The material in fillings has changed. One of the more prominent cases
involved Lucille Ball during WW2. She had come from the dentist and picked
up a radio It was traced to a Japanese gardner. He was sending ship
movements back to Japan. He was arrested as a result. Or so the story
goes,
YMMV.


http://www.snopes.com/radiotv/tv/fillings.htm
http://www.cord.edu/dept/concord/iss...ions/cody.html
http://answers.google.com/answers/threadview?id=367925

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KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR