Cracks in gold crowns cemented on amalgam restorations

Area of Science:

• Dental Materials Science
• Metallurgy
• Corrosion Engineering

Background:

• Gold alloy dental crowns are frequently used in restorative dentistry.
• Amalgam is a common material for core build-ups or large fillings beneath crowns.
• Patient-reported issues like pain and metallic taste can sometimes be associated with dental restorations.

Purpose of the Study:

• To investigate the nature and origin of cracks observed in gold dental crowns.
• To determine the composition of materials found within these cracks.
• To explore potential etiological factors for crack formation in gold crowns associated with amalgam.

Main Methods:

• Examination of 27 explanted gold crowns (Type III casting gold alloy) with amalgam cores/fillings.
• Microscopic analysis using a scanning electron microscope (SEM).
• Elemental analysis using an energy-dispersive detector (EDD) for crack characterization.

Main Results:

• Eight crowns exhibited cracks originating at the cervical margin and extending occlusally.
• Cracks were observed to propagate along the grain boundaries of the gold alloy.
• Corrosion products typically associated with amalgam were identified within the cracks.

Conclusions:

• Intercrystalline stress corrosion or overloading are potential causes for cracks in gold crowns.
• The presence of amalgam corrosion products within cracks suggests a possible interaction between the crown alloy and the underlying amalgam.
• Further investigation into the long-term stability and material interactions of gold crowns over amalgam is warranted.