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

Author(s)

Bocalon, Anne C. E. ; Mita, Daniela ; Narumyia, Isabela ; Shouha, Paul ; Xavier, Tathy A. ; Braga, Roberto Ruggiero

• Document type: Journal article
• Source: Dental Materials; v. 32, n. 9, p. E204-E210, SEP 2016.
• Web of Science Citations: 6

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 mu m) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4 mm in length, 7-13 mu m 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 m(0.5)) and the composites containing either 5.0% (2.7 1 +/- 0.6 MPa m(0.5)) or 7.5% of fibers (2.8 +/- 0.6 MPa m(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). 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. (C) 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 13/13805-7 - Effect of multidirectional glass fibers on the mechanical properties and contraction in experimental composite resins
• Grantee: Anne Caroline Encilia Bocalon
• Support Opportunities: Scholarships in Brazil - Scientific Initiation