Lesson_2

Lesson 2 A Tooth

1. Read the following words of the Greek-Latin origin and give their Russian equivalents:

stomatology

mucous

fibrous

periodontal membrane

dentine

enamel

cementum

pressure

subject

porous

premolar

2. Learn the following words and word combinations:

to deal with

gum

dental arch

crown

neck

root

brittle

to withstandto

bite (bit, bitten)

bite

— иметь дело с...

— десна

— зубная дуга

— коронка

—шейка

— корень

— хрупкий, ломкий

—выдерживать, противостоять

— кусать

— прикус

core	— сердцевина, ядро
foramen	— отверстие
tip	КОНЧИК
to reach	— достигать, простираться
set of teeth	— набор зубов, зубной ряд
deciduous teeth	— молочные зубы
permanent teeth	— постоянные зубы
incisor	— резец
jaw	— челюсть
canine	— КЛЫК
cuspid	— КЛЫК
to erupt	— прорезывать

3. Read and translate the text:

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 subjects. 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 through a 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 u_D and lower jaw: two incisors, one canine (cuspid), two premolars and thr 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.

4. 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?

5. Change the Active Voice in these sentences into the Passive Voice. Example:

Permanent teeth replace deciduous teeth. — Deciduous teeth are replaced by permanent teeth.

1. Dr. Somov will examine your teeth. — ...

2. Enamel covers the tooth crown. — ...

3. Dentine surrounds the pulp cavity. — ...

4. A rubber dam provides complete isolation of teeth from saliva and blood. — ...

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. Nurse Aiman will clean these chisels by 3 p. m. — ...

9. The teacher is explaining us how to maintain and sterilize handpi⁶' ces. — ...

10. Dentists use amalgams to restore posterior teeth. — ...

6. Read the text and find Russian equivalents to the underlined phrases, learn these phrases:

Teeth bite, chew and grind. If you like to eat chocolate, candies and cakes you have sweet tooth. Teeth are useful for eating and talking and they can also look attractive if they are well-kept. But in the English language they often indicate difficultly or aggression.

Dogs bare their teeth when they want to fight. If a person talks through his teeth or just shows his teeth it’s better to get out of his way quickly. He may be armed to the teeth. If you don’t, you may fight tooth and nail to defend yourself. If you can’t bite, never show vour teeth! If you are not good at fighting your teeth may start chattering with fear. People’s teeth chatter when they are very cold and frightened or when they have a fever.

If you get teeth into something, it does not mean that you are feeling dangerous or aggressive. It simply means that you are doing something that involves concentration or effort. You may to get your teeth into a good book — and it means you want to read it, not to eat it!

7. Answer the questions to the text:

1. What can teeth do?

2. Do you have a sweet tooth?

3. When do teeth look attractive?

4. What do «teeth» often indicate in the English language?

5. Dogs bare their teeth when they want to fight, don’t they?

6. What should you do if a person shows his teeth?

7. Do you often get your teeth into dental journals?