Question
Dental decay is caused when bacteria break down sugars and produce acids.
In which order are the parts of the teeth damaged by acid?
(A) dentine → pulp → enamel
(B) enamel → dentine → pulp
(C) enamel → pulp → dentine
(D) pulp → dentine → enamel
▶️Answer/Explanation
Ans: B
The correct answer is B, because :
In a tooth structure, the parts are as follows from outside to inside :
- Enamel
- Dentine
- Pulp
In the same way, the tooth gets destroyed due to acid, so the correct option is B.
Question
The diagram shows a cross-section of a human tooth.
Which row identifies the labels in the diagram?
▶️Answer/Explanation
Ans : D
The correct answer is D, because :
In a tooth structure, the parts of tooth are as follows from outside to inside :
- Enamel (Strongest part which provides protection to internal structures) – X
- Dentine (It provides support, protection to internal structures) – Y
- Pulp cavity (It contains blood vessels, nerves) – Z
Question
Which statements correctly describe the process of dental decay?
1 Food and bacteria coat the teeth.
2 The bacteria use the sugar in the food for respiration.
3 The bacteria produce acids.
4 The sugar dissolves the enamel.
(A) 1 and 2 only
(B) 2 and 3 only
(C) 3 and 4
(D) 1, 2 and 3
▶️Answer/Explanation
Ans: D
The correct answer is D, because :
- Bacteria and food, cover the teeth if not washed mouth properly
- These Bacteria, using sugars as energy source they multiply and makes colonies
- The colonies of bacteria produces acids, which are enough to erode the enamel of teeth
- On prolong action, tooth decay occurs
Question
The diagram shows a human jaw. Which labelled tooth is an incisor?
▶️Answer/Explanation
Ans B
The correct answer is B, because :
- A – Premolars (These have 2 or 3 cusps0
- B – Incisors (Narrow edged at front of mouth)
- C – Canines (Sharp and ;located after incisors)
- D – Molars (These have large flat surfaces, located at last of mouth)