Most adults in Wales will now only be called-up to see their dentist once a year, rather than twice a year, in a bid to help clear the coronavirus backlog and make it easier for people to get an appointment.
The Welsh Government said the move is part of plans to change the way dentistry works in Wales and free-up resources.
The country's Chief Dental officer, Andrew Dickenson, said scrapping the "outdated" routine of check-ups every six months will help allow Welsh practices to see up to 112,000 new patients a year.
However that claim has been branded "misleading" by the UK's national trade union representing dentists.
The British Dental Association (BDA) said the reality is most dentists already extend the six month recall period when they feel it will not harm patient health. The chair of the BDA's Welsh General Dental Practice Committee added that the "claims look like they were cobbled together on the back of an envelope".
But Professor Dickenson said data shows bi-yearly check-ups are now “unnecessary” for most people. He said there has been a vast improvement in oral health among adults over the last two decades and a decrease in tooth decay.
He said: "By moving away from often unnecessary check-ups, dentists will have more time to provide people with the personal, tailored care they need and free up space to take on new NHS patients."
Children and people under the age of 18 will continue to be offered check-ups every six months.
More than two-thirds of all NHS dental practices have voluntarily signed up to the changes, and have been given a small target of new patients to see.
Further changes could be seen in the next financial year following another consultation with dentists, with an aim eventually to put the new contract into law.
The Welsh Government also wants to recruit more dentists and dental staff by offering support for students to find placements with practices in Wales.
There are around 1,700 registered dentists and 540 hygienists and therapists in Wales according to the latest figures from General Dental Council - with the only school of dentistry in the country in Cardiff.
Professor Dickenson also said he wants to attract more dentists to work in Wales – particularly in rural areas – as well as better utilise dental hygienists and therapists.
Due to the difficulties created by the pandemic, he said it could take between three to five years before the benefits of the new system are felt and anyone asking for an NHS dentist slot is able to get one.
However the BDA believe the changes have been "designed to generate headlines" and will not, in reality, boost ability to see a vast amount of new patients.
It said NICE guidance, which has been in place for 18 years, recommends check-up intervals between every three months to two years - depending on a person's oral health. This means dentists already recall some patients yearly, or even less frequently.
BDA Wales also stressed that a high proportion of patients across Wales will require more frequent appointments anyway, given the high levels of need in the nation's most deprived communities.
Russell Gidney, Chair of the British Dental Association's Welsh General Dental Practice Committee, said: "The Welsh Government is attempting to conjure up new appointments, without meaningful investment. Sadly, these claims look like they were cobbled together on the back of an envelope.
"Dentists have worked to similar guidelines for the best part of two decades. The fact is it could take a dozen healthy patients forfeiting annual check-ups to allow one new high-needs patient to be seen.
"Patients across Wales are facing an access crisis, while demoralised dentists are leaving the service in droves. These problems will not be solved with empty soundbites and misleading numbers."
BDA Wales believes the only way to meaningfully boost access and stop the "exodus from the NHS workforce" is through sustained investment - something it claims Welsh Government has not offered yet.
The organisation said it is also seeking clarity on how new roles will be filled without changes in the budget.
Plaid Cymru criticised the changes too, calling them a "sticking plaster" on a "much wider issue".
The party's spokesperson for health and care, Rhun ap Iorwerth MS said: "The reality is that this will not address the shortage of dentists, the current postcode lottery in dental services, nor the issues with getting through on the emergency service number - issues which have previously been raised by Plaid Cymru in the Senedd.
"Until Welsh Government addresses the very real reasons underpinning the lack of access, then this solution will be no more than a very temporary sticking plaster over a much bigger problem."
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