There is so much disguised sugar in the foods Americans eat today that "dental decay is running wild in the American population," according to a dental researcher.

Dr. Ira L. Shannon, director of the Oral Disease Research Laboratory at the Veterans Administration Hospital here, told the 145th national meeting of the American Association for the Advancement of Science, "We estimate there are more than 1 billion unfilled cavities in the teeth of Americans right this minute."

Shannon blamed most of the cavities on what he called the "ubiquituous distribution of sugars" in Ameri can food.He said food processors put so much sugar into food that the "average American has lost discretionary control" over sugar intake.

"Time was when three-quarters of the sugar we ate came out of a bag or box that said sugar on it," Shannon said. "But now we get three-quarters of our sugar from food and drink where sugar is a constituent and on which there is no label that says sugar."

In a study of foods in and around Houston, Shannon said he has found that the average cereal contains 25 percent sugar and some are as much as 50 percent sugar. He said many cookies are 75 percent sugar and many candies 90 percent sugar.

"Breath mints that advertisers on television tell you to place between your gum and lower lip are over 95 percent sugar," Shannon said. "These things are damaging to the nation's teeth."

Shannon said there is so much sugar in cereals today that children eat them as snacks. He said sugarcoated and chocolate-coated cereals are "so delicious" they no longer taste like food.

"Cereals are now sticky, goopy things," Shannon said. "They must be regarded as highly dangerous to teeth when taken as snacks."

Shannon called for changes in the labeling laws that do not require listings of sugar concentrations on cereal boxes. He said that without the changes "parents can no longer plan diets for their children."