In the late 1980's the candy industry discovered how much young people enjoy the kick of a sour taste. They began creating their standard candies in a sour version. Over the years it has transformed the candy industry. The financial success of "sour" candies was even reported in the Wall Street Journal.
To give you a hint at what happened, consider "Warheads." The challenge to the young folks was to pop the Warhead in their mouth and time how many seconds they could keep it there before they had to spit it out because it was too sour! If they made 18 seconds, they mastered it. Candy had become sport!
Now consider your chemistry lessons. Sour taste means acid; remember? Acid dissolves things, especially mineral things (like tooth enamel). The candy industry has added three acids (citric, ascorbic and malic) to create this sour sensation. Those acids are dissolving the enamel of the teeth. Kid's complain of their teeth hurting when they bite into foods. Enamel is wearing away exposing sensitive areas of tooth, and of course cavities are more prevalent.
When your child considers a treat, discuss with him or her the effects and steer them to a healthier choice with less acid. Education is a key to winning!