Teeth are hard structures found exclusively in vertebrates. Granted, some invertebrates have analogous “teeth” but they are quite different in their structure and function.
Unlike pythons and pelicans, humans cannot swallow food in one big gulp. Food must be broken down into smaller pieces before it can be swallowed. This function is performed by hard, calcified structures called teeth.
Humans have different types of teeth that perform various functions such as cutting, tearing, shearing and crushing. The teeth are powered by the jaw muscles and lubrication is done with the help of saliva, which is produced in the salivary glands.
Vertebrates possess teeth that vary in form and number. These arrangements of teeth are expressed through a special formula called the dental formula.
Types of Teeth in Humans
Teeth have different shapes as each tooth has a particular role to perform during mastication (chewing) and eventually digestion. They are also positioned differently, so as to better serve their purpose.
There are four different types of teeth in humans. Their form and function are as follows:
Incisors are present at the front of the mouth. These teeth are adapted for cutting food into small, chewable pieces. Humans have 8 incisors, 4 incisors in each jaw.
Canines are situated at the ‘corners’ of the dental arches. They are characteristically sharp and elongated. Their primary function is to grip and tear food (tough food such as meat). Humans have 4 canines, 2 in each jaw.
Premolars are teeth located behind the canines. These teeth have a flat surface, which is adapted for crushing food. Humans have 8 premolars, 2 on each side of the jaws.
Molars are the largest of the teeth. It has a large and flat biting surface, which is well-adapted for grinding food. Humans have 12 molars, 6 in each jaw. (4 of those are wisdom teeth, which is also called the third molar.)
An adult will have 32 teeth (28 if Wisdom teeth are removed). Babies are born toothless as their primary source of food is mother’s milk. As the babies start to wean, milk teeth gradually start to appear. Milk teeth get replaced by permanent teeth by the time the individual turns 6 years old.
Also, during this phase, an individual will have a combination of milk and permanent teeth. Consequently, this stage is called mixed-stage.
Also Read: Facts About Teeth
Diphyodonts & Polyphyodonts
Humans and most other mammals are classified as diphyodonts, which means we possess two successive sets of teeth in a lifetime (milk teeth and permanent teeth).
Other vertebrates such as crocodiles and toothed fishes are classified as polyphyodonts, meaning that their teeth are continuously replaced during their lifetime. The only mammals which are polyphyodont are elephants, kangaroos and manatees.
Tough, Yet Irreplaceable
Human beings eat food all through their lives. Hence, to withstand their prolonged use through years of chewing, teeth must be really hard and firmly anchored. The white, exposed part of the tooth is covered by enamel layer. This is the body’s hardest material.
Enamel is incredibly strong and is also translucent – which means light can be observed through it. Though enamel is the body’s hardest tissue, it has no living cells. This means that if the tooth gets chipped or broken, there is no way for it to repair itself.
Frequently Asked Questions
What are the 4 types of teeth?
Teeth are classified into 4 types:
Which tooth is used for tearing food?
The incisors are the teeth at the front of the mouth and are responsible for tearing chunks and pieces of food.
What is the third tooth called?
Often called the third molar, the wisdom teeth usually appear between the age of 18 to 25.
How many teeth do humans have?
Humans are diphyodonts, which means that we possess two successive sets of teeth in our lifetime – the milk teeth and permanent teeth. Children usually have 20 milk teeth which get gradually replaced by 32 permanent teeth as they mature.
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