Wear Resistance of Luting Cements and the Influence of Marginal Gap Width on Substance Loss

Purpose: Scientific data on wear from toothbrushing of luting cements for fixed partial dentures (FPDs) are limited and inconsistent, therefore the study aimed: (1) to investigate the effect of marginal gap width on cement wear and (2) to compare the resistance to wear from toothbrushing of five luting materials in an in vitro model. Materials and Methods: one zinc phosphate cement (ZPC), glass-ionomer cement (GIC), resin-modified glass ionomer-cement (RGIC), compomer cement (CC) and resin cement (RC) were tested in a toothbrushing device for 2 hours (18,000 double strokes) using a standard tooth paste and a crown-cement-tooth model simulating the cervical region of a crowned tooth. Two gap widths, i.e. 100 and 250 μm were used. Tested surfaces were replicated and wear measured in a scanning electron microscope at three locations: at the metal/cement interface, the middle of the cement film and the cement/ dentin interface. Wear of cements were compared by one way analysis of variance (ANOVA) followed by Bonferroni multiple comparison tests. Two-sample t test was used for assessing the effect of marginal gap width on each product separately. Results and Conclusion: a tendency of reduced wear of water-based cements at the wider gaps was observed. Statistically significant differences in wear resistance were found between the cements at all three measurement places (P < 0.001), i.e. ZPC and GIC were found to have the least, CC and RC the highest and RGIC an intermediate resistance to wear.