Dentition in Humans
1. Where is the human teeth found?
Answer: It is found in the mouth.
2. What does the teeth do?
Answer: The teeth are used to break down (bite and chew) food into smaller pieces.
3. State whether each of the following statements is true or false.
a) There are different types of teeth in the mouth.
Answer: True.
b) The different types of teeth are built on the same structure.
Answer: True.
4. Name the three parts of a tooth.
Answer:
· Crown
· Neck
· Root.
5. Which part of the tooth shows above the gum? It is the visible part.
Answer: Crown.
6. Which part of the tooth is the meeting point of other two parts of the tooth?
Answer: Neck.
7. The part of the tooth that is embedded in the jaw bone or gum is the
Answer: Root.
8. Mention the four types of teeth in humans.
Answer:
· Incisors.
· Canines.
· Premolars.
· Molars.
9. Which types of the teeth are called cheek teeth?
Answer: Premolars and molars.
10. State whether each of the following statements is true or false.
a) The type of teeth that is conical and sharply pointed is the canines.
Answer: True.
b) There are two canines in the upper jaw and two in the lower jaw.
Answer: True.
c i) Canines are used for tearing flesh or food.
Answer: True.
c ii) Canines are sometimes used for cutting.
Answer: True.
11. a) Which type of teeth is chisel shaped with cutting edges? There are four in the upper jaw and four in the lower jaw.
Answer: Incisors.
b) State the function of incisors.
Answer: Incisors are used for cutting.
12. a) Which type of teeth has two raised parts on the crown? They have two cusps or small projections. There are two on the upper jaw and two on the lower jaw.
Answer: Premolars.
b) State the function of premolars.
Answer: They are used for tearing and grinding of food.
13. a) Which type of teeth has flat surfaces with cusps or small projections? They have more than one root. There are six on the upper jaw and six on the lower jaw.
Answer: Molars.
b) State the function of molars.
Answer: Molars are used for grinding food.
14. What is tooth plaque?
Answer: Tooth plaque is a layer or thin film of coating that forms on the teeth when food debris and bacteria build up.
15. State whether each of the following is true or false.
a) Plaque is a sticky mix of bacteria and the substance they secrete.
Answer: True.
b) Bacteria produce adhesive chemicals.
Answer: True.
c) Bacteria live on the biofilm.
Answer: True.
16. What is the biofilm?
Answer: Biofilm is the thin film on teeth created by bacteria’s adhesive chemicals.
17. State whether the following statement is true or false. At first, the slimy layer formed by bacteria’s adhesive chemicals is fragile and can be easily removed by tooth brushing.
Answer: True.
18. What happens if the slimy layer on teeth is not removed?
Answer: The bacteria in the tooth plaque are free to release acids that damage tooth enamel.
19. What do regular acid attacks on enamel do to the teeth?
Answer: It can wear holes in the teeth.
20. What are cavities?
Answer: Cavities are holes in the teeth.
21. a) What happens if cavities are left untreated?
Answer: Plaque buildup also gradually hardens, creating tartar on the teeth.
b) Tartar is also known as
Answer: calculus.
22. Name one thing that contributes to gingivitis or gum disease.
Answer: Tartar above the gum line.
23. A film of dirt on teeth and in the corners of the teeth is
Answer: plaque.
24. The germs or bacteria that cause tooth decay and gum disease grow in
Answer: plaque.
25. Describe how plaque is formed.
Answer: Plaque is formed on the teeth when food residues or food particles are not properly removed from the teeth. As more food particles accumulate in the teeth, a hard layer of dirt forms on the teeth.
26. Mention five bad habits that cause tooth plaque.
Answer:
· Not brushing regularly.
· Not flossing daily.
· Avoiding the dentist.
· Neglecting nature’s toothbrushes / Not eating fruits and vegetables.
· Indulging your sweet tooth.
27. Give two reasons why daily flossing is recommended by dentists.
Answer:
· Brushing does not reach the spaces between teeth, but plaque does. Flossing clears plaque before it can cause damage.
· It clears plaque at the gum line.
28. a) Is brushing the teeth gently twice a day using a fluoride toothpaste beneficial to the teeth?
Answer: Yes.
b) State two reasons why a fluoride toothpaste is beneficial to the teeth.
Answer:
· It makes tooth enamel more resistant to the acids produced by bacteria.
· It interferes with bacterial growth.
c) State one effect of using excessive amounts of fluorine.
Answer: Excessive amounts of fluorine may cause mottling of the teeth (no health problems but causes an unattractive appearance).
d) Does the mottling of the teeth due to use of excessive amounts of fluorine present any health problems?
Answer: No.
29. a) Do bacteria love simple carbohydrates like sugar?
Answer: Yes.
b) What gives bacteria something to munch on?
Answer: Eating candy or drinking sugary soft drinks lets sugar stick to our teeth, giving bacteria something to munch on.
c) What happens after bacteria create a film of plaque on teeth?
Answer: They digest sugar into acid which damages teeth.
30. List two ways to prevent plaques.
Answer:
· Use of dental sealants.
· Use of mouth rinse.
31. What are dental sealants?
Answer: Dental sealants are a clear plastic coating that covers the tooth surface, barring acid and bacteria from entering. Sealants are safe and effective in blocking plaque and preventing tooth decay.
32. How do you prevent tooth plaque with mouth rinse?
Answer: Several mouth rinses with fluoride helps prevent plaque and tooth decay.
33. a) What is tooth decay (dental caries)?
Answer: Tooth decay is the process that results in a cavity (dental caries).
b) Tooth decay is also known as
Answer: dental caries.
34. Describe how tooth decay occurs.
Answer:
· Bacteria in plaque ferment food particles that get stuck in the corners of the teeth and this results in (brings about) the production of acids.
· The acids slowly dissolve the calcium salts in the enamel of the tooth and this creates small holes or cavities on the tooth.
· Tooth decay affects the dentine and pulp cavity if cavities are not cleaned regularly or filled by a dentist.
· When pulp cavity is exposed, hot or very cold food irritates the nerves, causing severe pain or toothache.
35. List four causes of tooth decay.
Answer:
· Lack of vitamin D.
· Taking in too much sweet or sugary foods.
· Lack of calcium in diet.
· Improper cleaning of teeth.
36. List two ways of treating tooth decay.
Answer:
· Filling the cavities created on the tooth.
· Removal of the tooth by a dentist.
37. What is gum disease?
Answer: Gum disease is an infection of the tissues and bones that surround and support the teeth.
38. Another name for gum disease is
Answer: Periodontal disease.
39. What happens when bacteria in plaque cause the gums to become swollen?
Answer: Gum disease.
40. State what would happen if gum disease is not treated.
Answer: The fibres that hold the tooth in the jaw bone would be destroyed, and with time, the tooth becomes loose and has to be removed by a dentist.
41. State three causes of gum disease.
Answer:
· Not cleaning the teeth well.
· Smoking or chewing tobacco.
· Family relations.
42. List five ways of preventing tooth decay and gum diseases.
Answer:
· Rough use of teeth, such as opening bottle tops with teeth, should be avoided.
· Visiting the dentist regularly (at least twice a year).
· Cleaning teeth regularly.
· Avoid eating too hot and too cold foods.
· Avoid eating too many sugary foods.
· Chew hard fibrous foods like sugar cane from time to time.
· Eat food containing sufficient amount of calcium.
· Avoid removing food particles from the teeth with sticks after meals. Food particles must be removed by brushing.
· Remove all aching teeth.
· Ensure regular removal of tartar and scales, which settle on the enamel and in between the root, and the crown of the tooth.
43. Why should rough use of teeth be avoided?
Answer: Rough use of teeth should be avoided so as not to damage the enamel.
44. Why should the dentist be visited regularly?
Answer: To ensure early detection of cavities.
45. Name three materials that are recommended for brushing the teeth.
Answer:
· Toothbrush and tooth paste containing fluoride.
· Chewing stick.
· Chewing sponge.
46. Why should too many sugary foods be avoided?
Answer: They normally cause rapid tooth decay.
47. Why should hard fibrous foods like sugar cane be chewed from time to time?
Answer: To strengthen the teeth and gum.
48. Why should food containing sufficient quantities of calcium be consumed?
Answer: To encourage healthy growth of teeth.
49. a) The innermost layer of the crown of the tooth is called
Answer: dentine.
b) The outermost layer of the crown of the tooth is called
Answer: enamel.
50. a) The tooth is fixed in the jaw by a tough substance called
Answer: cement.
b) The hard bone-like material which covers the outside of the root, under the gum line is called
Answer: cement.
51. a) The membrane between the cement and jaw bone consists of fibres which
Answer: hold the tooth securely in its socket.
b) The membrane between the cement and jaw bone is known as
Answer: periodontal membrane.
52. a) List any three mineral salts needed for strong and healthy tooth formation.
Answer:
· Calcium
· Magnesium
· Phosphorous
b) List any four elements needed for strong and healthy tooth formation.
Answer:
· Calcium
· Magnesium
· Phosphorous
· Fluorine
53. State two functions of the pulp cavity.
Answer:
· It has sensory nerve endings which are sensitive to heat and cold.
· It contains blood vessels that supply food and oxygen to the tooth for growth and to keep it alive when growth has stopped.
54. a) A hard yellow substance which consists mostly of mineral salts and water is
Answer: dentine.
b) The layer of the crown which is a living tissue is the
Answer: dentine.
55. a) The hardest tissue that protects the dentine and pulp cavity is the
Answer: enamel.
b) The part of the crown which is a non-living substance containing calcium salts is the
Answer: enamel.
56. What is dentition?
Answer: Dentition is the type, number and arrangement of teeth in the buccal cavity.
57. State the two types of dentition.
Answer:
· Heterodont dentition
· Homodont dentition.
58. a) The type of dentition where teeth are of different sizes and shapes and perform different function is
Answer: heterodont dentition.
b) Mention four organisms with heterodont dentition.
Answer:
· Human beings
· Sheep
· Lion
· Dogs
59. a) The type of dentition where teeth are identical and perform the same function although they may differ in size is
Answer: homodont dentition.
b) Mention two organisms with homodont dentition.
Answer:
· Fishes
· Reptiles
60. Mention two organisms that have no teeth at all and therefore swallow their food wholly.
Answer:
· Birds
· Toads
61. State whether the following statement is true or false. Premolars can number up to eight in an adult human.
Answer: True.
62. The last or third molars are called
Answer: wisdom teeth.
63. State two characteristics by which the wisdom teeth can be identified.
Answer:
· They appear between the ages of 17 and 21.
· They do not play any role during chewing.
64. How many sets of teeth do humans develop in their lifetime?
Answer: Two.
65. Name the two sets of teeth that humans develop in their lifetime.
Answer:
· Milk (baby) teeth.
· Permanent teeth.
66. The first set of teeth that appear during a human’s first year of life is called
Answer: Milk (baby teeth).
67. Draw a flow chart to show the development of the different types of milk (baby) teeth.
Answer: Incisors -> Canines -> Premolars
68. The total number of teeth that appear as milk (baby) teeth is twenty because there are no
Answer: molars.
69. At what age do the milk (baby) teeth gradually fall out and are replaced by the permanent teeth.
Answer: Between the ages of 6 and 12 years.
70. State whether each of the following statements is true or false.
a) Permanent teeth consist of all the different types of teeth.
Answer: True.
b) The total number of permanent teeth in adult man is 32.
Answer: True.
c) Any permanent teeth removed or extracted for any reason does not grow again.
Answer: True.