If the experiments of Dr. Robert Marshall Stephan of the University of Illinois are borne out during the next few years, they may help to send the dentist's drill the way of blacksmith tools. Last week in Science, Dr. Stephan announced that he had found a neutralizer for tooth decay: urea.
Nobody knows exactly why teeth decay. Dentists generally agree on one clue to the mystery: certain acid-forming bacteria, such as lactobacilli, grow on tooth enamel, ferment crumbs of sweet and starchy foods which lodge in tooth crevices. The acid thus formed dissolves calcium in the teeth,...