(2107) Acidity, Carbonation and Tooth Decay
Alexandra Westcott
King George


This project examines the effects of acidity, carbonation and sugar content in drinks on teeth. The results of the experiment supported my hypothesis: the drinks with the greater acidity and higher sugar content had the greatest impact on the teeth.

Tooth decay has always been a serious health problem. For example, 50 years ago, 30% of Americans over 45 years old had no natural teeth. Brushing teeth was not common until after WW2.

A tooth has many parts: enamel, dentine, pulp, cementrum, blood vessels and nerves. Damage to enamel is the first stage in tooth decay. It begins with bacteria. When a person eats a meal, the bacteria get one too. They eat the sugar in the food and produce waste in the form of acid. If the bacteria are left too long in the mouth they form an organized "army" called plaque. The plaque forms a "seal" on the tooth and when acid gets caught between the plaque and the tooth it gets trapped and dissolves the enamel.

The carbonation in some drinks adds to their acidity. When the gas in carbonated drinks dissolves, it forms carbonic acid.

Tooth decay has many signs: sensitivity, discoloration, rounding, transparency, cracks and cupping. At the beginning of my experiment, I determined the sugar content of each drink (Red Bull, Back Cherry Soda, tap water and carbonated water), as well as its acidity (using a Ph strip). Each tooth was placed in a sterilized test tube containing one of the four types of drinks. Each tooth was examined and photographed on days 1, 3, 7 and 14 of the experiment. The effects on the teeth were categorised and recorded.

The acidity and sugar content of the liquids used were as follows:
Red Bull - Ph = 5, sugar content 3g/30ml
Tap water - Ph = 5, sugar content 0g/30ml
San Pellegrino - Ph = 4, sugar content 0g/30ml
Pop Shoppe Black Cherry Soda - Ph = 3, sugar content 4.4g/30ml

The drink that caused the most damage was the Black Cherry Soda which had the highest sugar and acidity. The second most harmful was Red Bull which had lower sugar and less acidity. The third most harmful was carbonated water which had higher acidity than the Red Bull but no sugar. The least harmful was tap water which had no sugar and was closest to a neutral Ph.

The results of this experiment highlight the importance of proper dental hygiene. Drinks with high sugar and carbonation can cause an amazing amount of damage unless they are quickly washed off the teeth. If a person has lots of plaque on her teeth, the acid will not be removed by the saliva and will cause tooth decay. Two ways I could have improved this experiment would be, first, to carefully identify the damage already on the teeth before the experiment started; and, two, to use a camera that had better magnification when being zoomed in, so I could have photographed the damage better.