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Which one of the following correctly represents the normal adult human dental formula?
A
$\frac{2}{2},\frac{1}{1},\frac{2}{2},\frac{3}{3}$
B
$\frac{3}{3},\frac{1}{1},\frac{3}{3},\frac{3}{3}$
C
$\frac{3}{3},\frac{1}{1},\frac{3}{2},\frac{1}{1}$
D
$\frac{2}{2},\frac{1}{1},\frac{3}{2},\frac{3}{3}$
Detailed Solution
An adult human has 32 permanent teeth of four types (heterodont dentition): incisors (I), canines (C), premolars (PM) and molars (M).
The dental formula gives the number of each type in one half of the upper jaw over one half of the lower jaw, in the order I, C, PM, M.
Each half of each jaw has 2 incisors, 1 canine, 2 premolars and 3 molars.
Dental formula: $\frac{2123}{2123}$, i.e., $\frac{2}{2},\frac{1}{1},\frac{2}{2},\frac{3}{3}$
Check: (2 + 1 + 2 + 3) × 2 halves × 2 jaws = 8 × 4 = 32 teeth.
The dental formula gives the number of each type in one half of the upper jaw over one half of the lower jaw, in the order I, C, PM, M.
Each half of each jaw has 2 incisors, 1 canine, 2 premolars and 3 molars.
Dental formula: $\frac{2123}{2123}$, i.e., $\frac{2}{2},\frac{1}{1},\frac{2}{2},\frac{3}{3}$
Check: (2 + 1 + 2 + 3) × 2 halves × 2 jaws = 8 × 4 = 32 teeth.