IX. Answer the following questions.

1. How many sets of teeth develop in humans?

2. What are they?

3. Which deciduous teeth are the first to arrive?

4. Why are deciduous teeth important for a child?

5. Do many children suffer from malocclusion?

6. How many teeth are there in a full set of deciduous teeth?

7. What happens with the child’s teeth at the age of 6?

8. Are 6-year molars permanent teeth? Why are they very important?

9. At what rate do permanent teeth replace baby teeth in the mouth?

10. Which teeth are the last to erupt?

11. How many teeth are there in a full set of adult teeth?

X. Complete the sentences using words from the active vocabulary. The first letters are given to help you.

1. A human has two s...of teeth: d… and p… .

2. E… of deciduous teeth starts at six month and is completed at two years.

3. After deciduous teeth I… , they are lost and replaced by permanent teeth.

4. Wisdom teeth are often e… if they come in c… or i… .

5. A lot of people suffer from some kind of m… .

6. Sometimes permanent teeth may form a c…d…a… .

7. It is very important for the child to preserve p…b… .

8. The eruption of wisdom teeth is d…until 18-25 years.

9. Deciduous teeth are replaced by permanent ones at the r of about 4 a year.

10. The t… b… are laid down before birth.

XI. Choose the correct answer.

1. I wasn’t sure how she would react because I … her long.

a) didn’t know

b) wasn’t knowing

c) hadn’t known

d) don’t know

2. I wanted to say goodbye to Jerry but he…

a) was already left

b) has already left

c) had already left

d) already left

3. He…his consulting room by this time tomorrow.

a) will leave

b) will have left

c) leaves

d) is leaving

4. When we got to the university I realized that I…my student’s card at home.

a) was left

b) had left

c) left

d) was leaving

5. All wisdom teeth…by early twenties.

a) were erupted

b) had erupted

c) will have erupted

d) will erupt

6. Jack … chess before, so I showed him how to play.

a) didn’t play

b) wasn’t playing

c) hadn’t played

d) hasn’t played

7. He normally stops working at 2 p.m. but today, I think, he …his work well before 1 p. m.

a) finishes

b) will have finished

c) will finish

d) finish

8. The child… 6 teeth by the end of this year.

a) will have

b) will have had

c) has

d) is having

9. We… lunch by the time the lesson begins.

a) finish

b) will finish

c) will have finished

d) finished.

XII. Translate the following word combinations:

первый набор зубов, молочные зубы, постоянные зубы, зубной зачаток, влиять на форму рта и лица, скученные зубы, правильно пережевывать пищу, сохранять правильный прикус. верхняя и нижняя челюсть, неправильный прикус, полностью рассосавшийся корень зуба, терять зубы, зубы выпадают, зуб мудрости, кривые зубы, удалять зуб, зубы с затрудненным прорезыванием, резать, разрывать и перетирать пищу

XIII. Read and translate the text at sight.

First and Second Dentition

All teeth start developing inside the jaws and their arrival in the mouth is known as eruption. Deciduous teeth start developing before birth and erupt after birth. Eruption starts at six months and is completed at two years. Individual variations are possible.

Permanent teeth are the second and final set. There are thirty two of them: sixteen in each jaw, eight on each side. Like deciduous teeth the eight on each side of both jaws have the same names.

After the deciduous teeth loosen they are shed and are soon replaced by eruption of their permanent successors. Deciduous incisors and canines are replaced by permanent teeth of the same name. Deciduous molars, however, are replaced by premolars. Thus the permanent molars erupt without having any deciduous predecessors. Deciduous teeth become loose by resorption of their roots which deprives them of their attachment to the jaws. The unerupted permanent successors lie adjacent to the absorbing deciduous roots and are thus able to erupt into their places when the deciduous teeth are finally shed.