Influence of variations in preparation of dental amalgam on dimensional stability and porosities.

The susceptibility of amalgam to deviations in the preparation procedure produced an overall trend for both the setting dimensional stability and the number of porosities. The dimensional stability of ANA 2000 was the least affected by the deviations, while ANA 68 exhibited low susceptibility to the deviations when porosities are concerned. Lowered condensation pressure usually increased both the setting expansion and the number of porosities, and vice versa. Dispersalloy exhibited an increased number of porosities with both higher and lower condensation pressure. Except for ANA 2000, undertrituration caused increased expansion and porosities, while overtrituration resulted in increased contraction but minor effects on porosities. Lower mercury/alloy ratio increased the setting expansion and the number of porosities, while the response to a higher ratio was relatively small with the exception of a markedly increased setting expansion for ANA 68.