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

Publication date: Available online 29 June 2016
Source:Dental Materials
Author(s): Anne C.E. Bocalon, Daniela Mita, Isabela Narumyia, Paul Shouha, Tathy A. Xavier, Roberto Ruggiero Braga
ObjectiveTo 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.MethodsFour experimental photocurable composites containing 1 BisGMA:1 TEGDMA (by weight) and 60vol% of fillers were prepared. The reinforcing phase was constituted by barium glass particles (2μm) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4mm in length, 7–13μm 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 5min (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).ResultsDC 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±0.17MPam^0.5) and the composites containing either 5.0% (2.7±0.6MPam^0.5) or 7.5% of fibers (2.8±0.6MPam^0.5, 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).SignificanceThe replacement of a small fraction of filler particles with glass fibers significantly increased fracture toughness and reduced post-gel shrinkage of experimental composites.



http://ift.tt/29irMmM

from #Med Blogs by Alexandros G.Sfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/295eWWC
via IFTTT

from #Med Blogs by Alexandros G.Sfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/29tZfcQ
via IFTTT