The warning comes on the day the BDA publishes a booklet for dentists called "Oral Cancer - guidelines for early detection".

Treatment of the cancer is more effective if lesions are detected before they have a chance to spread and early diagnosis can increase a patient's chance of surviving the disease for another five years from 50% to 80%.

Dentists are trained to detect tumours, which can start as whitish or reddish patches or ulcers in the mouth that fail to heal.

"If oral cancer is diagnosed early, it can be treated successfully," said Dr Geoff Craig, chairman of the BDA's Health and Safety Policy Group.

"Advances in technology and surgical techniques have also improved the quality of life of people who survive."

He said the association wanted to see a screening programme for high-risk groups, better health education aimed at smokers and more training for dentists and dental hygienists.

Oral cancer: the facts

• The disease kills four people a day in the UK each year, the same number as die from cervical cancer.

• People who smoke, chew tobacco or drink excessively are at particular risk.

• The incidence of the disease is twice as high in men as in women, although latest figures show the gender gap is decreasing.

• It mainly affects those over 40 years old.

• Signs and symptoms of oral cancer are a visible whitish or reddish mark in the mouth.

• Most oral cancers occur on the side of the tongue, the floor of the mouth, the grooves at the side of the tongue, and behind the teeth.

• Cancers related to chewing tobacco may arise in the cheek and at the junction of the lower and upper lips.