They are mineralized tissue structures through which we can chew food, a step essential for proper digestion. Their structure, their number and arrangement varies in children and adults.

1. Number
Types. There are four types of teeth: incisors, canines, molars and premolars.
The primary dentition, deciduous or deciduous, is composed of what is known of teeth “baby”.

It consists of 20 teeth arranged in the jaws, upper and lower. He distinguishes eight incisors, four canines and eight molars. Coforme the child grows it will start dropping these teeth and permanent teeth appear. Thus there is a time when the child’s mouth are two types of teeth.

The permanent or permanent dentition comprises 32 teeth between which there are 8 incisors, 4 canines, 8 premolars and 12 molars.

2. Disposition
The teeth are arranged in a line describing a curved line along the two dental arches, upper and lower.

2.1. In adults
Adult dentition. The adult dentition consists of 32 pieces. In adults, the upper arch, by order and from one end to the center, we find:

The third molar, second molar, first molar, second premolar, first premolar, the canine, second incisor, also called lateral incisor and the first incisor, also called central incisor, which contacts with the other first incisor.

From here follows the sequence and the reverse side we have seen. In the lower jaw is the same as in higher education.

2.2. In children
Infant teething. The deciduous dentition consists of 20 pieces. In children with deciduous teeth and all we see sigiente provision.

In the upper arch are from one end to the center the second molar, first molar, the canine, the second incisor and lateral incisor and the first incisor and central incisor contact with the other central incisor, thus following the reverse sequence. In the lower jaw is the same.

3. Structure
Cross section. These are the structures that make up the tooth.
The teeth have a portion called the crown, which is what we see when we look in a mirror, and he excels in the dental arch, and moreover, the root, which is included in the bone and attached to the tooth.

Both the shape of the crown, as the shape and number of roots vary with each type of tooth.

If we cut a tooth from top to bottom, we see that the teeth are formed by various tissues arranged in layers. In the crown, first of all, the enamel, which is transparent and is more resistant layer.

Here is the dentin that is opaque and less resistant. It surrounds a central part. It is what is known as pulp chamber and in it are the nerve and blood vessels of the tooth.

At root, the tissue is called cement surface below it is dentin, which surrounds the root canal, through which vessels pass and the dental nerve.