Anatomical Structure of the Tooth

The teeth are specialized, hard, calcified organs attached to the maxilla and mandible. The function of the teeth is to incise, masticate food and assist in phonation.

Anatomically, a tooth consists of two fundamental parts: the crown and the root, or roots. The crown of the tooth is the part that appears above the gum line; it is only about 1/3 of the whole tooth. Underneath the gum line lie the roots. The root is that part of the tooth which is in the alveolar bone and is covered by mucous membrane. Incisors have only one root; other teeth, two or three. The crown and the root of the tooth are connected together by the neck.

The crown of each tooth is covered with dental enamel, the hardest substance in the body. The roots are encased in cementum, not quite as hard. Inside the enamel and cementum is the softer bony substance called dentin, which is the bulk of the tooth. The dentin surrounds a pulp chamber (dental pulp), where nerves and blood vessels of the tooth are located.

The nerves and blood vessels run up and down through narrow channels, called root canals, through which they connect with the rest of the circulatory and nervous systems of the body.

The peridental membrane or alveolar-dental periosteum is a fibrous membrane. Covering the roots of the tooth it holds the tooth in its socket in the jaw and takes up some of the shock of chewing. This is why the teeth are slightly movable. The periodontal membrane serves to attach the tooth to the bone.

A thin layer of bone called the lamina dura serves to line the alveolus or tooth socket.

Grammar

Make questions to the text. Try to mention all the tooth structures.

Find the sentences in Passive Voice and change them into Active (where it is possible).

3. Give three forms of the verbs in the text. How would you translate the third form of these verbs?

4. Translate the sentences paying attention to the words "one - ones" and "that - those":

1. The upper second premolars have one root and the first ones have two roots.

2. The bones of the skull are those which compose the head and the face.

3. This lecture is more interesting than the one I attended last week.

4. The milk teeth are twenty in number and the permanent ones are thirty-two.

5. First baby teeth erupt at the age of 6 months after birth and those of the permanent set normally erupt at the age of 6 years.

6. Teeth of the first dentition must be treated as those of the second one.

Summary

Date: 2016-06-12; view: 10