Sulfinates and sulfonates as high performance co-initiators in CQ based systems: Towards aromatic amine-free systems for dental restorative materials

Objective. The aim of our study is to develop amine-free photoinitiating systems (PISS) for the polymerization of representative dental methacrylate resins under blue light irradiation. PISS based on camphorquinone (CQ)/sulfinate and CQ/sulfonate, eventually in combination with an iodonium salt, are proposed and compared to the well-established CQ/amine system. The polymerization performances of thick (1.4 mm) samples of different methacrylate blends upon exposure to a commercial blue LED centered at 477 nm under air are described. Finally, the performances of the new developed PISS are evaluated for dental composites application. Methods. FTIR is used to monitor the photopolymerization profiles. ESR spectroscopy and electrochemical experiments are used to identify the radicals generated. Mechanical properties measurements and color stability measurements are carried out to determine the key properties of the dental composites prepared. Results and Significiance. The performances of the new proposed PISS for the photopolymerization of thick (1.4 mm) samples of methacrylate upon exposure to a blue dental LED under air are excellent. Similar or better performances and bleaching properties are obtained with the new proposed amine-free systems compared to those reached with the CQ/amine reference system. Dental composites with excellent mechanical properties and exceptional color stability are obtained. The involved chemical mechanisms for the initiation step were also established. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.