Flexural strength of joined and intact amalgam

Area of Science:

• Dental Materials Science
• Materials Engineering
• Biomaterials

Background:

• Dental amalgam restorations are susceptible to marginal degradation over time.
• The mechanical properties of aged and newly joined amalgam interfaces are critical for restoration longevity.
• Understanding the behavior of different alloy compositions at these interfaces is essential.

Purpose of the Study:

• To evaluate the flexural strength of joined versus intact dental amalgam specimens.
• To assess the compressive properties, including fracture toughness and plastic strain, of various amalgam alloys.
• To investigate the correlations between mechanical properties in both joined and intact amalgam specimens.

Main Methods:

• Five different dental amalgam alloys were tested.
• Flexural strength was measured for both intact and newly joined specimens.
• Joined specimens were created by applying fresh amalgam to aged amalgam surfaces.
• Compressive testing was performed on both intact and joined specimens to determine fracture toughness and plastic strain.

Main Results:

• Joined amalgam specimens exhibited significantly reduced flexural strength, ranging from 11.5% to 51.4% of intact specimens.
• High copper amalgam alloys demonstrated the lowest fracture toughness and plastic strain values under compression.
• A positive correlation was observed between the flexural strength of joined specimens and their plastic strain.
• A positive correlation was found between the flexural strength of intact specimens and their fracture toughness.

Conclusions:

• Joining aged and fresh amalgam significantly compromises the material's flexural strength.
• High copper alloys may exhibit reduced ductility and fracture resistance at amalgam interfaces.
• The mechanical integrity of dental amalgam restorations is influenced by both the intrinsic properties of the alloy and the interface quality.