentive to carry out difficult work such as crowns and bridges.
NHS Information Centre statistics show that in the two years to last December less than half the adult population went to an NHS dentist in England.
Mike Penning, the Shadow Health Minister, said: "The government has shown gross complacency in persisting with this ludicrous contract for NHS dentistry.
"Many of the serious problems with patient access and the drastic reduction in complex treatments could have been prevented had Labour piloted the contract properly before imposing it.
"This review is in fact little more than an admission of failure."
Norman Lamb, for the Liberal Democrats, said: "When ministers introduced the new dentists' contract they said it would increase access to the NHS and make NHS work more attractive for dentists.
"Instead, access has got worse and in many areas NHS dentistry is in a real mess.
"Dentists are united in their opposition to a system which does nothing to encourage good preventive dental care and has led to a decline in complex treatments."
The British Dental Association welcomed the review.
Susie Sanderson, BDA executive board chair, said: "The announcement recognises the significant problems patients and dentists face and places the Department of Health on a path to addressing those problems."
Ashleye Gunn, of the consumer magazine Which?, said: "It is a disgrace that patients have suffered from a dental postcode lottery for so long.
"In the 21st century, it's disheartening that people still find it difficult to get an NHS dentist
"Patients must be at the heart of NHS dentistry and their views taken into consideration for these measures to have significant bite."