IADR Abstract Archives
Mechanical properties of composites polymerized at high temperature, high pressure
The aim of this study was to determine the effect of volume fraction filler (Vf) on the mechanical properties of resin composites (RC) polymerized at high temperature (180 °C) under high pressure (300 MPa) (HT/HP) to obtain materials suitable for CAD/CAM applications. The mechanical properties were compared to those of Paradigm (3M ESPE, USA).
Methods:
Silanated glass fillers [3 μm and 0.7 μm (EG 107), Esschem, Seaham, Germany], were incorporated into a 2/3 UDMA – 1/3 TEGDMA monomer mixture at Vf of 55 %, 60 %, and 65 %. The composites were polymerized at 180 °C under 300 MPa pressure to obtain RC blocks suitable for CAD/CAM. Samples for mechanical characterizations were cut from Paradigm and HT/HP RC blocks. Flexural strength (σf), fracture toughness (KIC), and Vickers hardness (VHN) were determined and compared by one way ANOVA test followed by Scheffe post hoc tests at a = 0.05. Fractured surfaces were characterized with a scanning electron microscope (SEM).
Results:
The results are summarized in the Table. All HT/HP RC blocks had significantly (p<0.05) higher σf, KIC, and VHN relative to Paradigm; the best mechanical properties were obtained at 60 % Vf.
Conclusions:
The results of this study suggest that HT/HP polymerization could be used to obtain dental RC blocks with superior mechanical properties, suitable for CAD/CAM processing.
Table. Mean and standard deviation of mechanical properties*
Composite |
σf (in MPa) |
KIC (in MPa·m1/2) |
VHN (MPa) |
HT/HP RBC 55 % Vf |
231.9 ± 26.9a |
1.5 ± 0.33b |
80.2 ± 4.2b |
HT/HP RBC 60 % Vf |
230.5 ± 18.5a |
2.06 ± 0.45a |
83.4 ± 4.4b |
HT/HP RBC 65 % Vf |
213.7 ± 28.5a |
1.88 ± 0.41a |
111.2±7.7 a
|
Paradigm |
138.2 ± 24.3 |
0.78 ± 0.21c |
114.8 ± 4.3a |
- Groups with same letter were nor statistically different from each other