7.3) Mechanical digestion

7.3) Mechanical digestion


Types of teeth and functions:


Incisor – biting off pieces of food

Canine – holding and cutting food

Premolar – tearing and grinding food

Molar – chewing and grinding food


Tooth structure:


Crown: The part of the tooth that is visible above the gum line.

Gum: Is a tissue the overlays the jaws.

Root: The rest of the teeth, embedded in the jaw bone.

Enamel: Covers tooth crown. Enamel is very hard (harder than bone), and prevents the tooth from decaying.

Dentine: Located under the enamel, this looks quite similar to bone. Not as hard as enamel.

Pulp: Found at center of tooth, and contains blood vessels, nerves and soft tissues which delivers nutrients to your tooth.

Cement: The layer of bone-like tissue covering the root. It is not as hard as enamel.

Nerves: Each tooth and periodontal ligament has a nerve supply and the teeth are sensitive to a wide variety of stimuli.


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.

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 buildup of plaque (a sticky layer on the teeth)