Q. Which one is correct regarding the number of teeth and dental formula with reference to a child of age between 4 to 6 years?
A) $\frac{212}{212} \times 2 = 20$
B) $\frac{212}{213} \times 2 = 24$
C) $\frac{2103}{2103} \times 2 = 24$
D) $\frac{2103}{2003} \times 2 = 22$
Explanation
Dentition in human is diphyodont, heterodont and teeth are arranged in socket of jaw bone, i.e., thecodont. Diphyodont means that teeth appears in two set during their life. A set of milky or temporary or deciduous teeth, which are replaced by permanent teeth between 6-12 of age. These milky teeth in human child includes 8 incisors, 4 canines and 8 molars (PM are absent). So, the dental formula of a child between the age of 4-6 years is $I\frac{2}{2}\ C\frac{1}{1}\ PM\frac{0}{0}\ M\frac{2}{2} \times 2 = 20$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.