Purpose: The purpose of this laboratory study was to evaluate the effect of different surface treatment combinations on resin zirconia bonding. Materials and methods: One hundred and five pre-sintered zirconia quadrangles were prepared out of zirconia blocks, polished, then sintered and divided into five groups (n=21). Group I (control): samples were untreated, group II: grit-blasting with 50 µm alumina particles, group III: grit-blasting with 100 µm alumina particles, group IV: Er,Cr:YSGG laser, and group V: selective infiltration etching technique. Microstructural analysis was performed using scanning electron microscopy, atomic force microscopy, a diffractometer, and a profilometer. Cylinders of composite resin were luted with Panavia resin composite cementand Clearfil ceramic primer. Shear bond strength (SBS) was determined using a universal testing machine. Results: SBS results were analyzed using one-way ANOVA followed by Tukey post hoc tests for multiple comparisons. The level of significance was set to 0.05. SBS values of the studied groups II, III, IV, and V were 16.2±1.8 MPa, 15.7±3.7 MPa, 14.8±3.4 MPa, and 16.8±3.0 MPa, respectively. All values were significantly higher than the control group (10.48±1.80 MPa), but without a significant difference between them. Group III exhibited the roughest surface, and Group I had a more significantly reduced surface roughness value than any other group. Group III presented the highest significant increase of tetragonal to monoclinic phase transformation (13%). Conclusion: The use of grit-blasting with greater particles size enhanced SBS with resin composite cement, but induced a higher amount of monoclinic phase transformation. The use of primer based on adhesive monomer with the resin cement is required to enhance the bonding efficiency. The use of laser enhanced the surface roughness and the bonding ability to zirconia.

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.

This study evaluated the effect of air abrasion before and after sintering with different particle type, shape, and size on the surface morphology, monoclinic phase transformation, and bond strength between resin cement and zirconia surface using primer containing silane and MDP. Airborne particle abrasion (APA) was performed on zirconia before and after sintering with different particle shape and size (50 μm Al2O3 and 25 μm silica powder). 120 square shaped presintered zirconia samples (Amann Girrbach) were prepared (3 mm height × 10 mm width × 10 mm length) and polished with grit papers #800, 1000, 1200, 1500, and 2000. Samples were divided into 6 groups according to surface treatment—group A: (control) no surface treatment; group B: APA 50 μm Al2O3 before sintering (BS); group C: APA 50 μm Al2O3 after sintering (AS); group D: APA25 μm silica powder (BS); group E: APA25 μm silica powder (AS) at a pressure of 3.5 bar; and group F: APA 25 μm silica powder (AS) at a pressure of 4 bar. Samples were analyzed using XRD, AFM, and SEM. The samples were submitted to shear bond strength (SBS) test. A dual cure resin cement (RelyX Ultimate) and primer (Scotchbond Universal) were used. Data were analyzed with ANOVA and Tukey test (α ≥ 0.05). APA in group B significantly increased the surface roughness when compared to all other groups. A significant monoclinic phase transformation (t-m) value was observed in groups C and F and a reverse transformation occurred in presintered groups. The SBS value of group A was 11.58 ± 1.43 and the highest significant shear bond strength value was for groups B (15.86 ± 1.92) and C (17.59 ± 2.21 MPa) with no significant difference between them. Conclusions. The use of APA 50 μm Al2O3 before sintering and the application of primer containing MDP seem to be valuable methods for durable bonding with zirconia. The use of APA 50 μm Al2O3 after sintering induced the highest (t-m) phase transformation.

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Aim:The aim of this study was to evaluate the effect of different surface treatments on roughness, grain size, and phase transformation of presintered zirconia. Materials and methods:Surface treatments included airborne particle abrasion (APA) before and after sintering with different particles shape, size, and pressure (50 μm Al 2 O 3 , 50 μm glass beads, and ceramic powder). Thirty-five square-shaped presintered yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic slabs (Zenostar ZR bridge, Wieland) were prepared (4 mm height × 10 mm width × 10 mm length) and polished with silicon carbide grit papers #800, 1000, 1200, 1500, and 2000 to ensure identical initial roughness. Specimens were divided into five groups according to surface treatment: group I (control): no surface treatment; group II: APA 50 μm Al 2 O 3 after sintering; group III: APA 50 μm Al 2 O 3 particles before sintering; group IV: APA 50 μm glass bead particles before sintering; and group V: APA ceramic powder before sintering. Specimens were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) analyses, and tested for shear bond strength (SBS). Data were statistically analyzed using one-way analysis of variance (ANOVA) followed by post hoc tests for multiple comparisons Tukey's test (α ≥ 0.05). Results: Air abrasion before sintering significantly increased the surface roughness when compared with groups I and III. The highest tetragonal to monoclinic (t-m) phase transformation (0.07%) was observed in group III, and a reverse transformation was observed in presintered groups (0.01%). Regarding bond strength, there was a significant difference between APA procedures pre-and postsintering. Structural and Morphological Evaluation of Presintered Conclusion:Air abrasion before sintering is a valuable method for increasing surface roughness and SBS. The abrasive particles' size and type used before sintering had a little effect on phase transformation.Clinical significance: Air abrasion before sintering could be supposed to be an alternative surface treatment method to air abrasion after sintering.