Calcium is helpful only when teeth are forming and not after that, as such children from good family do not require any calcium but if there is calcium deficiency then it is first detected on teeth, so regular check up from 2yrs would help in treating calcium deficiency. Fluorides help because they increase the resistence of the teeth to acid dissolution which is what happens in tooth decay. Fluorides can be given in drinking water, as tablet, in tooth paste and applied by dentist as gel on regular intervals.