Paper 2 · November 2018 · Teeth and dental decay
How is a cavity formed in a tooth?
ASaliva reacts directly with the dentine layer beneath the enamel, slowly dissolving it away
BExcess calcium and phosphate build up on the enamel surface over time, forming a hard protective cap
CThe pulp cavity fills with trapped air after a filling, and the pressure causes the enamel to crack
DBacteria ferment sugar in plaque, producing acid that corrodes the enamel
Explanation
Bacteria in plaque ferment sugar, producing acid that corrodes the enamel.
Derived from ZIMSEC Biology 4025/2 Paper 2 Theory, November 2018, Q2