The human mouth contains eight premolars, playing a key role in the process of chewing by transferring food from the canines to the molars. Each premolar features at least two cusps - the pointed, raised part of the tooth. It's important to note that there are no baby teeth equivalents for premolars.
Premolars are categorized into two groups: mandibular and maxillary, and first and second premolars. Let's delve into the differences.
Situated next to the canine teeth in both the upper and lower jaws, the first premolars are known as the maxillary first premolar (upper jaw) and the mandibular first premolar (lower jaw).
Their function is to assist in the tearing of food during the chewing process. The first premolars possess two root canals and have sharp, elevated cusps. In the universal system of notation, the right mandibular first premolar is labeled as 28, the left as 21, the right maxillary first premolar as 5, and the left as 12.
The second premolars, positioned between the first premolars and the first molars in both jaws, are known as the maxillary second premolar (upper jaw) and the mandibular second premolar (lower jaw). These premolars have one root and their cusps are rounded and less prominent.
The universal system of notation identifies the right mandibular second premolar as 29, the left as 20, the right maxillary second premolar as 4, and the left as 13.
| First Premolar | Second Premolar |
| Description | |
| The first premolar is positioned away from the midline of the face, adjacent to the canine. | The second premolar is located away from the midline of the face, nestled between the first premolar and the first molar. |
| Structure | |
| First premolars are sharper with more pronounced cusps. | Second premolars are rounded with smaller cusps. |
| Root | |
| First premolars have a smaller root. | Second premolars have a longer root that anchors the tooth into the gums. |
| Similar to | |
| First premolars are more similar to the canines. | Second premolars are more similar to the molars. |
| Number of Cusps | |
| The mandibular first premolars have two cusps. | The mandibular second premolars have three cusps. |
| Activity of the Cusp | |
| The lingual cusp (near the tongue) of the mandibular first premolar does not participate in chewing. | All three cusps of the mandibular second premolar are functional. |
| Universal Number of Notation | |
| Mandibular first premolar: 28, 21 Maxillary first premolar: 5, 12 |
Mandibular second premolar: 29,20 Maxillary second premolar: 4, 13 |
Also Read:
How do you tell the difference between a first and second premolar?
The major visible difference between the first and second premolar can be observed in their cusps. The first premolar has more sharp and prominent cusps, but the second premolar has rounded and small cusps.
How do you differentiate maxillary first and second premolar?
The buccal cusp (near the cheek) is almost V-shaped and is more prominent than the second premolar.
What premolar often has three cusps?
The mandibular second premolar has three cusps.
Which premolar has two root canals?
The first premolars have two root canals.