Many dental patients in parts of south west England will need to travel at least 40 miles (64km) to find an NHS dentist who will register them.
In Cornwall, dental places are available on the Isles of Scilly
According to the NHS website, the nearest dentist who will register a new patient from south Devon is at Northam, near Bideford, 50 miles (80km) away.
In Cornwall, Northam is the nearest mainland practice for someone living in Truro, more than 75 miles (120km) away.
Many dentists are opting out of the NHS because of new government contracts.
Despite government reforms, there are only five dentists in the Devon, Cornwall, south Somerset and west Dorset area accepting new NHS patients without restrictions, according to the NHS website.
About 15,000 NHS dental patients in south Devon were told this week they were to be de-registered by their dentist.
Harris Dental Surgeries, which has four practices in Torbay, said it was unhappy with new government contracts dentists were being asked to sign.
In Devon, 26 surgeries have decided to opt out of the government scheme, according to the South West Peninsula Strategic Health Authority
In Cornwall, four practices have opted out.
The government said the new contracts would ensure dentists had a guaranteed income and allow them to spend more time with their patients
Many dentists said the new contracts did not allow them to do the thorough work they thought patients needed, particularly in terms of preventative measures.
In terms of surgeries accepting NHS patients, as well as Northam, there are two in Yeovil, Somerset; one in Weymouth, Dorset; and one in the Isles of Scilly, 30 miles (38km) off the Cornwall coast.
The Peninsula Medical School said its new regional medical school had places for 62 students and it hoped its graduates would help alleviate the shortage of NHS dentists in the region.