how many teeth grow only once in life of man?

1)8 2) 12 3) 20 4) 32

Molar and premolar grow only once in a life time.Acc. to dental formula 2123/2123 ( for upper half jaw and lower half jaw)Total no of premolar and Molar(in order) we get 20 teeth (for complete set)So, total no. of teeth= 32 total no. of non deciduous teeth= 20Total teeth = 32-20=12So the answer is 12.(option 2)