Zirconia Ceramic Surface Research Articles

Effect of ultrashort pulsed laser on bond strength of Y-TZP zirconia ceramic to tooth surfaces.

There is limited knowledge about the effects of ultrashort pulsed laser on zirconia ceramic surfaces. The aim of this study was to evaluate the effects of ytterbium (Yb)-doped fiber laser and other surface treatment methods -namely, sandblasting with 110 µm aluminum oxide or 30 µm silica-coated alumina on shear bond strength (SBS) of zirconia to tooth surface. A total of 128 zirconium oxide disks were made by using CAD-CAM technology. Disk surfaces were sandblasted with Al2O3 particles or silica-coated alumina or irradiated with Yb-doped fiber based nanosecond pulsed laser at 85W output power at 25 kHz. Disks were luted to dentin using two different resin cement. SBS of each specimen was measured. Results were statistically analyzed using two-way analysis of variance (ANOVA) and Bonferroni and Dunnett tests (p<0.005). Highest bond strength was obtained when zirconia surface was pretreated with Yb-doped fiber-based nanosecond pulsed laser regardless of the resin cement used.

Shear bond strength of the repair composite resin to zirconia ceramic by different surface treatment.

The purpose of this study is the evaluation of the amount of surface roughness (Ra) of Zirconia Ceramic following different surface treatments as well as the assessment of its shear bond strength to composite resin. 40 sintered zirconia ceramic block samples were randomly divided in 4 groups of 10 and underwent the following surface treatments: a) Control group without treatment b) Air abrasion with Al2O3 particles (50um) c) Er:YAG laser with 2W power for 10s d) Nd:YAG laser with 1.5W power for 2min Then the mean surface roughness (Ra) was evaluated by profilometer. In the next step, Alloy primer was used on a section of 9mm(2) on the samples following the manufacturer's instructions. After that Clearfil AP-X composite resin in cylinder shape with an internal diameter and height of 3mm were cured on the sections mentioned. At the end, all samples were tested to assess the shear bond strength by the Universal Testing Machine at a speed of 0.5mm/min until fracture occurred. The mean shear bond strengths were calculated and statistically analyzed by One Way ANOVA. ANOVA analysis showed that roughness (Ra) was significantly different between the groups (P≤0.05). Ra was higher in the Nd:YAG group compared to the other groups (P≤0.05). The lower Ra was related to the control group. Air abrasion group showed highest amounts of shear bond strength and Nd:YAG laser group demonstrated lower amounts of shear bond strength (P≤0.05). Various surface treatments are differently effective on bond strength. Air abrasion is the most effective method to condition zirconia ceramic surfaces.

Effect of different laser surface treatment on microshear bond strength between zirconia ceramic and resin cement.

The purpose of this study was to evaluate the effect of sandblasting, carbon dioxide (CO₂), and erbium,chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers on the microshear bond strength of zirconia to resin cement. Sixty-one sintered yttria stabilized tetragonal zirconia blocks (10 × 5 × 2 mm) were prepared and divided into four experimental groups (n = 15); one sample was retained as a control. The samples were treated by aluminium oxide air abrasion, CO₂4W, Er,Cr:YSGG 3W, and Er,Cr:YSGG 2W, respectively. One sample from each group and the control sample were analyzed by scanning electron microscope. Panavia F2.0 resin microcylinders were prepared and placed on treated surfaces, light cured, and incubated for 48 h. Microshear bond strength testing was done by a microtensile tester machine, and the type of bond failures were determined by stereomicroscope. Data were analyzed by one-way anova and Tukey's test at a significance level of P < 0.05. Air abrasion showed the highest microshear bond strength (P < 0.05) among all groups. CO₂and Er,Cr:YSGG 3W laser showed significantly higher bond strength than Er,Cr:YSGG 2W (P < 0.05). Apparent micromechanical roughening and irregularities were seen in the air abrasion-treated samples, and the bond failure was mostly mixed type. In the laser-treated surfaces, the roughness was much less than the air abrasion-treated surfaces, and the mode of failure was almost pure adhesive. Air abrasion has a greater effect than CO₂and Er,Cr:YSGG lasers in the treatment of zirconia ceramic surfaces to enhance the bonding strength of resin cement to zirconia. CO₂laser at 4W and Er,Cr:YSGG laser at only 3-W output power can be regarded as surface treatment options for roughening the zirconia surface to establish better bond strength with resin cements.

Effect of Surface Treatment with Carbon Dioxide (CO2) Laser on Bond Strength between Cement Resin and Zirconia.

Since it is not possible to form an adequate micromechanical bond between resin cement and zirconia ceramics using common surface treatment techniques, laser pretreatment has been suggested for zirconia ceramic surfaces. The aim of this study was to evaluate the effect of Carbon Dioxide (CO2) Laser treatment on shear bond strength (SBS) of resin cement to zirconia ceramic. In this in vitro study thirty discs of zirconia with a diameter of 6 mm and a thickness of 2 mm were randomly divided into two groups of 15. In the test group the zirconia disc surfaces were irradiated by CO2 laser with an output power of 3 W and energy density of 265.39 j/cm(2). Composite resin discs were fabricated by plastic molds, measuring 3 mm in diameter and 2 mm in thickness and were cemented on zirconia disk surfaces with Panavia F2.0 resin cement (Kuraray Co. Ltd, Osaka, Japan). Shear bond strength was measured by a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture type was assessed under a stereomicroscope at ×40. Surface morphologies of two specimens of the test group were evaluated under SEM before and after laser pretreatment. Data was analyzed by paired t-test (p value < 0.05). The mean SBS values of the laser and control groups were 12.12 ± 3.02 and 5.97 ± 1.14 MPa, respectively. Surface treatment with CO2 laser significantly increased SBS between resin cement and zirconia ceramic (p value = 0.001). Under the limitations of this study, surface treatment with CO2 laser increased the SBS between resin cement and the zirconia ceramic.

Effect of surface treatment on the bond strength between yttria partially stabilized zirconia ceramics and resin cement

No consensus has been reached on the best bonding protocol between a zirconia ceramic surface and the tooth structure. The purpose of this study was to evaluate the extrusion shear strength between yttria partially stabilized zirconia ceramics and resin cement (Panavia F) after different surface treatments. The surface treatments evaluated (n=7) included the following: G1-control group (no surface treatment); G2-treated with MDP primer (Alloy Primer); G3-treated with 40% hydrofluoric acid (210 seconds); and G4-treated with 40% hydrofluoric acid (210 seconds) followed by MDP primer. The specimens were bonded to 2.5-mm-thick disks of bovine root dentin, and the extrusion shear tests were performed after they had been stored for 24 hours in distilled water at 37°C. The surface modifications were assessed on 2 specimens that were selected from each group by scanning electron microscopy. Data were analyzed with 1-way ANOVA and the Tukey-Kramer honestly significant difference test (α=.05). G4 (mean 2.84, standard deviation [SD] 0.43 MPa) presented significantly higher (P<.001) extrusion shear strength when compared with the other groups in the study (G1: mean, 1.57; SD 0.28 MPa; G2: mean 1.46, SD 0.28 MPa; G4: mean 1.16, SD 0.41 MPa). No significant differences were found among the other groups in the study. Yttria partially stabilized zirconia ceramics can be treated with 40% hydrofluoric acid for 210 seconds to increase the bond strength with the resin cement.

DURABILIDADE DA UNIÃO À CERÂMICA DE ZIRCÔNIA TETRAGONAL POLICRISTALINA CONTENDO ÍTRIO (Y-TZP)

Purpose: This study evaluated in vitro the durability of the bond between resin cement and Y-TZP ceramic, testing the effect of different surface treatments and the previous application of an adhesive system over the ceramic. Methods: Forty Y-TZP ceramic plates were distributed into four experimental groups (n=10) according to the combination between surface treatment (air abrasion or Er:YAG laser irradiation) and adhesive system application (Scotchbond Multi Purpose – catalyst or Single Bond 2) in the plate previously to the use of the resin cement. After the surface treatment, resin cement cylinders were built using 0.8x1mm matrices (diameter x height). In each group, 5 specimens were tested for microshear after 24h, and other 5 specimens were tested after 6 months of water storage. Results: Regardless of the adhesive system or period, greater means were obtained in air abraded groups. No statistically significant difference between adhesive systems or periods. Conclusion: It could be concluded that the air abrasion improves bonding to T-TZP ceramic, regardless of the adhesive system used to coat zirconia ceramic surfaces.

Influence of Glazed Zirconia on Dual-Cure Luting Agent Bond Strength

The current study evaluated the influence of a novel surface treatment that uses a low-fusing porcelain glaze for promoting a bond between zirconia-based ceramic and a dual-cure resin luting agent. Bond strengths were compared with those from airborne particle abrasion, hydrofluoric acid etching, and silanization-treated surfaces. Twenty-four yttrium-stabilized tetragonal zirconia (Cercon Smart Ceramics, Degudent, Hanau, Germany) discs were fabricated and received eight surface treatments: group 1: 110 μm aluminum oxide air-borne particle abrasion; group 2: 110 μm aluminum oxide airborne particle abrasion and silane; group 3: 50 μm aluminum oxide airborne particle abrasion; group 4: 50 pm aluminum oxide airborne particle abrasion and silane; group 5: glaze and hydrofluoric acid;group 6: glaze, hydrofluoric acid, and silane;group 7: glaze and 50 pm aluminum oxide airborne particle abrasion; and group 8: glaze,50 pm aluminum oxide airborne particle abrasion and silane. After treatment, Enforce resin cement (Dentsply, Caulk, Milford, DE, USA) was used to fill an iris cut from microbore Tygontubing that was put on the ceramic surface to create 30 cylinders of resin cement in each treatment group (n=30). Micro shear bond test-ing was performed at a cross head speed of 0.5mm/min. One-way analysis of variance, and multiple comparisons were made using Tukey's test (p<0.5). The bond strength was affected only by surface treatments other than silanization. The groups that utilized the low-fusing porcelain glaze with airborne particle abrasion or hydrofluoric acid showed bond strength values statistically superior to groups that utilized conventional airborne particle abrasion treatments with 50 or 110 pm aluminum oxide (p<0.001). The treatment that utilized low-fusing porcelain glaze and hydrofluoric acid showed bond strength values statistically superior to remaining groups (p<0.001). Treatment of zirconia ceramic surfaces with a glaze of low-fusing porcelain significantly increased the bond strength of a dual-cure resin luting agent to the ceramic surface.

Effect of air abrasion and dye on the surface element ratio and resin bond of zirconia ceramic**This work was presented at the 8th China–Korea Symposium on Biomaterials and Nano-Bio Technology (Pyeongchang, Korea, Dec. 13–17 2010).

The purpose of this study was to evaluate the effect of the surface element composition and roughness of dyed or non-dyed zirconia ceramic by air abrasion on the bond durability to resin luting cement. The sintered zirconia ceramic specimens were divided into four groups as follows: polished, dyed/polished, abraded, dyed/abraded. The surface roughness of each group was measured by a 3D laser scanning microscope. Energy-dispersive spectroscopy was applied for identifying and quantifying the elemental composition of the zirconia ceramic surfaces Each group had 20 shear test specimens of zirconia to Panavia F and was divided into two subgroups (n = 10) after 0 or 10 000 thermal cycles to receive the shear test. Compared with polishing, air abrasion significantly reduced the oxygen atom and weight ratio, increased the zirconium atom and weight ratio, increased Ra and Ry of zirconia ceramic surface, and also increased the bond strength of dyed and non-dyed zirconia ceramic to Panavia F after 0 and 10 000 thermal cycles. The dying procedure could affect the abraded and non-abraded zirconia ceramic surface oxygen and zirconia element ratios and surface characteristics. However, the dying procedure does not affect the resin bond strength and durability of zirconia ceramic.Corrections were made to this article on 3 November 2011. The footnote for the corresponding authors was incorrectly labelled.

Effects of Surface Treatment on the Microstructural and Crystallographic Changes of Dental 3Y-TZP Ceramic

Objective: To investigate the effects of different surface treatments on the microstructural and crystallographic changes of dental 3Y-TZP ceramics. Methods: 21 pieces of zirconia specimens (15 ´ 15 ´ 1.5 mm) were prepared and divided into 7 groups: control group; grinding group; polishing group; sandblasting group; sandblasting + veneer porcelain sintering group; sandblasting + veneer porcelain sintering twice group and sandblasting + annealing group. The crystal structure of specimen was monitored by X-ray diffraction (XRD) before morphological observation with scanning electron microscope. Results: monoclinic phase increased after grinding while decreased little after polishing, bigger phase change presented after sandblasting compared with decreased phase change induced by veneer porcelain sintering; annealing eradicated the surface m phase. Grinding produced coarse scratches on the surface of samples with removal of surface particles; after grinding and polishing to 7 um level, the surface particles were removed massively, and the surface became smooth with remaining scare scratches and substantial micro cracks. Sandblasting removed scratches near completely producing coarse and irregular surface of samples. Conclusions: Grinding, sandblasting and polishing could produce the transition of Zirconia Ceramic surface from t to m phase. It is better to use heat treatment after mechanical treatment to reverse the changed surface phase.

The effect of different power outputs of carbon dioxide laser on bonding between zirconia ceramic surface and resin cement

Objective. The purpose of this in vitro study was to evaluate the influence of different power outputs of a carbon dioxide (CO2) laser on shear bond strength of resin cement to zirconium dioxide-based ceramic. Materials and methods. Fifty zirconium dioxide core specimens (10 mm diameter and 2 mm thickness) were produced and they were embedded in the centers of auto-polymerizing acrylic resin blocks. Ten specimens served as control and no surface treatment was applied. Subsequently specimens were randomly divided into four groups, each containing 10 specimens for surface treatment with CO2 laser with different output power; laser treated with 2 W (Group 2 W), 3 W (Group 3 W), 4 W (Group 4 W) and finally 5 W (Group 5 W). Fifty composite resin discs were fabricated and cemented with adhesive resin cement to the specimen surfaces. A universal test machine was used for shear bond strength test at a crosshead speed 1 mm/min. Data were statistically analyzed by one-way analyses of variance (ANOVA) with Post-Hoc Tukey tests (α = 0.05). Results. It was found that the shear bond strength values were affected by power outputs of laser (p < 0.05). Highest shear bond strength values were obtained with group 2 W (21.0 ± 2.7). Lowest values were obtained with group 5 W (14.4 ± 1.6). Conclusion. The current study revealed that there was a relationship between laser output power and shear bond strength for zirconium dioxide ceramics. However, output power of the laser and the energy level is a critical factor on micromechanical retention.

Effects of sandblasting on surface character and resin bond of zirconia ceramic

To evaluate the effect of Al2O3 particles sandblasting on the surface roughness, element composition and resin bond durability of zirconia ceramic. Sixty 2.5 mm thick computer aided design and computer aided manufacture (CAD/CAM) zirconia ceramic (Vita Inceram YZ) plates were fired, polished and cleaned. Half of polished ceramic plates was sandblasted with 50 µm alumina particles at 0.3 MPa for 20 s. The surface roughness of polished and sandblasted ceramic surface were measured by 3D-laser scanning microscope, and the surface element weight and atom ratio of the ceramic surface were measured by energy disperse spectroscopy (EDS). Then polished and sandblasted ceramic plates were randomized into six groups. In Group 1 and 2 the polished and sandblasted ceramic plates were bonded irrespectively with conventional resin cement (DUOLINK). In Group 3 and 4 the ceramic plates were bonded with resin cement containing MDP (Panavia F), In Group 5 and 6 the specimens were pretreated with silane coupler acitivated by MDP (Clearfil Ceramic Primer), then bond with Panavia F. The specimens of each test group were then divided into two subgroups, and to received shear test after 0 and 10 000 time thermal cycle. The data was analyzed by one-way ANOVA and independent t test. Comparing with polishing, sandblasting reduced the oxygen atom and weight ratio of zirconia ceramic surface (P < 0.001), and increased the zirconium atom and weight ratio (P < 0.001), meanwhile increased the surface roughness (P < 0.001). The bond strength between ceramic plates and resin cement in all test groups decreased after thermocycling (P < 0.001). All specimen in test group 1 and 2 lost bond, and the bond strength of test group 3 and 5 [(0.59 ± 0.17), (0.89 ± 0.84) MPa] were significantly lower than that of test group 4 and 6 [(14.63 ± 3.03), (16.64 ± 1.90) MPa], and the bond strength of test group 6 were significanlty higher than that of test group 4. Sandblasting improves durability of bond between zirconia ceramic and resin cement containing MDP, not only by increasing the roughness and area of ceramic surface, but also by changing its surface element composition to obtain more chemical bond.

Determination of Resin Bond Strength to Zirconia Ceramic Surface Using Different Primers

Objective. To evaluate the effect of different primers on the bond strength of adhesive resin cement to zirconia ceramic surface in vitro. Material and methods. Thirty zirconia disk-shaped ceramic specimens (10×2 mm2) were divided into three equal groups for the application of different primers: Monobons-S, Clearfil Ceramic Primer and Signum Zirconia Bond. A further 10 specimens served as a control group. Forty composite resin blocks (6×2 mm2) were cemented (Panavia F 2.0) to zirconia ceramic specimens. Shear bond strengths were measured. Treated zirconia ceramic surfaces were examined using scanning electron microscopy. Results. One-way ANOVA showed that the application of different primers affected the shear bond strength of adhesive resin cement to zirconia ceramic. The highest test values were obtained with application of Signum Zirconia Bond, and the lowest values were obtained in the control group. Conclusion. Signum Zirconia Bond is effective for increasing the bond strength of adhesive resin cement to zirconia ceramic.

The Effect of Laser Treatment on Bonding Between Zirconia Ceramic Surface and Resin Cement

Objective. The purpose of this in-vitro study was to evaluate and compare the effects of different surface treatments and laser irradiation on the shear bond strength of resin cement to zirconia-based ceramic. Material and methods. Forty zirconia core specimens (10-mm diameter, 2-mm thickness) were produced and embedded in the centers of autopolymerizing acrylic resin blocks. Subsequently, specimens were randomly divided into four groups, each containing 10 specimens, for different surface treatment methods. The details of the groups are as follows: Group C, no treatment applied (control); Group SB, bonding surfaces of ceramic disks were airborne particle-abraded with 110-μm alumina oxide particles; Group HF, bonding surfaces of ceramic disks were etched with 9.6% hydrofluoric acid; and Group L, bonding surfaces of ceramic disks were irradiated by a CO2 laser. A total of 40 composite resin disks were fabricated and cemented with an adhesive resin cement to the specimen surfaces. A universal test machine was used for the shear bond strength test at a crosshead speed of 1 mm/min. Results. The highest shear bond strength values were obtained with Group L (20.99 ± 3.77 MPa) and the lowest values with Group C (13.39 ± 3.10 MPa). Although there was no significant difference between Groups C, HF and SB (P > 0.05), Group L showed a significant difference from all other groups (p < 0.05). Conclusion. All surface treatment methods improved the bond strength between resin cement and the zirconium oxide ceramic surface. CO2 laser etching may represent an effective method for conditioning zirconia surfaces, enhancing micromechanical retention and improving the bond strength of resin cement on zirconia ceramic.

Biomimetic Preparation and Characterization of Bioactive Coatings on Alumina and Zirconia Ceramics

For the preparation of bioactive coatings on alumina and zirconia ceramic surfaces a fast biomimetic method using a supersaturated solution containing Na+, Ca2+, Cl−, HCO3−, and PO43− ions was used. The coatings were analysed with the use of an X‐ray diffraction spectrometer and a transmission electron microscope equipped with an energy‐dispersive spectroscopy detector. After the precipitation both coatings were composed of poorly crystallized, nanosized, plate‐like particles with the octacalcium phosphate (OCP) crystal structure. The adhesion of the coatings was improved by a heat treatment at 1050°C for 1 h. During this heat treatment the calcium phosphate layer, deposited from a supersaturated solution onto the surface of the substrates, was sintered to form a dense coating. At the same time the OCP crystal structure was transformed into that of hydroxyl apatite, the coating's crystallinity was increased, and the particles grew isotropically up to 300 nm in size. The bioactivity of the coated ceramic was confirmed before and after the heat treatment using a simple simulated body fluid test.

Influence of different surface treatments on surface zirconia frameworks

Objectives To evaluate the effect of different chemo-mechanical surface treatments of zirconia ceramic in the attempt to improve its bonding potential. Methods Sintered zirconium oxide ceramic discs (Lava™ Ø10 mm × 1 mm height) were treated with ( n = 4): (1) airborne particle abrasion with 125 μm Al 2O 3 particles; (2) 9.5% HF acid etching; (3) selective infiltration etching (SIE); (4) experimental hot etching solution applied for 10, 30 and 60 min; (5) no treatment. Ceramic discs surfaces were analyzed by atomic force microscopy (AFM) recording average surface roughness measurements of the substrate. Data were statistically analyzed by Kruskall–Wallis analysis of variance and Mann–Whitney tests ( α = 0.05). The same discs were used for bi-dimensional zirconia ceramic surface characterization with scanning electron microscope (SEM). Results Ceramic surface treatments significantly influenced surface topography and roughness ( p < 0.001). Bi-dimensional changes in ceramic surface morphology were assessed on a nanometric scale. The experimental hot etching solution improved surface roughness, independently from the application time. Conclusion Zirconia conditioning with the experimental hot etching solution may enhance ceramic roughness and improve the surface area available for adhesion allowing the formation of micromechanical retention. The influence of this surface treatment with regard to bond strength of zirconia needs to be addressed.

Attachment and growth behaviour of human gingival fibroblasts on titanium and zirconia ceramic surfaces

The attachment, growth behaviour and the genetic effect of human gingival fibroblasts (HGF) cultured on titanium and different zirconia surfaces were investigated. HGF cells were cultured on (1) titanium discs with a machined surface, (2) yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) with a smooth surface and (3) Y-TZP with 100 µm grooves. The cell proliferation activity was evaluated through a MTT assay at 24 h and 48 h, and the cell morphology was examined by SEM. The mRNA expression of integrin-β1, type I and III collagen, laminin and fibronectin in HGF were evaluated by RT-PCR after 24 h. From the MTT assay, the mean optical density values for the titanium and grooved zirconia surfaces after 48 h of HGF adhesion were greater than the values obtained for the smooth zirconia surfaces. SEM images showed that more cells were attached to the grooves, and the cells appeared to follow the direction of the grooves. The results of RT-PCR suggest that all groups showed comparable fibroblast-specific gene expression. A zirconia ceramic surface with grooves showed biological responses that were comparable to those obtained with HGF on a titanium surface.

Adsorption of salivary and serum proteins, and bacterial adherence on titanium and zirconia ceramic surfaces

The aim of this study was to determine the pattern of salivary and serum proteins present in pellicles formed on titanium (Ti) and zirconia ceramic (ZrO(2)) surfaces, and the ability of bacterial cells to adhere to the experimental pellicles. In addition, the protein profiles and bacterial binding properties of pellicles on Ti and ZrO(2) were compared to those formed on hydroxyapatite (HA) surface. The pellicles were formed in vitro by incubating the materials with whole saliva, serum or saliva+serum. Protein composition in each of the pellicles was investigated by SDS-PAGE and immunodetection. The adherence of radiolabeled Streptococcus mutans and Actinomyces naeslundii to uncoated surfaces and experimental pellicles was determined by means of scintillation counting. Statistical analyses were done using ANOVA and Tukey's test at significance level at P<0.05. In general, the electrophoretic analysis of the pellicles formed on HA, Ti and ZrO(2) revealed few qualitative differences of the composition of proteins of the pellicles formed on HA, Ti and ZrO(2) surfaces. Pellicle components identified included amylase, IgA, IgG, albumin, fibronectin and fibrinogen. The number of S. mutans cells adhered to uncoated Ti and ZrO(2) was significantly higher than those adhered to HA (P<0.05). In contrast, lower number of A. naeslundii cells adhered to uncoated Ti and ZrO(2) than to HA (P<0.05). However, the presence of saliva and saliva+serum pellicles greatly reduced the number of S. mutans cells bound to each of the surfaces. The data showed that Ti and ZrO(2) display similar pellicle protein composition and bacterial binding properties; however, significant differences were observed when both materials were compared to HA.

Preparation of graded zirconia–CaP composite and studies of its effects on rat osteoblast cells in vitro

Hydroxyapatite (HAP) has excellent biocompatibility and bone bonding ability, but it is mechanically weak and brittle. To overcome this problem, we prepared a graded composite with calcium phosphide (CaP, decomposed from HAP during sintering) coating on the surface of zirconia (ZrO 2) ceramics. The mechanical properties and microstructure characteristics were studied with various techniques. The biocompatibility of graded ZrO 2–CaP composite was examined with rat osteoblast cells (OB cells) in vitro. Its effects on the production of alkaline phosphatase (ALP), Interleukin-6 (IL-6) and Growth-transforming Factor-β (TGF-β) by the OB cells were measured. The results showed that the mean tensile strength of the graded ZrO 2–CaP composites was 17.8 MPa, the maximum bending strength was 1112.24 MPa, and K IC was 7.3–11.4 MPa·m 1/2, indicating that the composite was physically strong for use as an implant material. The ALP activity, IL-6 and TGF-β concentrations of the graded composite treated OB cells were much higher than that of the pure ZrO 2 treated group. There was no significant difference in ALP activity, the IL-6 and TGF-β concentrations between the graded ZrO 2–CaP composite group and HAP. The cytotoxicity of the composite material to rat fibroblast cells was insignificant. The graded zirconia–CaP composite greatly facilitated the proliferation and differentiation of rat OB cells in vitro, demonstrating excellent biocompatibility.

Influence of Contamination on Zirconia Ceramic Bonding

The removal of contaminants prior to the bonding of ceramics is critical for the clinical success of a long-term durable resin bond. This study tested the null hypotheses that there are no contaminants on the zirconia ceramic surface left after try-in simulation, and there are no influences of contamination and cleaning methods on zirconia ceramic bonding durability with 10-methacryloyloxy-decyl dihydrogenphosphate-containing composite resins. After saliva immersion and the use of a silicone disclosing agent, airborne-particle-abraded ceramic specimens were cleaned with acetone, 36% phosphoric acid, additional airborne-particle abrasion, or only water spray. Chemical analyses of specimen surfaces were performed by x-ray photoelectron spectroscopy. The influences of contamination and cleaning methods on ceramic bond durability were examined by tensile testing after 3 or 150 days' water storage with 37,500 thermal cycles. Contamination, existing after try-in simulation as confirmed by chemical analysis, significantly reduced zirconia ceramic-resin bonds. Airborne-particle abrasion may be the most effective cleaning method.

Bond strength of composite luting cement to zirconia ceramic surfaces

To evaluate the bond strength of dental resin agent to zirconia ceramic after surface pre-treatment with different techniques. Specimens of hot isostatic pressed yttrium-oxide-partially-stabilized zirconia blocks (ZF) were fabricated (Procera Zircon, Nobel Biocare, Sweden) and compared to glossy dense zirconia blocks (ZG). Four groups of specimens with different surface treatment were prepared. Group I: ZF (n = 5) and ZG (n = 5) without any pre-treatment, Group II: ZF-s (n = 5) and ZG-s (n = 5) treated with silane solution, Group III: ZF-P (n = 10) and ZG-P (n = 10) treated with RF plasma spraying (hexamethyldisiloxane) using a reactor (Plasma Electronic, Germany), Group IV: ZF-p (n = 10) and ZG-p (n = 10) treated with micro pearls of low fusing porcelain (720 degrees C) on the surfaces. Composite cylinders (Charisma, Hereus Kulzer, Dormagen, Germany) were luted with Variolink II (Ivoclar-Vivadent, Schaan, Liechtenstein) to the test specimens. The specimens were then stored in air for 1 h before shear loading in a universal testing machine (LRX, Lloyd Instruments, Farnham, England) until failure. No statistical difference was found between the untreated ZF and ZG specimens (Group I) neither between the specimens treated with silane (Group II). Plasma spraying treatment improved bond strength by a factor of three (p < 0.001). Treatment with low fusing porcelain micro pearls increased the bond strength by a factor of 10 compared to untreated surfaces (p < 0.001). No significant difference was seen between the surfaces treated ZF-p and ZG-p specimens. The thickness of the glass pearls layer did not exceed 5 microm. SEM showed dense grain borders of ZF and a flat glossy texture of ZG. Treatment of zirconia ceramic surfaces with plasma spraying or a low fusing porcelain pearl layer significantly increased the bond strength of resin cement to the ceramic surface.