More than 500 people have been queuing outside two Cumbria dental surgeries to be registered as private patients.
Patients have been queuing for a second day
Earlier this week, Richard Wilson and partners announced both their Carlisle and Penrith premises would cease NHS practice for adults in February.
Hundreds of people started queuing on Wednesday morning and hundreds joined queues again on Thursday.
There is a shortage of dentists in North Cumbria and health bosses are taking steps to address it.
Patients are waiting in line to remain with the practices because there is a shortage of dentists in the area - even among those who do not carry out NHS work.
Mr Wilson's decision to opt out of NHS work has prompted the move to reduce his 17,000-strong patient list.
Inundated with calls
He said uncertainty over a new NHS contract, which is being introduced in April, was one of the reasons for the decision.
He also said he had experienced problems recruiting within the NHS but when he had advertised a post as a private position had received an immediate response.
Another nearby practice said it had been so inundated with calls since Richard Wilson and partners had announced it was leaving the NHS, it had had to close its books to private patients.
And another practice had an answerphone message saying it was not taking any new patients.
A North Cumbria Primary Care Trusts spokeswoman said: " I think we have been honest about the fact that there is a shortage of NHS dentists in Cumbria."
But she said it was a problem they were working to address.
The trust said it was determined to replace the loss and also provide 36,000 more NHS dental places across North Cumbria.
It urged dentists to consider details about the new contracts when they were issued in the next few weeks rather than make a decision now.
Patients who want to stay with an NHS dentist are urged to contact the Dental Direct service, which means they are put on a database which matches them to spaces at dental practices.