It is the final day for dentists in England and Wales to sign a controversial new NHS contract.
Many dentists are unhappy with the new arrangements
One in 10 have rejected it and will withdraw from NHS work, while many more have registered objections, a British Dental Association survey suggests.
It says about 60% of those who signed did so "in dispute" and will contest the terms under an appeals procedure while continuing to provide NHS care.
The government argues the contract will encourage dentists to offer NHS care.
It will give the dentists a guaranteed income for NHS work, patients a simpler system of charges and local decision makers more power to organise services, ministers say.
NEW DENTAL FEES
£15.50 - Will cover a check up, diagnosis and preventative care such as scale and polish
£42.40 - Covers all treatment in £15.50 pay band plus fillings, root canal treatment and extractions
£189 - Includes treatment in first two pay bands and also more complex procedures such as crowns, dentures and bridges
But the BDA said it will create even more barriers to patients receiving treatment on the NHS.
And some orthodontists, who have set up new practices and mainly treat children, fear the nature of the contract will give them no option but to build up waiting lists.
Under the new system, to be introduced in England and Wales, dentists are supposed to be given more time to carry out preventative work while the pricing system is being simplified.
The changes mean the old system of over 400 different charges for dental work will be replaced by three bands - £15.50 for a check up, £42.40 for a check up and filling and £189 for more complex work such as crowns.
However, the BDA argues that the targets set out in the new contract are unachievable. They say it will not increase the time dentists can spend with patients, or lead to an improved standard of care.
The BDA survey of local dental representatives found 90% of respondents believe access to NHS dentistry will worsen.
It is estimated that under the new contract, to be implemented from 1 April, dentists will receive an average annual income of £80,000.
But this figure is vigorously disputed by dentists, who argue that expenses, which are spiralling ahead of inflation, will eat substantially into profits.
Of the 109 local dental committees in England and Wales, 35 responded to the BDA survey.