Effect of curing mode on the hardness of dual-cured composite resin core build-up materials

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 buildup composite resins (LuxaCore  -Dual, DMG; and FluoroCore  2, 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°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 FluoroCore  2 (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.

Bond performance of “Touch and Cure” adhesives on resin core systems

“…In a conventional type of "Touch and Cure'' system, polymerization starts when the adhesive comes in contact with the core material. Therefore, corresponding core materials and adhesives can only be used in combination 11) . On the other hand, twobottle type chemical cure adhesives could adhere with resin cements, light-cure resin composites and resin core materials.…”

Microhardness of dual-polymerizing resin cements and foundation composite resins for luting fiber-reinforced posts

“…17 No scientific evidence supports the effectiveness of the physical properties of resin cements, including their bonding, when an appropriate post space is produced. 16 Dual-polymerizing foundation composite resins showed superior KHNs, an important physical property of the material, to dual-polymerizing resin cements even at greater cavity depths. Therefore, when luting prefabricated post and core material or coronal-radicular foundation, it may be preferable to use dual-polymerizing foundation composite resins.…”

“…Dual-polymerizing foundation composite resins have been developed to allow the clinician to build extended foundation restorations efficiently, and in bulk, since the chemical mode of the polymerization process can initiate resin polymerization at greater depths. 15 Recently, dual-polymerizing foundation composite resins have also been used to lute prefabricated posts into flared root canals, 16 where a thick composite resin layer would normally be present between the fiber-reinforced post and root walls. 17 However, an excessively thick cement layer in that region may not confer the requisite mechanical properties to withstand occlusal loading.…”

Influência das unidades fotoativadoras e do material restaurador indireto sobre a dureza de um cimento resinoso dual auto-adesivo e um cimento resinoso dual convencional por meio de teste de nanoendentação

“…Diversos estudos revelaram que o mecanismo de ativação exclusivamente químico é menos efetivo que o dual (Fonseca, 2001;Attar et al, 2003;Fonseca et al, 2004;Shimura et al, 2005;Dutra-Corrêa et al, 2006;Arrais et al, 2010).…”

“…Essa compensação, seria possibilitada pela ativação química do material, que ocorre mesmo em regiões mais profundas do preparo, em que a chegada de luz é limitada (Hofmann et al, 2001). Diversos estudos revelaram que o mecanismo de ativação química sozinho é menos efetivo que o dual (Fonseca, 2001;Attar et al, 2003;Fonseca et al, 2004;Shimura et al, 2005;Dutra-Corrêa et al, 2006;Arrais et al, 2010).…”