Correlation between recordings obtained with a light-intensity tester and degree of conversion of a light-curing resin.

The present study evaluated the ability of a light-intensity tester (CL-Tester) to predict the degree of conversion of a resin. A light-curing resin was mixed from 25 mol-% BISGMA and 75 mol-% TEGDMA. The resin was cured with one of five different curing units whose light intensity varied from poor to very good when recorded with the CL-Tester. The degree of conversion was found by determination of the number of remaining double bonds (RDB) from transmission infrared spectra of the resin. The five mean values of RDB varied with statistical significance. A significant linear correlation was found between recordings of the CL-Tester and degree of conversion. It was concluded that the CL-Tester was able to predict the degree of conversion to such a degree that it may be expected to constitute a useful means of regular control of curing units.