Characteristics of amalgam restorations with variable clinical appearance

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Corrosion Science

Background:

• Dental amalgam is a widely used restorative material.
• Marginal integrity of amalgam restorations is crucial for longevity.
• Understanding amalgam degradation is key to improving dental treatments.

Purpose of the Study:

• To investigate the microstructural characteristics of amalgam restorations with varying degrees of marginal integrity.
• To identify corrosion products associated with amalgam deterioration.
• To correlate clinical evaluation with microscopic findings.

Main Methods:

• Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) was used for microstructural analysis.
• 165 extracted teeth with amalgam restorations were categorized by marginal integrity.
• Samples representing highest and lowest integrity grades were examined.

Main Results:

• Poor marginal integrity amalgams showed tin-rich and tin-chlorine-rich corrosion products, with absent gamma-2 phase.
• Fractures and cracks at the cavosurface were evident in samples with poor integrity.
• Calcium-associated corrosion products were found at the tooth-amalgam interface; copper-rich amalgams were absent in this group.

Conclusions:

• Marginal deterioration in dental amalgam is linked to specific corrosion products and microstructural defects.
• Corrosion product formation is not the sole determinant of marginal breakdown.
• Further research is needed on intermediate deterioration and copper-rich amalgams.