What Are Premolar Teeth Definition Structure and Functions
Premolars or bicuspids or premolar teeth are a type of teeth present between our molars and our canine teeth. Humans have two sets of premolars for every quadrant leading to 8 premolars in total in our mouth. These premolars have at least 2 cusps and are used for chewing food.
They contain properties of both canines (in the front) and molars (in the rear), and they help food transfer from the canines to the molars. The function of premolar teeth is to act as a transitional vessel for the food from the front to the back of our mouth for proper breakdown, thus earning it the name of “transitional” teeth.
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Structure of Premolars
The premolar teeth numbers are 8 in our mouth with 2 of each of the following -
Maxillary first premolar
Maxillary second premolar
Mandibular first premolar
Mandibular second premolar
The structure of these premolars all differ from each other. Let’s take a look at them.
Maxillary First Premolar
The crown is more ovoid, being wider than the rest.
At first, these first premolars look similar to their neighbor, the canines.
They generally contain two roots but can sometimes have just one.
Maxillary Second Premolar
Their shape and structure are similar to the first premolars but their distobuccal and mesial-buccal corners are more rounded.
Their cups are more equal and smaller in size.
They usually have one root.
They have smaller occlusal fissures.
Mandibular First Premolar
These premolars are the smallest out of the 4 premolars.
They have a very short lingual cusp with a broader buccal cusp. The lingual cusp is just half the size of the buccal cusp.
From the occlusal, only 2/3rd of the buccal surface of this premolar is visible.
They usually have one root with a round or oval cross-section.
Mandibular Second Premolar
Their crown is larger than even the mandibular first premolar.
They have a smaller better-developed lingual cusp with a broader buccal cusp.
The buccal and the lingual cusp is separated by an occlusal fissure which is both mesiodistal and well-defined.
They usually have one root with a round or oval cross-section.
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Taking Care of Premolar Teeth
The most common cause of premolar teeth pain is cavities. Due to their wide cusps, a lot of food gets stuck there leading to cavities. However, there is no extra special care to be taken of one’s premolars. Just like the rest of our teeth, premolars require thorough brushing twice daily with a good quality toothbrush. This will strengthen your tooth enamel. You can also use floss to clear out any plaque from your teeth.
Difference Between Premolar and Molar Teeth
There is very little difference between our molar and premolar teeth. But even that little difference is significant. Their main difference lies in their shape and size. Premolars might look wider and larger than your narrower canine teeth, but they are smaller than molars.
Again, while both molars and premolars contain fissures and pits in their cusps, the fissures are much deeper in the molars. This leads to a greater risk of cavities in your molars than in your premolars.
The molars and premolars also differ regarding the number of roots they have. Only the maxillary or the upper first premolar has two roots while the rest have a single root. On the other hand, the molars are always accompanied by roots except for the upper molars, which may also have three roots.
Premolars in Other Mammals
Premolars were found in primitive placental mammals. The premolar teeth numbers in them were 4 every quadrant but two of them, the medial ones (closest to the front of their mouth) have been lost already since apes and old world monkeys.
Fun Facts
Human premolars are known as Pm3 and Pm4 by paleontologists.
Our premolars are our most commonly removed teeth. Almost 48.8% of cases require the removal of premolars during orthodontic treatment.
FAQs on Premolar Teeth Structure Types and Role in Chewing
1. What are premolar teeth?
Premolar teeth are transitional teeth located between the canines and molars that help in chewing and grinding food. They are also called bicuspids because most have two cusps on their chewing surface. In permanent dentition, premolars:
- Are positioned behind the canines
- Assist in both tearing and grinding food
- Have a broader surface than incisors and canines
2. How many premolars do humans have?
Humans typically have 8 premolars in their permanent dentition, with two in each quadrant of the mouth. Specifically:
- 2 in the upper right jaw
- 2 in the upper left jaw
- 2 in the lower right jaw
- 2 in the lower left jaw
3. What is the function of premolar teeth?
The main function of premolar teeth is to crush and grind food during chewing. They act as a transition between the tearing function of canines and the heavy grinding function of molars. Their functions include:
- Breaking food into smaller particles
- Assisting in efficient mastication
- Supporting proper alignment of the dental arch
4. What is the difference between premolars and molars?
The key difference between premolars and molars is that premolars usually have two cusps while molars have multiple cusps and a larger chewing surface. Major differences include:
- Size: Molars are larger than premolars
- Cusps: Premolars typically have 2 cusps; molars have 4–5 cusps
- Function: Premolars crush food; molars grind it more thoroughly
- Roots: Molars often have more roots than premolars
5. What is the structure of a premolar tooth?
A premolar tooth consists of a crown, neck, and root, along with internal dental tissues. Its main structural components include:
- Enamel – hard outer protective layer
- Dentin – layer beneath enamel that supports it
- Pulp cavity – contains nerves and blood vessels
- Cementum – covers the root and anchors the tooth
6. Why are premolars called bicuspids?
Premolars are called bicuspids because they usually have two pointed cusps on their chewing surface. The term “bi” means two, and “cuspid” refers to the pointed projections. These cusps:
- Help grip and crush food
- Assist in the transition from tearing (canines) to grinding (molars)
7. At what age do premolars erupt?
Premolars typically erupt between 10 and 12 years of age as part of the permanent dentition. Their eruption pattern generally follows:
- First premolars: Around 10–11 years
- Second premolars: Around 11–12 years
8. Do children have premolars?
Children do not have premolars in their primary teeth; premolars appear only in the permanent dentition. In primary (deciduous) teeth:
- There are incisors, canines, and molars
- Premolars are absent
9. How many roots do premolars have?
Premolars usually have one or two roots, depending on their position in the mouth. Generally:
- Upper first premolars often have two roots
- Upper second premolars usually have one root
- Lower premolars typically have one root
10. What is the role of premolars in digestion?
Premolars play a crucial role in digestion by performing mechanical digestion through crushing and grinding food. Their action:
- Breaks food into smaller fragments
- Increases surface area for enzyme action
- Facilitates easier swallowing and further digestion in the stomach
