What is the gamma 2 phase in amalgam?

The gamma 2 phase in amalgam primarily refers to the specific intermetallic compound formed during the setting reaction of dental amalgam, particularly related to the tin-mercury interaction. The correct choice, Sn8Hg, is important because it represents the phase that can influence the mechanical properties and durability of the amalgam restoration.

In dental amalgams, the microstructure consists of different phases, including gamma (Ag3Sn), gamma 1 (Ag2Hg3), and gamma 2 (Sn8Hg). The gamma 2 phase is considered undesirable because it can degrade over time, leading to the potential failure of the amalgam restoration.

Understanding the role of these phases, especially gamma 2, is crucial for dental professionals as they impact the longevity and effectiveness of dental amalgam materials. The other choices represent different phases or components in the amalgam system but do not specifically identify the gamma 2 phase which is characterized by tin and mercury in the stated ratio.