Replacement of glass particles by multidirectional short glass fibers in experimental composites: Effects on degree of conversion, mechanical properties and polymerization shrinkage

Replacement of glass particles by multidirectional short glass fibers in experimental composites: Effects on degree of conversion, mechanical properties and polymerization shrinkage

Abstract Objective To test the null hypothesis that the replacement of a small fraction of glass particles with random short glass fibers does not affect degree of conversion (DC), flexural strength (FS), fracture toughness (FT) and post-gel polymerization shrinkage (PS) of experimental composites....

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Bibliographic Details
Published in:Dental materials Vol. 32; no. 9; pp. e204 - e210
Main Authors: Bocalon, Anne C.E, Mita, Daniela, Narumyia, Isabela, Shouha, Paul, Xavier, Tathy A, Braga, Roberto Ruggiero
Format: Journal Article
Language:English
Published: England Elsevier Ltd 01-09-2016
Subjects:
Advanced Basic Science
Analysis of variance
Composite Resins
Composites
Dentistry
Fibers
Glass
Glass fiber reinforced plastics
Glass fibers
Materials Testing
Mechanical properties
Particulate composites
Polymerization
Shrinkage
Mechanical properties
Composites
Shrinkage
Glass fibers
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Summary:Abstract Objective To test the null hypothesis that the replacement of a small fraction of glass particles with random short glass fibers does not affect degree of conversion (DC), flexural strength (FS), fracture toughness (FT) and post-gel polymerization shrinkage (PS) of experimental composites. Methods Four experimental photocurable composites containing 1 BisGMA:1 TEGDMA (by weight) and 60 vol% of fillers were prepared. The reinforcing phase was constituted by barium glass particles (2 μm) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4 mm in length, 7–13 μm in diameter). DC ( n = 4) was obtained using near-FTIR. FS ( n = 10) was calculated via biaxial flexural test and FT ( n = 10) used the “single edge notched beam” method. PS at 5 min ( n = 8) was determined using the strain gage method. Data were analyzed by ANOVA/Tukey test (DC, FS, PS) or Kruskal–Wallis/Dunn's test (FT, alpha: 5% for both tests). Results DC was similar among groups ( p > 0.05). Only the composite containing 5.0% of fibers presented lower FS than the control ( p < 0.001). FT increased significantly between the control (1.3 ± 0.17 MPa m0.5 ) and the composites containing either 5.0% (2.7 ± 0.6 MPa m0.5 ) or 7.5% of fibers (2.8 ± 0.6 MPa m0.5 , p < 0.001). PS in relation to control was significantly reduced at 2.5% fibers (from 0.81 ± 0.13% to 0.57 ± 0.13%) and further reduced between 5.0% and 7.5% (from 0.42 ± 0.12% to 0.23 ± 0.07%, p < 0.001). Significance The replacement of a small fraction of filler particles with glass fibers significantly increased fracture toughness and reduced post-gel shrinkage of experimental composites.
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ISSN:0109-5641
1879-0097
DOI:10.1016/j.dental.2016.06.008