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KMID : 0362319990240040604
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Journal of Korean Academy of Operative Dentistry
1999 Volume.24 No. 4 p.604 ~ p.613
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EFFECT OF RESIN AND FILLER TYPE ON THE FRACTURE TOUGHNESS OF UTMA-BASED LIGHT-CURED COMPOSITES
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Abstract
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This study was performed to evaluate the effect of resin and filler type on the fracture toughness of light-activated composites. Experimental composites were prepared using urethane tetramethacrylate(UTMA) and bisphenol glycidylmethacrylate(Bis-GMA) monomers and five different types of silica fillers. Fracture toughness was measured by a single edge V-notched beam(SEVNB) method, which was discussed from ASTM E399-78. Rectangular bars of 2.5 x 5 x 26mm were prepared with experimental composites and a notch about 2.25mm deep was carved at the center of the long axis of the specimen using a dental diamond disk driven by a dental micro engine. The flexural test was carried out at a crosshead speed of 0.05mm/min and fracture surfaces were observed under scanning electron microscope.
The results obtained were summarized as follows:
1. The fracture toughness values of UTMA-based composites were relatively higher than those of Bis-GMA-based composites.
2. The highest fracture toughness value was observed in the UTMA-based composite containing the 1.5㎛-spherical fillers.
3. Aging in the ,distilled water at 37℃ for 10 days showed the increase of fracture toughness, which was severer in the Bis-GMA-based composites than those of UTNIA-based composites.
4. The AE amplitude occurring during the fracture toughness tests was the highest at the point of macroscopic fracture.
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