Abstract
This study evaluated the Knoop Hardness (KHN) values of two dual-cured composite resin core build-up materials and one resin cement exposed to different curing conditions. Two dual-cured core build-up composite resins (LuxaCore-Dual, DMG; and FluoroCore2, Dentsply Caulk), and one dual-cured resin cement (Rely X ARC, 3M ESPE) were used in the present study. The composite materials were placed into a cylindrical matrix (2 mm in height and 3 mm in diameter), and the specimens thus produced were either light-activated for 40 s (Optilux 501, Demetron Kerr) or were allowed to self-cure for 10 min in the dark (n = 5). All specimens were then stored in humidity at 37 degrees C for 24 h in the dark and were subjected to KHN analysis. The results were submitted to 2-way ANOVA and Tukey's post-hoc test at a pre-set alpha of 5%. All the light-activated groups exhibited higher KHN values than the self-cured ones (p = 0.00001), regardless of product. Among the self-cured groups, both composite resin core build-up materials showed higher KHN values than the dual-cured resin cement (p = 0.00001). LuxaCore-Dual exhibited higher KHN values than FluoroCore2 (p = 0.00001) when they were allowed to self-cure, while no significant differences in KHN values were observed among the light-activated products. The results suggest that dual-cured composite resin core build-up materials may be more reliable than dual-cured resin cements when curing light is not available.
Highlights
Core build-up materials are often required to provide an ideal anatomic form to severely damaged teeth prior to their preparation for indirect restorations
Considering that the maximum shear stress is primarily located at the post/cement/dentin interface,[6] a luting material with improved mechanical properties could resist occlusal loading, and other stresses generated by chewing forces, better than dual-cured resin cements
Two dual-cure core composite resin build-up materials and one dual-cure resin cement were used in the present study: LuxaCore -Dual (DMG, Chemisch Pharmazeutische Fabrik, Hamburg, Germany), FluoroCore 2 (Dentsply Caulk, Milford, DE, USA), and Rely X ARC
Summary
Core build-up materials are often required to provide an ideal anatomic form to severely damaged teeth prior to their preparation for indirect restorations. Dual-cured resin composites for core build-up have been developed The use of these resinous materials allows clinicians to build the damaged tooth using thick resin layers, as self-curing components may assure proper polymerization even when the curing light is severely attenuated by resin shade.[2,3]. Considering that the maximum shear stress is primarily located at the post/cement/dentin interface,[6] a luting material with improved mechanical properties could resist occlusal loading, and other stresses generated by chewing forces, better than dual-cured resin cements. Dual-cure composite resin core build-up materials may be more appropriate for cementing pre-fabricated posts into root canals as they supposedly have better mechanical properties than dual-cured resin cements
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