Quantification of marginal leakage of amalgam restorations in vitro.

A method is described to quantify marginal leakage of amalgam restorations in vitro as a function of time. The method consists of the determination of the amount of nitrogen gas passing through the margins of the restoration at 2 atm. pressure in 30 min. The method described needs about sixteen specimen per experiment. The standard error is 20-30% of the mean leakage value and is independent of the type of condensation and the amalgam type. Two amalgams, the non-gamma 2-Dispersalloy and the conventional, Amalcap was compared longitudinally over a period of 4 months. The results showed: (1) The marginal leakage of Dispersalloy decreased strongly with time; the time dependency of Amalcap was less pronounced. (2) That carefully condensed Amalcap showed significantly less marginal leakage than Dispersalloy. (3) Whereas the marginal leakage of Amalcap was dependent on the condensation procedure, the leakage of Dispersalloy did not depend strongly on it.