Fifty eight per cent of the British Medical Association (BMA) members who took part in the referendum also moved to reject the terms that were agreed at Acas in May with the Secretary of State for Health.
Both organisations are now reviewing their next steps in light of the ballot.
Peter Dyer, chair of the BDA's Central Committee for Hospital Dental Services, said:
“An overwhelming majority of juniors have sent a clear signal on the contract.
“Our determination remains to achieve a contract that works for patients and practitioners. We will be conferring with our colleagues at the BMA on our next steps.”
Results: Do you accept the Terms and Conditions of Service for NHS Doctors and Dentists in Training 2016?
Dentists Medics
No 63.3% 58.1%
Yes 36.7% 41.9%