Degree of Conversion of Metacrylate- and Silorane-based Dental Composites at Various Depths and Using Different Matrix Bands

To improve the quality of tooth-colored restorations, various equipment and materials are being used. In this study, we sought to determine the degree of conversion of metacrylate- and silorane-based composites using transparent blue matrix strip at different depths.
In this experimental-laboratory study, 48 specimens of methacrylate- and silylane-based composites were prepared in pre-made molds in thicknesses of 1, 2 and 3 mm. half of the specimens were cured with transparent polyester strips and the other half with blue strips, and then they were hardened by using a light-curing unit. The degree of conversion was determined by FT-IR. The degree of polymerization was assessed by comparing the IR absorption spectra between monomer and polymer specimens. The data were analyzed by performing Mann-Whitney and Kruskal-Wallis tests in SPSS.
The highest degree of conversion pertained to P90 composite with using transparent strip in 1 mm thickness (45.5±1.29), while the lowest degree belonged to Z350 composite with using transparent strip in 3 mm thickness (14.7±1.70). In comparison of the four groups, the silorane-based group with blue strip (41%) had the highest conversion degree, followed by the same composite (silorane) with transparent strip (39.6%). Conversion degrees in these types of materials were much greater than those in metacrylate-based types (21%).
In deep restorations with limited access to a light source, the use of silorane-based composites and blue polyester strips enhances the degree of conversion.