Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/242283
Type: Artigo de periódico
Title: Thio-urethane Oligomers Improve The Properties Of Light-cured Resin Cements
Author: Bacchi
Atais; Consani
Rafael L.; Martim
Gedalias C.; Pfeifer
Carmem S.
Abstract: Thio-urethanes were synthesized by combining 1,6-hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 10-30 phr to BisGMA-UDMA-TEGDMA (5:3:2, BUT). 25 wt% silanated inorganic fillers were added. Commercial cement (Relyx Veneer, 3M-ESPE) was also evaluated with 10-20 phr of aromatic oligomer. Near-IR was used to follow methacrylate conversion (DC) and rate of polymerization (Rp(max)). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (KO. Polymerization stress (PS) was measured on the Bioman. Volumetric shrinkage (VS, %) was measured with the bonded disk technique. Results were analyzed with ANOVA/Tukey's test (alpha = 5%). In general terms, for BUT cements, conversion and mechanical properties in flexure increased for selected groups with the addition of thio-urethane oligomers. The aromatic versions resulted in greater FS/FM than aliphatic. Fracture toughness increased by twofold in the experimental groups (from 1.17 +/- 0.36 MPa m(1/2) to around 3.23 +/- 0.22 MPa m(1/2)). Rp(max) decreased with the addition of thio-urethanes, though the vitrification point was not statistically different from the control. VS and PS decreased with both oligomers. For the commercial cement, 20 phr of oligomer increased DC, vitrification, reduced Rpmax and also significantly increased K-IC, and reduced PS and FM. Thio-urethane oligomers were shown to favorably modify conventional dimethacrylate networks. Significant reductions in polymerization stress were achieved at the same time conversion and fracture toughness increased. (C) 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Subject: Mechanical-properties
Polymerization Shrinkage
Fracture-toughness
Dental Resins
Stress
Contraction
Composites
Conversion
Networks
Systems
Country: OXFORD
Editor: ELSEVIER SCI LTD
Rights: embargo
Identifier DOI: 10.1016/j.dental.2015.02.008
Address: http://www.sciencedirect.com/science/article/pii/S0109564115000573
Date Issue: 2015
Appears in Collections:Unicamp - Artigos e Outros Documentos

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