219.The total pore volume of dark zone is

a.2-4%
b.20-40%
c.5-10%
d.0.1-1%


Ans:a.2-4%


Expalanation:Ref sturdevant 4th ed /pg 95

218.The appearance of streptococcus mutans in pit and fissure caries is usually followed by caries

a.6 to 10 months later
b.2 to 6 months later
c.within 2 months
d.6 to 24 months later


Ans.d.6 to 24 months later


Explanation:Ref sturdevant 4 th ed/pg 83

217.Peak rates for the incidence of new carious lesions occurs how many years after eruption of the teeth

a.1 year
b.2 years
c.3 years
d.At the time of eruption

Ans:c.3 years


Explanation:Ref sturdevant 4th ed/pg 92