Question

How many teeth in man grow twice in life?
A. 32
B. 28
C. 20
D. 12

Answer 1

Hint: The hardest substance of the human body is teeth because of the presence of enamel.
There are about 4 kinds of teeth: incisor (middlemost 4 teeth on the upper, and lower jaws), canine (present in either side of incisor), Premolar (present in either side of canine), and molar (at the back of the mouth).

Complete answer:
There are 2 sets of teeth forms in almost all the mammals comprising Human beings. Diphyodont is defined as the kind of dentition in which a pair of temporary teeth should be changed by a pair of permanent or adult teeth. Temporary teeth are also known as milk or deciduous teeth.
There are about 32 permanent teeth present in the adult human. These are of four distinct kinds i.e. Incisors (I), Canine (C), Premolars (PM), and Molars(M). By using the dental formula we can assume the interpretation of teeth present in each half of the lower and upper jaw in the order of I, C, PM, and M. In the case of human beings, the dental formula is 2123/2123.
In the case of children, premolars and molars are absent. So the teeth that grow twice in the life of humans are incisors, canines, and 2 molars. Hence 20 will be the total number of teeth.

So, the correct answer is C, 20.

Note: In our lifetime we get twice the full sets of teeth. The first time when we are babies, we have 20 teeth, and the second time when we are adults, we have 32 teeth. Among the 32 teeth, each tooth has its technique for chewing and eating food. Two wisdom teeth known as the third tooth are also present which arises after the age of 18 years.