title: Onium salt improves the polymerization kinetics in an experimental dental adhesive resin.
abstract: The aim of this study was to evaluate the influence of an onium salt in the polymerization kinetics of a dental adhesive model resin. A monomer mixture, based on Bis-GMA, TEGDMA and HEMA, was used as a model dental adhesive resin, which was polymerized using camphorquinone (CQ) as a photo-initiator in addition to either binary or ternary photo-initiator systems. The binary systems were formulated with different concentrations of diphenyliodonium hexafluorphosphate or ethyl 4-dimethylaminobenzoate in relation to the monomer and 1mol% of CQ. The ternary system was a blend of 1mol% of CQ, 2mol% of ethyl 4-dimethylamino benzoate and 0.25, 0.5, 1, 2 or 4mol% of onium salt. Real time Fourier Transform infrared spectroscopy was used to investigate the polymerization reaction over the photo-activation time. When CQ was used as photo-initiator, a slow polymerization reaction was observed and a lower monomer conversion. The addition of a second component (onium salt or amine) increases the polymerization rate and conversion independent on the co-initiator concentration. Ternary photo-initiator system showed an improvement on the polymerization rate of the dental adhesive model resin leading to high conversion in short photo-activation time. Also, a mechanism for initiating polymerization using an amine or onium salt as a co-initiator component is proposed.
authors.affiliation: Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil.
authors.forename: Fabrício Aulo
authors.initials: FA
authors.lastname: Ogliari
authors.forename: Caroline
authors.initials: C
authors.lastname: Ely
authors.forename: Cesar Liberato
authors.initials: CL
authors.lastname: Petzhold
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
mesh_terms: D000269:Adhesives / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D009861:Onium Compounds / Q000737:chemistry*; D010777:Photochemistry; D011108:Polymers / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013729:Terpenes / Q000493:pharmacokinetics*
chemical_list: D000269:Adhesives; D003764:Dental Materials; D009861:Onium Compounds; D011108:Polymers; D013729:Terpenes; C048339:camphoroquinone