There is nothing more beautiful than child's smile, but a beautiful smile needs good teeth and good oral health.
Teeth are an important of our self-image, and also play an important role in speech mastication (chewing of food ) and the appearance of our face. Yet many people neglect to look after their teeth properly.

Look at the figure: Human beings have two sets of teeth. The first set of teeth is called a milk teeth or temporary teeth or deciduous teeth.

They are twenty in number. The primary teeth start erupting when the child is about 6-7 erupted by the end of 2 to 2 ½ years of age.

As the child grows old, the primary teeth start falling and permanent teeth starts erupting in place of primary teeth. The second sets of teeth are called permanent teeth and they are 32 in number.

Why are milk teeth so important?

Even though primary teeth (milk teeth) eventually fall out, they do serve very important function besides helping, in chewing, speech and good looks, milk teeth serves to preserve the space for permanent teeth. So, if milk teeth are lost too early, the new permanent tooth could grow in an irregular way. If milk teeth are looked after well, then it is more likely that the permanent teeth will grow in correct position.

A tooth has two parts , the visible parts in mouth is called the crown of the tooth. The major portion of the tooth , which is about 2/3 of its length, is called the root. The roots are hidden the bone. The roots anchor the teeth in the jawbone.

STRUCTURE OF A TOOTH The enamel is the hardest calcified tissue in the human body covering the outer surface of the crown . It is white or slightly yellow in color. Directly beneath the enamel is the dentine, which is yellow in color. It is the most sensitive part of the tooth. Within the dentine, at the center of the crown and root is the pulp, which contains the nerves and the blood vessels. The roots of the teeth are embedded in the bone. The thin layers of bone like tissue called cementum covers the roots. The roots are connected to the jaw bone by a thin layer of soft tissue called periodontal ligament. It has elastic property and stretches between the cementum and bone around the tooth. The main functions of the teeth are -mastication( chewing of food), speech and esthetics.

The human beings have four types of teeth. They are incisors, canines, premolar and molars. The incisors have sharp chisel-shaped crowns and they are helpful in cutting the food. The canines have one longer root and a crown with a pointed cusp for tearing the food. The premolars have two cusps for crushing and tearing. The molars have wide chewing surface chewing surface comprising elevation and depressions called cusps and groove. In contact with the opposing molars and the side to side movements of the jaw ; they help in grinding the food like mortar and pestle.

Molars

EXERCISE

1. How many sets of teeth do human beings have?

2. How many temporary teeth are present?

3. How many permanent teeth are present?

4. What are the parts of the tooth?

5. What are the layers of our teeth?

6. Name the different teeth in our mouth and write about the function of each tooth?