Are you sitting comfortably?

Terror of the dentist can be cured in 70 per cent of cases by behavioural therapy, according to research at the Institute of Psychiatry in London.

And those who make it to the dentist's waiting room can significantly reduce their anxieties if they are given information on how to control what their dentist does, the British Dental Association (BDA) was told last week.

A third of adults are terrified of dentists, and a tenth probably do not go because of their fears, the BDA heard at its annual conference in Birmingham.

Researchers have found that many such patients - called the dentally anxious - are reacting to a bad experience in the past, or to their family's attitude to dentists.

"But for probably as many as 20 per cent we don't know the cause," said Stan Lindsay, clinical psychologist at London's Institute of Psychiatry.

Dr Lindsay told the meeting that he had devised two leaflets, one discussing anxiety in general and the other telling patients how to stop the dentist instantly by giving a control signal, and describing how the dentist successfully manages pain. Patients' anxiety scores dropped both before and after seeing the dentist if they had received the detailed leaflet beforehand, he said.

Dr Lindsay also gives behaviour therapy to the dentally anxious. He gradually exposes them to elements of a typical visit to the dentist: seeing a syringe, smelling surgery smells, listening to a tape of drilling noise and then doing relaxation therapy. When they can tolerate simulated dental treatment he passes them to a "collaborator dentist". Dr Lindsay said that he has a 70 per cent success rate, over six to 18 weeks.

Tony Mellor, of the University Dental Hospital in Manchester, who chaired the session, said that most dentists have a 99 per cent success rate with local anaesthetics, commonly given before drilling.

"We are victims of our own success," he said. "If dentists say it isn't going to hurt and it does, that can be worse for the anxious than if they know it's going to hurt."

A booklet on dental phobia put together by the Behavioural Sciences in Dentistry Group was launched at the meeting.