What is the approximate contraction of gold alloys upon solidification?

The approximate contraction of gold alloys upon solidification is around 1.40%. When gold alloys are melted and then allowed to cool, they typically undergo a slight decrease in volume as the metal solidifies. This volumetric contraction is attributed to the change in atomic structure that occurs when the alloy transitions from a liquid to a solid state. A contraction of 1.40% is commonly observed in dental applications, which is important for fitting precision in restorations and other dental work.

Understanding the solidification characteristics of gold alloys is crucial for dental practitioners as it affects the final fit of dental restorations. Notably, other contraction percentages mentioned in the choices are not typically observed for gold alloys; they are either too high or too low, which would not align with the expected behavior during the solidification process of these materials.