The Four Types of Teeth and How They Function

We tend to take our teeth and oral health for granted until something goes wrong. But your teeth play an important role in digestion, speech, and your overall health. By taking care of your teeth and gums today, you can keep your mouth healthy, and protect your overall health in the long-run.

The Development of Teeth

Humans have two sets of teeth, primary (or baby) teeth and then permanent teeth, which develop in stages. Although the timing is different, the development of each of these sets of teeth is similar. Here are some facts about how people develop teeth:

• Teeth tend to erupt in parallel, meaning that the top molar on your left side should grow in at about the same time as the top molar on the right.
• Tooth development begins long before your first tooth becomes visible. For example, a baby’s first tooth appears at around six months of age, but development of those teeth actually begins during the early second trimester of pregnancy.
• The crown of a tooth forms first, while the roots continue to develop even after the tooth has erupted.
• The 20 primary teeth are in place by age 3 and remain until around 6 years of age when they begin to fall out to make way for the permanent set of teeth.
• Adult teeth start to grow in between 6 and 12 years of age. Most adults have 32 permanent teeth.
• Permanent teeth are larger and take longer to grow in than primary teeth.

The Parts of the Tooth

A tooth is divided into two basic parts: the crown, which is the visible, white part of the tooth, and the root, which you can’t see. The root extends below the gum line and anchors the tooth into the bone. Your teeth contain four kinds of tissue and each does a different job. These include:

• Enamel. Enamel is the visible substance that covers the tooth crown. Harder than bone, enamel protects the tooth from decay. Enamel is made up of phosphorous and calcium.
• Dentin. Underneath the enamel you find dentin, which is calcified and looks similar to bone. Dentin is not quite as hard as enamel, so it is at greater risk for decay should the enamel wear away.
• Cementum. This tissue covers the tooth root and helps anchor it (cement it) into the bone. It is softer than enamel and dentin; the best way to protect this softer tissue from decay is by taking good care of your gums. Cementum has a light yellow color and is usually covered by the gums. But with inadequate dental care, the gums may become diseased and shrink, exposing the cementum to harmful plaque and bacteria.
• Pulp. Pulp is found at the center of your tooth and contains the blood vessels, nerves, and other soft tissues that deliver nutrients and signals to your teeth.

Types of Teeth and What They Do

Teeth help you chew your food, making it easier to digest. Each type of tooth has a slightly different shape and performs a different job. Types of teeth include:

• Incisors. Incisors are the eight teeth in the front and center of your mouth (four on top and four on bottom). These are the teeth that you use to take bites of your food. Incisors are usually the first teeth to erupt, at around 6 months of age for your first set of teeth, and between 6 and 8 years of age for your adult set.
• Canines. Your four canines are the next type of teeth to develop. These are your sharpest teeth and are used for ripping and tearing food apart. Primary canines generally appear between 16 and 20 months of age with the upper canines coming in just ahead of the lower canines. In permanent teeth, the order is reversed. Lower canines erupt around age 9 with the uppers arriving between 11 and 12 years of age.
• Premolars. Premolars, or bicuspids, are used for chewing and grinding food. You have four premolars on each side of your mouth, two on the upper and two on the lower jaw. The first premolars appear around age 10 and the second premolars arrive about a year later.
• Molars. Primary molars are also used for chewing and grinding food. These appear between 12 and 15 months of age. These molars are replaced by the first and second permanent molars (four upper and four lower). The first molars erupt around 6 years of age while the second molars come in between 11 and 13 years of age.
• Third molars. Third molars are commonly known as wisdom teeth. These are the last teeth to develop and do not typically erupt until age 18 to 20, and some people never develop third molars at all. For those who do, these molars may cause crowding and need to be removed.

Your mouth is important. Don’t take your teeth or oral health for granted. For good dental health, brush and floss your teeth regularly, don't smoke, eat a healthy diet, and see your dentist regularly for dental cleanings and checkups. A healthy mouth makes for a healthy body ... and a pretty smile.