Filler Content, Surface Microhardness, and Rheological Properties of Various Flowable Resin Composites.

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Flowable resin composites are widely used in restorative dentistry.
• Understanding their physical and mechanical properties is crucial for clinical success.
• Filler content and rheology significantly influence composite performance.

Purpose of the Study:

• To determine filler content, surface microhardness, and rheological properties of various flowable resin composites.
• To assess the effect of water immersion on microhardness over two years.
• To correlate filler content with mechanical and rheological characteristics.

Main Methods:

• Tested seven flowable resin composites, including commercial and experimental formulations.
• Determined filler content via calcination.
• Measured Vickers surface microhardness after polymerization and up to 720 days of water immersion.
• Analyzed rheological properties using a dynamic shear rheometer.

Main Results:

• Actual filler content varied from manufacturer claims.
• Higher filler content correlated with increased microhardness.
• Microhardness generally maintained or increased after 720 days, with some exceptions.
• All composites exhibited non-Newtonian, shear-thinning behavior.
• Grandio Flow (GRF) displayed lower viscosity compared to Grandioso Heavy Flow (GHF) and Filtek Supreme XTE Flow (XTE).

Conclusions:

• Grandio Flow (GRF) offers a favorable combination of low pre-polymerization viscosity and high filler content.
• This balance results in excellent spreadability and robust mechanical properties post-photopolymerization.
• Findings provide valuable insights for selecting and developing flowable resin composites.