What is the effect of OVER-trituration of amalgam?

Correct answer: D. A shortened working time with reduced setting expansion

• A. This describes UNDER-trituration, which leaves a dry, crumbly, grainy mix with a longer working time and greater expansion.
• B. Both of these effects belong to under-trituration, not over-trituration.
• C. Working time is definitely affected, and strength is not greatly increased.
• D. CORRECT. OVER-trituration mixes the alloy and mercury too long or too vigorously. The amalgamation reaction is driven further before the material reaches the tooth, so the mix sets FASTER and the WORKING TIME is shortened. The dimensional change also shifts toward CONTRACTION — setting expansion is reduced. The mix appears soupy and hot and pulls away from the capsule walls.

Note: The literature is inconsistent here — slight over-trituration can raise early strength in some alloys, while gross over-trituration reduces it. The reliable examinable facts are the shortened working time and the reduced setting expansion. Worth raising with the group.