Tooth decay, tooth erosion and the importance of saliva

Every time a food or drink is consumed, teeth are exposed to an acid attack. The bacteria in the mouth (plaque) ferments food or drink to make acids, and if teeth are exposed to these acids long enough, cavities develop – this is known as tooth decay (dental caries).

On the other hand, tooth erosion occurs when acidic foods and drinks dissolve away tooth enamel, leading to a loss of tooth structure and the need for dental treatment.1 Enamel is the hardest material in the body, it covers the outside of teeth in order to protect the inner layers of the teeth.2 Foods and drinks that are acidic (with a pH below about 5.5) are generally thought to trigger tooth erosion. 

Saliva is the body’s natural defence against tooth decay and tooth erosion. It helps to dilute and wash acids and sugars from the mouth and reduces the effects of the acids produced by plaque bacteria. If ‘acid attacks’ occur too often, saliva doesn’t have enough time to repair the damage and a cavity will eventually develop in the tooth.3

1 Australian Dental Association (ADA). Dental Health Week 2–8 August 2010. Tooth Erosion. [Internet]. ADA, Leonards, 2010. Available: 

2 Australian Dental Association (ADA). Tooth Decay – Australia’s Most Prevalent Health Condition [Internet]. ADA, Leonards, 2012. Available:

3 Moynihan P, Petersen P. Diet, nutrition and the prevention of dental diseases. Public Health Nutr. 2004;7(1a).