2. PK Testing How many teeth do you have? Do you go to a dentist? Why should all of us go to a dentist regularly?

3. We will learn: Kinds of Teeth Parts of a tooth Care of teeth Digestive System Microbes

4. Sets of Teeth Babies are without teeth By age 2, twenty teeth come up These are called “milk teeth” or “temporary teeth” After age six, “permanent teeth” come up which stay for the rest of the life. These are 32 in number.

5. Kinds of Teeth There are 4 kinds of teeth Incisors: There are 8 incisors in all (4 in upper jaw & 4 in lower jaw). Used for cutting & biting the food Canines: There are 4 canine teeth in all (2 in upper jaw & 2 in lower jaw). Used for tearing of food Premolars: There are 8 premolars in all (4 in upper jaw & 4 in lower jaw). Used to crack & chew the food. Molars: There are 12 molars in all. Used to chew & grind the food.

7. PK Testing How many sets of teeth do humans have? Ans: 2 How many kinds of teeth do we have? Ans: 4 Name all the kinds of teeth? Ans: Incisors, Canines, Premolars, Molars How many i) Incisors, ii) Canines, iii) Premolars, iv) Molars do humans have? Ans: i) 8, ii) 4, iii) 8, iv) 12

8. Parts of Tooth Even though there are 4 types of teeth, they all have same basic structure. Each tooth has a crown and a root. The visible part is called the crown of the tooth. The roots are inside the gums. The gums hold the teeth in place.

9. Enamel is the hard, white part of the tooth Below the enamel lies the dentine which is like a bone Inside the dentine is the pulp which is very soft and full of nerves & blood vessels. It is the central part of the tooth.

10. PK Testing Name the parts of a tooth. Ans: i) Crown, ii) Root What is the white hard part of the tooth called? Ans: Enamel Where does dentine lie? Ans: Below the enamel Where does the pulp lie? It lies inside the dentine

11. Care of Teeth We should brush our teeth twice every day. If we do not clean, germs will grow between our teeth forming a yellow layer called plaque. Brush your teeth twice a day Rinse your mouth after meals Clean the tongue to remove germs Use floss to clean between teeth Eat healthy food Avoid sweets and junk food Visit your dentist

12. Calcium It is very important It helps in building strong teeth It can be got from i) Paneer ii) Cheese iii) Milk iv) Curd

13. Digestive System Digestion: The process by which the food is broken down into a simple form so that it can be taken in or absorbed by the body. There are many organs that work together and help in digestion. These together form the digestive system. PROCESS OF DIGESTION Digestion starts in the mouth by the process of chewing the food. Saliva gets mixed with the food.

14. Food passes from mouth to the food pipe or oesophagus. It is a long tube. Stomach is the sac like organ where food is broken down. From stomach it moves to small intestine. Here all the important parts of food are removed and moved to the blood. Blood takes it to all parts of body. Liver produces juices that are required for digesting food.

15. Large Intestine holds food that can not be digested. Anus removes the faeces from the body.

16. Healthy Eating Habits Eat 4 to 5 meals in a day Chew the food before swallowing it Eat fruits and vegetables everyday. Always wash hands before and after meals Eat a well balanced diet

17. Microbes These are very small living things and can be seen only with a microscope. These can be useful or harmful. Harmful microbes cause disease and are called germs These are of 4 types: a) Viruses: cause diseases like common cold, influenza, etc. b) Bacteria: cause diseases like typhoid, cholera, etc. c) Fungi: cause diseases like ringworm, athlete’s foot d) Protozoa: cause food poisoning, malaria, etc.

18. Difficult Words Temporary Permanent Incisors Canines Premolars Molars Enamel Dentine Plaque Floss Digestion Oesophagus Stomach Intestine Microbes protozoa

19. New Terms Incisors: Teeth that help in cutting and biting the food are called incisors Canines: Teeth that are used for tearing the food. Premolars: Teeth that help in cracking and chewing the food are called premolars Molars: Teeth that help in chewing and grinding the food are called molars Crown: The upper part of the tooth that is visible is called the crown

20. Root: Part of the tooth inside the gums is called the root Plaque: A yellow sticky layer of germs that forms on the teeth is called plaque Digestion: The process of changing food onto a simple form that can be used by the body Microbes: Small living things which can be seen only with the help of a microscope are called microbes.

21. Question Answer Q1. Why are milk teeth also called temporary teeth? How many teeth are there in a temporary set? Ans. Milk teeth are called the temporary teeth because they are only till the age of about two years. There are twenty teeth in a temporary set. Q2. Name the four kinds of teeth in an adult. How does each kind help us? Ans. The four kinds of teeth are: a) Incisors, b) canines, c) Premolars, d) Molars.

22. Incisors help us to cut and bite the food. Canines help us to tear the food. Premolars help us to crack and chew the food. Molars help us to chew and grind the food. Q3. Describe the basic structure of a tooth. Ans. The tooth is divided into two parts; a) crown, b) root. The crown is the part visible to us. The hard white part of tooth is called enamel. Below enamel is the dentine. Under dentine lies the pulp. Q4. Why do we need to brush our teeth properly? Ans. We need to brush our teeth properly to stop the growth of plaque