An analysis of the polymerization reaction of the light curing type of self-etching bonding system using ESR

Abstract

The aim of this in vitro study was to investigate polymerization reactions of the self-etching primer bondingsystem (Clearfil Mega Bond, Kuraray) using electron spin resonance spectroscopy (ESR). The sample was dividedinto three groups: bonding agent alone (B), bonding agent with self-etching primer (B-P), and bonding agent withair-dried self-etching primer (B-AP). Each sample was placed in the quartz ESR flat cell and was irradiated for1min (Solidilite, Shofu). Radical concentrations were recorded at an interval of1min for20min. A characteristic “5+4-line” spectrum, which indicates the presence of a polymerization radical from the methacryl derivatives inall groups, was observed. The average value of the maximum radical concentration of B-P (1.47±0.14×10^-4M) was significantly lower than B (3.64±0.44×10^-4M) and B-AP (3.47±0.30×10^-4M)(p<0.01). According to theresults of this study, it was recommended that the self-etching primer should be strongly air-blown, because of thevolatile solvent in self-etching primer might acts as a polymerization inhibiter for the bonding agent.