Sweet enough for you? The harmful effects of soft drinks on teeth

Fizzy drinks can affect teeth in 2 main ways: caries (cavities) and acid erosion (tooth wear).

Acid erosion is beyond the scope of this article and will be discussed in a separate piece entitled “The wear essentials – a discussion of the causes of tooth wear.”

A 350ml can of fizzy soft drink typically contains 40 grams of sugar. That’s a whopping 10 teaspoons of sugar!
Food for thought: A 350ml can of fizzy soft drink typically contains 40 grams of sugar. That’s a whopping 10 teaspoons of sugar! Would you take the same amount of sugar in a mug of tea or coffee?

This sugar load is fermented by bacteria in the mouth to produce lactic acid as a byproduct. Coupled with the phosphoric acid already present in fizzy drinks, this reduces the pH in the mouth which demineralises tooth enamel. Demineralisation is superficial dissolving of the surface enamel where minerals (mainly calcium) are removed from the hard tissues of the teeth. It is also the earliest stage of tooth decay.

SEE ALSO: The Wear Essentials – a Discussion of the Causes of Tooth Wear

In a normal setting, following a sugar load, saliva has a buffering effect and restores the pH close to neutral and remineralises the enamel.

However, repeated intake of fizzy drinks leads to a net acid pH in the mouth and net demineralization of tooth enamel. One of my patients proudly exclaimed that she drinks 2 liters of soft drinks a day!

Dental caries due to heavy daily consumption of soft drinks

Signs (something the dentist can see)

Early enamel lesions appear as a chalky white spot. Eroded, weakened enamel is now permeable to caries forming bacteria, which begin to eat away at the organic component of dentine leading to tooth decay.

As caries progresses into dentine, the colour changes to an area of yellow or light brown. Progressed lesions appear darker brown or grey in colour.

If allowed to continue to this stage (months), the caries begins to undermine the enamel and cavitates, hence cavity.

Symptoms (something the patient complains of)

Patients may notice sensitivity on biting or with hot, cold and sweet. The pain is short-lived from a few seconds-minutes (reversible). Larger lesions can be spontaneously painful and the pain can last a few hours (irreversible). Patients may complain of a throbbing pain which is not relieved with painkillers.


The symptoms and size of the lesion clinically (what the dentist can see with their eyes) and on x-ray will determine the type of treatment. As a rule of thumb, reversible lesions can often be fixed with a simple filling. Irreversible symptoms often need for the tooth to be root canal treated or extracted.

In Summary

Limit the intake of soft drinks to meal times. It is not usual to have fizzy drinks at breakfast, so this leaves lunch and dinner. Use of a straw also helps limit the exposure of the teeth to the sugar and acid. Avoid doing what some people do in swishing fizzy drinks around their mouths or holding the drink in their mouths.

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