Influence of resin cement viscosity on microleakage of ceramic inlays

The aim of the present investigation was to evaluate the effect of the different viscosities of two resin luting cements on microleakage of ceramic inlays at dentinal margins. The effect of the width of the space between inlay and tooth, on the quality of the marginal seal was also investigated.

Mesial and distal class V cavities were prepared in 48 extracted third molars. The incisal margins of the cavities were in enamel and the cervical margins in dentin. Subsequently, Empress inlays with different cervical margin gap dimensions were fabricated. The mean cervical gap dimensions in the respective groups were as follows: group 1 (27 microm); group 2 (232 microm); group 3 (406 microm). Half the inlays in each group (16) were cemented with a low viscous resin luting cement, and half (16) with a highly viscous resin luting cement. The teeth were subjected to occlusal loading with synchronized thermal cycling in a masticatory simulator. Then, the specimens were immersed in basic fuchsin solution, and dye penetration along the cavity walls was measured. In addition, marginal adaptation was analyzed in the SEM at baseline and after loading, using a replica technique.

With regard to dye penetration at dentinal margins, the highly viscous cement performed statistically significantly better at dentin/composite margins than the low viscous cement (p=0.0158). These findings are supported by SEM analysis.

It is assumed that polymerization stress within the luting cement could not be completely compensated for by larger luting spaces. Highly viscous luting cements are recommended for cementing class V inlays in larger luting spaces.