The last NHS dental provider in a Northamptonshire town will only see private patients from the summer.
In a letter to patients, seen by the BBC, Bridge Dental Practice in Towcester said it was "no longer viable" to offer NHS services after a recent change in the contract.
Conservative MP for South Northamptonshire, Sarah Bool, raised the issue in the House of Commons in April and said: "This represents a significant loss, especially in a rapidly expanding town and also with no other NHS dentistry provision around for miles."
Northamptonshire Integrated Care Board (ICB) confirmed the dentists' contract with the NHS will end in July. The Department of Health has been approached for comment.
The practice stated in its letter that it had been offering NHS dental services since 2009, but will need to reduce its patient list by approximately 70%.
Anne Parkes, 78, of Towcester, has been an NHS patient at the practice for around eight years and said: "I think it's a great shame because there are a lot of people who need an NHS dentist who don't have the facility to pay for private care and without NHS dentistry, I think a lot of people are going to suffer."
She added that it took "18 months to get onto an NHS register, and I think it's a great shame that there is no NHS dentistry here".
There are three dental practices in Towcester, two of which already only accept private patients.
Terry Richards has lived in the town for about six years, but has stayed with his NHS dentist in Milton Keynes.
"I think it's shameful, I think dentists all around need looking at and sorting out," he said.
Colin Simmonds, who lives in Gayton and has been a patient at Bridge Dental Practice for more than 17 years, told BBC Radio Northampton: "I'm very lucky I don't need much treatment, but I believe in preventative care, and I've always relied on regular, affordable check-ups."
He added: "This has happened overnight; this is the result of years of failure by successive governments to properly fund and fix NHS dentistry."
Over the last ten years, the number of routine NHS examinations has fallen by 6% in England.
Bool told the Commons she had written to the ICB and the Health Minister about what NHS dental services would be available for local people.
A spokesperson for Northamptonshire ICB said: "Bridge Dental in Towcester has given notice to end their contract, and this will finish at the end of July 2026.
"We recognise there has been significant ongoing access issues for NHS dentistry across South Northamptonshire, particularly for patients without an existing NHS dentist, and we are actively working to identify a viable solution to improve access in this area."
Bridge Dental Practice was contacted for comment.