Long-term strength of aesthetic restoratives

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Glass-ionomer cements (GICs) are widely used in clinical dentistry.
• Hybrid GICs incorporate resin to enhance mechanical properties, particularly strength.
• Understanding the long-term flexural strength of these materials is crucial for clinical application.

Purpose of the Study:

• To evaluate the long-term flexural strength of two hybrid glass-ionomer cements.
• To compare the flexural strength of hybrid GICs with conventional GICs and composite resins.
• To investigate the influence of resin content and setting mechanism on flexural strength over time.

Main Methods:

• Utilized a bi-axial flexural strength test (Shell test) for material evaluation.
• Tested two distinct hybrid glass-ionomer cements.
• Included a light-curing composite resin and a conventional glass-ionomer cement as comparators.

Main Results:

• Materials with a high resin component, primarily setting via polymerization, exhibited greater initial flexural strength.
• Hybrid GICs where the glass-ionomer acid-base reaction significantly contributed to setting showed increased strength with maturation.
• Materials dominated by resin setting reactions displayed a decline in flexural strength over time.

Conclusions:

• Resin-rich hybrid GICs offer superior initial strength due to polymerization.
• Materials leveraging the glass-ionomer acid-base reaction demonstrate improved long-term durability and strength gain.
• The dominant setting mechanism significantly impacts the flexural strength profile of glass-ionomer cements over time.