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Microstructures of admixed amalgams produced from Pd-containing dispersants
J H Chern Lin1, K H Chung, E H Greener
1Department of Materials Engineering, National Cheng Kung University, Taiwan.
Summary
Adding palladium (Pd) to traditional dental amalgams suppresses harmful phases like eta' (Cu6Sn5) and gamma 2 (Sn8Hg). This palladium addition improves amalgam stability and reduces reaction zones, enhancing dental material performance.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Materials Science
Background:
- Traditional dental amalgams, primarily silver-mercury (Ag-Hg) alloys, have been widely used but can undergo phase transformations affecting their properties.
- The eta' (Cu6Sn5) and gamma 2 (Sn8Hg) phases in dental amalgams are associated with corrosion and reduced mechanical integrity.
- Palladium (Pd) is explored as a substitute for silver (Ag) or copper (Cu) in dental amalgam alloys to enhance performance.
Purpose of the Study:
- To develop and characterize blended palladium-containing dental amalgams.
- To investigate the effect of palladium substitution on the phase composition and microstructure of dental amalgams.
- To evaluate the suppression of eta' (Cu6Sn5) and gamma 2 (Sn8Hg) phases with increasing palladium content.
Main Methods:
- Development of Ag-Cu-Pd alloys by substituting palladium for silver or copper.
- Preparation of experimental amalgams by blending traditional amalgam with experimental Ag-Cu-Pd particles.
- Fabrication of amalgams using mechanical trituration and hand condensation.
- Analysis of phase composition using X-ray diffraction (XRD).
- Microstructural examination using Scanning Electron Microscopy (SEM).
Main Results:
- Palladium addition effectively suppressed the formation of the eta' (Cu6Sn5) phase in dental amalgams.
- No gamma 2 (Sn8Hg) phase was detected in the palladium-containing amalgams.
- At 3.3 w/o Pd, the eta' (Cu6Sn5) concentration was below the XRD detection limit (<1%).
- SEM analysis showed a reduction in reaction zones around eutectic particles with increased palladium concentration.
Conclusions:
- Palladium incorporation into dental amalgam alloys significantly inhibits the formation of detrimental eta' (Cu6Sn5) and gamma 2 (Sn8Hg) phases.
- The reduced reaction zones observed with palladium suggest improved microstructural stability and potentially enhanced corrosion resistance.
- Blended palladium-containing amalgams represent a promising advancement in dental restorative materials.