And officials in Palm Beach, Florida, believe that there may be as many as 300 unlicensed dentists in the city and surrounding counties.

Rosario Diaz is thought to have drawn his hapless customers from the large numbers of people who do not have proper medical and dental insurance cover.

His surgery consisted of patio furniture, and one of his principal tools a pair of pliers, said police, who found only three genuine dental tools in the house.

Enrique Torres, an undercover medical malpractice investigator with the state, raided the house in central Palm Beach.

Guatemalan background

He said: "This is the most disgusting place I've ever come in contact with. He also did dental lab work, crowns, bridges."

Diaz has told police that he spent six years working in a Guatemalan dental lab.

Lucio Perez, the executive director of a US Guatemalan centre, said that dental licensing in the South American country was in chaos.

"The agencies and institutions who are supposed to see these kinds of things, like people who are working without a licence, don't care in Guatemala."

Mr Perez said that patients who could not afford to go to a better dentist had little choice.

"They don't have health insurance, so they go to people who charge less money."

The estimates of large numbers of unlicenced dentists operating in Florida come hot on the heels of revelations that a bogus doctor, also from Miami Beach, performed cosmetic surgery without a licence.

Reinaldo Silvestre went on the run after police discovered he had left patients deformed.