The acids in many beverages can have a damaging effect on your teeth. Demonstrating this makes a great science project for school science fairs or classes. If you have lost a baby tooth lately, you could experiment on actual teeth, but if not you can substitute eggshell. Eggshell is not as tough as human teeth, as it lacks a layer of enamel, but it does provide a graphic example of the effect some beverages have on your teeth.

Compare the effects of different drinks on your teeth using eggshell as substitutes for teeth. Choose a variety of drinks to test, such as:

• milk
  
• juice
  
• soda
  
• coffee
  
• sports drinks

For each drink, place a piece of eggshell in a glass. Make sure you use the same size eggshell in each glass. Fill each glass half-full with the different drink. Each day, remove the eggshell from each glass and examine it. Write down what changes have occurred. Repeat this for five to seven days.

Some beverages can also stain your teeth. For this activity, use beverages of different colors, such as:

• colas
  
• root beers
  
• orange soda
  
• juices

Pour each beverage into a glass. Place a piece of eggshell into each glass. The eggshells should remain in each glass for the same period of time. Place one eggshell in a glass of water to act as a control. Remove the eggshells after the allotted time and determine which one has received the most staining.

Demonstrate whether brushing makes a difference. Fill two glasses with cold coffee (without milk or sugar added). Place a hard-boiled egg in each glass. Leave the egg in for 10 minutes and then remove the eggs. Carefully brush one of the eggs, using a toothbrush and toothpaste. Let both eggs dry and then repeat the activity four or five times. Decide which egg is more stained.

Different sodas have different types of acid in them. The most common types of acid used in soda are citric acid and phosphoric acid. You can find which acid is in each soda by looking on the list of ingredients on the label. Pour some of each soda into separate glasses and place a piece of eggshell into each glass. Leave the shells for one day and then remove them and examine them. Figure out if one shell shows more wear than the other. Continue the experiment for several days.