Labour was branded "utterly reckless" over its failure to carry out an impact assessment into its national insurance raid on dentists.
There have been fears after the hike in employers' national insurance contributions was announced at the Budget.
Health minister Stephen Kinnock confirmed in response to a written parliamentary question that no assessment had been made on the impact on dentists.
British Dental Association chair Eddie Crouch said: "When millions can't access NHS dentistry it's utterly reckless to heap new costs on struggling practices without even considering the impact.
"The Treasury failed to grasp that primary care is delivered by thousands of small businesses. Each requires immediate answers on how they're expected to balance their books."
The Lib Dems are calling for dentists to be exempt from the rise, along with GPs, pharmacies and hospices.
The party's health and social care spokesperson Helen Morgan, who submitted the written question, said: "The Government has pulled the rug out from under crucial public health services without thinking twice.
"It's shocking that this careless decision has been taken with no regard to the impact it would have on NHS dentists. Many will have no choice but to cut services and staff numbers.
"NHS dentists and other health and care providers must be exempted from the Chancellor's tax increase. Without reversing the hike, the Government's plan to rescue our health service is a plan in name only."
NHS dentists have warned that they will be forced to cut services for patients or reduce staff numbers following the increase.
A Government spokesperson said: "Taking the difficult choices to fix the foundations of the economy at the Budget meant we could deliver a £26 billion extra investment in health and social care
"We will set out further details on allocation of funding for dentistry for next year in due course. In the meantime, we are committed to rebuilding NHS dentistry, starting by providing an extra 700,000 urgent dentistry appointments to help those who need it most, and by reforming the dental contract to encourage more dentists to offer NHS services to patients."
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