Micro-mechanical characterization of experimental direct core build-up resin composites

What is it about?

Dual-cured resin-based composites are gaining popularity as core build-up materials. Physical and elastoplastic characteristics of new experimental core build-up materials with variable filler contents (+2.5 and +5 wt%) were investigated using classic macroexperiments and nanoindentation. Flexural fracture strength increased from 91.7±11.8 to 114.1±9.1 and 116.6±14.7 MPa in the +2.5 and +5 wt% groups, respectively; similarly, elastic moduli increased from 12.6±0.9 to 15.4±1.2 and 15.3±2.0 MPa, respectively. Fracture toughness increased from 1.82±0.60 to 2.28±0.53 and 2.67±0.88 MPa•m1/2 for the +2.5 and +5 wt% groups, respectively; indentation hardness increased significantly from 0.45±0.03 to 0.55±0.04 and 0.60±0.10 GPa, respectively. The addition of +5 wt% filler content led to a mechanically superior material; the addition of +2.5 wt% filler led to better reliability.

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Why is it important?

Within the limitations of this study, it can be concluded that an increase in filler contents with 2.5 and 5 wt% of the control core build-up material (Clearfil DC Core Automix One) led to improved mechanical properties. Regarding reliability, the 2.5 wt% increase in filler yielded the most reliable material and could be the preferred choice for clinicians when strength and toughness are of primary importance. Further studies are also warranted to reveal the clinical longevity of these materials.

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