Simulated Gap Wear of Self-Adhesive Resin Cements

One of the primary areas of concerns with luting agents is marginal gap erosion and attrition. Objectives: The purpose of this laboratory study was to use a new model to simulate marginal gap wear and examine the loss of material during simulated generalized wear. Methods: Three self-adhesive resin cements were used in this study: G-CEM LinkAce[GC] (GC); Maxcem Elite [ME] (Kerr Corp.); and RelyX Unicem2[RU] (3M ESPE).  A two-piece stainless steel custom fixture was designed with a gap 300 µm wide and 4 mm in length.  Twenty specimens for each of the adhesive cements were made with both light cure and chemical cure techniques. The cured cements were polished with a series a carbide papers to a 4000 grit surface and subjected to 100,000 cycles in a Leinfelder-Suzuki (Alabama) wear simulator (maximum load of 80N) using a stainless steel flat-ended antagonist in a water slurry of PMMA beads for simulation of generalized contact free area (CFA) wear. Before and after the wear challenges, the specimens were profiled with a Proscan 2100 non-contact profilometer and wear (volume loss and mean gap depth) was determined using AnSur 3D software. A two-way ANOVA and Tukey's post hoc test were used for data analysis. Results: The two-way ANOVA showed a significant effect among the three resin cement materials for the factors of resin cement (p<0.001) and cure method (p<0.001) and for the interaction of resin cement and cure method (p<0.001). Table 1 shows the mean gap depth (µm) and volume loss (mm³) after 100,000 cycles in the wear simulator and the significant differences (p<0.05) among the cements and cure methods evaluated.

Conclusion: A new gap model for evaluation of simulated generalized wear of luting agents demonstrated significant differences (p<0.05) in wear among three self-adhesive resin cements and between visible light and chemical cure techniques.