• The Journal of Advanced Prosthodontics
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• v.11 no.5
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• pp.297-304
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• 2019

PURPOSE. This in vitro study investigated the repair bond strength of the zirconia ceramic after different aging conditions. MATERIALS AND METHODS. In order to imitate the failure modes of veneered zirconia restorations, veneer ceramic, zirconia, and veneer ceramic-zirconia specimens were prepared and were divided into 4 subgroups as: control ($37^{\circ}C$ distilled water for 24 hours ) and 3000, 6000, 12000 thermal cycling groups (n=15). Then, specimens were bonded to composite resin using a porcelain repair kit according to the manufacturer recommendation. The repair bond strength (RBS) test was performed using a universal testing machine (0.5 mm/min). Failure types were analyzed under a stereomicroscope. Two-way ANOVA and Bonferroni test were used for statistical analysis. RESULTS. The RBS values of zirconia specimens were statistically significant and higher than veneer ceramic and veneer ceramic-zirconia specimens in control, 3000 and 6000 thermal cycling groups (P<.05). When 12000 thermal cycles were applied, the highest value was found in zirconia specimens but there was no statistically significant difference between veneer ceramic and veneer ceramic-zirconia specimens (P>.05). Veneer ceramic specimens exhibited cohesive failure types, zirconia specimens exhibited adhesive failure types, and veneer ceramic-zirconia specimens exhibited predominately mixed failure types. CONCLUSION. Thermal cycling can adversely affect RBS of composite resin binded to level of fractured zirconia ceramics.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.136-142
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• 2014

Nowadays, dental zirconia is widely used as a framework material for a fixed dental prosthesis as well as a single restoration. However, clinical studies have reported high incidence of veneer chipping of zirconia-ceramic restorations compared to that of metal-ceramics. Several factors were raised as the possible causes of veneer ceramic chipping, however, it is still in debate. Recently, residual stresses in the veneer ceramics after cooling process gathers attention as one possible cause of chipping and many studies reported that the rate of cooling significantly influenced the types and the amount of residual stress. The purpose of current review was to briefly describe the effect of cooling rate on the residual stress in zirconia-ceramics. It was also described that the different behavior of residual stress between zirconia-ceramics and metal-ceramics following different cooling rate.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.451-455
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• 2014

PURPOSE. The most common failure seen in restorations with a zirconia core is total or layered delamination of the ceramic veneer. In the present study, the shear bond strengths between veneering ceramics and colored zirconia oxide core materials were evaluated. MATERIALS AND METHODS. Zirconia discs ($15{\times}12{\times}1.6mm$) were divided into 11 groups of 12 discs each. Groups were colored according to the Vita Classic scale: A3, B1, C4, D2, and D4. Each group was treated with the recommended shading time for 3 s, or with prolonged shading for 60 s, except for the control group. Samples were veneered with 3 mm thick and 3.5 mm in diameter translucent ceramic and subjected to shear test in a universal testing machine with a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) and Tukey's HSD tests were used for comparisons of the groups having the same shading times. A paired t-test was used for groups of the same color (3 s/60 s). RESULTS. Among the 11 groups investigated C4 (3 s) had the highest bond strength with a value of 36.40 MPa, while A3 (3 s) showed the lowest bond strength with a value of 29.47 MPa. CONCLUSION. Coloring procedures can affect zirconia/ceramic bond strength. However, the results also showed that bond strengths of all the investigated groups were clinically acceptable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.335-341
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• 2020

This study examined the shear bond strength between the zirconia core and pressed lithium disilicate veneering ceramics. The Schmitz-Schulmeyer test method was used to investigate the core-veneer shear bond strength of industrially manufactured zirconia core ceramic (Zirtooth, HASS, Gangneung, Korea) and pressed veneer ceramic (IPS e.max Zirpress, Vita PM9, GC Initial IQ, HASS Rosetta SM) (N=40). Data were statistically analyzed using one-way ANOVA and Tukey's test (a=0.05). The fractured surfaces of the specimens were examined to determine the failure pattern using a digital microscope. The mean ± SD shear bond strength in MPa were 16.69±3.11, 14.21±3.63, 11.17±2.92, and 27.90±5.71 for IPS e.max Zirpress, VITA PM9, GC Initial IQ, and HASS Rosetta SM, respectively. The average shear bond strength was largest for HASS Rosetta SM, followed by IPS e.max Zirpress, Vita PM9, and GC Initial IQ(p<0.05). The digital microscopy examination of the fracture surface showed adhesive and cohesive failure in pressed lithium disilicate veneering ceramics. The use of lithium disilicate veneer ceramic produced a significantly higher shear bond strength.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.259-264
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• 2018

PURPOSE. The purpose of this study was to evaluate the effect of the zirconia surface architecturing technique (ZSAT) on the bond strength between veneering porcelain and zirconia ceramic. MATERIALS AND METHODS. 20 sintered zirconia ceramic specimens were used to determine the optimal surface treatment time, and were randomly divided into 4 groups based on treatment times of 0, 1, 2, and 3 hours. After etching with a special solution, the surface was observed under scanning electron microscope, and then the porcelain was veneered for scratch testing. Sixty 3 mol% yttria-stabilized tetragonal zirconia polycrystal ceramic blocks were used for tensile strength testing; 30 of these blocks were surface treated and the rest were not. Statistical analysis was performed using ANOVA, the Tukey post-hoc test, and independent t-test, and the level of significance was set at ${\alpha}=.05$. RESULTS. The surface treatment of the zirconia using ZSAT increased the surface roughness, and tensile strength test results showed that the ZSAT group significantly increased the bond strength between zirconia and veneering porcelain compared to the untreated group (36 MPa vs. 30 MPa). Optimal etching time was determined to be 2 hours based on the scratch test results. CONCLUSION. ZSAT increases the surface roughness of zirconia, and this might contribute to the increased interfacial bond strength between zirconia and veneering porcelain.

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.415-422
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the translucency of shaded zirconia allceramic systems. MATERIALS AND METHODS. Translucency of 3 different zirconia all-ceramic systems colored by different techniques was compared with a lithium disilicate glass-ceramic (IPS e.max Press). Square-shaped specimens with 0.5 mm thickness were fabricated from In-Ceram YZ, ICE Zirkon and Katana systems in A1, A2 and A3.5 shades according to Vitapan Classical shade tab (n=11). Specimens were then veneered and glazed with corresponding veneer ceramic recommended by each zirconia system manufacturer and the total thickness was set to 1.5 mm. Translucency measurements were performed with VITA Easyshade Compact spectrophotometer after each stage and translucency parameter was calculated. Data were statistically analyzed with repeated measures ANOVA and Tukey multiple comparison test. RESULTS. The control group was significantly more translucent than the zirconia systems (P<.05). ICE Zirkon cores showed the least translucency; neither In-Ceram YZ nor Katana systems were superior to each other in terms of translucency. Translucency of all specimens was decreased after veneering, and the translucency rankings were changed. CONCLUSION. Coloring technique did not have a significant effect on translucency of zirconia cores. Although zirconia systems were less translucent than lithium disilicate glass ceramic, they had partial translucency and there were translucency differences among the zirconia systems. Chroma affected the translucency of precolored zirconia cores.

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.65-74
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• 2019

PURPOSE. To evaluate and compare the effect of different materials and techniques on the shear bond strength of veneering ceramic materials to zirconia. MATERIALS AND METHODS. 136 sintered zirconia cubes were prepared and randomly divided into four study groups according to corresponding methods of surface treatment and materials: GLN (grinding followed by laser scanning using Noritake Cerabien ZR), SLN (sandblasting followed by laser scanning using Noritake Cerabien ZR), GLV (grinding followed by laser scanning using VITA VM 9), and SLV (sandblasting followed by laser scanning using VITA VM 9). Spraying technique was performed to coat the core. Profilometer, SEM, XRD, EDS, universal testing machine, and stereomicroscope were used to record surface roughness Ra, surface morphology, phase transformation, elemental compositions, shear bond strength SBS values, and failure types, respectively. Specimens were investigated in unaged (not immersed in artificial saliva) and aged (stored in artificial saliva for a month) conditions to evaluate SBS values. RESULTS. Grinding and GLN as first and second surface treatments provided satisfactory Ra values in both conditions ($1.05{\pm}0.24{\mu}m$, $1.30{\pm}0.21{\mu}m$) compared to sandblasting and other groups (P<.05). The group GLN showed the highest SBS values in both conditions ($30.97{\pm}3.12MPa$, $29.09{\pm}4.17MPa$), while group SLV recorded the lowest ($23.96{\pm}3.60MPa$, $22.95{\pm}3.68Mpa$) (P<.05). Sandblasting showed phase transformation from t-m. Mixed failure type was the commonest among all groups. CONCLUSION. GLN showed to be a reliable method which provided satisfactory bond strength between the veneer ceramic and zirconia. This method might preserve the integrity of fixed dental crowns.

• Journal of Technologic Dentistry
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• v.43 no.1
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• pp.6-12
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• 2021

Purpose: This study aimed to compare the shear bond strength between zirconia cores and veneer ceramics as per the sand blasting and liner treatments. Methods: The following 4 groups of zirconia-veneering ceramic specimens were prepared: (1) Group I, untreated; (2) Group II, with 110 ㎛ aluminium oxide (Al2O3) sandblasting; (3) Group III, with liner (IPS e.max ZirLiner; Ivoclar Vivadent); and (4) Group IV, with 110 ㎛ Al2O3 sand blasting and liner. Surface roughness was measured for all the prepared specimens, and the surface morphology was observed using a scanning electron microscope. All the samples (n=40) were fixed with measuring jigs, and shear bond strengths were obtained using a universal testing machine with a crosshead speed of 0.5 mm/min. The shear bond strength data were analyzed using one-way analysis of variance and t-test. The post hoc comparison was performed using the Tukey's test (α=0.05). Results: A significant difference in the surface roughness was observed between the specimens of groups I and II (p<0.05). Surface treatment with liner and sandblasting showed higher shear bond strength between zirconia core and veneering ceramic (p<0.05). Conclusion: The sand blasting and liner treatment increased the shear bond strength between zirconia core and veneering ceramic.

• The Journal of Advanced Prosthodontics
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• v.1 no.3
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• pp.129-135
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• 2009

STATEMENT OF PROBLEM. Zirconia-based restorations have the common technical complication of delamination, or porcelain chipping, from the zirconia core. Thus the shear bond strength between the zirconia core and the veneering porcelain requires investigation in order to facilitate the material's clinical use. PURPOSE. The purpose of this study was to evaluate the bonding strength of the porcelain veneer to the zirconia core and to other various metal alloys (high noble metal alloy and base metal alloy). MATERIAL AND METHODS. 15 rectangular ($4\times4\times9mm$) specimens each of zirconia (Cercon), base metal alloy (Tillite), high noble metal alloy (Degudent H) were fabricated for the shear bond strength test. The veneering porcelain recommended by the manufacturer for each type of material was fired to the core in thickness of 3mm. After firing, the specimens were embedded in the PTFE mold, placed on a mounting jig, and subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.5mm/min until fracture. The average shear strength (MPa) was analyzed with the oneway ANOVA and the Tukey's test ($\alpha$= .05). The fractured specimens were examined using SEM and EDX to determine the failure pattern. RESULTS. The mean shear strength ($\pm\;SD$) in MPa was 25.43 ($\pm\;3.12$) in the zirconia group, 35.87 ($\pm\;4.23$) in the base metal group, 38.00 ($\pm\;5.23$) in the high noble metal group. The ANOVA showed a significant difference among groups, and the Tukey' s test presented a significant difference between the zirconia group and the metal group. Microscopic examination showed that the failure primarily occurred near the interface with the residual veneering porcelain remaining on the core. CONCLUSION. There was a significant difference between the metal ceramic and zirconia ceramic group in shear bond strength. There was no significant difference between the base metal alloy and the high noble metal alloy.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.341-350
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• 2010

Purpose: This study focused on achieving desired shades by combining zirconia core with different thickness porcelain in order to make dental prostheses effectively. Methods: White and colored $LAVA^{TM}$ All Ceramic (3M-ESPE, Seefeld, Germany), and Zirkonzahn (Bruneck, Italy) Trans and prettau were used to have Zirconia. LAVATM Ceram (3M-ESPE, Germany) and ICE (Zirkonzahn, Italy) powder were used to have the porcelain. We made quadrilateral specimen of thickness 0.3mm, 0.5mm, 0.7mm and diameter 10 to use zirconia ceramics system of 2 kinds that color tone reappearance way is different and produced total 120 specimens to 4 experimental groups. We used Spectrophotometer to analyze color tone. Data's value getting by dispersal colorimetry period found L*, a*, b* value using Excel program. We used one-way ANOVA to use SPSS WIN 12.0 program. Results: All L*, a*, b* indexes of zirconia core and porcelain veneer in LAVA group and Zirkonzahn group were different. When you combine the white zirconia core of LAVA group with a porcelain veneer, the thickness of the porcelain must be more than 0.5mm to meet the standard target. When all the colored zirconia cores of LAVA group were combined with porcelain veneers, there was no significant difference from the standard target. When the zirconia cores of Zirkonzahn group are combined with porcelain veneers, the thinner thicknesses were closer to the standard tab than thicker thicknesses; however, there was a significant difference in all combinations, with Delta E* value indicating more than 3. Conclusion: When it comes to colored zirconia, which is the most popular, the thicknesses of both a core and a dentin veneer must be more than 0.3mm to get an appropriate shade. There is more possibility to get desirable shades when the thicknesses of a white core are thinner; however, they would be vulnerable to the environment and lose their color. When combine a zirconia core with a dentin veneer, using Zirkonzahn group needs more considerations in order to meet the standard target.