Egg and Soda: A Dental Health Activity

What Does Soda do to Your Teeth?

Close-up of woman's smiling mouth and soft drink
Dimitri Otis / Getty Images

If you have a hard time getting your child to brush his teeth, it might be time to try the egg and soda experiment to explore the concept of dental health. In theory, a hard-boiled egg’s shell works similarly to the enamel on a child’s tooth. It’s there to protect the soft inside, or dentin, from damage. Unfortunately, some of our eating and drinking habits make it difficult for the enamel to protect our teeth from damage, and the egg and soda experiment demonstrates how our dietary choices can impact our bodies.

Try this experiment to help show your child the damage soda can do to his teeth and why brushing after drinking soda is important.

What You Will Need:

  • 3 white-shelled hard boiled eggs
  • soda
  • diet soda
  • water
  • a toothbrush and toothpaste
  • 3 clear plastic cups

Before the Egg and Soda Experiment

Start by talking to your child about good dental hygiene practices and how important it is to brush their teeth every day, making sure to explain how certain foods, drinks, and activities can stain and damage teeth. You might also want to discuss how drinking a lot of acidic beverages can erode the outside of teeth.

Ask your child if they can come up with a few types of drinks that might hurt their teeth? They might have answers like soda, coffee, or juice because of sugar and acid. You might also want to ask your child if they can think of drinks that might be better for their teeth? Most likely, they'll come up with something like milk and water. You can also ask your child if they think brushing after drinking some of the drinks that could hurt their teeth could reduce the risk of damage.

Explain the Experiment

Tell your child you have a way to find out what might happen if he left those drinks on his teeth overnight. Show him a hard-boiled egg and ask him how it reminds him of his teeth (a hard but thin outer shell and a soft inside). Take some time to ask your child what might happen to the egg if you leave it soaking in soda overnight, as compared to water. You might also consider different types of soda and if dark sodas, like colas, might have different effects on teeth than clear sodas, like lemon-lime sodas.

Perform the Experiment

  1. Boil the eggs, making sure to have a few extra in case some of them crack while you boil them. A cracked shell will change the results of the experiment.
  2. Help your child fill each of the plastic cups, one with regular soda, one with diet soda and one with water.
  3. Once the eggs have cooled, have your child put one in each cup and leave it overnight.
  4. Ask your child to check the eggs the next day. You may need to pour the liquid out of the cup to see how each egg has been affected. Most likely, the eggs in the cola have been stained by the liquid overnight.
  5. Discuss the changes you see in each egg and ask your child what they think happened. Then ask what they think you can do to “help” the eggs that have been immersed in soda get back to their original state (no stains).
  6. Give your child a toothbrush and some toothpaste to see if he can brush the stains off the eggshell.

As a variation, you might also want to boil a few extra eggs and add cups with clear soda, orange juice, and coffee for comparison.

Conclusions

There are two main things you and your child can take away from this experiment. The first is that, as reported in the journal General Dentistry, the citric and phosphoric acid contained in soda has enormous potential to erode tooth enamel. In fact, one study reported that soda is ten times more erosive than fruit juice in the first few minutes after drinking it.

The second, and easier for your child to see, is that it takes more than just a couple of quick swipes of the toothbrush to get teeth clean. Try helping your child time to see how long it takes to brush the majority of the stains of the eggs.