How does saliva assist in the remineralisation of enamel?

Patient case: Prosthodontic and restorative materials

Scenario: Three items on pontics, cements and saliva.

It mechanically flushes away the demineralised surface layer
It provides antibodies that neutralise cariogenic bacteria
It supplies calcium and phosphate ions that redeposit into the demineralised lattice
It raises the plaque pH by secreting bicarbonate only

Show answer and explanation

Correct answer: C. It supplies calcium and phosphate ions that redeposit into the demineralised lattice

A. Mechanical clearance reduces substrate and acid but does not deposit mineral.
B. Salivary IgA does limit bacterial adherence, an antimicrobial rather than a remineralising role.
C. Correct. Saliva is supersaturated with calcium and phosphate. Once the pH recovers above the critical value, those ions — with fluoride — reprecipitate into the partly dissolved crystal surface as fluorapatite.
D. Buffering by bicarbonate is real and important, but buffering alone raises pH without supplying the mineral needed to rebuild the crystal.