Plaque is a deposit which collects around teeth


#1

Plaque is a deposit which collects around teeth. The following table shows the pH value of the plaque surrounding the teeth of a girl over 4 hrs.

(i) Other than food remains, state three constituents of plaque.
(ii) State the time during the day when condition are most favourable for the process of tooth decay.


#2

(i) The three constituents of plaque other than food are acid, saliva and bacteria.
(ii) Time 4 has the lowest pH, which indicates the highest amount of acid produced by the bacteria.