1. The human teeth are made up of four tissues.
2. Dental pulp is found in the soft center of the tooth.
3. The pulp is surrounded by dentine.
4. The pulp of a tooth is composed of a fibrous network containing nerves, blood and lymph vessels that nourish the tooth.
5. In the crown the dentine is covered with enamel and in the root and neck it is covered with cementum.
6. It was decided to examine the oral cavity of the patient.
7. It is known that the cervical portion of the teeth is surrounded by gingival.
8. By the end of the second year a child is supposed to have a complete set of deciduous teeth.
9. By the age of 12 a child is supposed to have all the permanent teeth except the third molar.
10. Sticky carbohydrate is being transformed into the acid responsible for dissolving enamel and dentine.
IV. Read and translate the text.
Text A. A Tooth
Dentistry or stomatology is the science which deals with human teeth, gums, dental arches, mucous, fibrous and periodontal membranes of the oral cavity. But still the central figure of dentistry is a tooth. Each tooth has a crown, a neck and a root (or roots). Pulp makes up the center of the tooth. It is surrounded by dentine. In the crown dentine is covered with enamel and in the root and neck it is covered with cementum. Enamel is the hardest tissue of a human body. It is relatively inelastic and rather brittle. Enamel must withstand very high pressures when a person bites on hard objects. Cementum is also rather hard. In fact, it is a layer of modified bone which blends with the fibers of the periodontal membrane. Inside enamel and cementum is the main body of the tooth made of dentine. Dentine is softer, more porous and more elastic than enamel. Dentine is sensitive. In the very center of the tooth is a soft core dental pulp. It contains nerves and blood vessels. The nerves and vessels enter the tooth and are closely connected with the pulp. They are often considered together.
A human has two sets of teeth: deciduous (or milk, baby) teeth and permanent teeth. The first deciduous tooth is one of the incisors. It should appear at the age of about six months. By the end of the second year a child is supposed to have a complete set of deciduous teeth.
The deciduous teeth are 20 in number, 5 on each side of the upper and lower jaw: two incisors, one canine (cuspid), two premolars and three molars. The first permanent tooth to erupt is one of the molars. It should appear during the sixth year. By the age of 12 a child is supposed to have all the permanent teeth except the third molar which may appear at different age, usually starting from 17.
V Answer the questions.
1. What does dentistry deal with?
2. What are the main parts of a tooth?
3. What is the hardest tissue of a human body?
4. What is inside enamel and cementum?
5. Which is softer dentine or enamel?
6. What does dentine cover?
7. How do nerves and vessels enter the tooth?
8. How many deciduous teeth does a human have?
9. When does the first milk tooth erupt?
10. When do the first permanent teeth appear?
11. How many permanent teeth are there and what are they namely?
12. What is specific about the third molar?
VI. Change the sentences in the Active Voice into Passive according to the model.
Model: Permanent teeth replace deciduous teeth.
Deciduous teeth are replaced by permanent teeth.
1. This doctor will examine your teeth.
2. Usually dentists treat this disease.
3. Enamel covers the tooth crown.
4. Dentine surrounds the pulp cavity.
5. A saliva ejector evacuates fluids from the mouth.
6. Dentists use cotton rolls to absorb saliva and other fluids.
7. Dr. Davidson used this excavator to remove a temporary filling.
8. Periodontium attaches the tooth to the bone tissue.
9. Dentists use amalgams to restore posterior teeth.
