Amalgams made from liquid Hg-In

Area of Science:

• Materials Science
• Biomaterials Science
• Metallurgy

Background:

• Dental amalgam is a widely used restorative material.
• Mercury vapor release from dental amalgam during setting is a concern.
• Indium addition has been proposed to mitigate mercury vapor emission.

Purpose of the Study:

• To investigate the structural and physical properties of dental amalgams with varying indium (In) additions.
• To assess the impact of In on the microstructure and mechanical performance of amalgam.
• To determine the suitability of In-containing amalgams based on established standards.

Main Methods:

• X-ray diffraction (XRD) and scanning electron microscopy (SEM) for structural analysis.
• Energy dispersive spectroscopy (EDS) for elemental composition analysis.
• Compression strength testing to evaluate mechanical properties.

Main Results:

• No new phases or undissolved indium were detected in the amalgam structure.
• Indium incorporation increased the silver-mercury (Ag/Hg) ratio in the gamma 1-phase.
• Compression strength significantly decreased with increasing indium content, falling below ISO 1559 standards at 30 vol.% In.
• Evidence of embrittlement in the gamma 1 and eta phases was observed with higher indium concentrations.

Conclusions:

• Indium addition to dental amalgam does not alter its fundamental phases but significantly impacts its mechanical properties.
• Increased indium content leads to reduced compression strength and embrittlement, potentially compromising clinical durability.
• Further research is needed to balance mercury vapor reduction with maintaining adequate mechanical integrity for dental applications.