Zirconia Ceramic Surface Research Articles

Research on laser polishing process of zirconia ceramic surface

Abstract In order to investigate the polishing results of carbon dioxide pulsed laser on the surface of zirconia ceramics, this paper analyzes the significance of the influence of each process parameter on the surface roughness in the laser polishing process based on the experimental design of the response surface method and taking the surface roughness as the optimization objective. And the best combination of process parameters for the laser polishing process is predicted by establishing a surface roughness prediction model. The results of the experiments show that among the laser polishing process parameters, the scanning speed and laser power have an extremely significant effect on surface roughness, while the pulse frequency has a more significant effect on surface roughness. The model predicts the optimum combination of working parameters as: laser power P = 75W, pulse frequency f = 4 kHz, scanning speed v = 380 mm/s. Under the optimum combination of process parameters, surface roughness Ra = 0.595μm of the material, which is 76% lower than that of the original surface roughness of 2.479μm after laser polishing.

Tailoring zirconia surface topography via femtosecond laser-induced nanoscale features: effects on osteoblast cells and antibacterial properties

The performance and long-term durability of dental implants hinge on the quality of bone integration and their resistance to bacteria. This research aims to introduce a surface modification strategy for zirconia implants utilizing femtosecond laser ablation techniques, exploring their impact on osteoblast cell behavior and bacterial performance, as well as the integral factors influencing the soft tissue quality surrounding dental implants. Ultrafast lasers were employed to craft nanoscale groove geometries on zirconia surfaces, with thorough analyses conducted using x-ray diffraction, scanning electron microscopy, atomic force microscopy, and water contact angle measurements. The study evaluated the response of human fetal osteoblastic cell lines to textured zirconia ceramics by assessing alkaline phosphatase activity, collagen I, and interleukin 1βsecretion over a 7 day period. Additionally, the antibacterial behavior of the textured surfaces was investigated usingFusobacterium nucleatum, a common culprit in infections associated with dental implants. Ciprofloxacin (CIP), a widely used antibacterial antibiotic, was loaded onto zirconia ceramic surfaces. The results of this study unveiled a substantial reduction in bacterial adhesion on textured zirconia surfaces. The fine biocompatibility of these surfaces was confirmed through the MTT assay and observations of cell morphology. Moreover, the human fetal osteoblastic cell line exhibited extensive spreading and secreted elevated levels of collagen I and interleukin 1βin the modified samples. Drug release evaluations demonstrated sustained CIP release through a diffusion mechanism, showcasing excellent antibacterial activity against pathogenic bacteria, includingStreptococcus mutans, Pseudomonas aeruginosa, andEscherichia coli.

Improving zirconia ceramics grinding surface integrity through innovative laser bionic surface texturing

Zirconia ceramics have become an important material for the manufacture of key components in aerospace, military, energy, and other fields due to their excellent mechanical properties. However, their inherent high hardness and brittleness make them difficult to machine with high efficiency and low damage, resulting in poor surface integrity. Inspired by the ribbed groove structure of shark skin and the fractal structure of insect wing veins, two zirconia ceramics with different bionic textures are designed in this paper, and zirconia ceramic surfaces are bionically textured by using an ultrafast picosecond pulse laser. The effects of the special bionic textures on the grinding behavior of zirconia ceramics, specifically surface morphology, surface roughness, edge morphology, and subsurface damage, were investigated. The experimental results show that the surface integrity of the bionic textured zirconia ceramics is better compared to the untextured surface. In particular, the bionic insect wing veins texture exhibits the best surface quality with the least sub-surface damage, and the surface roughness Sa is reduced by a maximum of 21.46 %, and Sz is reduced by a maximum of 18.87 %. However, the best edge morphology is exhibited by the bionic shark skin texture. Additionally, bionic texturing improves grinding lubrication and cooling conditions. The results confirm that applying bionic texturing to zirconia ceramics effectively enhances grinding performance and improves grinding surface integrity.

Effect of laser and coating surface treatment on the bond strength of zirconia ceramics.

This study aims to investigate bond strength between zirconia and resin cement through surface treatments with Er: YAG laser, Nd: YAG laser, and Si-Zr coating. Seventy-five round pre-sintered zirconia discs with a diameter of 18 mm and a thickness of 1.5 mm were prepared by a powder compactor. Fifty discs were randomly divided into five groups of 10 discs each and were subjected to five surface treatments: no treatment (control group), sandblasting with alumina particles (sandblasting group), Er: YAG laser treatment (Er: YAG laser group), Nd:YAG laser treatment (Nd: YAG laser group), and Si-Zr coating treatment (Si-Zr coating group). The discs were then bonded to composite resin columns with resin cement. The shear bond strength of each group was tested with a universal tester. Roughness tester, scanning electron microscope (SEM), and energy dispersive spectroscopy were used to analyze surface performance. The bond strength of the Si-Zr coating group was higher than that of the remaining groups (P<0.05). The difference in bond strength between the sandblasting group and the Er: YAG laser group was not statistically significant (P>0.05), but both of them had higher bond strength than the Nd: YAG laser group (P<0.05). The Si-Zr coating group had the highest surface roughness (P<0.05). The surface roughness of the sandblasting, Er: YAG laser, and Nd: YAG laser groups was higher than that of the control group (P<0.05), but the difference among the three groups was not statistically significant (P>0.05). SEM observations showed irregular scratches on the surface of the sandblasting group and large pits with holes on the surface of the Er: YAG and Nd: YAG laser groups. In the Er: YAG laser group, the crystal structure was replaced by a smooth surface with a large amount of microcracks due to partial melting. Complex porous structures that comprised "island-like" structures and mass pores among the grains were observed on the surface of the Si-Zr coating. Only Zr, O, and Y were detected on the surfaces of the control, Er: YAG laser, and Nd: YAG laser groups. Al was found on the surface of the sandblasted group, and a higher proportion of Si was detected on the surface of the Si-Zr coating group. Er: YAG laser and Nd: YAG laser treatment on the zirconia ceramic surface could increase roughness and improve the bond strength to resin cement. Si-Zr coating treatment is an effective alternative for increasing the roughness and bond strength of zirconia surface and is superior to sandblasting and laser treatments.

Shear bond strength between standard or modified zirconia surfaces and two resin cements incorporating or not 10-MDP in their matrix

ObjectiveThis study aimed first to compare the shear bond strength between zirconia samples luted to enamel with a 10-MDP- containing resin cement (Panavia F2.0, Kuraray, Japan) and those luted with a resin cement using a separated 10-MDP monomer-containing bottle (Panavia V5, Kuraray, Japan). The second objective was to evaluate the bond stability after 150 days of aging in water, between enamel and zirconia ceramic surface enhanced with a glass-ceramic coating. Materials and methods80 specimens composed of ceramic cylinders and enamel disks were obtained, within eight experimental groups (n = 10). 60 zirconia cylinders (Katana STML zirconia, Kuraray, Japan) were assigned to 3 groups according to their surface treatment: milled/sintered surface (ZRCT), tribochemical silica-coating (Cojet™ Sand, 3 M ESPE, Seefeld, Germany) (ZRTC), and glass-ceramic coating (IPS e.max Zirpress) (ZRZP). 20 cylinders of lithium disilicate had a milled surface (IPS e.max CAD, Ivoclar-Vivadent, Schaan, Liechtenstein) (ECAD). The cylinders of each group were further divided into two subgroups according to the resin cement used: Panavia F2.0 (-PF) and Panavia V5 (-PV). All specimens were stored in distilled water for 150 days before shear bond strength (SBS) tests. The fracture mode was analyzed, and data were statistically computed (two-way ANOVA, post hoc Tukey test, p < 0.05, SPSS, IBM, v26). ResultsThe ECAD-PF group recorded the highest SBS values (31.75 ± 2.2), and the ZRCT-PF group recorded the lowest values (5.59 ± 1.1). The two-way ANOVA test showed that ceramic surface treatment had a statistically significant effect on SBS (F (3,72) = 38.95, p < 0.001) while the type of ARC did not (F (1,72) = 2.40, p = 0.126). Tukey’s post hoc test revealed no statistical difference between the ZRZP and the ZRTC or ECAD groups. ConclusionWithin the limitations of this study, the PV resin achieved similar shear bond strength results between tribocoated zirconia and enamel compared to the one for glass-ceramic and enamel. Furthermore, a long-term durable bond, similar to the glass-ceramic one, was achieved with the heat pressed ceramic coated specimens. Thus, this new surface treatment could be recommended for anterior cantilever bridges for its fracture resistance and bonding ability.

Femtosecond Pulsed Laser Irradiation of Zirconia for Embedding Silver Nanoparticles in Surface Nanopores

Femtosecond pulsed laser irradiation was performed to investigate the feasibility and fundamental characteristics of embedding silver nanoparticles onto zirconia ceramic surfaces. By irradiating laser, nanopores were fabricated on the surface of the yttria-stabilized zirconia (YSZ) substrate, and silver nanoparticles were infiltrated and immobilized into the pores using a commercial nano-silver dispersion solution. Numerous nanopores embedded with silver nanoparticles were successfully obtained on the YSZ surface while keeping the grains’ shapes unchanged by controlling laser parameters. Optimizing laser fluence and scanning speed near the ablation threshold made it possible to remove only the excess dispersant that remained on the surface while keeping silver in the pores and without causing machining of the surface of the YSZ substrate. In addition, about 60% embedding in the nanopores was achieved. It was found that the shorter pulse width was suitable to avoid evaporating both dispersant and silver. Cross-sectional observation revealed that the silver nanoparticles were agglomerated to form clumps and were embedded without a gap at the bottom of the pores at a depth of about 600 nm. After laser irradiation, no significant laser-induced phase change was observed in the YSZ substrate, indicating that there was no in-process thermal damage to the bulk. These findings demonstrated the possibility of adding a metal nanoparticle to the zirconia surface by using only a laser process without damaging the properties of the base material during the process. New applications of zirconia, such as the generation of functional surfaces with antibacterial properties, are expected.

Effect of Different Decontamination Agents on The Bond Strength of CAD/CAM Blocks and Repair Composite Materials

The purpose of this study was to examine the effect of different decontamination agents on the bond strength of saliva-contaminated CAD/CAM blocks and repair composite materials. Two hunderd eighty 3-mm-thick specimens were prepared from four different CAD/CAM materials: Katana Zirconia UTML disc, IPS e.max CAD block, Shofu block, and Vita Enamic block. Each material was divided into seven different subgroups (N=70). Group 1 had a clean surface. The other groups were comprised of the samples, which were contaminated with human saliva: group 2: negative control (non-cleaned); group 3: cleaned with water spray; group 4: cleaned with 70% ethanol; group 5: cleaned with Ivoclean; group 6: cleaned with Katana Cleaner; and group 7: cleaned with phosphoric acid. After the decontamination protocols, the resin composite cylinders were bonded to the CAD/CAM surfaces with a thin layer of dual-cured resin cement. The samples were stored for 24 hours at 37°C in distilled water. Then, they were subjected to a shear bond strength test (SBS). The values were recorded, and fracture types were evaluated using a microscope. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test. Generally, all decontaminating agents improved the SBS of composites to Katana Zirconia UTML, IPS e.max, and Vita Enamic materials (p&lt;0.05). However, for Shofu materials, group 6 samples exhibited significantly higher bond strength values as compared with group 2 samples (p=0.026). The highest SBS values were seen in the phosphoric acid-treated group in Katana zirconia materials (26.45 ± 9.38 MPa), whereas the lowest values were seen in group 2 samples in Shofu materials (13.17 ± 3.40 MPa). Each decontaminant agent improved the bond strength of composites to the contaminated CAD/CAM materials. If saliva is not cleaned before adhesive procedure, SBS values may decrease. All decontamination agents can be used safely on zirconia, lithium-disilicate glass-ceramic, hybrid ceramic, and polymer-infiltrated ceramic surfaces.

Facile laser-based process of superwetting zirconia ceramic with adjustable adhesion for self-cleaning and lossless droplet transfer

Zirconia ceramics can be extensively used as biological implant materials because of its excellent mechanical properties and biocompatibility. In order to further enhance the biocompatibility of zirconia ceramics and its application in oral medicine, a nanosecond laser-silicone oil-heat treatment (LSH) composite process was designed to fabricate superhydrophobic zirconia ceramic surfaces with adjustable adhesion to water droplet. The surface topography, chemical composition and wettability of zirconia ceramic surfaces were characterized. The experimental results indicated that the wettability and adhesion of water droplets on zirconia ceramic surfaces were significantly affected by the surface morphology and density of surface micro/nanostructures. The relative content of chemical elements and polar/non-polar functional groups on the surfaces could be changed as the process parameters changed, which would also affect the transition of surface wettability. Meanwhile, the adhesion of water droplets on the zirconia ceramic surfaces could be precisely regulated by changing the laser texturing parameters. Droplet lossless transport and self-cleaning effect were demonstrated, which could provide a key avenue for the application of superhydrophobic zirconia ceramics in biological implants.

Investigation on Polishing the Concave Surface of Zirconia Ceramics with Magnetic Compound Fluid Enhanced by Hydration Reaction

Zirconia ceramics are prominent engineering materials and are widely used in computers, consumer electronics, and the fifth-generation communication industry. However, zirconia ceramics are a typical hard-to-cut material, and the product structures are more complex as the demanding on the industry increases. In this case, the polishing efficiency should be improved for meeting these requirements. To overcome the problem of polishing concave surfaces of zirconia ceramics, a small polishing tool with a magnetic compound fluid (MCF) was invented. The effect of the polishing parameters on the surface roughness and material removal rate was analyzed by an L9(33) orthogonal experiment. The weight ratio of the parameters was also studied based on the experimental results. With the combination of chemical and mechanical functions, the polishing characteristics were further examined. Based on the soaking experiments, the material removal mechanism is discussed. The results are as follows: (1) the optimal polishing parameters were the revolution speed of the MCF carrier nc of 400 rpm, the working gap h of 0.1 mm, the CIP size D of 5 μm for better surface roughness, the revolution speed of the MCF carrier nc of 400 rpm, the working gap h of 0.1 mm, and the CIP size D of 7 μm for a higher material removal rate. The impact degrees on surface roughness and material removal rate were a revolution speed of the MCF carrier of 54% &gt; working gap of 31%&gt; CIP size of 15% and working gap of 40% &gt; revolution speed of the MCF carrier of 32% &gt; and CIP size of 18%, respectively. (2) Surface roughness was rapidly reduced in the first 20 min and tended to be stable in the last 10 min of polishing. A circular polished area was observed on the flat workpiece for studying the typical material removal curve, and the deepest point was found at the fringe of the material removal curve. The concave workpiece was polished successfully, and the best surface roughness Ra reached 1 nm and 1.2 nm. (3) A pH = 10 with a sodium hydroxide (NaOH) solution has a greater performance in hardness reduction. The chemical and mechanical functions were combined to remove material to enhance the polishing efficiency. All in all, the proposed polishing method with a combination of a small MCF polishing tool and hydration reaction was effective for polishing zirconia ceramics.

Temperature-Responsive, Femtosecond Laser-Ablated Ceramic Surfaces with Switchable Wettability for On-Demand Droplet Transfer.

Reversible wettability transition has drawn substantial interest because of its importance for widespread applications, but facile realization of such transition on ceramic surfaces, which is promising for achieving on-demand droplet manipulation under harsh conditions, remains rare. Herein, superhydrophobic zirconia ceramic surfaces that can reversibly and repeatedly transit between superhydrophobicity and superhydrophilicity after alternate heating treatments have been fabricated using a femtosecond laser. The underlying mechanisms of the complex wettability transitions on the laser-ablated zirconia surfaces are elucidated. Hydrophilic polished zirconia surfaces immediately become superhydrophilic after laser ablation, which is mainly attributed to the amplification effect of the laser-induced micro/nanostructures and has no obvious relationship with oxygen vacancies. The obtained superhydrophilic surfaces are transformed into superhydrophobic surfaces because of rapid adsorption of airborne organic compounds driven mainly by physical interaction under heating conditions. With the alternate removal and re-adsorption of organic compounds, reversible and repeatable wettability transition between superhydrophobicity and superhydrophilicity happens on the zirconia surfaces. The laser-induced micro/nanostructures also contribute to the wettability transitions. Furthermore, utilizing the superhydrophobic zirconia surfaces with switchable wettability, on-demand transfer of strong acid droplet in air and oil droplet under strong acid solution has been achieved. This work will inspire the environmentally friendly fabrication of switchable superhydrophobic ceramic surfaces and their multifunctional applications under harsh conditions.

Influence of nanosilica coating on the color and the microleakage of zirconia ceramics

Objective The purpose of this study was to assess the effect of Nano-silica Coating on the Color and the Microleakage of Zirconia Ceramics. Materials and methods: Eighty-five specimens of commercially available Yttrium-stabilized-zirconia ceramics were constructed and divided into forty-five discs (8 mm in diameter) with thickness (1.2mm) They were divided into three groups (thermocycling – nano-silica surface treatment – and thermocycling with nano-silica surface treatment) to assess the color parameters, while the other forty samples were divided into ( control group – thermocycling – nano-silica surface treatment – and thermocycling with nano-silica surface treatment) to perform a fully contoured crowns to assess the microleakage. Initial color measurements were taken using a digital spectrophotometer based on CIE L*a*b* color system using a spectrophotometer Standard permanent molar tooth preparation was conducted into a full veneer preparation. Nano silica sol-gel material painted on the fitting surface of zirconia ceramics in groups of nano-silica and nano-silica with thermocycling surface treatment and processed to firing that were finally cemented on the prepared teeth using resin adhesive luting agent. Samples in aged group were subjected to 5000 thermal cycles then crown samples were sectioned to measure the microleakage. Color measurements of all samples were measured again.

Antimicrobial efficacy and topographical alterations of photodynamic therapy versus conventional antimicrobials on contaminated zirconia ceramic in vitro

PurposeThe aim of this in vitro study was to assess the efficacy of antimicrobial photodynamic therapy (aPDT), neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, and two other disinfecting agents against P. gingivalis and T. forsythia that colonized over zirconia ceramics and to evaluate if the disinfecting protocols result in zirconia surface alteration. Materials and methodsThe experiment was conducted on pre-sintered, commercially available Yttria Stabilized Zirconia (Y-TZP) ceramic blocks. The bacterial strains of P. gingivalis and T. forsythia were used to contaminate the zirconia specimens. The infected zirconia specimens were randomly divided into 4 groups (n=20/group): aPDT, Nd:YAG laser, hydrogen peroxide (H2O2), and chlorhexidine groups. The viability of bacteria was assayed using the MTT protocol. The surface roughness (Ra) of all zirconia specimens was estimated using a profilometer and a drop-shape analyzer was used to evaluate the contact angle using a special sessile drop method. ResultsA statistically significant reduction by the aPDT group is noticed for P. gingivalis and T. forsythia species compared to other disinfection methods (p<0.05). The second highest reduction was seen for chlorhexidine followed by Nd:YAG laser. The least reduction was demonstrated for the hydrogen peroxide group. Statistically, there was no significant difference in Ra scores between the four groups. However, the contact angles were significantly reduced from the zirconia specimens after the aPDT method which indicates a hydrophilicity increase compared to other groups. The SFE scores of all decontamination protocols from highest to lowest were aPDT (41.68), chlorhexidine (39.83), Nd:YAG (34.52), and H2O2 (29.88). ConclusionsAntimicrobial photodynamic therapy demonstrated a high antibacterial efficacy over zirconia ceramic surface without altering surface topography.

Application of Zirconia Ceramic Biomaterial Implants in the Restoration of Tooth Loss Caused by Periodontal Disease

Zirconia ceramics (ZiC) has become a biomaterial with good clinical application prospects due to its good biocompatibility, stability, and excellent mechanical properties. In this study, bioactive glass (BioS) was undertaken as the modifier, and the ZiC precursor solution was penetrated on the surface of the ZiC body or the ZiC particles were coated with the BioS precursor solution, so as to obtain the ZiC with biological activity by introducing the BioS phase. While the material was characterized, its mechanical properties and biological activity were analyzed by simulating the mineralization of the body fluid, including the cell adhesion, proliferation, and differentiation of the material. The ZiC was applied as an implant for restoration of patients with teeth loss caused by periodontal disease. In the test, after surface infiltration of BioS sol or coating of ZiC particles, a very thin BioS phase can be formed on the surface of ZiC after high temperature sintering. The in vitro mineralization test showed that the activation of the grain boundary promoted the deposition of calcium and phosphorus layers on the surface of the sample. The mechanical test revealed that the relative density, flexural strength, and fracture toughness of the material decreased with the infiltration and coating of BioS. However, under proper preparation conditions, the modified ZiC still showed good mechanical properties and can promote the spreading, adhesion, and differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs). Clinical trials proved that after the modified ZiC implant material was implanted in patients with teeth loss, the structure was not loose or broken, and the intraoral prosthesis could function normally. After treatment, the level of IL-1β in the gingival crevicular fluid of the patient decreased obviously (P &lt;0.05). In addition, the probing depth (PD), clinical attachment loss (CAL), and other indicators decreased greatly (P &lt;0.05).

A novel Non-Newtonian fluid polishing technique for zirconia ceramics based on the weak magnetorheological strengthening thickening effect

Zirconia ceramics have excellent physical and chemical properties and have several applications. However, owing to their hardness and brittleness, it is difficult to realise the non-destructive high-efficiency machining of zirconia ceramics. Herein, we propose an efficient non-Newtonian fluid polishing method for zirconia ceramics based on the weak magnetorheological strengthening thickening effect. The nanoscale material removal and evolution mechanisms of the zirconia ceramic surface were investigated. Based on the results obtained through scanning electron microscopy and a derivation of the fluid shear stress model in the polishing zone, we clarify the microscopic material removal mechanism during the machining process, and establish the prediction model of material removal rate. The detection results of the surface quality were in good agreement with the established material removal mechanism. The model of material removal rate could predict the processing effectively, and the average relative error was 4.45%. The experimental results demonstrate that the proposed weak magnetorheological shear thickening polishing (WMRSTP) method can realise lossless, self-adaptive, ultra-precision machining of a hemispherical zirconia ceramic workpiece. Compared to the traditional non-Newtonian fluid polishing method, the polishing quality and polishing efficiency of this method are significantly improved. The surface roughness Sa, the surface accuracy PV, and the material removal rate MRR of the zirconia hemispherical workpiece after 1 h of WMRSTP were 13.2 nm, 0.104 μm, and 5.96 μm/h, respectively.

Preparation of the rod-shaped SiO2@C abrasive and effects of its microstructure on the polishing of zirconia ceramics

This study aims to achieve higher-efficiency zirconia ceramic polishing demands, using a novel rod-shaped SiO2@C abrasive that was synthesized by a simple three-step method. The scanning electron microscopy and transmission electron microscopy results showed that composite abrasives were rod-shaped. As confirmed by Fourier transform infrared spectrometer and Raman spectra, the composite particle had a core-shell structure with a core of silica and a shell of carbon. According to the N2 adsorption-desorption results, this composite abrasive had a mesoporous structure. The material removal rate of 242.5 nm/h and the zirconia ceramic surface roughness of 1.86 nm are 70.4% higher and 27.9% lower, respectively, than those achieved with conventional silica abrasives. The improved polishing performance may be attributed to its line contact mode, the reduction of Young's modulus and the improvement of tribochemical reaction. This study highlights the interaction between the surface microstructure of abrasives and the surface planarization of ceramics.

Effect of Incorporating a Dimethacrylate Monomer on the Shear Bond Strength of Two Adhesive Resin Cements to Zirconia Ceramic.

Self-assembled nano-layering resulting from interaction of the phosphate functional group of adhesive monomers with zirconia ceramic surface has been proposed. The purpose of this study was to investigate the bond strengths of two adhesive resin cements (Panavia F 2.0 and BisCem) containing phosphate monomers added with various concentrations (0.0, 1.0, 3.0, and 5.0 wt%) of triethylene glycol dimethacrylate (TEGDMA) to air-abraded zirconia ceramic. The polished/air-abraded zirconia plates (KaVo Everest® ZS-Ronde) were imaged using atomic force microscopy and the average surface roughness (Ra) values were calculated (n = 5). The surface energy parameters of the zirconia plates and the resin cements were calculated based on the extended Fowkes theory. All resin-bonded (diameter: 2.38 mm) zirconia specimens were stored in water at 37 °C for 24 h and then half of them additionally thermocycled 10,000 times before the shear bond strength (SBS) test (n = 10). Air-abrasion of zirconia surface significantly increased the γhS (hydrogen bonding component) value (p < 0.001), as well as greatly increasing the surface area (p < 0.001). For both resin cements, the γhS (dipole-dipole component) gradually increased with increasing incorporated TEGDMA concentrations, whereas the γhS gradually decreased. Overall, the addition of 3.0 wt% of TEGDMA consistently resulted in higher SBS values even after thermocycling. Under the tested condition, reducing the concentration of the adhesive monomers with phosphate functional group by adding the dimethacrylate monomer (up to 3.0 wt%) increased the bond strength between the resin cements and zirconia ceramic.

Effect of Aging on the Microstructure and Optical Properties of Translucent ZrO 2 Ceramics.

ObjectivesThe development and placement of translucent zirconia ceramics on the dental materials market is in full swing. This research aimed to investigate how aging protocols affect the microstructure, color parameters and translucency of a new-generation monolithic zirconia ceramic.Material and methodsTranslucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (as sintered - control, glazed, polished) was tested using two aging protocols (hydrothermal degradation in autoclave at 134 °C and 2 bars for three hours, chemical degradation in four-percent acetic acid at 80 °C for 16 hours) in order to examine phase composition using X-ray diffraction analysis and ΔE, ΔL and ΔC color parameters through spectrophotometry. The translucency parameter (TP) was calculated using parameters L*, a* and b* on a black and white surface.ResultsRegardless of the surface treatment, aging protocols did not cause a tetragonal-to-monoclinic phase transformation, although hydrothermal degradation in the autoclave transformed the hybrid tetragonal-cubic structure of all specimens to a tetragonal one. All polished and glazed specimens during chemical degradation demonstrated a significant color change ΔE. Lightness ΔL significantly changed in polished specimens aged in the autoclave. In all specimens, ΔC underwent a change manifested through statistically insignificant yellowing. None of the aging protocols altered the translucency of specimens.ConclusionsAging, regardless of the final surface treatment, did not manifest a monoclinic phase in the specimens. A tetragonal-cubic microstructure dominates. Unlike polishing, glazing the surface of translucent zirconia ceramics contributed to minor changes in color, lightness and chromaticity. The translucency of translucent zirconia ceramics remains stable regardless of aging and surface treatment.

The Influence of Short Pulse Er:Cr: YSGG Laser on the Shear Bond Strength of Cad-Cam Zerconia Material to Resin Cement

Background: Surface enhancement of CAD-CAM zerconia for increasing the matching to resin cement, using Er:Cr:YSGG Laser.Materials and Methods: 40 sintered zerconia disc specimens( VITAYZ HT) were prepared. They are dividedinto six groups, each group of seven samples.Laser groups are depending on laser power, laser irradiation time and pulse duration, group(A): 20 s, 60µs pulse duration. Group (B): 30 s , 60 µs pulse duration. Group (C): 40 s, 60 µs pulse duration. Group (D): 20 s, 700 µs pulse duration. And group (E): 30 s, 700 µs pulse duration, for different powers (1, 1.50, 2, 2.50, 3, 3.50, 4) W.Luting cementwas bonded to treated zerconia surfaces and light cured for 40 s.The Shear bond strength was measured using a universal testing machine. The optained results were stastistically analyzed. Thebond failur modes were also examined.Results: There was a clear increment in the shear bond strength especielly in group B (4 W, 30 s,60 µs) reaching to 8.63 Mpa.No crackes were observed.Conclusion: It was detected that the shear bond strength was related to the pulse depth.The pulse duration of Er:Cr:YSGG is a crucial parameter in the enhancement of zirconia ceramic surface.

Construction and properties of the antibacterial epitaxial transition layer on a zirconia ceramic surface.

Secondary caries is one of the main causes of dental zirconia restoration failure in the clinic. Therefore, it is urgent to improve the antibacterial performance of zirconia ceramics to reduce the occurrence of secondary caries. In this study, a quaternary ammonium compound antibacterial polymer was innovatively synthesized by solution polymerization with a quaternary ammonium salt monomer as the antibacterial component. The antibacterial epitaxial transition layer was successfully prepared on the surface of zirconia ceramics by the hydroxyl group on HEMA reacting with the siloxane group in the KH570 hydrolysate, which makes the antibacterial polymer indirectly chemically combine with the silicate epitaxial transition layer. The antibacterial epitaxial transition layer exhibited excellent mechanical properties, satisfactory biocompatibility and significant antibacterial effects, and the maximum antibacterial rate is 99%. The antibacterial epitaxial transition layer plays an important role in preventing secondary caries and improving the success rate of clinical zirconia ceramic restorations.

Influence of Sandblasting Particle Size and Pressure on Resin Bonding Durability to Zirconia: A Residual Stress Study.

The influence of residual stress induced by sandblasting the zirconia ceramic surface on the resin bonding to the ceramic is still unclear. The effect of four different sandblasting conditions (with 50 and 110 μm alumina at pressures of 0.2 and 0.4 MPa) on the bonding of adhesive resin cement (Panavia F 2.0) to zirconia (Cercon® ht) was investigated in terms of residual stress. The surface roughness and water contact angle of the zirconia surfaces were measured. The tetragonal-to-monoclinic (t–m) phase transformation and residual stresses (sin2ψ method) were studied by X-ray diffraction. The resin-bonded zirconia specimens were subjected to shear bond strength (SBS) tests before and after thermocycling (10,000 and 30,000 cycles) (n = 10). As the particle size and pressure increased, the roughness gradually and significantly increased (p = 0.023). However, there were no significant differences in roughness-corrected contact angle among all the sandblasted groups (p > 0.05). As the particle size and pressure increased, the m-phase/(t-phase + m-phase) ratios and compressive residual stresses gradually increased. After thermocycling, there were no significant differences in SBS among the sandblasted zirconia groups (p > 0.05). In conclusion, increased surface roughness and residual stress do not directly affect the resin bonding durability.