What Drinks Stain Teeth the Most
Natalie South
Mulgrave School
Floor Location : J 085 H

I want to educate people on the effects of different drinks and how they can keep their teeth healthy.

For my experiment I have used eggs as a substitute for teeth. Tooth enamel is made up of calcium, phosphorus and calcium salt. An egg shell is made up of the same substances so is a good substitute for teeth.

My hypothesis was that darker coloured drinks and more acidic drinks will stain and darken the egg shells more because those drink will erode the eggshell more.

Based on my survey of Grade 7 to 9 students and suggestions of a dentist (Dr Glen Joyce) I decided to test the following drinks:
Coke, Black Coffee, Green Tea, Milk, Water, Cranberry Juice, Apple Juice, Blueberry Juice

My materials were:
78ml of each drink , 24 medium egg shells (hard boiled eggs), 24 plastic cups (100 ml)
24 plates (18cm diameter)

My Procedure was as follows:
1 - Get all the equipment and place it on a table in front of you
2 - Hard boil the eggs
3 - Weigh the initial mass of the eggs and record
4 - Pour ? cup (78 ml) of liquid of the different drinks into a separate cup for each egg
5 - Place an egg into each cup
6 - Check on the eggs every 24 hours for 3 days. Remove the eggs from the liquids and put them on plate, take pictures and write observations on the effect each liquid has on the eggs. Measure the severity of staining and compare it to the colour staining chart.
7 - Each day weigh the eggs and record the mass
8 - Afterwards put the egg back in the liquid.
8 - Make sure all results (staining severity and mass) are recorded in a data table
9 - Repeat steps 2-9 two more times

Conclusion:
I have found that drinks can stain teeth severely and that all drinks stain teeth to some degree. My hypothesis was supported because the drinks that were dark coloured stained the eggs to a greater degree. My hypothesis was also supported in saying drinks that are acidic stain the teeth more.

I concluded that my experiment showed cranberry juice as the most severe staining. This is supported by my acidity table which showed cranberry juice to be the most acidic drink. This is also supported by my Photographic and Mass change evidence.

The drink that stained the least was water. Water is clear and is neutral on the pH scale. Water had no change in mass and was a 0 on my staining chart all the way through. It also had no change in mass. I expected black coffee to stain the most because it is a very dark colored drink, so you may conclude that acidity is a greater factor. Coffee had the same amount of stain as Grape juice.