Dentists heard about the Bard's oral hygiene problems at a one-day seminar in his home town of Stratford-upon-Avon in Warwickshire on Friday.

The meeting was addressed by Professor Mel Rosenberg, a microbiologist from Israel who has studied bad breath

He looked at references to the problem in Shakespeare's works, and offered dentists advice on what to tell patients suffering from "dragon breath".

Poor dental hygiene in the 16th and 17th centuries means Shakespeare and his contemporaries would have suffered tooth decay, mouth infections and halitosis.

Professor Rosenberg noted that mouthwashes and tongue cleaners were not available in Shakespeare's lifetime.

Bard breath

He said: "Shakespeare had a lot to say about good breath and bad breath.

"So many people in Shakespeare's day, probably including the Bard himself, had bad breath, that a person with good breath was to be savoured. A girl with good breath was one in a million."

Professor Rosenberg has published extensively on the causes of halitosis and ways to beat it. He has looked at the history of the problem, particularly through literature.

There are also references to it in major religious works - the earliest reference appearing in Genesis.

He says bad breath is becoming big business as fresh breath centres pop up around the world. They are popular in the US, and there are two fresh breath centres in the UK.

Professor Rosenberg began studying the problem in 1982. He realised then that by "smelling people he had stumbled on a goldmine".

He said: "I have smelt thousands of people and it is a job that physicians and dentists do not seem to want to do."

Political stink

He told the 100 dentists asembled at the Stratford Manor Hotel that, in the modern world, politicians and lawyers had among the worst bad breath.

Home to the smelliest mouths in the UK?

He said this was because they were forever talking.

"Their mouths dry out as they talk, and when your mouth dries out, the saliva - the body's mouthwash - cannot carry away the bacteria.

"Also the movement of the tongue airs the smelly gases and sends them out."

MPs and teachers were more likely to have halitosis than social workers or marriage counsellors, he added.

International problem

Professor Rosenberg says bad breath has been with us for centuries, and his teaching material covers different types of remedy.

"Over the years, different folks have developed different strokes.

"In Thailand, sufferers chew the peels of oversize guavas. Iraquis keep cloves between their teeth. Italians chew parsley. Indians chew fennel seeds. At least one Israeli woman swears by yellow dates.

"Almost all of us believe in the mouth-freshening potential of mint. Chinese imbibe crushed eggshells in rice wine, but will also eat a grapefruit for alcohol breath and, for garlic odour, persimmon or red dates."