Influence of shade of adhesive resin cement on its polymerization shrinkage

Resin cements have the ability to bond to the tooth structure and to several indirect restorative materials and they are available in different transparency and shades. However, polymerization shrinkage remains to be a problem that leads to gap formation at the margins of restoration, and accordingly microleakage may occur. The purpose of this study was to investigate the influence of the shade of adhesive resin cement on its polymerization shrinkage. Five shades (Group 1: universal; Group 2: brown; Group 3: clear; Group 4: opaque white; Group 5: opaque yellow) of a dual-cure composite cement system (Clearfil Esthetic Cement, Kuraray, Tokyo, Japan) were studied with 10 specimens of each shade. Volumetric shrinkages of the composite cements of these five shades were evaluated using a video-imaging device (Acu-Vol; Bisco, Inc.) by measuring the volumes before and after polymerization. Different shades displayed different volumetric shrinkages. Group 5 (2.62%) and Group 2 (3.96%) displayed the lowest and highest shrinkage percentages, respectively, with their respective shrinkage values being significantly different from those of the other groups (p < 0.05). The obtained results indicate that the shade of resin cement does affect its degree of polymerization shrinkage