Toughening and polymerization stress control in composites using thiourethane-treated fillers

Autor(es)

Piovezan Fugolin, Ana Paula ^[1] ; Costa, Ana Rosa ^[2] ; Correr-Sobrinho, Lourenco ^[2] ; Chaw, R. Crystal ^[3] ; Lewis, Steven ^[1] ; Ferracane, Jack Liborio ^[1] ; Pfeifer, Carmem Silvia ^[1]

Afiliação do(s) autor(es)

^[1] Oregon Hlth & Sci Univ, Dept Restorat Dent, Div Biomat & Biomech, Portland, OR 97201 - USA

^[2] Piracicaba Dent Sch UNICAMP, Dept Restorat Dent, Div Dent Mat, Piracicaba, SP - Brazil

^[3] Oregon Hlth & Sci Univ, Dept Neurol, Adv Light Microscopy Core, Portland, OR 97201 - USA

• Tipo de documento: Artigo Científico
• Fonte: SCIENTIFIC REPORTS; v. 11, n. 1 APR 7 2021.
• Citações Web of Science: 0

Resumo

Filler particle functionalization with thiourethane oligomers has been shown to increase fracture toughness and decrease polymerization stress in dental composites, though the mechanism is poorly understood. The aim of this study was to systematically characterize the effect of the type of filler surface functionalization on the physicochemical properties of experimental resin composites containing fillers of different size and volume fraction. Barium glass fillers (1, 3 and 10 mu m) were functionalized with 2 wt% thiourethane-silane (TU-Sil) synthesized de novo and characterized by thermogravimetric analysis. Fillers treated with 3-(Trimethoxysilyl)propyl methacrylate (MA-Sil) and with no surface treatment (No-Sil) served as controls. Fillers (50, 60 and 70 wt%) were incorporated into BisGMA-UDMA-TEGDMA (5:3:2) containing camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 0.2 wt% di-tert-butyl hydroxytoluene. The functionalized particles were characterized by thermogravimetric analysis and a representative group was tagged with methacrylated rhodamine B and analyzed by confocal laser scanning microscopy. Polymerization kinetics were assessed by near-IR spectroscopy. Polymerization stress was tested in a cantilever system, and fracture toughness was assessed with single edge-notched beams. Fracture surfaces were characterized by SEM. Data were analyzed with ANOVA/Tukey's test (alpha =0.05). The grafting of thiourethane oligomer onto the surface of the filler particles led to reductions in polymerization stress ranging between 41 and 54%, without affecting the viscosity of the composite. Fracture toughness increased on average by 35% for composites with the experimental fillers compared with the traditional methacrylate-silanized groups. SEM and confocal analyses demonstrate that the coverage of the filler surface was not homogeneous and varied with the size of the filler. The average silane layer for the 1 mu m particle functionalized with the thiourethane was 206 nm, much thicker than reported for traditional silanes. In summary, this study systematically characterized the silane layer and established structure-property relationships for methacrylate and thiourethane silane-containing materials. The results demonstrate that significant stress reductions and fracture toughness increases are obtained by judiciously tailoring the organic-inorganic interface in dental composites. (AU)

• Processo FAPESP: 16/03576-9 - Efeito de cimentos resinosos experimentais formulados a partir de oligômeros tiouretanos na resistência à flexão, ciclagem térmica e fadiga da cerâmica odontológica submetida à condicionante
• Beneficiário: Lourenço Correr Sobrinho
• Modalidade de apoio: Bolsas no Exterior - Pesquisa