Onium salt improves the polymerization kinetics in an experimental dental adhesive resin

Ogliari, Fabrício Aulo; Ely, Caroline; Petzhold, Cesar Liberato; Demarco, Flávio Fernando; Piva, Evandro

doi:10.1016/j.jdent.2007.04.001

« Previous Next »Journal of Dentistry
Volume 35, Issue 7 , Pages 583-587, July 2007

Onium salt improves the polymerization kinetics in an experimental dental adhesive resin

Fabrício Aulo Ogliari
- Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil
Caroline Ely
- Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil
Cesar Liberato Petzhold
- Chemistry Institute, Organic Chemistry Department, Federal University of Rio Grande do Sul, RS, Brazil
Flávio Fernando Demarco
- Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil
Evandro Piva
- Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, RS, Brazil
- Corresponding author at: Biomaterials Development and Control Center (CDC-Bio), School of Dentistry, Federal University of Pelotas, Rua Gonçalves Chaves, 457, Pelotas, CEP: 96015-560, RS, Brazil. Tel.: +55 53 32226690; fax: +55 53 32226690.

Received 19 January 2007; received in revised form 30 March 2007; accepted 3 April 2007.

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.