Monodisperse silica-filled composite restoratives mechanical and light transmission properties

- At equal loading, all filler sizes produce similar flexural properties.
- At maximum loading, larger particles produce better flexural properties.
- Smaller particles produce more transparent composites and higher depths of cure.
- More closely matched refractive index resin and fillers give better depth of cure.

ObjectivesThe aim of this study was to formulate resin-based composites using spherical silica particulate fillers with graded size (75, 150, 350, 500, and 1000 nm), and to evaluate the influence of their size and loading on the mechanical and light transmission properties of the resulting material.MethodsA series of five spherical silica fillers were synthesized, and then formulated with BisGMA/TEGDMA or UDMA/TEGDMA resins. These were then tested for maximum filler loading, flexural strength and modulus, as well as transparency and depth of cure.ResultsLow dispersity spherical silica particles of 75, 150, 350, 500, and 1000 nm were synthesized. Maximum loading was 70 wt% for the three largest particle, and decreased for the smaller sizes, where UDMA-based resins allowed slightly higher loading. When maximally loaded, the largest particle sizes produced the highest flexural properties. However, when using the same loading, all filler sized produced similar flexural strengths and moduli. The optical properties and depth of cure were increased as the filler size decreased.SignificanceWhile hybrid filler particles are the norm in commercial materials, by studying and understanding the influence of individual components on the material properties, we can finely tune the properties of the materials as desired.

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