Time-dependent deformation of composite restorative materials in compression

Area of Science:

• Dental Materials Science
• Polymer Science
• Biomaterials Engineering

Background:

• Composite resins are widely used dental restorative materials.
• Understanding their mechanical properties, including viscoelasticity, is crucial for clinical longevity.

Purpose of the Study:

• To measure the time-dependent strain (viscoelastic response) of different composite resins under compressive load.
• To investigate the influence of filler content and material type (microfine vs. conventional) on viscoelastic behavior.

Main Methods:

• Six composite resins (microfine and conventional) were subjected to compressive loads.
• Strain was measured as a function of time to quantify viscoelastic response.
• Samples were of clinically relevant size.

Main Results:

• Viscoelastic response generally decreased with higher filler content.
• Microfine composites showed substantial linear strain (up to 20%) at high stress levels.
• This strain suggests viscoelastic deformation of both filler and matrix in microfine composites.

Conclusions:

• High stress can induce significant viscoelastic deformation in microfine dental composites.
• Clinical use of microfine restorative materials in high-stress-bearing areas requires caution due to potential deformation.