title: 1,3-Diethyl-2-thiobarbituric acid as an alternative coinitiator for acidic photopolymerizable dental materials.
abstract: The ethyl-4-dimethylaminobenzoate (EDAB) is widely used as a coinitiator of the camphorquinone (CQ), but in acidic circumstances it might present some instability, reducing the polymerization efficiency of the material. Considering this, new coinitiators are being evaluated. Hence, this study evaluated the kinetic of polymerization (KP), the degree of conversion (DC), and the rate of polymerization (RP ) of experimental resin adhesives containing 1,3-diethyl-2-thiobarbituric acid (TBA) as a coinitiator of the CQ. The experimental monomeric blend was prepared with bisphenol A glycidyl dimethacrylate, 2-hydroxyethyl methacrylate, and acidic monomers. CQ was added at 1 mol % as photoinitiator. Six groups were formulated: four containing concentrations of 0.1, 0.5, 1, and 2 mol % of TBA, one without coinitiator, and the last one containing 1 mol % of EDAB (control group). The KP and the RP were performed using real-time Fourier Transform infrared spectroscopy. The group without coinitiator has not formed a polymer, whereas the addition of TBA resulted in the conversion of monomers in polymer. The DC of the adhesives was as higher as the increase in the TBA content. The group with 2 mol % of TBA presented improved DC and reactivity (RP ) than the other groups and the control one. Hence, the TBA has performed as a coinitiator of the CQ for the radical polymerization of methacrylate resin adhesives and it has improved the DC and the reactivity of the materials. Thus, it is a potential coinitiator for the photopolymerization of dental materials.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Eliseu A
authors.initials: EA
authors.lastname: Münchow
authors.forename: Lisia L
authors.initials: LL
authors.lastname: Valente
authors.forename: Sonia L
authors.initials: SL
authors.lastname: Peralta
authors.forename: María Raquel
authors.initials: MR
authors.lastname: Fernández
authors.forename: Giana da S
authors.initials: Gda S
authors.lastname: Lima
authors.forename: Cesar L
authors.initials: CL
authors.lastname: Petzhold
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
authors.forename: Fabrício A
authors.initials: FA
authors.lastname: Ogliari
mesh_terms: D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry; D055668:Photochemical Processes; D058567:Photoinitiators, Dental / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D012117:Resins, Synthetic / Q000138:chemical synthesis* / Q000737:chemistry; D013858:Thiobarbiturates / Q000737:chemistry*
chemical_list: D058567:Photoinitiators, Dental; D011109:Polymethacrylic Acids; D012117:Resins, Synthetic; D013858:Thiobarbiturates; D002164:Camphor; C046058:1,3-diethyl-2-thiobarbituric acid; C553149:camphorquinone
keywords: EDAB; barbiturates; co-initiators; radical polymerization; real-time infrared spectroscopy