Phil Gowers, chairman of the Hampshire and Isle of Wight Local Dental Committee, said the decrease was 'cataclysmic' and that greater financial support was needed.
'There's been a slow erosion of funding for decades,' he said. 'It's now reached the point where it's just not sustainable and we've seen this with contracts being handed back.
'We need more money – that's the bottom line. There has to be more investment so that we can create the preventative system we need.'
But he added that there were 'potential' improvements being developed in the city that would see extra spaces provided.
Smile Dental Care opened a new NHS dental surgery in the former Hanway Medical Practice building in Buckland in June but its spaces were filled up within two weeks having been 'inundated' with calls.
This followed in the wake of the 2019 closure of Colosseum Dental Group and its three practices which left an estimated 20,000 people without an NHS dentist.
The woeful situation sparked The News’s ‘Kick in the Teeth’ campaign, which demanded a radical overhaul of Portsmouth’s decaying dental industry.
Politicians threw their weight behind the effort and have now warned that the latest revelation demonstrated the 'desperate' need for more work to be done in the city.
Stephen Morgan, the Labour MP for Portsmouth South, who has raised the issue in parliament, urged the government to step up its efforts to increase provision.
'For far too long Portsmouth people have been struggling to find appointments,' he said. 'Spiralling waiting lists and closures of practices across our city add to concerns I share with many that we are sleepwalking into generational damage to patient care.
'Good oral health is good health full stop, yet we know that millions of patients struggle to get access to NHS dentistry as practices struggle to fill vacancies, with many patients falling through the cracks.'
Across England and Wales, more than 2,500 dental posts have been lost, leaving patients waiting years for routine check-ups.
The British Dental Association has warned this could be exacerbated with 'significant numbers' of dentists planning to leave the NHS due to 'years of failed contracts and underfunding'.
'NHS dentistry is hanging by a thread, because without NHS dentists, there will be no NHS dentistry,' Shawn Charlwood, the chairman of its general dental practice committee, said.
'It’s a really serious situation and every dentist that is lost or every vacancy for NHS dentistry that remains unfilled affects thousands of patients in terms of care and their ability to access care.'
He said the pandemic had accelerated the decline in numbers and that there was now an 'exodus' in the sector.
An NHS spokesman said: 'The NHS has taken unprecedented action to support NHS dentists throughout the pandemic by providing additional funding for practices unable to deliver their usual levels of activity, alongside rapidly setting up 600 urgent dental centres across England so patient services could be maintained during the pandemic.
'People should continue to come forward for the dental care they need and the care and treatment of people who need it most should be prioritised.'
A message from the Editor, Mark Waldron
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