High Translucent Zirconia Research Articles

Bond strength of self-adhesive resin cements to a high transparency zirconia crown and dentin

Background/purposeThe bond strength and durability of highly translucent zirconia ceramics to dentin is still unclear. The purpose of this study was to investigate the effect of various surface treatments on the bond strength of self-adhesive resin cements to high-translucent zirconia crowns and dentin. Materials and methodsA high-transparent zirconia and three self-adhesive resin cements (G-CEM LinkAce (GCL), RelyX U200 (RXU) and TotalCem (TTC)) were used. The zirconia surface was sandblasted with 50 μm alumina particles or coated with an SR Link primer, while a dentin primer (Tetric N-Bond Universal, TBU) was applied to the surface of the dentin. By using three self-adhesive resin cements, zirconia samples were bonded to the dentin surfaces of human teeth. The shear strength of the specimens was measured before and after 10,000-cycle thermocycling or 90-day aging. ResultsWhen using GCL to bond with the untreated dentin and various zirconia surfaces, the shear bond strength of the sandblasted (ZSB) and RS Link primer-coated (ZLK) groups was significantly higher than that of the untreated control group (Zc). However, in the case of TBU-treated dentin, the shear strength of the ZSB + LK + DTBU group was significantly higher than that of the other groups. After thermocycling and aging, the shear strength of the ZSB + LK + DTBU group using GCL and RXU cements decreased slightly, while the TTC showed no impact. ConclusionThe zirconia surface pretreated by sandblasting and bonding agent, which was sequentially bonded with a primer-treated dentin by using resin cements, can provide excellent shear bond strength and anti-aging performance.

The effects of different silicatization and silanization protocols on the bond durability of resin cements to new high-translucent zirconia.

The aim of this study was to assess the influence of different silicatization protocols with various silane treatment methods on the bond performance to high-translucent zirconia. High-translucent zirconia specimens were assigned to five groups according to mechanical surface pretreatment: as-sintered (Con), 0.2MPa alumina sandblasting (AB2), tribochemical silica coating (TSC), 0.2 and 0.4MPa glass bead air abrasion (GB2) and (GB4). Each group was subjected to 4 different cementation protocols: Panavia SA Universal (SAU), Panavia SA plus (SAP), silane + SAP (S-SAP), and Universal adhesive + SAP (U-SAP). Tensile bond strength (TBS) was measured after 24h and 10,000 thermocycling (TC). Surface topography, surface energy, and elemental composition of the abraded zirconia surface analyses were completed. TBS data was analyzed using the Weibull analysis method. Surface roughness and surface energy were compared by one-way ANOVA analysis of variance (α = 0.05). After 24h, higher TBS was achieved with all cementation protocols in AB2 and TSC, also, in GB2 with all protocols except U-SAP, and in GB4 with SAU and S-SAP. After aging, GB4/S-SAP, GB2/S-SAP, AB2/U-SAP, and TSC/S-SAP showed the highest bond strength. GB groups showed the lowest surface roughness and highest surface energy. Glass bead abrasion achieved the durable bond strength to high-translucent zirconia using a separate silane coupling agent while altered surface chemistry, surface energy, and roughness without effect on morphology. Glass bead air abrasion is an alternative to alumina sandblasting and tribochemical silica coating and improves bond strength to high translucent zirconia.

Do high translucency zirconia shades contribute to the degree of conversion of dual-cure resin cements?

The opacity of the zirconia ceramic restoration may influence the degree of conversion (%DC) of dual-cured resin cements. The aim of this study was to evaluate the degree of conversion of resin luting agents photocured under different high translucency zirconia shades. The opacity of each ceramic shade was evaluated. The opacity percentage of Lava Frame and three Lava Plus High Translucency Zirconia ceramic shades (W1, A2, and B4) was determined. A spectrophotometer MiniScan was used to measure the opacity percentage of each specimen (0.7 mm thick) and then the opacity was calculated. Specimens from three different resin cements (Panavia F2.0, RelyX Unicem 2 Automix Self-Adhesive, and PermaFlo DC) were prepared with 100-µm thickness. The specimens were photocured according to the manufacturers' instructions under a ceramic block (0.7 mm thick). Specimens photocured without the ceramic block were used as control. Fifteen groups (n = 3) were evaluated. Micro-ATR/FTIR (micro-attenuated total reflectance/Fourier-transformed infrared spectroscopy) spectrometry was used to evaluate the extent of polymerization of all specimens after 24 hours. The %DC was determined using experimentally polymerized versus maximally polymerized composite. The opacity percentages (mean ± SD) of W1, Lava Frame, A2, and B4 ceramics were 72.41% ± 0.04%, 74.24% ± 0.09%, 77.63% ± 0.11%, and 78.17% ± 0.12%, respectively. There was a statistically significant difference in %DC among the different cements investigated (P = .003) and a statistical difference in %DC was also found among the different ceramic shades studied (P = .030). For the Lava Frame and A2 ceramic blocks, the resin cements tested presented the lowest %DC except for the RelyX Unicem resin cement. The %DC of RelyX Unicem 2 cement under low zirconia opacities (W1 and Lava Frame) was greater compared to high zirconia opacities (A2 and B4). For the Panavia F2.0 cement, no effect on the %DC under different high translucency shades was observed. The highest %DC of PermaFlo cement was exhibited when the ceramic shade W1 was used. Dual-cured resin cements exhibited different degrees of conversion depending on the opacity of the zirconia restoration. However, different brands demonstrated higher or lower dependency of the light transmittance on their degree of conversion.

Effect of toothbrushing on the optical properties and surface roughness of extrinsically stained high-translucency zirconia.

The effect of toothbrushing on the color, relative translucency, and surface roughness of extrinsically stained zirconia dental restorations is still unclear. The purpose of the present study was to evaluate the optical properties and surface textures of extrinsically stained or glazed partially stabilized zirconia with 5mol% yttria (5Y-PSZ) after toothbrushing by determining changes in the color, translucency parameter (TP), and surface roughness. Specimens (2mm thick; n = 50) were sectioned from 5Y-PSZ blanks. Three brands of powdered stains (namely VI, SH, IV) and a glaze (GL) were used to extrinsically stain the specimen surfaces (n = 10 per group). The specimens were subjected to 10,000-50,000 simulated toothbrushing strokes using a toothpaste slurry (Ora2 PREMIUM Stain clear paste). The color parameters were measured before staining or glazing and before and after simulated brushing. The color changes and TP values can be calculated before and after simulated brushing. The surface roughness was also evaluated. Significant changes were found in the shade and TP values of 5Y-PSZ after extrinsic staining, but no significant changes were found after toothbrushing, irrespective of the staining brand (p > 0.05). The surface roughness of the characterized 5Y-PSZ specimens decreased after toothbrushing, whereas that of the non-characterized 5Y-PSZ group increased. Toothbrushing markedly affects the surface roughness of extrinsically stained or glazed 5Y-PSZ specimens, whereas no impacts on the color or translucency were observed. For esthetic reasons, clinicians and dental technicians prefer to apply extrinsic stains to zirconia restorations, which profoundly affects its appearance. The limited influence of toothbrushing on color and translucency of 5Y-PSZ is promising for clinical applications.

Effects of milling method and artificial ageing on optical properties of high translucent zirconia for chairside restorations

ObjectivesThis study aimed to evaluate the optical properties of highly translucent 5 mol% yttria, partially stabilised monolithic zirconia, and 3 mol% yttria-stabilised tetragonal zirconia after their subjection to different milling methods and artificial ageing. MethodsTwo types of pre-shaded zirconia materials were used: inCoris TZI C and Katana STML. A total of 120 specimens were categorised according to the milling method (dry or wet-milling) and the solution used for milling (fresh distilled water or impregnated water with residues of CAD/CAM ceramic materials). The translucency and contrast ratios of all specimens were calculated after they were subjected to sintering and accelerated ageing. The material phase composition was tested before and after ageing, using X-ray diffraction analysis to evaluate T-M phase transformation. Data were statistically analysed via a three-way analysis of variance between the subject factors, the material and milling method, and the within-subject factor, ageing. The analysis of covariance model was used to analyse the changes in translucency and contrast ratio between baseline and ageing, with statistical significance set at p < 0.05. ResultsKatana STML and inCoris TZI C showed the highest translucency when dry-milled (21.9 ± 1.4, and 11.8 ± 0.7, respectively), and the lowest when milled with used impregnated water (5.4 ± 1.2 and 10.7 ± 1.3, respectively). Wet-milling using impregnated water, should be avoided owing to the saturation of alumina particles. Accelerated ageing resulted in the same pattern for both materials.SignificanceDry milling of highly translucent zirconia can result in higher translucency and lower contrast ratio values.

The effect of thermocyclic aging on color stability of high translucency monolithic lithium disilicate and zirconia ceramics luted with different resin cements: an in vitro study

BackgroundHigh-translucency monolithic zirconia were developed to combine the esthetics of all ceramic restorations with the strength properties of zirconia. The purpose of this study was to compare the color stability of high-translucency monolithic zirconia ceramics with lithium disilicate luted using light-cure versus dual-cure resin cements following thermocyclic aging.MethodsForty specimens, each composed of 10 × 10 × 1 mm ceramic slice luted to dentin surface of an extracted tooth, were prepared and assigned into four groups (n = 10) as follows; LiDi/LC: lithium disilicate luted by light-cure resin cement; LiDi/DC: lithium disilicate luted by dual-cure resin cement; Zr/LC: zirconia luted by light-cure resin cement; and Zr/DC: zirconia luted by dual-cure resin cement. Color analysis of the specimens was performed before and after 3000 thermal cycles by means of spectrophotometry. The CIE L*a*b* values of the specimens were measured, and data were analyzed statistically at a significance value of p < 0.05.ResultsThermocycling resulted in a significant change in color coordinates of specimens with an overall ΔE = 3.59 ± 1.60, but there was no statistically significant difference in the color change value among all tested groups (P = 0.756).ConclusionsAt 1 mm restoration thickness, the color stability of high-translucency monolithic lithium disilicate and zirconia ceramics were not significantly different irrespective of the cement type used.Clinical implication Understanding the difference in color stability of dental ceramics may help in determining long-term esthetic result.

Effect of Two Brands of Glaze Material on the Flexural Strength and Probability of Failure of High Translucent Monolithic Zirconia.

(1) Background: The effect of glazing on the mechanical properties of monolithic high translucent zirconia is not well reported. Therefore, the purpose of this study was to evaluate the effect of glazing on the flexural strength of high translucent zirconia; (2) Methods: Ninety specimens were prepared from second-generation 3Y-TZP high translucent blocks and divided into three groups. Glaze materials were applied on one surface of the specimen and subjected to a four-point bending test and flexural stress and flexural displacement values were derived. Descriptive fractographic analysis of surfaces was conducted to observe the point of failure and fracture pattern.; (3) Results: Control-nonglazed (647.17, 1σ = 74.71 MPa) presented higher flexural strength values compared to glaze I (541.20, 1σ = 82.91 MPa) and glaze II (581.10, 1σ = 59.41 MPa). Characteristic strength (σƟ) from Weibull analysis also observed higher (660.67 MPa) values for the control specimens. Confocal microscopy revealed that glazed surfaces were much rougher than control surfaces. Descriptive fractographic analysis revealed that there was no correlation between the point of failure initiation and flexural strength; (4) Conclusions: The test results demonstrated that glazing significantly decreased the flexural strength and flexural displacement of the zirconia specimens.

External gap progression after cyclic fatigue of adhesive overlays and crowns made with high translucency zirconia or lithium silicate.

ObjectivesTo evaluate three‐dimensional external gap progression after chewing simulation of high translucency zirconia (HTZ) and zirconia‐reinforced lithium silicate (ZLS) applied on endodontically treated teeth with different preparation designs.Materials and MethodEndodontically treated molars were prepared with low‐retentive (adhesive overlay) and high‐retentive (full crown) designs above cementum‐enamel junction and restored with HTZ and ZLS. Micro‐computed tomography analysis was assessed before and after chewing simulation to evaluate three‐dimensionally the external gap progression. Results were statistically analyzed with two‐way ANOVA and post‐hoc Tukey test.ResultsHigh‐retentive preparation design had a significantly inferior gap progression compared to the overlay preparation (p < 0.01); ZLS exhibited a significant inferior gap progression compared to HTZ (p < 0.01).ConclusionsHigh‐retentive preparations restored with ZLS seem to better perform in maintaining the sealing of the external margin after cyclic fatigue.Clinical significanceThe clinician should pay attention to the proper combination of preparation designs and ceramic material selection for an endodontically treated molar restoration. HTZ seems to perform worse than lithium silicate in terms of marginal sealing, still showing lacks in resistance to cyclic fatigue when adhesive preparations are performed.

The Effect of Translucency and Surface Treatment on the Flexural Strength of Aged Monolithic Zirconia.

Aims This in vitro study aimed to evaluate the effect of the degrees of translucency in different types of monolithic zirconia as well as the aging and surface treatment with airborne particle abrasion on the flexural strength of monolithic zirconia. Materials and Methods Sixty bar-shaped specimens were fabricated from three different types of presintered monolithic zirconia (n = 20 per group) including low translucent (LT) (DD Bio ZW iso, high strength zirconia, Dental Direkt, Germany), high translucent (HT) (DD Bio ZX2 98, high translucent zirconia, Dental Direkt, Germany), and multilayered system (ML) (DD cubeX2®ML, multilayer, cubic zirconia system, Dental Direkt, Germany). Each monolithic zirconia group was equally subdivided according to be either air-abraded with 110 µm aluminium oxide particles or left untreated (control). After thermocycling, the flexural strength was measured by using a universal testing machine. Two-way ANOVA followed by Tukey's post hoc and independent samples t-test were used for the statistical analyses (P < 0.05). Results Surface treatment and types of zirconia were found to have a significant interaction (P = 0.010). Having controlled the effect of surface treatment, the flexural strength of HT and LT zirconia was found to be significantly higher than the ML zirconia system (P ≤ 0.001). Airborne particle abrasion could significantly decrease the flexural strength of monolithic zirconia only in ML zirconia (P = 0.002). Conclusions Multilayered zirconia system had the lowest flexural strength among all groups. Moreover, the flexural strength of this system was attenuated by surface treatment with airborne particles abrasion.

Effect of Veneering and Hydrothermal Aging on the Translucency of Newly Introduced Extra Translucent and High Translucent Zirconia with Different Thicknesses.

Purpose The purpose of this study was to evaluate the effect of veneering and aging on the translucency of newly introduced extra and high translucent zirconia with different thickness. Materials and Methods One hundred forty disk-shaped specimens were fabricated from two translucent zirconia blocks (VITA YZ XT and VITA YZ HT), and they are milled with CAD/CAM system. Then, specimens were divided into nonveneered (XT, HT) and veneered groups (XTV, HTV). Nonveneered groups were prepared with four different thicknesses (0.5-1-1.5-2 mm). Veneered groups were divided into three subgroups (n = 10) for veneering with base dentin ceramic with thicknesses of 0.5 + 0.5, 0.5 + 1, and 0.5 + 1.5 mm. A spectrophotometer was used to calculate the translucency parameter (TP) and contrast ratio (CR) of all specimens before and after aging. Statistical analysis was performed using 3-way ANOVA and Tukey HSD tests (p < 0.05). Results TP values were significantly affected by thickness of specimens (p < 0.001). VITA YZ XT was significantly found more translucent than VITA YZ HT. The highest translucency was observed in the XT-0.5 mm group. There is no significant difference between translucency of the veneered and nonveneered groups in the same thickness for XT. On the contrary, veneering significantly affected translucency of HT. TP values significantly decreased after aging for all groups. After aging, translucency value difference before and after aging was the highest in the XT-0.5 mm group whereas the HTV-2 mm group showed the lowest difference after aging. TP decreased significantly as thickness of specimen increases regardless of the material type. Extra translucent and nonveneered zirconia groups are more prone to hydrothermal aging. Conclusions The translucency parameter of zirconia ceramics was significantly influenced by both material type and veneering. Also, extra translucent and nonveneered zirconia groups are more susceptible to hydrothermal aging.

Influence of Low-pH Beverages on the Two-Body Wear of CAD/CAM Monolithic Materials.

The aim of this in vitro study is to evaluate the effect of different acidic media on volumetric wear and surface roughness of CAD/CAM monolithic materials. Forty-eight rectangular specimens were prepared using different CAD/CAM monolithic materials: nanohybrid composite (Grandio Blocks, Voco), resin-based composite (Cerasmart, GC), lithium disilicate (E-Max, Ivoclar), and high-translucency zirconia (Katana STML, Kuraray Noritake). After storage in distilled water at 37 °C for two days, the specimens were tested using a chewing machine with a stainless-steel ball as an antagonist (49N loads, 250,000 cycles). Testing was performed using distilled water, Coca-Cola, and Red Bull as abrasive media. Wear and surface roughness analyses of the CAD/CAM materials were performed using a 3D profilometer and analyzed with two-way analysis of variance and post hoc pairwise comparison procedures. Worn surfaces were examined using scanning electron microscopy. Resin-based materials suffered higher volumetric wear than ceramics (p = 0.00001). Water induced significantly less volumetric wear than the other tested solutions (p = 0.0014), independent of the material tested. High-translucency zirconia showed less surface roughness than all the other materials tested. The selection of monolithic CAD/CAM materials to restore worn dentition due to erosive processes could impact restorative therapy stability over time. Resin-based materials seem to be more influenced by the acidic environment when subjected to a two-body wear test.

Translucency and flexural strength of translucent zirconia ceramics

Statement of problemTranslucent zirconias have been developed with better esthetics than high-strength zirconias by reducing opacity. However, studies on their translucency and strength are sparse. PurposeThe purpose of this in vitro study was to compare the relationship between translucency and biaxial flexural strength of recently developed high-translucency zirconia, high-strength zirconia, and lithium disilicate ceramics. Material and methodsDisks (n=12) were fabricated for 5 ceramic materials: high-strength zirconia (BruxZir 16 shaded), translucent zirconia (BruxZir Anterior shaded, Katana UTML, Katana STML), and lithium disilicate (IPS e.max, Press HT, and LT). A standard tessellation language (STL) file was designed, and the specimen milled, finished, and glazed according to manufacturer's instructions for each material. The translucency parameter was calculated against black and white backgrounds and white and stump shade with ND4 background by using a spectrophotometer. Biaxial flexural strength was calculated by using the 3-ball test. The load was applied at a crosshead speed of 0.5 mm/min with a 49-N load cell until failure occurred. Translucency parameter and biaxial flexural strength data were analyzed with 1-way analysis of variance (ANOVA). A Tukey honest significant difference multiple comparison test was used to determine significant differences (α=.05). ResultsThe IPS e.max HT was more translucent against both backgrounds (32.85 for black/white and 15.34 for white/stump), while BruxZir 16 was the least translucent (19.78 for B/W and 8.83 for W/S). All groups tested differed in translucency (P<.001) except for BruxZir Anterior and Katana STML, which were not significantly different (P=.052). For biaxial flexural strength, BruxZir 16 had the highest strength (995.44 MPa) and e.max HT, the lowest (186.75 MPa). No significant differences were found between BruxZir anterior and Katana STML, Katana UTML and IPS e.max LT, or IPS e.max LT and IPS e.max HT (P>.05). Translucency parameter values using both backgrounds were strongly correlated (r=0.99). However, biaxial flexural strength values were inversely related to translucency parameter values when using black/white and white/stump shade but with high correlation (r=-0.777 and -0.756 respectively). ConclusionsLithium disilicate was the most translucent and yet the weakest material, whereas high-strength zirconia was the most opaque ceramic and the strongest. Katana UTML had the highest translucency but was weakest among translucent and high-strength zirconia materials. Overall, translucency was negatively correlated with biaxial flexural strength.

INFLUENCE OF DIFFERENT AIR ABRASION PRESSURE ON SHEAR BOND STRENGTH OF DIFFERENT TYPES OF ZIRCONIA

This study aimed to evaluate the use of different pressure of air particle abrasion (APA) on four different types of monolithic zirconia and its effect on their shear bond strength. Methodology: The study was divided into 4 groups according to the type of monolithic zirconia used: opaque, high translucency, ultra-high translucency and supra-high translucency. Each group was subdivided into two groups according to the amount of APA application used (2 or 4 bars). For the treatment of the zirconia specimens, zirconia MDP containing primer was applied on the cemented surface. Composite resin cubes were fabricated and cemented over zirconia cubes under 5kg for 6 minutes.Shear bond strength test was carried out on an Instron machine at a speed of 0.5mm/min, with the load measured in Newtons and the SBS determined as follows: Load (N)/area = SBS. Effect of APA application were examined using scanning electron microscopy to determine surface roughness on different tested zirconia groups. The data was statistically analized. Results: The one way ANOVA test revealed statistical differences between the APA pressure groups (P<0.001). Statistical analysis showed that high translucent zirconia scored the highest shear bond after using 2 bar and 4 bar APA in comparison to all other groups; the shear bond strength increased with increasing the pressure. Conclusion: The lower values of shear bond strength in successive, more translucent generations, forewarning the necessity for greater caution in clinical implementation.

Influence of staining beverages and surface finishing on color stability and surface roughness of all-ceramic restorations: Laboratory study

Purpose: Objectives of this study were to assess and compare the impact of coloring beverages and surface finishing on color stability and surface roughness of dental ceramics. Material and methods: Twenty-eight identical cuboids (14*12*1mm) were cut from zirconia-reinforced lithium silicate blocks (suprinity) using a precision cutting machine. Another 28 identical cuboids with the same dimensions were milled from high translucent zirconia ceramic blank (zolid fx). The specimens of each ceramic material were divided into 2 main groups (n=14) according to the finishing technique used; group G: specimens were glazed. group P: specimens were polished. Each subgroup was subdivided into 2 subgroups (n=7) according to the immersion solution used; Tea or Cola. Color measurements and surface roughness of all specimens were measured at the beginning and after 28 days of immersion in the staining beverages. Results: Tea possessed the highest color changes in all tested groups, and these changes were statistically significant compared with those of Cola in both surface finishing groups and in both types of ceramics. The color changes of Tea were not clinically acceptable in the zirconia ceramic groups (ΔE ˃3.3). While Cola possessed the highest mean Ra in all tested groups, and these changes were statistically significant compared with those of Tea in both surface finishing groups and in both types of ceramics. Conclusions: Tea showed the highest impact on the color of polished and glazed types of used ceramics, while Cola significantly increased the surface roughness of both polished and glazed types of used ceramics.

Biaxial flexural strength and phase transformation characteristics of dental monolithic zirconia ceramics with different sintering durations: An in vitro study

Statement of problemZirconia is a polymorphic metastable material which can react through a phase transformation from tetragonal to monoclinic when exposed to mechanical, physical, or chemical stimuli. PurposeThe purpose of this in vitro study was to investigate the fracture strength and phase structure of different high-translucency zirconia ceramics depending on the changes in sintering duration and thermocycling. Material and methodsTwo monolithic zirconia ceramics, Katana (KAT) and NexxZr (NEX), were used to prepare disk-shaped specimens (n=66). The sintering temperature was 1500 °C, and 3 different sintering durations were tested: 1 hour, 2 hours (recommended by the manufacturer), and 3 hours. Thermocycling was applied to half the specimens. Fracture strength was calculated, and the specimens were analyzed with an X-ray diffractometer (XRD) to determine the level of the phase transformation. The normal distribution of the data was analyzed by using the Shapiro-Wilk test. Two-way ANOVA was used to compare multiple groups (α=.05). The Fisher least significant difference test was applied to identify significant differences in fracture strength. The paired-specimen t test was applied to perform intragroup comparisons. ResultsSintering duration significantly affected the fracture strength of KAT (P=.007). For nonthermocycled specimens, the fracture strength of NEX was significantly higher than that of KAT (P<.001). Thermocycling had a significant effect on fracture strength depending on sintering duration and zirconia ceramic interaction (P=.046). ConclusionsThe sintering duration only affected the KAT zirconia, and the fracture strength of KAT decreased when sintered for 3 hours. Thermocycling decreased the fracture strength of both zirconias, except when the sintering duration was 2 hours for NEX. The fracture strength was higher for NEX than for KAT. Tetragonal-monoclinic phase transformation was not found for either zirconia according to the XRD analysis.

Effect of Air-Particle Abrasion Protocol and Primer on The Topography and Bond Strength of a High-Translucent Zirconia Ceramic.

To evaluate effect of air-particle abrasion protocol and primer on surface topography and bond strength of resin cement to high-translucent zirconia ceramics. Two hundred disk-shaped high-translucent zirconia specimens of 5Y-PSZ were prepared. The specimens were assigned to 5 groups in terms of particle type and air-particle abrasion pressure: (1) control, (2) alumina with 0.2 MPa-air pressure [AB-0.2], (3) alumina with 0.4 MPa-air pressure [AB-0.4], (4) glass beads with 0.2 MPa-air pressure [GB-0.2], and (5) glass beads with 0.4 MPa-air pressure [GB-0.4]. Two different primers 1% MDP (Experimental) and MDP-silane primer (Clearfil Ceramic Primer Plus) was also tested. Stainless steel rods were bonded to the 5Y-PSZ specimens with PANAVIA V5. For each group, the tensile bond strength (TBS) was measured after 24-hour water storage (n = 10) and after 5000 thermal-cycling (n = 10) at crosshead speed of 2 mm/min. The data were statistically analyzed using Weibull analysis. Surface roughness (Sa) was measured using a 3D-Laser Scanning Confocal Microscope (n = 5) and analyzed by t-test with Bonferroni correction. Surface topography using scanning electron microscopy (SEM) and surface elemental analysis using energy dispersion spectroscopy (EDX), and cross-section SEM at the interface with composite cement were also investigated. In MDP-silane groups, the highest TBS was observed in AB-0.4 after 24 hours and GB-0.4 after thermal-cycling (p < 0.05). In MDP groups, AB groups resulted in the significantly higher TBS than GB groups (p < 0.05). AB-0.4 group showed the highest Sa value compared to all groups (p < 0.005), meanwhile GB groups did not show different Sa compared to control (p > 0.005). Air-abrasion with different particle and blasting pressure can improve bonding to zirconia with proper primer selection. Particularly, glass beads abrasion followed by MDP-silane primer and alumina abrasion followed by MDP primer alone provided stable bond strength of resin cement to high-translucent zirconia after aging. High-translucent zirconia abraded with glass beads achieves a desirable bonding performance without creating surface microcracks which may hinder zirconia's mechanical properties.

Toothbrushing Wear Resistance of Stained CAD/CAM Ceramics

Aim: To investigate the effect of toothbrushing on different stained Computerd Aided Design/Computer Aided Manufacturing CAD/CAM ceramics. Materials and Methods: Fifty specimens (high translucency zirconia, YZHT; zirconia-reinforced lithium silicate, ZLS; feldspathic, FDL; hybrid ceramic, HC; all from Vita Zahnfabrik) were divided into five groups according to their staining technique. ZLS allowed the composition of two groups: ZLS1 with crystallization and staining together; ZLS2, with the stain firing after the crystallization. YZHT received a stain firing after the sintering process, and FDL received stain firing directly. The HC was stained with acrylic staining, and was light-cured on its surface. The specimens were brushed in total for 150,000 cycles at 2.45 N with 180 strokes/min. Surface measurements to obtain Rz were performed after 50,000, 100,000 and 150,000 cycles, with five evaluation lines (5 mm) per specimen orthogonal to the brushing direction, covering brushed and unbrushed areas. The wear was analyzed using two-way ANOVA and Tukey tests (α = 5%). Scanning electron microscopy (SEM) was performed to access the surface profile. The wear was affected by material (p &lt; 0.001) and time (p = 0.139). Superior wear (µm) was observed for HC (6.6 ± 4.4; 6.8 ± 4.0; 9.2 ± 3.5) compared to ZLS2 (1.0 ± 0.3; 1.2 ± 2.2; 1.3 ± 0.3), YZHT (1.0 ± 0.1; 1.2 ± 0.3; 1.2 ± 0.3), ZLS1 (0.9 ± 0.1; 1.1 ± 0.5; 1.2 ± 0.3) and FDL (0.9 ± 0.1; 0.9 ± 0.1; 1.0 ± 0.2) after 5, 10 and 15 years of simulation, respectively. SEM showed different wear patters for HC with the removal of the glaze layer. HC showed a higher staining wear rate compared to the glass-based and polycrystalline ceramics after 15 years. The extrinsic characterization of feldspathic ceramic showed its superior longevity compared to the evaluated high-translucency zirconia, zirconia-reinforced lithium silicate, and hybrid ceramic.

Novel Femto Laser Patterning of High Translucent Zirconia as an Alternative to Conventional Particle Abrasion.

Background: currently applied surface treatments for zirconia bonding may create undesired microcracks and surface flaws. The aim of the present study was to evaluate the efficacy of alternative surface treatments on the shear bond strength of high translucency zirconia to 10-Methacryloyloxydecyl dihydrogen phosphate (MDP)-containing resin-based cement. Methods: fifty disk-shaped specimens (10 mm × 5 mm) were fabricated from a commercial yttria-stabilized zirconia with 5 mole% yttrium oxide tetragonal zirconia polycrystal (5Y-TZP), and underwent air-abrasion with alumina particles (50 μm-AL50 and 90 μm-AL90), glass beads (GB 10–60 μm), and ablation with femtosecond laser (FEMTO). Shear bond strength was evaluated with a universal testing machine under a crosshead speed of 0.5 mm/min until fracture. Fracture type was evaluated with an optical stereomicroscope. Differences among groups were evaluated by one-way ANOVA and Bonferroni pairwise comparison tests (p < 0.05). Results: the highest shear bond strength values were presented by the laser treated group (23.97 ± 3.7 MPa). No statistically significant differences were found among the Cl, Al50, Al90 and FEMTO groups. The lowest mean value was presented by the glass-beads treated group (11.93 ± 2.88 MPa) which was significantly lower compared to all other groups (p < 0.001). Conclusions: under the limitations of this in vitro study, femtosecond laser treatment of High-translucent monolithic zirconia (HTZ) ceramics is a promising alternative method for the mechanical retention of resin cements.

The need for polishing and occlusal adjustment of zirconia prostheses for wear on antagonist teeth.

The attrition of enamel when opposed by ceramics is of great concern. The purpose of this study was to evaluate enamel wear against high translucent zirconia (Zr), lithium disilicate (LD), gold (Au), and enamel (E) with different surface and contact conditions. The materials were divided into two groups: polished and ground (n=8 each). Two-body wear tests were performed against human enamel with vertical and horizontal, horizontal, and vertical repetitive movements as experiments 1 to 3 respectively. The surface roughness of all materials except Zr changed throughout the experiments. In experiment 1, Zr and Au showed less antagonist wear when polished than when ground. In experiment 2, polished groups showed less antagonist wear than ground groups in all materials. In experiment 3, Zr and LD exerted greater antagonist wear than E, regardless of Ra. These findings confirm the importance of polishing and occlusal adjustment of zirconia.

Effect of Corrosion On Some Properties of Dental Ceramics

Objective: The purpose of this study was to investigate Effect Of Corrosion On Some Properties Of Dental Ceramics. Materials and Method: Twenty four samples were constructed and divided into 3 groups according to ceramic materials used (8 samples for each) group 1(E max), group 2(High Translucent Zirconia (DD BioZx2)) and group 3 (Opaque Zirconia. (DD BioZ)). Then each group was subdivided into three subgroups (3 samples each) according to sequence of tests performed. Then 4 samples from each subgroup were subjected to acetic acid as a corrosive agent. Those samples were first weighted, after that subjected to corrosion test, then weighted again to determine weight loss of each sample. Then samples were tested for color stability using the VITA Easy shade before and after corrosion. shade guides for samples were used (A3). Disinfection methods included immersion for 10 minutes in 1 of the tested disinfectant solutions (5.25% sodium hypochlorite, 2% alkaline gluteraldehyde or 1.7% trialkyl ammonium propionate). The specimens were cleaned after disinfection; the cleaning methods included ultrasonic cleaning in distilled water for 5 minutes and for 10 minutes, steam cleaning for 30 seconds, and under tap water for 30 seconds (n=5). The L*a*b value were recorded and ΔE were calculated. Two-way Repeated Measure ANOVA was used to compare the mean differences over time. Result: All the samples used showed a perceivable change in color (∆E>1). Conclusion: All ceramic samples after corrosion show significant change in color (P