Nanomechanical properties of dental resin-composites
Dental Materials
Volume 28, Issue 12 , Pages 1292-1300, December 2012
Volume 28, Issue 12 , Pages 1292-1300, December 2012
Abstract
Objective
To determine by nanoindentation the hardness and elastic modulus of resin-composites, including a series with systematically varied filler loading, plus other representative materials that fall into the categories of flowable, bulk-fill and conventional nano-hybrid types.Methods
Ten
dental resin-composites: three flowable, three bulk-fill and four
conventional were investigated using nanoindentation. Disc specimens (15
mm×2mm)
were prepared from each material using a metallic mold. Specimens were
irradiated in the mold at top and bottom surfaces in multiple
overlapping points (40s each) with light curing unit at 650mW/cm2. Specimens were then mounted in 3cm
diameter phenolic ring forms and embedded in a self-curing polystyrene
resin. After grinding and polishing, specimens were stored in distilled
water at 37°C
for 7 days. Specimens were investigated using an Agilent Technologies
XP nanoindenter equipped with a Berkovich diamond tip (100nm
radius). Each specimen was loaded at one loading rate and three
different unloading rates (at room temperature) with thirty
indentations, per unloading rate. The maximum load applied by the
nanoindenter to examine the specimens was 10mN.
mm×2mm)
were prepared from each material using a metallic mold. Specimens were
irradiated in the mold at top and bottom surfaces in multiple
overlapping points (40s each) with light curing unit at 650mW/cm2. Specimens were then mounted in 3cm
diameter phenolic ring forms and embedded in a self-curing polystyrene
resin. After grinding and polishing, specimens were stored in distilled
water at 37°C
for 7 days. Specimens were investigated using an Agilent Technologies
XP nanoindenter equipped with a Berkovich diamond tip (100nm
radius). Each specimen was loaded at one loading rate and three
different unloading rates (at room temperature) with thirty
indentations, per unloading rate. The maximum load applied by the
nanoindenter to examine the specimens was 10mN.Results
Dependent on the type of the resin-composite material, the mean values ranged from 0.73GPa to 1.60GPa for nanohardness and from 14.44GPa to 24.07GPa for elastic modulus. There was a significant positive non-linear correlation between elastic modulus and nanohardness (r2=0.88). Nonlinear regression revealed a significant positive correlation (r2=0.62) between elastic moduli and filler loading and a non-significant correlation (r2=0.50)
between nanohardness and filler loading of the studied materials.
Varying the unloading rates showed no consistent effect on the elastic
modulus and nanohardness of the studied materials.
GPa to 1.60GPa for nanohardness and from 14.44GPa to 24.07GPa for elastic modulus. There was a significant positive non-linear correlation between elastic modulus and nanohardness (r2=0.88). Nonlinear regression revealed a significant positive correlation (r2=0.62) between elastic moduli and filler loading and a non-significant correlation (r2=0.50)
between nanohardness and filler loading of the studied materials.
Varying the unloading rates showed no consistent effect on the elastic
modulus and nanohardness of the studied materials.
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