In spite of being the hardest substance in the body, our tooth enamel is very susceptible to many threats, including acid attacks. When the pH in the mouth drops below the so called “critical level” of 5.5 for too long, the enamel starts to demineralise, and this is how cavities begin to form. There are many simple things we can do to counteract this demineralisation, such as reducing sugar intake, brushing in the mornings and evenings, and using a fluoride containing toothpaste. Fluoride ions replace the Calcium ions in our enamel, changing the hydroxyapatite crystals to stronger, more resistant fluorapatite crystals and thus reducing the risk of caries. This simple experiment clearly shows these effects.

Eggshells contain calcium, very similar to tooth enamel

We take a normal chicken egg and cover half of the shell with a fluoride containing toothpaste readily available in most stores

The egg stays coated like this for 7 days

After a week when the toothpaste is washed off the eggshell shows a clear colour difference between the coated and the non-coated halves. The fluoride has already had a visible effect on the calcium ions

Then we fill a cup with vinegar (any kind will do) and place the egg inside

The side of the egg that was not coated with toothpaste shows a much more severe reaction (little bubbles forming) to the vinegar than the other side

After 4 hours in the vinegar the appearance of the eggshell has changed quite drastically, but the half that was covered with toothpaste still retains much more of its natural colour and texture than the other half

This control egg was not covered with toothpaste, and the entire shell has lost its colour and smooth surface texture. So remember to brush your teeth with a good quality toothpaste, and if you want to paint Easter eggs next year maybe place them in vinegar beforehand and you will have a much lighter base colour (we cannot guarantee how they will taste though) ;)