Thornhill Dental Practice has issued letters to 3800 people due to the anticipated departure of one of its two dentists.
However, they say they will continue to provide NHS services for children and private dental care for adults.
Health bosses say the move will contribute to “a worsening situation around access to NHS dental services within Dumfries and Galloway.”
Director of dentistry Alison Milne said: “This is obviously very bad news for all the adult NHS patients registered with Thornhill Dental Practice.
“We continue to work as a health board to encourage and support dentists to provide NHS general dental services, but lack of dentists coming to work in the region is a key issue. Challenges in dental workforce is being seen across the UK.
“However, as has been noted before, this is a situation which is likely to worsen before there is the prospect of any improvement.”
Anyone losing their registration at Thornhill will now need to seek alternative provision.
But there are currently no dentists within the region accepting new NHS registrations, so people will need to look elsewhere or go private.
Reacting to the news, South Scotland MSP Colin Smyth said: “My worst fears that recent closures of dental practices to adult NHS patients in Gretna and Castle Douglas would trigger a domino effect have been realised with the practice in Thornhill now adding to the dental crisis in Dumfries and Galloway.
“This will be a huge blow to patients in Mid-Nithsdale who will either have to pay for private care or try to find another dentist that provides NHS care. That is becoming more and more difficult as practice after practice ends NHS care.
“It makes me angry that the Scottish Government have failed to wake up to the growing dental crisis.
“The health board needs to provide as much assistance to support patients finding alternative NHS provision but unless both governments face up to the dental crisis in our area, I believe the very existence of NHS dental care is under threat in Dumfries and Galloway.”
