Some patients have been waiting since 2021 to be seen by their dentist.
It comes amid anecdotal evidence suggesting dentists are prioritising private appointments, with NHS bosses admitting there is 'no level playing field'.
Speaking at a Hampshire County Council select committee meeting on Tuesday, councillors voiced their concerns about how the NHS will recover.
Independent member for Whitehill, Bordon and Lindford, Councillor Andy Tree, said: 'I wonder whether there is any motivation or encouragement for dentists to actually get their NHS patients seen to.
'People who didn't go to the dentist during the pandemic - instead doing their public duty and staying at home - have been bumped off the waiting lists for appointments.
'This is creating more and more problems for the future, and I dread to think what will happen to the patients being dropped off the lists when they need an appointment.'
Appearing via video link, Alison Cross from NHS England said: 'We have instructed dentists not to drop patients off their lists.
'Unfortunately, what we instruct and what happens can sometimes be two different things.'
According to Ms Cross, the NHS is still dealing with a backlog of appointments dating back to the Covid-19 pandemic.
Operational capacity in Hampshire is now at 95 per cent, with plans to move up to 100 per cent in the next financial quarter.
But while NHS patients are left waiting for months on end for an appointment, private patients can get an appointment within seven days - at the same practice.
Conservative member for Lee, Cllr Graham Burgess, criticised practices for turning private dentistry into a 'goldmine'.
Ms Cross said: 'Practices are still operating at a threshold, but we have heard of them telling NHS patients they can get an appointment privately.
'Our dentists are working through a backlog and I'm afraid there is no quick fix. This is going to take time.'