Why do we Clean our Teeth?

We  started an experiment yesterday to see the effect of different drinks on our teeth if we didn't brush our teeth. We are using an egg as a tooth. In each cup we have put  a different drinks like water, juice, coke and milk. We used our observation skills to check each egg tooth at the start.The eggs were smooth and brown.
Each day we are going to look  to see if the egg tooth is changing.

We predict that there will be changes like colour and smell.