Why is it important to brush our teeth?

Yesterday, we conducted an experiment using boiled eggs and dark colored drinks (Pepsi and coffee). We soaked the eggs in the liquids for the entire day to see what would happen.

Next, we removed the eggs and observed the changes that had taken place. We couldn't believe the amount of stain that had taken place on the eggs. 

Lastly, we used a toothbrush and toothpaste to try and remove as much of the stain as possible. We learned that the Pepsi stain came off much easier than the coffee stain.