Dentition in Human Beings

   Most mammals have well developed teeth. In other animals, if teeth are present , they are of the same type and only serve to grasp food before it is swallowed. In mammals, however, the teeth play an important role in mechanical digestion. Their dentition is therefore complex. Dentition is the number and kinds of teeth present in mammal and their arrangement in the lower and upper jawbones. It is related to the type of food a mammal eats.

 Types of teeth
Human beings are omnivorous and their dentition is suited for this mode of feeding. They also have two sets of teeth. Their life lifetime. At birth , a baby does not have any teeth as he feeds mainly on milk. The first set, the milk teeth, grows when the child is a few months old and ready to feed on the solid food. It lasts for only a short time. There are 20 milk teeth. The second consist of 32 permanent teeth. These are made up of four different types of teeth. The incisors are chisel shaped. They are used for hitting off pieces of food. The canines in humans are quite similar to the incisors.

They are conical , and in carnivorous animals, have sharp pointed tips. The premolar and molars have broad surfaces for grinding food.

Dental formula
The dental formula shows the number and types of teeth an animals has in one half of each jaw. Different mammals have different dental formulae depending on their diet. The dental formula of a human is : (Upper jaw ÷ Lower jaw) i2/2 c1/1 pm2/3 m3/3 = 16

 Note: Each of the four types of teeth is indicated by its initial letter. The total number of teeth is 32 and it's obtained by multiplying the total number of teeth in the dental formula by 2.

 Structure of a tooth All teeth have the same basic structure. The crown projects above the guns. The root lies embedded. The jaw bone. The neck is the junction of the crown and root.  

     The centre of the tooth consists of pulp cavity. It contains blood vessels and nerves which are extremely sensitive to heat and cold. Enclosing the pulp is a layer of dentine contains some living cytoplasm. a hole at the tip of each root allows the blood vessels and nerves of the pulp to be connected to those of the bones and gums. 
   
     Covering the dentine is a white layer, the enamel. Enamel is the hardest material made by animals. It protects the pulp and dentine within.

     Enamel is not present in the root region. Instead, a thin layer of cement is, In turn, surrounded by the periodontal membrane which fixes the tooth to the jawbone. However, the tooth is not fixed rigidly to the jawbone but can move slightly during biting and chewing.

     Each tooth has a continuous supply of blood through the holes at the tip of the root. This supply of blood is enough to keep the tooth alive but not enough to allow the tooth to grow. This sort of teeth are known as closed teeth.

Dental care
Teeth can easily decay because germs readily grown in bits of food that tend to stick to the teeth after a meal. The germs break down food particles (especially carbohydrates) to produce acids. The acids wear away the enamel and engine of a tooth to expose the nerves and blood vessels in the pulp cavity. The tooth begins to ache and gum becomes infected. Finally, the tooth falls off. Once a permanent tooth falls , it cannot be replaced by another tooth. Therefore , it is very important to take care of our teeth.

 We can prevent tooth decay by

• Practising regular oral hygiene, proper tooth brushing and vigorous rinsing of mouth every morning and night, and after meals and snacks;

• Eating a well balanced diet that contains sufficient vitamin C, phosphorus and calcium, nutrients necessary for the development and maintenance of healthy teeth, especially in infants and young children;

• Finishing a meal with Hard, fibrous fruits;

• Eating very little sweet food; and • Visiting a dentist regularly