In my last anatomy lesson, I discussed the anatomy of a tooth, including the three main sections (crown, neck, and root), as well as the four major tissues that make up the tooth (enamel, dentin, cementum, and pulp).
Now let’s talk about the different types of teeth and their function.
Two Sets of Teeth (Dentitions)
First, it’s important to note that throughout life, humans generally develop two sets of teeth.
The first set of teeth can be referred to as baby teeth, primary teeth, deciduous teeth, or milk teeth, and there are 20 baby teeth that develop. These teeth begin to erupt at around 6 months of age and continue erupting until the toddler is around 33 months old.
Note: the chart below depicts the common way teeth erupt, along with the timeline. Teeth eruption can vary from child to child. You might want to review our video on baby teething tips.
The second set of teeth will eventually replace the baby teeth, and these are called your secondary or permanent teeth. Adults typically develop up to 32 permanent teeth. These teeth begin erupting around age 6 and continue until the third molars (wisdom teeth) erupt in the late teens or early 20s.
Of course, if you lose your permanent teeth, you might get a third set of teeth, called dentures. However, those don’t count! Therefore, you only develop two sets of teeth, and each set is known as a “dentition.”
The Dental Arches
Your teeth form along the upper and lower jawbones in the shape of an arch, so they are referred to as your dental arches.
You have an upper dental arch in the maxilla (upper jawbone), which is called the maxillary arch. You also have a lower dental arch along your mandible (lower jawbone), which is called your mandibular arch.
Four Quadrants of the Mouth
The mouth / teeth are divided into for quadrants similar to the way that the abdomen is divided into four quadrants.
- Quadrant 1 is called the maxillary right
- Quadrant 2 is called the maxillary left
- Quadrant 3 is called the mandibular left
- Quadrant 4 is called the mandibular right.
Different Types of Teeth and Their Function
Humans have four main types of teeth: incisors, cuspids (canines), bicuspids (premolars), and molars. However, only three types of teeth appear in the baby teeth (first dentition) because the premolars do not develop with the first dentition. Instead, baby teeth include a total of 20 teeth (10 on each arch), including 8 incisors, 4 canines, and 8 molars.
Adolescents and adults have all four types of teeth in their permanent dentition, eventually developing 8 incisors, 4 canines, 8 premolars, and 12 molars. This adds up to 32 teeth in a complete set (or 16 teeth in each arch).
Notice I said a “complete set,” because not all people receive the full 32 teeth. In addition, some people can have more than 32 teeth in their permanent dentition, and those extra teeth are called supernumerary teeth.
Now let’s take a look at the four types of teeth, starting with the incisors.
Incisor Teeth Anatomy and Function
The incisors are located at the anterior (or front) portion of the mouth. Each dental arch has two central incisors, which are separated by the mouth’s midline, and two lateral incisors that sit alongside the two central incisors distally. When you add the incisors on both arches, you get eight incisors total for both the baby teeth and permanent teeth.
Incisors tend to have only one conical root, and their crowns are shaped like small chisels or shovels. The main function of incisors is for cutting off food. In fact, the word incisor comes from an old word that means “cutting tooth.”
However, incisors also work with your tongue and lips to produce words and sounds.
Canine (Cuspid) Teeth
Next you have the canine teeth, which are also called cuspids or “eyeteeth.” If you consider the name of these teeth then you’ll always remember them because “cuspid” means “point”, and canine refers to dogs, which have those sharp, pointy teeth.
Both the baby (primary) teeth and permanent teeth include four canines (two in the maxillary arch and two in the mandibular arch), which sit alongside the lateral incisors distally.
Canines tend to have one long root, and the crown has one sharp point, called a cusp – hence the “cuspid” name. However, your canines can lose their point over time if you have a misaligned bite or grind your teeth.
The main function of the canine teeth is to puncture food and tear it off with their sharp cusp (point).
Premolar (Bicuspid) Teeth
Distal to the canine/cuspid teeth are the bicuspid teeth, which are also called premolars. In each quadrant, you have a first premolar, which is distal to the canine, and a second premolar, which is distal to the first premolar.
It’s easy to remember the location of these teeth because “premolar” tells you these are before (or mesial to) the molars.
Also, the prefix “bi” means two, and cuspid means point, so the name itself tells you that the crown of these teeth generally have two main points or cusps, though they can also have an extra 1-2 cusps (3-4 total), especially on the mandibular second premolar.
However, remember that the baby teeth do not include any premolars/bicuspids. These only erupt with the permanent dentition, and you have four in each arch, making eight bicuspids/premolars in total.
Premolars tend to have one root, but they can have 2 or even 3 roots on the maxillary first premolar, and their main function is to grind up food.
Molar Teeth
Finally, we have the molars, which are located at the posterior portion of each arch. Children have eight molars in their primary (baby) teeth: a first and second molar in each quadrant (four in each arch), which are distal to the canines.
Adults have up to twelve molars in their permanent dentition: a first, second, and third molar in each quadrant (or six in each arch).
The third molars are also called wisdom teeth because they don’t develop until the late teens or early 20s, which is when you are supposed to have wisdom, but sometimes they fail to erupt properly.
I never developed my maxillary third molars, and my mandibular third molars were impacted and had to be surgically removed. All of my wisdom teeth are gone, so I only have dumb teeth now.
The crown of molars have a larger surface area than the other teeth, and usually have 4-5 dull cusps. The maxillary molars tend to have three roots, whereas the mandibular molars tend to have only two roots.
The main function of the molars is to crush and grind food for easier digestion.
Free Quiz and More Anatomy Videos
Take a free comprehensive quiz on types of teeth to test your knowledge, or review our types of teeth anatomy video. In addition, you might want to watch our anatomy and physiology lectures on YouTube, or check our anatomy and physiology notes.