An in vitro comparison of marginal microleakage of four groups of temporary cements in provisional crowns

Purpose: The aim of this in vitro study was to compare the marginal microleakage in provisional crowns cemented on extracted human premolars using four temporary cements formulated using different chemical bases (zinc oxide eugenol, zinc polycarboxylate, resin, and additional-silicone). Materials and Methods: Twenty-four non-carious human premolars were prepared in a standardized manner for full-coverage crown restorations. Provisional crowns were made from a methacrylate resin using a direct technique and the specimens were randomized into four groups of temporary cementing agents (n=6): zinc oxide eugenol cement (TempBond®), zinc polycarboxylate cement (UltraTemp®), additional silicone cement (TempoSil® 2), and resin-based cement (UltraTemp® REZ). After 24 hours of storage in distilled water at 37ºC, the specimens were thermocycled and then stored again for 24 hours in distilled water at room temperature. Next, they were placed in freshly prepared 2% aqueous methylene blue dye for 24 hours, then embedded in autopolymerizing acrylic resin blocks and sectioned in buccolingual and mesiodistal direction to assess the dye penetration using a stereomicroscope. The results were statistically analyzed using a non-parametric Kruskal-Wallis test. Dunn's post hoc with a Bonferroni correction test was used to compute multiple pairwise comparisons that identified differences among groups; the level of significance was set at P<0.05. Results: All groups showed marginal microleakage; the resin-based temporary cement and the additional silicone temporary cement showed the lowest microleakage scores, which were statistically different from those of polycarboxylate temporary cement and zinc oxide eugenol cement. Conclusions: The results of this study demonstrated that the temporary cementing agents exhibited different sealing abilities. Resin based temporary cement (UltraTemp® REZ) and additional-silicone based cement (TempoSil® 2) exhibited the most favorable sealing properties against dye penetration compared with polycarboxylate based cement (UltraTemp®) and conventional zinc oxide eugenol cement (TempBond®).