Surfaces of the teeth

The biting surface of molars and premolars is called the occlusal surface. On incisors and canines it is called the incisal edge. The occlusal surface is the biting surface of the posterior teeth, i.e. of molars and premolars, which is raised up into cusps. Between the cusps are crevices known as fissures.

The outer surface of molars and premolars — the surface fac­ing the cheeks — is called the buccal surface. In the case of incisors and canines this surface is called labial as it faces the lips instead of the cheeks.

The inner surface of every lower tooth faces the tongue so it is called the lingual surface. This surface in all upper teeth is known as the palatal surface.

The remaining surfaces are those between adjoining teeth. The surface facing towards the front of the mouth is called mesial and that facing backwards is called distal. The adjective cervical is used for the neck of the tooth.

POST-TEXT ASSIGNMENTS

Exercise 5. Ask 10 questions to the text and answer them.

Exercise 6. Insert prepositions or adverbs:

1.There are ten teeth ... each jaw.

2. Deciduous teeth start developing... birth and erupt ... birth.

3. Permanent teeth start developing ... birth.

4. Eruption times are subject ... consider­able individual variation.

5. They are replaced ... eruption of their permanent successors.

6. The permanent molars erupt ... having any deciduous predecessors.

7. The resorpted roots deprive temporary teeth ... their attachement ... the jaw.

Exercise 7. Read and translate the text:

The general function of teeth is mastication, facial aesthetics and speech.

The incisors cut off parts of food which are forced by the tongue and muscles of the mouth between the posterior teeth, where they are ground by these larger teeth.

Cuspids are also called canines. The premolars crush the food that has been cut off by incisors and cuspids.

The molars are the largest teeth in the mouth and they are also the strongest teeth because of their crown size and root development. They grind the food particles.

Exercise 8. Translate into English:

1. Дитина має 20 тимчасових зубів: у кожній щелепі — 10 (по п'ять з кожного боку).

2. Зуби починають прорізуватися в шість місяців, другі моляри прорізуються в два роки ос­танніми.

3. Постійні зуби починають розвиватися у людини з дня народження.

4. Строк прорізування зубів у кожної лю­дини різний.

5. Тимчасові різці і клики замінюються на по­стійні з такою ж назвою.

6. Тимчасові зуби випадають тому, що внаслідок розсмоктування їх коренів вони позбавлені опори в щелепі.

7. Постійні моляри не мають своїх тимчасо­вих попередників.

8. Тимчасові моляри замінюються премолярами.

9. Коли тимчасовий зуб випадає, на його місце прорізується його наступник — постійний.

10. Прорізування постійних зубів завершується до 18-25 років.

Exercise 9. Speak of:

a) temporary teeth

b) permanent teeth

c) the number of the deciduous teeth

d) the number of the permanent teeth

e) the surfaces of the teeth.

TEST

1.What is the first set of teeth?

a. permanent b. lateral

c. upper d. lower

e. deciduous

2. How many are there temporary teeth?

a. 32 b. 24 c. 20 d. 18 e. 22

3. Where do all teeth start developing?

a. on the lateral surface of jaws b. inside the jaws

c. outside the jaws d. on an external surface of jaws

e. inside the gums

4. When do temporary teeth become developing?

a. before the birth b. at six month

c. at two years d. at one month

e. at birth

5. When do permanent teeth become developing?

a. at six years b. after the birth

c. before the birth d. at 2

e. at birth

6. What teeth usually erupt first?

a. upper b. 3rd molar c. 2^nd molar d. lower e. posterior

7. When does eruption of permanent teeth completed?

a. at 10 b. at 6

c. from 6 to 8 d. from 18 to 26

e. at 12

8. How many are there permanent teeth in dentition?

a. 33 b. 20

c. 24 d. 32

e. 28

9. How many are there permanent teeth on each side?

a. 5 b. 16

c. 8 d. 32

e. 24

10. Deciduous teeth start developing … birth.

a. at b. before

c. during d. after

e. for

11. Deciduous teeth erupt … 6 month.

a. at b. in c. during d. for e. out of

12.Occlusal surface is biting surface of …

a. molars and canines b. molars and incisors

c. premolars and cuspids d. premolars and incisors

e. molars and premolars

13. Lingual surface is the surface which faces …

a. lips b. palate

c. tongue d. cheeks

e. face

14. Labial surface faces …

a. lips b. cheeks c. palate d. canines e. incisors

15. The inner surface of upper teeth … as the palatal surface.

a. is known b. are known

c. knows d. known

e. knew

16. Eruption … at six month.

a. is started b. has started

c. start d. started

e. starts

17. Deciduous teeth … by permanent ones.

a. is replaced b. replace

b. are replaced d. are replacing

e. replacing

18. Why … deciduous teeth become loose?

a. does b. do

c. are d. is

e. ---

19. When … lateral incisors erupt?

a. does b. do c. are d. were e. has

20. What …molar … at 12?

a. does… erupt b. --- … erupts

c. is… erupted d. --- … erupt

e. are… erupted