<p>Evaluation Of The Effect Of Different Surface Treatments, Aging And Enzymatic Degradation On Zirconia-Resin Micro-Shear Bond Strength</p>

Abstract

The purpose of this study was to evaluate the effect of surface treatments on zirconia-resin bonding and the effect of aging on bond durability for one year. Method: Three hundred and twenty zirconia blocks were divided into 4 equal study groups. Group 1 (control): as-sintered, group 2: (GB): grit-blasted, group 3: (LAS): laser-etched, group 4: (SIE): selective infiltration etching. Composite cylinders were bonded to the zirconia with resin cement and ceramic primer. Aging was performed following 3 different aging protocols: thermocycling, storage in distilled water, or storage in an enzymatic esterase solution. Micro-shear bond strength test (μSBS) was recorded using a universal testing machine. μSBS values were analyzed using twoway Analysis of Variance followed by Tukey post-hoc tests. Level of significance was set at 0.05. Results: GB, LAS and SIE groups showed significantly higher values when compared to control. Groups GB, LAS and SIE reported a significant decrease up to 50% in μSBS after water storage and enzymatic degradation, while control group reported a 90% decrease. Failure analysis showed mainly adhesive failure for control group, while the percentage of cohesive failure in resin cement was higher in SIE group compared to GB and LAS groups. Conclusion: Water aging and esterase solutions played a significant role by increasing bond degradation. A minimum of one-year water and esterase storage medium should be used to evaluate the durability of the bond between resin cement and zirconia.

Adhesion to Zirconia: A Systematic Review of Surface Pretreatments and Resin Cements

“…The studies agree that the zirconia surface needs to be prepared before applying the resin cement since all the pretreatments increased the bond strength, improving the values of the control group [ 34 , 35 , 36 ]. The first requirement for adhesion is to achieve a surface free of contaminants.…”

“…Sandblasting with alumina particles improved the bond strength values due to the increase in surface energy, wettability, roughness, and the appearance of hydroxyl groups that will facilitate bonding with the primer/universal adhesive/cement [ 34 , 38 , 41 , 43 , 48 ]. The particle size used ranged from 30 to 110 µm, at 0.5–4 bar for 10–20 mm [ 30 , 33 , 34 , 35 , 36 , 38 , 39 , 40 , 41 , 43 , 44 , 45 , 46 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ]. An increase in particle size and pressure had long been associated with the formation of microcracks and weakening the mechanical properties of the material [ 35 , 39 , 41 , 49 , 58 ,…”

“…Zirconia is coated with silica-based material that diffuses in the zirconia structure during the fusion at 960 °C, followed by the application of HF for 10 min to dissolve the glass component. This method obtained contradictory results, and more studies are needed to demonstrate its efficacy [ 33 , 35 ].…”

The Retentive Strength of Zirconium Oxide Crowns Cemented by Self-Adhesive Resin Cements before and after 6 Months of Aging

“…In all aforementioned studies, only mechanical treatment of the Y-TZP blocks or crowns was applied without chemical treatment, and the incubation periods were either short-24 h [17] and 60 days [16]-or long (one year) [24]. A minimum incubation period of six months for testing the bond strength durability of SARCs to zirconia is advocated, whereas shorter incubation periods might provide misleading results [20,21]. A long-term aging process (nine months water storage and 10,000 thermocycles) was also applied in our previous study conducted with an identical study design [6], but in contrast to the current study, it reported unsatisfactory retention strength values of the Lava Y-TZP crowns, which greatly differed between the SARCs.…”

“…Several authors have pointed to the fact that long-term water storage should be used to evaluate the durability of the bond between resin cements, including SARCs, and zirconia. A minimum incubation period of six months is advocated [20,21]. Combined long-term water storage and thermocycling are well-established artificial aging methods, which are mandatory to test the bond strength durability of SARCs to zirconia [22,23].…”