Effects of systematically varied thiourethane-functionalized filler concentration on polymerization behavior and relevant clinical properties of dental composites. (1st January 2021)

• Record Type: Journal Article
• Authors: Lewis, S.H.; APP, Fugolin; Lam, S.; Scanlon, C.; Ferracane, J.L.; Pfeifer, C.S.
• Is Part Of: Materials & design. Volume 197(2021)
• Publication Date: 2021-01-01
• Subjects: Dimethacrylates -- Thiourethane oligomers -- Dental composites -- Polymerization stress -- Fracture toughness -- Surface properties; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2020.109249
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Introduction of thiourethane (TU) oligomer to resin-based dental restorative materials reduces stress and improves fracture toughness without compromising conversion. Localization of TU at the resin-filler interface via silanization procedures may lead to more substantial stress reduction and clinical property enhancements. The objective of this study was to evaluate composite properties as a function of TU-functionalized filler concentration. TU oligomers were synthesized using click-chemistry techniques and subsequently silanized to barium glass filler. Resin-based composites were formulated using varying ratios of TU-functionalized filler and conventional methacrylate-silanized barium filler. Material property testing included thermogravimetric analysis, real-time polymerization kinetics and depth of cure, polymerization stress, stress relaxation and fracture toughness. Clinical property testing included water sorption/solubility, composite paste viscosity, and gloss and surface roughness measured before and after subjecting the samples to 6 h of continuous tooth brushing in a custom-built apparatus using a toothpaste/water mixture. Increasing TU-filler in the composite resulted in as much as a 78% reduction in stress, coupled with an increase in fracture toughness. Conversion was similar for all groups. After simulated tooth brushing, gloss reduction was lower for TU-containing composites and surface roughness was less than or equal to the control. Graphical abstract: Unlabelled Image Highlights: The surface of conventional silica-based dental fillers was systematically functionalized with novel thiourethane oligomers. Incorporation of thiourethane-modified fillers dramatically reduced polymerization stress and uniformly increased composite fracture toughness. Thiourethane-modified composites demonstrated reduced surface roughness and lower gloss reduction after simulated toothbrushing.