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Objective:The objective of this study is to evaluate the effect of a cleaning agent and priming on the bond strength (BS) of a resin cement (RC) to zirconia ceramics after 24 h and 1 year of water-storage.Materials and Methods:Fifty-six Katana and 56 ZirCAD zirconia ceramic plates were prepared and each zirconia brand was divided into four groups (n = 14): (1) untreated; (2) treated with Ivoclean cleaning agent; (3) treated with Monobond Plus coupling agent; (4) treated with Ivoclean + Monobond Plus. Cleaning and coupling agents were applied to zirconia following the manufacturers' instructions. The RC was manipulated, inserted into tubes (0.75 mm diameter/1 mm height) that were positioned on the zirconia surfaces and light activated. Specimens were tested after 24 h and 1 year of water storage. A shear load was applied to the base of the RC cylinders (until failure. Data were analyzed by three-way ANOVA and Tukey tests (α = 5%).Results:No significant difference in BS was noted between zirconia ceramics, except when the combination of cleaning and coupling agents was used. This combination increased the BS for Katana zirconia. One year of water storage leads to a decrease in BS for all experimental groups.Conclusion:The combination of cleaning agent and priming can yield higher BS for Katana at 24 h. BS to zirconia ceramics reduced approximately 50% after 1 year.

Objectives To evaluate the effect of atmospheric pressure plasma (PLA), sandblasting (SAN), silanization (SIL) and hydrophobic bonding resin (HBR) on the micro‐shear bond strength (MSBS) of fresh nanofilled (NF) or microhybrid (MH) composites to water‐aged nanofilled composite. Materials and methods NF plates were fabricated and stored in distilled water for 4 months. The aged plates were assigned to the groups (n = 6): 1‐ untreated; 2‐ SAN + SIL + HBR; 3‐ HBR; 4‐ PLA + HBR; 5‐ SAN + HBR; 6‐ SAN + PLA + HBR; and 7‐ PLA. Two fresh composite cylinders were constructed on each plate with NF or MH composites and tested after 24 h or 1 year of water‐storage, using the MSBS testing. Data were analyzed by three‐way ANOVA and Tukey test (α = 0.05). Results NF yielded better outcomes than MH at 24 h, which was not observed at 1 year. HBR showed the highest MSBS results, while untreated and PLA groups yielded the lowest one. MSBS reduced for all groups after 1 year. Conclusions Only HBR can obtain good MSBS results, while PLA alone was not beneficial. After 1 year, a reduction in repair MSBS was observed and the type of composite did not influence the results. Clinical relevance The repair technique can be simplified with the use of only an adhesive and macromechanical retentions in the old composite, regardless the type of fresh composite.

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Objective: to evaluate the effect of aluminum oxide sandblasting (AOS), argon plasma application (APL) and their combination (AOS+APL) on the shear bond strength (SBS) of dual-cure resin cement (Panavia F 2.0, Kuraray Noritake) to two zirconiabased ceramics (Lava, 3M ESPE and Katana, Kuraray Noritake). Material and Methods: One hundred twenty zirconia plates (13 mm in length X 5 mm in width X 1 mm in thickness) were prepared and treated according to the following treatments: 1- AOS, 2- APL,3- AOS+APL and 4- no treatment (control). After treatments, resin cement cylinders (1.4 mm in diameter x 1 mm in height) bonded to zirconia surface were obtained by filling up the silicon matrix. The shear bond test was performed following storage of the samples for 24 hours and one year. Bond strength values were recorded in MPa and the data were analyzed by three-way ANOVA and Tukey post-hoc test (preset alpha of 0.05). Results: In general, AOS and AOS+APL showed the higher SBS. After one-year storage, SBS of the resin cement to the Katana zirconia did not reduce, regardless of the zirconia surface treatment. Conclusion: AOS alone was able to increase the SBS of the resin cement to both zirconia ceramics compared to control and SBS remained stable after one year depending on type of zirconia ceramic.KeywordsAluminum Oxide; Ceramics; Plasma; Resin Cements

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