Quantification of Conversion Degree and Monomer Elution from Dental Composite Using HPLC and Micro-Raman Spectroscopy

Abstract

The purpose of the study was to analyze the correlation between the quantity of eluted monomers from dental resin-based composite using reverse-phase HPLC and the degree of conversion (DC) using micro-Raman spectroscopy, and to evaluate the influence of the energy of polymerization delivered on the composite material and the applied resin layer thickness on these properties. There was direct proportion in degree of conversion and inverse proportion in monomer elution when the energy of light polymerization was increased from 20 to 40 J cm−2; however, further increase in energy density did not influence significantly the DC and the elution of monomers. Investigating the depth of cure significant differences could be measured both in DC and the elution of monomers. 1 mm layer increment up to 3 mm from the top led to 10 % decrease in DC and 30–35 % increase in monomer elution. Further increase in depth from 3 to 4 mm caused 30 % drop in DC and 55 % increase in the amount of leached monomers. The overall result of the findings indicates that direct correlation exists between DC of composite and the elution of unreacted monomers.