New contracts for NHS dentists were introduced in 2006
NHS dentists in England are earning significantly more since new contracts were introduced two years ago, official figures will suggest.
The contracts were meant to improve NHS access, but a recent study suggested fewer patients were being treated.
The British Dental Association said the figures - showing average annual incomes as up from £87,000 to £96,000 - did not accurately reflect reality.
The government said it would comment when the figures came out on Tuesday.
The BDA said the figure on average incomes did not accurately represent dentists' income, because it did not take into account tax and other business costs.
The statistics also included payment for work carried out before the contracts were introduced in 2006, said the BDA.
Under the new contract dentists are also subject to a new system called 'claw back', which means the NHS pays them in advance for a stated number of treatments.
If they do not carry out all the work they may have to pay some of the money back.
The BDA said 48% of dentists fell into this category and could eventually end up earning less under the new deal.
In July a report by MPs said the changes to the system had not been successful.
The new contract, introduced in 2006, was intended to simplify charges and make it easier to find an NHS dentist.
But the Commons Health Committee said access remained "patchy" and there had been a sharp fall in the number of complex procedures.
In response to the MP's report the Department of Health insisted the reforms - which were later adopted in Wales - were starting to work in England.
In the first year of the contract, the number of complex treatments - including bridges and crowns - halved, and the number of root canal treatments fell by 45%. Both attract higher fees under the new scheme.
The committee said there were concerns that some patients were not getting the complex treatment they needed.
Last month figures from the NHS Information Centre showed fewer patients were being treated, despite more dentists joining the NHS after the new contract.
Some 27m patients were seen by an NHS dentist in England during the past two years - 1.1m fewer than the previous two years.
But there were 655 more dentists doing NHS work in 2007/08 than in the previous year - an increase of 3.2%.