Question

he total number of teeth in a rat are
(a) 10
(b) 16
(c) 20
(d) 28

Answer 1

Hint: A dental formula is written as I n/n C n/n P n/n M n/n where I, C, P, and M refer to the incisors, canines, premolars, and molars respectively. Here, n/n refers to the number of upper and lower teeth of each type found on one side of the mouth.

Complete answer:
The rat's dental formula is I 1-1, C 0-0, P 0-0, M 3-3. Rats have 8 teeth on the lower jaw and 8 on the upper, a total of sixteen teeth. Rats have only two types of teeth i.e. incisors and molars. Incisors are the front-most teeth in the mammals. In rats, these are the four, long, sharp front teeth, present as two on the top and two on the bottom. Rat incisors are highly specialized for gnawing (to bite or chew). They are open-rooted, which means they grow throughout their life cycle. Molars are the rearmost teeth in the mouth and used for grinding food before swallowing it. Rats have 12 molars, which are six on the top and six on the bottom (and three on each side of each jaw). Molars are never replaced during their life cycle. Rats have only one set of teeth during their life so are called monophyodont.
So, the correct answer is, ’16.’

Note: Rats lack canines (the conical, pointed teeth used for holding prey, defense, and combat), or premolars (grinding teeth behind the canines and in front of molars). The rats have a long, toothless space in their mouth where the second incisors, canines, and premolars are missing. This space is known as a diastema.