Teeth.pdf

Otir "I*ccthand CHAPTER Microbes r. Warm-Up A list of pictures of objects are given below. Make a smiley face in front of the object which we use for cleaning our teeth....

Otir "I*ccthand CHAPTER Microbes r. Warm-Up A list of pictures of objects are given below. Make a smiley face in front of the object which we use for cleaning our teeth. Ice cream Tongue cleaner Antiseptic fiquid Toothpaste Chewing gum Soap Mouthwash Cl.-k.xx-. Shampoo Toothbrush 61  rtéeth are very importantpart of our body. STRUCTURE OF A TOOTH They help us to bite and chew our food. A tooth has three parts: the crown, the They give proper shape to our face. neck and the root. The crown is the visible They help us to speak clearly. part of the tooth. The root is the part of Shiny and clear teeth make our smile the tooth which is inside the gum and beautiful. holds the tooth firmly in its place. The region where the crown meets the root is When the baby is six months old, the called the neck. teeth start appearing. By the time a child The outer layer which is visible to us is about two years, he or she has twenty covers the crown is called enamel. The teeth. These teeth are called milk teeth or enamel is white and protects the tooth temporary teeth. from wear and tear of chewing. Below théi enamel is the dentine. Inside the dentine, the pulp is present which is a very soft material.It has nerves and blood vessels. It also supplies nutrition for enamel and dentine. Enamel - New bom baby Five-year-old child Crown Dentine Neck Gum upper Teeth Lower Teeth Pulp At the age of six, the milk teeth start falling o and new teeth start appearing in their place. These are called permanent teeth. Root Nerve An adult person has 32 teeth, 16 each are and vessels present in the upper jaw and lower jaw. Upperjaw Structure of a tooth Lowerjaw After 20 years, you will have all the 32 teeth. All our teeth are not the same in shape or size. There are different teeth for different purposes. Teethin an adult 62  molars in our mouth, i.e. six in the TYPES OF TEETH upper jaw and six in the lowerjaw. Thereare four types of teeth. 1. Incisors 2. Canines 4. Molars -r arkösKeÖ theirteeth 3. premolars Do You throughout their life and Know? grow new ones to replace I. Incisors or Cutting Teeth the Jost teeth. Incisors are present at the front of each aw and have sharp straight edges. Tab. rfGement of teeth in our mouth They help us to cut or bite our food. Upper jaw Lowerjaw We have eight incisors in our mouth, 4 i.e. four in the upper jaw and four in Incisors 4 the lower jaw. 2 Canines 2 2. Canines or Tearing teeth 4 Premolars 4 Canines are sharp pointed teeth present on either side of the incisors. hese teeth Molars 6 6 are used for tearing food. They are four in number in our mouth, i.e. two in the f. - Quick Check upperjaw and two in the lowerjaw. Choose the correct answers. 3. Premolars or Cracking teeth l. At the age of two years, a child has Premolars are present next to canines, (twenty/ eighteen) teeth. which are broad and flat. hey help in 2. The (crown/ dentine) is the visible part cracking food. e have eight premolars of the tooth. in our mouth i.e. four in the upper jaw 3. The region of the tooth where the crown and four in the lowerjaw. meets the root is (neck/ enamel). 4. Molars or Grinding teeth 4. Canines are also called (cutting teeth/ tearing teeth). Molars are located next to premolars anaa 5. There are 12 (premolars/ molars) in the and are broad. They help in grinding mouthof an adult. and chewing the food. We have twelve Various types o/ teeth 63  How do the teeth decay? If your permanent teeth decay and fall off When we eat food, small pieces of food no new teeth will grow in their place. sometimes get stuck in between the teeth. Some rules are given below to show you This causes the growth of bacteria in these the best way of brushing. areas. Bacteria first attack the enamel and Brush the upper teeth with downward form a yellow sticky layer called plaque. strokes and in one directionand lower They further break down the food material teeth with upward strokes in one into acid. This acid acts on the enamel and direction. causes holes inside the teeth called cavities Brush the flat surface of teeth exposing the pulp. Then the bacteria reach (molars and premolars) with scrubbing the nerves within the pulp and cause pain. stroke. Bad breath, cavities, tooth ache, bleeding Brush each area at least 5-7 times. gums and indigestion are the results of teeth decay. Brush each jaw separately. CARE OF TEETH The most important measure to protect the teeth from decay is brushing teeth. A toothbrush removes the food particles stuck to the teeth and between the teeth. It is good to brush your teeth after every meal or atleast brush your teeth twice a day, i.e in the morning and at night (before sleeping). Use a dental floss to clean between the teeth. After every meal rinse your mouth (gargling). Go to a dentist for dental check-up regularly preferably after every six months. Different strokes of Do not eat too many sweets or chocolates. brushing Don't eat too hot and too cold food. The hardest substance present in our Eat balanced diet to give strength to body is enamel. your teeth. that you 64 SEARCH MIRROR indigestion: upset stomach I stroke: a series of movements make during brushing I scrubbing: clean by rubbing hard MICROBES They are used in making yogurt or curd. Microbes/microorganismsare so small Some of them help animals to digest that they cannot be seen with the naked food. eyes. They can be seen only through a They also help in digestion of roughage microscope. in animals. They are present in air, water, soil and They cause diseases like typhoid, even inside our body. tuberculosis, pneumonia and food They grow rapidly whenever they get poisoning in humans. warmth, moisture, food and air. Fungi Some microbes are useful to us whereas some are harmful. Fungi are non-green plants which are usually grow on other plants or dead Many of them cause diseases. and decaying matter. Disease-causing microbes are called They are used in making bread soft germs. and fluffy. Amazing Facf e They can cause skin diseases like ringworm, dandruff and athlete's foot. A snail has more than one thousand teeth. Protozoa They are single-celled microorganisms. TYPES OF MICROBES They can cause diseases like malaria There are four main kinds of microbes. These and dysentery. are bacteria,fungi, protozoa and viruses. Viruses Bacteria Viruses are the smallest in all microbes. Bacteria are single-celled microorganisms. They are on the borderline between They may be rod-shaped, spiral or round. living and non-living things. They help in the decay of dead plants They cause diseases like chickenpox, ad imals. common cold, influenza and dengue. Protozoa Varioustypes of microbes SEARCH MIRROR microscope: an instrumentused to see things that are too small in size 65  Flowchart Teeth Permanent Teeth Milk Teeth or Temporary Teeth Structute of a Tooth Types of Teeth CCanitÅem (+remol@/j KMOlarO Care of Teeth Microbes Types Bacteria Single-celled Non-green Single-celled Smallest microorganisms plants microorganisms microorganisms Quick Scroll Human beings have two sets of teeth —temporary and permanentteeth. A tooth consists of crown, neck and root. V A tooth has three layers—enamel,dentineand pulp. Enamel of the tooth is the hardestsubstance. There are four types of teeth— incisors, canines, premolarsand molars. Tooth decay results in bad breath,cavities,bleeding of gums and indigestion. V We should always take care of our teeth. Bacteria, fungi, protozoa and viruses are four types of microbes. V Some microbes are harmful as they cause diseases. V Some microbes are useful as they help in decay of dead plants and animals. 66