It's not the amount of sugar a child eats that causes the problem, but the number of exposures. Every time you expose your mouth to that, you get that bacteria active. Children sipping or drinking any drink other than water, every time they sip, it increases the amount of bacteria.

Most people don't understand they have to start cleaning those teeth the minute they erupt into the mouth. Bacteria can form on that tooth, plaque can form on that tooth, as soon as that tooth erupts.