Since eggshell is made out of similar material to our teeth, we did an investigation in science into the effect of different liquids. We left five boiled eggs overnight in 150ml of liquid: water, milk, blackcurrant squash, distilled vinegar and cola. We then examined the eggs to see how much damage had been done to the shells.
The cola (to Miss Harvey's disappointment!) caused very little damage - just a little change of colour. We think perhaps it would have caused more damage if we had left it for longer. The blackcurrant had made the eggshell turn purple and the shell was very rough, with lines running around it. The vinegar had made the shell go soft and the egg was rubbery. When it was held and squashed, there was a dent. With the milk and water, as we predicted, there was no damage to the eggs. We know that water and milk are the best drinks for our teeth.