Todays topic for biology class 12 is Structure of the Teeth. Teeth are very important part of human body. They help us to break down or chew our food properly so they play a vital role in the process of digestion.
Types of Teeth
1.Thecodont Teeth
2.Diphyodont Teeth
3.Heterodont Teeth
1.Thecodont Teeth- Teeth that are embedded in the jaw bones of humans are known as thecodont teeth.
2.Diphyodont teeth- These are those teeth that occur in two sets in humans that is temporary or milk teeth and permanent teeth. Temporary or milk teeth are also known as decidous teeth.They start appearing at the age of six or seven months after the birth of the baby.Usually there are 20 temporary teeth present by the age of two and a half or three years.These teeth are then replaced by permanent teeth at the age of six to twelve years.
2.Heterodont teeth-Humans have different types of teeth that have different types of shapes. These are known as heterodont teeth .
Let's now discuss about the different types of heterodont teeth in humans. They are mainly of four types--
1. Incisors-Their edges are sharp and are located in the front or anterior part of the mouth. They are used for cutting or chopping the food.
2.Canines- They are located just behind the Incisors. They are used for tearing the food.
3.Premolars- They appear behind the Canines. They are generally used for grinding the food.
4.Molars- They are located at the backside of the jaw. Like premolars they are also used for grinding and crushing the food. Babies who have milk teeth lack premolars as premolars only grow in the permanent set of the teeth.
Milk teeth or temporary teeth are 20 in number. There are eight Incisors, four Canines and eight molars. Premolars are not present in the temporary set of teeth.
Permanent teeth are 32 in number. There are eight Incisors, four Canines, eight premolars and twelve molars.
Structure of the Teeth
Almost all the teeth have the same basic structure. There are three main parts of a tooth. These are-
1.Root
2.Neck
3.Crown
Root is the lowermost part of the tooth . It is fixed in the alveolus of jaw bone with a substance called cementum. Different types of teeth have different number of roots. There is a single root in incisors, canines and lower pre-molars. There are two roots in lower molars and upper pre-molars. There are three roots in upper molars.
Neck is present in the middle of the tooth. It lies in the gum.
Crown is that part of the tooth which is present externally. It is covered by enamel which is a white coloured substance and is the hardest substance present in the human body.
Tooth is made up of a hard material known as dentine. A tooth has pulp inside it which consists of blood vessels,lymph vessels and nerve fibres.It provides nourishment to the tooth. This pulp is present inside the pulp cavity which is lined with odentoblasts.
Now let's discuss how to keep your teeth healthy.It's very important to take care of your teeth otherwise you may suffer from teeth problems such as white spots (plaque) starts appearing on the teeth which turns into a yellow layer(tartar). If this is not treated then it may lead to pain and a lot of swelling over a period of time.You can watch my video on tooth decay. If you will take proper care of your teeth you can keep yourself away from this trouble.Here are some tips how you can keep your teeth healthy.
1 . Brush your teeth at least twice a day especially at night before sleeping so that the bacteria would not be able to spoil your teeth in the night.
2 .A flouride toothpaste or a toothpaste containing baking soda are good.
3 . Floss at least one time a day.It is proved by studies that plaque can be removed upto 74% by a water flosser and a manual toothbrush but a string flosser and a manual toothbrush can remove only upto 58% of plaque.It is very important as if the white spots (plaque) turn into a yellow layer called tartar that can only be removed by a dental expert.
4.Green tea is also good for your teeth
5.A mouthwash with ADA seal of approval is good to control plaque and tartar as it consists of ingredients such as chlorhexidine and cetylpyridinium that fight bacteria and protect your teeth.
6 . It is also proved by studies that those people suffer less from tartar who use hydrogen peroxide whitening strips than those who only brush their teeth.
Hope you liked the above topic Structure of the Teeth for notes of biology class 12. Please share it. The Worksheets for Science for this topic is also provided which you can practice to sharpen your knowledge.
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