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Food is broken down into smaller pieces in the mouth by chewing.

This is an example of mechanical digestion.

The teeth cut and crush food, and the pieces are mixed with saliva to form a ball of food called a bolus. [1]

Tooth decay

Tooth decay happens when the hard outer enamel of the tooth is damaged.

This can happen when bacteria in the mouth convert sugars into acids that react with the enamel.

Bacteria can then enter the softer dentine inside. [3]

Fluoride reduces tooth decay by

- reducing the ability of bacteria on plaque to produce acid

- helping to replace calcium ions and phosphate ions lost by tooth enamel because of acid attack [5]

Types of human teeth

Incisor – for biting and cutting

Canine – for holding and cutting

Premolar and Molar - crushing and chewing [2]

Tooth decay can be prevented by

- avoiding foods with a high sugar content

- using toothpaste and drinking water containing fluoride

- regular, effective brushing to prevent the build-up of plaque (a sticky layer on the teeth) [4]







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