A person has two sets of teeth over their lifetime – ‘baby’ teeth and ‘adult’ teeth. Children usually have their full set of 20 baby teeth (also known as deciduous, primary or milk teeth) by age three. Baby teeth start to fall out at about six or seven years of age and are slowly replaced by the permanent (adult) teeth. By around 21 years of age, the average person has 32 permanent teeth; 16 on the top and 16 on the bottom.
Teeth have an important role in digestion. They are different shapes and sizes to bite, tear, crush or grind food before it is swallowed. They help us to form sounds and speak clearly. They are an important part of a person’s smile, connected with confidence and part of social interaction.
Baby teeth play an important role in chewing and nutrition, and in holding space for the adult teeth. For these reasons it is important to prevent disease and early loss of these teeth.
Parts of the tooth
Teeth are made of the following components:
- crown – the part of the tooth that sits above the gum line
- enamel – the hard outer layer that protects the crown. Enamel is harder than bone and doesn’t have any nerves or a blood supply. It is usually smooth and off-white in colour. Chipped or decayed enamel cannot grow back
- dentine – most of the tooth is made up of dentine. It is a hard bone-like substance. If the protective layer of enamel is damaged, and the underlying dentine is exposed, the tooth will be sensitive to temperature and sweet or acidic foods. A tooth which has exposed dentine may also be at greater risk of tooth decay
- pulp – the living centre of the tooth that contains blood vessels and nerves. The nerves communicate sensory information such as temperature, pressure and pain
- root – the section of tooth that sits below the gum line. The root is held firmly within the bone of the jaw by connective tissue fibres. Depending on its size, a tooth will have between one and three roots. Each root has a small hole at the tip, to let nerves and blood vessels pass in and out of the pulp
- cementum – a hard material that covers the root surface.
Teeth and eating
Teeth help us to eat by breaking food into smaller pieces so that it can be further digested in the stomach and intestines.
Teeth have different shapes to do different jobs. Types include:
- incisors – these front teeth in the upper and lower jaws are used to bite. The blade-like surfaces of the upper and lower incisors come together like a pair of scissors. There are four upper and four lower incisors each in the deciduous (‘baby’) and permanent sets of teeth
- canines (sometimes called ‘eye’ teeth) – are located next to the incisors in the upper and lower jaws. They are used to tear food. There are two upper and two lower canines each in the deciduous (‘baby’) and permanent sets of teeth
- premolars – these teeth have flat surfaces to crush food. There are four upper and four lower permanent premolars. There are no premolars in the deciduous (‘baby’) set of teeth
- molars – these are the back teeth. They are larger than premolars and have big flat surfaces that grind food. The flat surfaces of both premolars and molars have small pointy parts called cusps that help to grind food. Over time, cusps are worn down. There are six upper and six lower permanent molars, and four upper and four lower molars in the set of baby teeth.
Tips for caring for teeth
Teeth are important for eating, speaking and socialising, so it’s important to take good care of them.
Some tips include:
- Brush your teeth and along your gum line twice a day, in the morning and at night before bed. Use a toothbrush that has a small head and soft bristles.
- Over 18 months of age, use fluoride toothpaste. Use low-fluoride children’s toothpaste for children aged 18 months to six years of age, and standard fluoride toothpaste for people aged six years and older.
- Avoid sugary foods and drinks. If you do have these foods, it is better to have them at meal times rather than between meals. Also avoid foods and drinks that are acidic – for example, soft drinks and fruit juices, as acid damages the tooth surface.
- Drink plenty of tap water. Most of Victoria’s tap water has fluoride in it, which helps to repair the tooth surface.
- Ask your oral health professional how often you should have a dental check-up.
- Wear a mouthguard when you train for and play sports where your teeth could get damaged (for example football, rugby, soccer, basketball, netball, water polo or hockey).
- Quit smoking to improve your oral health and general health.
- Limit your alcohol consumption.
Some examples of problems that can affect the teeth include:
- tooth decay
- gum disease
- loss of the tooth surface (enamel) through:
- dental erosion (caused by acids from food and drinks, or acids coming up from the stomach)
- dental abrasion (often due to incorrect or forceful tooth brushing)
- dental attrition ( often due to grinding or chewing)
- tooth and jaw alignment problems such as crooked, crowded or overlapping teeth
- tooth grinding (bruxism)
- tooth trauma, such as a knocked out or broken tooth
- developmental defects of the teeth such as molar hypomineralisation (‘chalky teeth’)
Where to get help
This page has been produced in consultation with and approved by:
Dental Health Services Victoria
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.