Up to 15,000 NHS dental patients in south Devon are to be de-registered by their dentist.
Mr Harris will continue free treatment for under-5s
Harris Dental Surgeries, which has four practices in Torbay, said it was unhappy with new government contracts dentists are being asked to sign.
The Strategic Health Authority said 30 practices in Devon and Cornwall will opt out of the new contract next week.
Torbay Care Trust said it was doing everything it could to maximize the availability of NHS dentists in Torbay.
In a statement, the trust said it had found NHS places for more than 12,000 patients in the past 14 months.
Principal practitioner Mark Harris said his main objection to the government's contract concerned the withdrawal of support for dental education for children.
He told BBC News: "At some stage as a professional responsible to my community, we have to make changes."
The practice will continue to provide free treatment for under-5s and has set up a membership scheme which patients can pay into to cover the cost of dentistry.
Last month the White Rose surgery in Camborne, which is one of Cornwall's biggest dental surgeries, announced it would stop its NHS service for adults.
It is one of four practices in Cornwall to opt out. In Devon, 26 surgeries have decided to opt out of the government scheme, according to the South West Peninsula Strategic Health Authority.