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Aim:This study aims to evaluate the microshear bond strength of zirconia-based ceramics with different resin cement systems and surface treatments.Materials and Methods:Forty blocks of zirconia-based ceramic were prepared and embedded in polyvinyl chloride (PVC) tubes with acrylic resin. After polishing, the samples were washed in an ultrasonic bath and dried in an oven for 10 min. Half of the samples were subjected to sandblasting with aluminum oxide. Blocks were divided into four groups (n = 10) in which two resin cements were used as follows: (1) RelyX™ U100 with surface-polished zirconia; (2) RelyX™ U100 with surface-blasted zirconia; (3) Multilink with surface-polished zirconia; and 4) Multilink with surface-blasted zirconia. After performing these surface treatments, translucent tubes (n = 30 per group) were placed on the zirconia specimens, and resin cement was injected into them and light cured. The PVC tubes were adapted in a universal testing machine; a stiletto blade, which was bolted to the machine, was positioned on the cementation interface. The microshear test was performed at a speed of 0.5 mm/min. Failure mode was analyzed in an optical microscope and classified as adhesive, cohesive, or mixed.Results:The null hypothesis of this study was rejected because there was a difference found between the resin cement and the surface treatment. There was a statistical difference (P < 0.005) in RelyX™ U100 with surface-blasted zirconia, in relation to the other three groups. For Multilink groups, there was no statistical difference between them.Conclusion:Self-adhesive resin cement showed a more significant tendency toward bond strength in the ceramic-based zirconium oxide grit-blasted surfaces.

Aim: The objective of this study was to investigate the performance of experimental resinous adhesives containing different combinations of photoinitiators systems through the bending test. Material and Methods: Resinous adhesive formulations were prepared with monomer mixtures consisting of 50% by mass of bisphenol dimethacrylate glycidyl (BisGMA) and 50% by mass of triethyleneglycol dimethacrylate (TEGDMA). The photoinitiators were used, camphorquinone (CQ) and bis-alkyl phosphinic oxide (BAPO). The co-initiators were diphenyliodonium hexafluorophosphate (DFI) and the amine (dimethylamino methylmethacrylate - DMAEMA) in the 1:1 proportion by mass. The photopolymerizable initiator systems were dissolved in the organic matrix at 0.5% by mass concentrations, creating eight groups (G1- CQ, G2- CQ/amine, G3- CQ/DFI, G4- CQ/amine/DFI, G5- BAPO, G6- BAPO/amine, G7- BAPO/DFI, G8- BAPO/amine/DFI). Samples with 7.0 mm in length, 2.0 mm wide and 1.0 mm height were prepared (n=12). The curing light used was VALO – Ultradent and the curing time was 20 s. The samples were subjected to evaluation of bending test at three points at a speed of 1 mm/min to evaluate the flexural resistance (FR). Results: The results were submitted to analysis of variance with one criterion (p < 0,001) and multiple comparisons were performed using Tukey test. Systems with the photoinitiator BAPO showed higher or equivalent bending values that demonstrated by the conventional system containing CQ/amine. Systems with the DFI had higher flexural values in relation to those demonstrated by systems without the DFI to CQ. Conclusion: The use of systems with alternative photoinitiators and co-initiators allows to obtain superior properties to the conventional system, making these promising systems to act both in isolation as associated with conventional systems.

The aim of this study was to evaluate the depth of cure of conventional (Filtek Z350 and Esthet-X HD) and bulk fill resins composites (Filtek bulk fill flow and SDR) using different photoactivation methods. Samples were made using five discshaped matrices (1 mm high and 8 mm central diameter) with interposed polyester strips. The samples were photoactivated using different methods [continuous high-irradiance light (LCA), continuous low-irradiance light (LCB), and soft-start (SS)], maintaining 24 J/cm² radiant exposure. After 24h, Knoop microhardness test was performed at 5 depths (surface, 1 mm, 2 mm, 3 mm and 4 mm). The Knoop microhardness were analyzed by ANOVA two-way and Tukey's test (5%). Conventional resins presented the highest results up to 2 mm depth, except for Esthet-X photoactived by LCB, which showed significant lower Knoop hardness from 2 mm depth. Bulk fill resins photoactivated with LCA and SS had the highest results in 4 mm depth. The LCA and SS photoactivation methods produce suitable photoactivation in conventional composites up to 2 mm and bulk fill up to 4 mm depth and the bulk fill composites present higher polymerization depth than conventional composites.