Premolar is double pointed teeth that are present between canine and a first molar. They are also called transitional teeth because they have the property of both canine and molars.
You can easily differentiate your premolar from other teeth by seeing the cusps and location in the oral cavity. The primary task of premolars is to tear and crush the food that eases in swallowing food.
Let’s explore this article ahead to learn more about the structure of premolar, differentiating two types, their function, and a few interesting facts.
What are premolars?
A total number of eight premolars are present in your oral cavity. First premolar and second premolar are the two types which are present in each quadrant of the jaw.
You can find the first premolar next to your canine posteriorly. The second premolar comes posterior to the first premolar, just before the first molar.
There are two pointed elevations that are present on the chewing surface of premolars. They are also referred to as cusps. Premolars are often termed as bicuspids as there are two cusps.
What functions a premolar perform?
Premolars maintain the occlusion of teeth in the oral cavity. Occlusion refers to a manner in which upper and lower teeth touches each other such that they perform functions effectively in your mouth.
Besides this, premolars help in the crush and rip up the food that you eat. This function along with saliva production enable food to convert into small form so that digestion can be proper.
How does my premolar look?
In premolar, cusps are present on the occlusal or chewing surface. Cusp is a raised structure that plays an essential role in chewing of food.
The chewing surface of premolar is broad and as a result, the tooth appears diamond shaped. Pits and fissures are present on its upper surface.
Two cusps are present in premolars, one on your lip side and other towards the tongue. The former is called buccal cusp and latter is lingual cusp.
The buccal cusp is usually larger than lingual cusp. In an exceptional case, lower second premolar contains three cusps with two lingual cusps and one buccal cusp.
Similarly, there are two surfaces present in premolar that are buccal and lingual. It is evident that buccal surface faces towards your lip and the lingual surface is situated towards your palate and tongue.
The buccal surface is convex with the largest convexity present towards the gums in the lower one-third of the crown. Lingual surface is also convex but its convexity is more on the middle third.
Also, the lingual surface is narrower than the buccal surface in premolars.
Moreover, two other surfaces are mesial and distal that you can’t see properly. The side that is present towards canine is mesial surface and the front facing molar is distal surface.
Usually, upper premolars have two roots. Whereas, lower premolars have only one root. Root is the part of teeth in which root canals are present. Root canal treatment is also performed in this region.
How can I differentiate the first and second premolar?
You can differentiate both premolars through their morphological appearance. However, the functionality of both premolars is relatively same.
Upper first and second premolar
Buccal cusp of upper first premolar is long and has a pointed tip. The tip of buccal cusp resembles the canine. On the other hand, the buccal cusp of the upper second premolar is shorter and less sharp than the first premolar.
Lingual cusp of the first premolar is not long as the buccal cusp of same teeth. Whereas, the lingual cusp of the second premolar is longer than its buccal cusp.
The occlusal surface of the first premolar is hexagonal. On the other side, the outline of the second premolar crown is rounded or oval.
Lower first and second premolar
The buccal aspect of lower first premolar crown is nearly symmetrical. While the oral surface of the second premolar is not symmetrical.
Buccal cusp tip of the first molar is pointed and tilted from the center of crown towards the canine. Whereas, cusp tip of the second premolar is shorter than the first premolar.
The lingual cusp of the first premolar is shorter and non-functional, while the lingual cusp of the second premolar is relatively longer and functional.
The first premolar has only one lingual cusp, while the second premolar has one or sometimes two lingual cusps also.
The occlusal surface of the first premolar is a roughly diamond shape. Although, in second premolar occlusal surface is either square or round in shape.
Some interesting facts
1. You can’t find premolars in a child’s mouth
If you see your child’s oral cavity and you don’t find premolars there don’t get worried because premolars are not present in kids below the age of 10 years.
Children have only 20 teeth in total and in the place of premolar they have primary molar.
2. Extraction is preferred
Usually, premolars are the most common teeth for extraction in people who don’t have enough space in their mouth for an eruption of other teeth. Also, premolars can be removed by an orthodontist during braces treatment.
The extraction of premolar is common because they are similar to canine and molar. There is no concern to esthetic and functionality even if they are removed.
In some cases, your doctor may advise removing all the premolars to gain the space during the orthodontic procedure.
3. Most common congenital missing
Congenitally missing refers to teeth that are not present due to congenital disability. Lower second premolar is the most common teeth that can be seen missing in the oral cavity.
The cases of missing premolars are seen in hypodontia. The problem is mainly with the dental lamina which is tissue beneath the gums. Dental lamina is the region where your teeth start to develop.
The defect with dental lamina is mainly due to genetic factors. Sometimes the adjacent tooth dental lamina is absent because of changes in genes that is called mutation.
If a mutation occurs and dental lamina doesn’t form, then it may also affect the development of neighboring teeth.
4. Each premolar has its own number
Every tooth in the mouth is characterized on the basis of the number system. The number system is followed for the convenience of your dentist.
When you visit dental clinic you probably have seen dentist writing some numbers. That is what he denotes the particular teeth.
According to universal number system premolars are numbered as 4, 5,12,13 for upper arch and 20,21,28,29 for lower premolars.
Here, 4, 12, 28 and 21 are first premolars whereas 5, 13, 20 and 29 are second premolars respectively.
5. Primitive humans used to have 12 premolars
You might not believe but it’s true that ancient humans including old world monkeys and apes used to have three premolars per quadrant of the jaw.
That means a total number of 12 premolars were there collectively in the upper and lower part.
Over to you
Premolars are diamond shaped teeth that have two cusps. Their functionality is the combination of both canine and molars.
In the case of misaligned teeth, the premolars are crucial for gaining space in the arch.
During orthodontic treatment, premolars are the most common teeth to be removed. Their position can be compromised for maintaining the position of other adjacent teeth.