L5 - Human Teeth

objectives

• Identify the types of human teeth and describe their structure and functions
• State the causes of dental decay and describe the proper care of teeth

Parts of the Tooth

Teeth are found in the mouth and operate the first part of mechanical digestion.

Mechanical Digestion is where the food is physically broken down into smaller pieces. Our teeth and muscles around our jaw help us to tear, rip and chew food into smaller parts.

Different teeth have different shapes as they have different functions in the mouth.

A diagram of the parts of a conventional tooth can be found below:

The tooth has two anatomical parts. The crown of a tooth is that part of the tooth which is covered with enamel and this is the part usually visible in the mouth.

The root is the part embedded in the jaw. It anchors the tooth in its bony socket and is normally not visible.

Enamel The hard outer layer of the crown. Enamel is the hardest substance in the body.

Dentine Not as hard as enamel, forms the bulk of the tooth and can be sensitive if the protection of the enamel is lost.

Pulp Soft tissue containing the blood and nerve supply to the tooth. The pulp extends from the crown to the tip of the root.

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

Gingivae (gums): Soft tissue that immediately surrounds the teeth and bone. It protects the bone and the roots of the teeth and provides an easily lubricated surface.

Bone: Provides a socket to surround and support the roots of the teeth.

Nerves and blood supply: Each tooth and periodontal ligament has a nerve supply and the teeth are sensitive to a wide variety of stimuli. The blood supply is necessary to maintain the vitality of the tooth.

Types of Teeth

Tooth Decay

Tooth decay is the destruction of tooth structure and can affect both the enamel (the outer coating of the tooth) and the dentin layer of the tooth.

Tooth decay occurs when foods containing carbohydrates (sugars and starches), such as breads, cereals, milk, soda, fruits, cakes, or candy are left on the teeth.

Bacteria that live in the mouth digest these foods, turning them into acids.

The bacteria, acid, food debris, and saliva combine to form plaque, which clings to the teeth.

The acids in plaque dissolve the enamel surface of the teeth, creating holes in the teeth called cavities.

The stages of tooth decay can be seen below:

Preventing Tooth Decay

• Brush your teeth at least twice a day with a fluoride-containing toothpaste. Preferably, brush after each meal and especially before going to bed.
• Clean between your teeth daily with dental floss or interdental cleaners.
• Rinse daily with a fluoride-containing mouthwash. Some rinses also have antiseptic ingredients to help kill bacteria that cause plaque.
• Eat nutritious and balanced meals and limit snacks. Avoid carbohydrates such as candy, pretzels and chips, which can remain on the tooth surface. If sticky foods are eaten, brush your teeth soon afterwards.