What happens to marginal leakage around an amalgam restoration over the first year after placement?

Correct answer: B. It decreases as corrosion products accumulate and seal the interface

• A. Marginal leakage decreases rather than increases; this is one of amalgam's most useful clinical properties.
• B. CORRECT. Amalgam is unique among restorative materials in this respect. It does not bond to tooth structure, so leakage is initially significant — but corrosion at the interface generates oxide and chloride products that progressively fill the microgap. Leakage therefore DECREASES over the first months, and the restoration effectively seals itself.
• C. There is no such sharp early increase; the trend is a gradual decline.
• D. There is a definite change, and it is favourable.

Note: The irony worth appreciating: corrosion is what damages amalgam mechanically (through gamma-2 and creep) and simultaneously what seals it marginally.