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    Sol-gel derived bioactive coating on zirconia: Effect on flexural strength and cell proliferation. Shahramian Khalil,Leminen Heidi,Meretoja Ville,Linderbäck Paula,Kangasniemi Ilkka,Lassila Lippo,Abdulmajeed Aous,Närhi Timo Journal of biomedical materials research. Part B, Applied biomaterials The purpose of this study was to evaluate the effect of sol-gel derived bioactive coatings on the biaxial flexural strength and fibroblast proliferation of zirconia, aimed to be used as an implant abutment material. Yttrium stabilized zirconia disc-shaped specimens were cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n = 15) were fabricated, zirconia with sol-gel derived titania (TiO ) coating, zirconia with sol-gel derived zirconia (ZrO ) coating, and non-coated zirconia as a control. The surfaces of the specimens were analyzed through images taken using a scanning electron microscope (SEM), and a non-contact tapping mode atomic force microscope (AFM) was used to record the surface topography and roughness of the coated specimens. Biaxial flexural strength values were determined using the piston-on-three ball technique. Human gingival fibroblast proliferation on the surface of the specimens was evaluated using AlamarBlue assay™. Data were analyzed using a one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Additionally, the biaxial flexural strength data was also statistically analyzed with the Weibull distribution. The biaxial flexural strength of zirconia specimens was unaffected (p > 0.05). Weibull modulus of TiO coated and ZrO coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO showed significantly lower fibroblast proliferation compared to other groups (p < 0.05). In conclusion, sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO coated specimens showed significantly lower cell proliferation after 12 days than TiO coated or non-coated control. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2401-2407, 2017. 10.1002/jbm.b.33780
    Biomimetic Surfaces Coated with Covalently Immobilized Collagen Type I: An X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy, Micro-CT and Histomorphometrical Study in Rabbits. Scarano Antonio,Lorusso Felice,Orsini Tiziana,Morra Marco,Iviglia Giorgio,Valbonetti Luca International journal of molecular sciences BACKGROUND:The process of osseointegration of dental implants is characterized by healing phenomena at the level of the interface between the surface and the bone. Implant surface modification has been introduced in order to increase the level of osseointegration. The purpose of this study is to evaluate the influence of biofunctional coatings for dental implants and the bone healing response in a rabbit model. The implant surface coated with collagen type I was analyzed through X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), micro-CT and histologically. METHODS:The sandblasted and double acid etched surface coated with collagen type I, and uncoated sandblasted and double acid etched surface were evaluated by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) analysis in order evaluate the different morphology. In vivo, a total of 36 implants were positioned in rabbit articular femoral knee-joint, 18 fixtures for each surface. Micro-CT scans, histological and histomorphometrical analysis were conducted at 15, 30 and 60 days. RESULTS:A histological statistical differences were evident at 15, 30 and 60 days ( < 0.001). Both implant surfaces showed a close interaction with newly formed bone. Mature bone appeared in close contact with the surface of the fixture. The AFM outcome showed a similar roughness for both surfaces. CONCLUSION:However, the final results showed that a coating of collagen type I on the implant surface represents a promising procedure able to improve osseointegration, especially in regions with a low bone quality. 10.3390/ijms20030724
    Air-abrasion using new silica-alumina powders containing different silica concentrations: Effect on the microstructural characteristics and fatigue behavior of a Y-TZP ceramic. Cadore-Rodrigues Ana Carolina,Prochnow Catina,Rippe Marília Pivetta,Oliveira Jivago Schumacher de,Jahn Sérgio Luiz,Foletto Edson Luiz,Pereira Gabriel Kalil Rocha,Valandro Luiz Felipe Journal of the mechanical behavior of biomedical materials This study assessed the fatigue performance (biaxial flexure fatigue strength), surface characteristics (topography and roughness) and structural stability (t-m phase transformation) of a Y-TZP ceramic subjected to air-abrasion using new powders (7% and 20% silica-coated aluminum oxide particles) in comparison to commercially available powders. Disc-shaped specimens were manufactured (ISO 6872-2015) and randomly allocated into four groups considering the air-abrasion materials: SiC: commercially available silica-coated aluminum oxide; AlOx: commercially available aluminum oxide; 7%Si and 20%Si: experimentally produced materials consisting of 7% and 20% silica-coated AlOx, respectively. Air-abrasion was executed by a blinded researcher (1 cm distance from the tip to the specimen surface, under 2.8 bar pressure for 10 s). The fatigue tests (n = 15) were performed by the staircase method under a piston-on-three-balls assembly. Topography and roughness assessments (n = 30) of abraded samples and fractography of failed discs were performed. The highest fatigue strength (MPa) was observed for 7%Si (887.20 ± 50.54) and SiC (878.16 ± 29.81), while the lowest fatigue strength for 20%Si (773.89 ± 46.44) and AlOx (796.70 ± 46.48). Topography analysis depicted similar surface morphology for all conditions. However, roughness (μm) was only statistically different between 7%Si (Ra = 0.30 ± 0.09; Rz = 2.31 ± 0.63) and SiC (Ra = 0.26 ± 0.04; Rz = 1.99 ± 0.34). Monoclinic phase grains appeared on Y-TZP surface in a similar content (≈11-12%) for the protocols. Fractography showed all failures starting on air-abraded surface/sub-surface defects from the tensile side. In terms of roughness, phase transformation and fatigue, the new 7% silica-coated aluminum oxide presented similar behavior to the commercially available powder. Increasing silica-coating concentration to 20% did not lead to a gentle air-abrasion protocol. 10.1016/j.jmbbm.2019.05.032
    Formation and bioactivity of HA nanorods on micro-arc oxidized zirconium. Zhang Lan,Zhu Shaoyu,Han Yong,Xiao Chengzhang,Tang Wu Materials science & engineering. C, Materials for biological applications A microporous and CaO partially stabilized zirconia (Ca-PSZ) coating covered with hydroxyapatite (HA) nanorods is fabricated on Zr substrate by a hybrid approach of micro-arc oxidation (MAO) and hydrothermal treatment (HT). The effect of P ions in HT solution on the density and morphology of HA was investigated; the hydrophilicity and apatite-forming ability of the Ca-PSZ coating with HA nanorods were also examined. High-density HA nanorods (with a mean diameter of 50 nm and length of 450 nm) grow on the Ca-PSZ coating after HT in a solution containing 0.002 M β-glycerophosphate disodium (β-GP). However, only a few of coarse-grained HA crystallites grow in the MAOed pores after HT in distilled water or in an ammonia aqueous solution with an initial pH value equal to the solution containing 0.002 M β-GP. P ions in the HT solution are thought to significantly promote the formation of HA nanorods. The Ca-PSZ coating covered with HA nanorods displays good hydrophilicity and excellent apatite-inducing ability, and the induced apatite prefers to nucleate on the basal-faceted surfaces of HA nanorods. 10.1016/j.msec.2014.06.029
    Bioactivity and biocompatibility of hydroxyapatite-based bioceramic coatings on zirconium by plasma electrolytic oxidation. Aktuğ Salim Levent,Durdu Salih,Yalçın Emine,Çavuşoğlu Kültigin,Usta Metin Materials science & engineering. C, Materials for biological applications In the present work, hydroxyapatite (HAP)-based plasma electrolytic oxide (PEO) coatings were produced on zirconium at different current densities in a solution containing calcium acetate and β-calcium glycerophosphate by a single step. The phase structure, surface morphology, functional groups, thickness and roughness of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), eddy current method and surface profilometer, respectively. The phases of cubic-zirconia, calcium zirconate and HAP were detected by XRD. The amount of HAP and calcium zirconate increased with increasing current density. The surface of the coatings was very porous and rough. Moreover, bioactivity and biocompatibility of the coatings were analyzed in vitro immersion simulated body fluid (SBF) and MTT (3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyl tetrazolium bromide) assay, hemolysis assay and bacterial formation. The apatite-forming ability of the coatings was evaluated after immersion in SBF up to 28days. After immersion, the bioactivity of HAP-based coatings on zirconium was greater than the ones of uncoated zirconium and zirconium oxide-based surface. The bioactivity of PEO surface on zirconium was significantly improved under SBF conditions. The bacterial adhesion of the coatings decreased with increasing current density. The bacterial adhesion of the coating produced at 0.370A/cm was minimum compared to uncoated zirconium coated at 0.260 and 0.292A/cm. The hemocompatibility of HAP-based surfaces was improved by PEO. The cell attachment and proliferation of the PEO coatings were better than the one of uncoated zirconium according to MTT assay results. 10.1016/j.msec.2016.11.012
    Modification of the Ceramic Implant Surfaces from Zirconia by the Magnetron Sputtering of Different Calcium Phosphate Targets: A Comparative Study. Kozelskaya Anna I,Bolbasov Evgeny N,Golovkin Alexey S,Mishanin Alexander I,Viknianshchuk Alice N,Shesterikov Evgeny V,Ashrafov Аndrey,Novikov Vadim A,Fedotkin Alexander Y,Khlusov Igor A,Tverdokhlebov Sergey I Materials (Basel, Switzerland) In this study, thin calcium phosphate (Ca-P) coatings were deposited on zirconia substrates by radiofrequency (RF) magnetron sputtering using different calcium phosphate targets (calcium phosphate tribasic (CPT), hydroxyapatite (HA), calcium phosphate monobasic, calcium phosphate dibasic dehydrate (DCPD) and calcium pyrophosphate (CPP) powders). The sputtering of calcium phosphate monobasic and DCPD powders was carried out without an inert gas in the self-sustaining plasma mode. The physico-chemical, mechanical and biological properties of the coatings were investigated. Cell adhesion on the coatings was examined using mesenchymal stem cells (MSCs). The CPT coating exhibited the best cell adherence among all the samples, including the uncoated zirconia substrate. The cells were spread uniformly over the surfaces of all samples. 10.3390/ma11101949
    Synthesis of bioactive β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics. Stefanic Martin,Milacic Radmila,Drazic Goran,Škarabot Miha,Budič Bojan,Krnel Kristoffer,Kosmač Tomaž Journal of materials science. Materials in medicine The objective of this work was to develop a synthesis procedure for the deposition of β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics. The synthesis procedure involved two steps: (i) a rapid wet-chemical deposition of a biomimetic CaP coating and (ii) a subsequent post-deposition processing of the biomimetic CaP coating, which included a heat treatment between 800 and 1200 °C, followed by a short sonication in a water bath. By regulating the heating temperature the topography of the β-TCP coatings could be controlled. The average surface roughness (Ra) ranged from 42 nm for the coating that was heated at 900 °C (TCP-900) to 630 nm for the TCP-1200 coating. Moreover, the heating temperature also affected the dissolution rate of the coatings in a physiological solution, their protein-adsorption capacity and their bioactivity in a simulated body fluid. 10.1007/s10856-014-5246-9
    Microarc oxidation discharge types and bio properties of the coating synthesized on zirconium. Cengiz Sezgin,Azakli Yunus,Tarakci Mehmet,Stanciu Lia,Gencer Yucel Materials science & engineering. C, Materials for biological applications This study is an attempt for gaining a better understanding on relationship between microarc oxidation (MAO) coating discharge types and bioactivity of an oxide-based coating synthesized on a Zr substrate. The discharge types and the coating growth mechanism were identified by the examination of the real cross-section image of the coating microstructure. The coating was conducted by using MAO in an electrolyte containing NaSiO, Ca(CHCOO) and CHNaOP, for different durations of 2.5, 5, 15, and 30mins. The effect of the process duration on the different discharge model types (Type-A, B, and C) and bioactivity of the coatings were investigated by using X-ray Diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy-Dispersive X-ray spectroscopy measurements (SEM-EDS) and Optical Surface Profilometry (OSP). It was found that the increasing MAO duration resulted in thicker and rougher coatings. The XRD data revealed that all the samples prepared at different process durations contained the t-ZrO (tetragonal zirconia) phase. During the MAO process, non-crystalline hydroxyapatite (HA) formed, which was confirmed from the FTIR data. The surface morphology, the amount and distribution of the features of the coating surface were modified by increasing voltage. The simulated body fluid (SBF) tests showed that the more bioactive surface with more HA crystals formed owing to chemical composition and high surface roughness of the coating. The pore, crack and discharge structures played a key role in apatite nucleation and growth, and provided ingrowth of apatite into discharge channels on the coating surface. 10.1016/j.msec.2017.03.230
    Characteristics and osteogenic effect of zirconia porous scaffold coated with β-TCP/HA. Song Young-Gyun,Cho In-Ho The journal of advanced prosthodontics PURPOSE:The purpose of this study was to evaluate the properties of a porous zirconia scaffold coated with bioactive materials and compare the in vitro cellular behavior of MC3T3-E1 preosteoblastic cells to titanium and zirconia disks and porous zirconia scaffolds. MATERIALS AND METHODS:Titanium and zirconia disks were prepared. A porous zirconia scaffold was fabricated with an open cell polyurethane disk foam template. The porous zirconia scaffolds were coated with β-TCP, HA and a compound of β-TCP and HA (BCP). The characteristics of the specimens were evaluated using scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), and x-ray diffractometry (XRD). The dissolution tests were analyzed by an inductively coupled plasma spectrometer (ICP). The osteogenic effect of MC3T3-E1 cells was assessed via cell counting and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS:The EDX profiles showed the substrate of zirconia, which was surrounded by the Ca-P layer. In the dissolution test, dissolved Ca(2+) ions were observed in the following decreasing order; β-TCP > BCP > HA (P<.05). In the cellular experiments, the cell proliferation on titanium disks appeared significantly lower in comparison to the other groups after 5 days (P<.05). The zirconia scaffolds had greater values than the zirconia disks (P<.05). The mRNA level of osteocalcin was highest on the non-coated zirconia scaffolds after 7 days. CONCLUSION:Zirconia had greater osteoblast cell activity than titanium. The interconnecting pores of the zirconia scaffolds showed enhanced proliferation and cell differentiation. The activity of osteoblast was more affected by microstructure than by coating materials. 10.4047/jap.2014.6.4.285
    Surface Modification of Zirconia Substrate by Calcium Phosphate Particles Using Sol-Gel Method. Jin So Dam,Um Sang Cheol,Lee Jong Kook Journal of nanoscience and nanotechnology Surface modification with a biphasic composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) was performed on a zirconia substrate using a sol-gel method. An initial calcium phosphate sol was prepared by mixing a solution of Ca(NO3)2 · 4H20 and (C2H5O)3P(O), while both porous and dense zirconia were used as substrates. The sol-gel coating was performed using a spin coater. The coated porous zirconia substrate was re-sintered at 1350 °C 2 h, while coated dense zirconia substrate was heat-treated at 750 °C 1 h. The microstructure of the resultant HA/TCP coatings was found to be dependent on the type of zirconia substrate used. With porous zirconia as a starting substrate, numerous isolated calcium phosphate particles (TCP and HA) were uniformly dispersed on the surface, and the particle size and covered area were dependent on the viscosity of the calcium phosphate sol. Conversely, when dense zirconia was used as a starting substrate, a thick film of nano-sized HA particles was obtained after heat treatment, however, substantial agglomeration and cracking was also observed. 10.1166/jnn.2015.10439
    Zirconia implants with improved attachment to the gingival tissue. Shahramian Khalil,Gasik Michael,Kangasniemi Ilkka,Walboomers X Frank,Willberg Jaana,Abdulmajeed Aous,Närhi Timo Journal of periodontology BACKGROUND:Gingival tissue attachment is known to be important for long-term prognosis of implants. This in vitro study evaluated the gingival attachment to zirconia implants and zirconia implants modified with sol-gel derived TiO coatings. METHODS:Zirconia endodontic posts (n = 23) were used to function as implants that were inserted into the center of full-thickness porcine gingival explants (n = 31). The tissue/implant specimens were then individually placed at an air/liquid interface on a stainless-steel grid in cell culture wells containing a nutrient solution. The tissue cultures were incubated at 37°C in a 5% CO environment and at days 7 and 14, the specimens were harvested and analyzed by dynamic mechanical analysis (DMA) measurements under dynamic loading conditions mimicking natural mastication. Specimens were also analyzed by immunohistochemical staining identifying the laminin (Ln) γ2 chain specific for Ln-332, which is known to be a crucial molecule for the proper attachment of epithelium to tooth/implant surface. RESULTS:Tissue attachment to TiO -coated zirconia demonstrated higher dynamic modulus of elasticity and higher creep modulus, meaning that the attachment is stronger and more resistant to damage during function over time. Laminin γ2 was identified in the attachment of epithelium to TiO -coated zirconia. CONCLUSIONS:Both DMA and histological analysis support each other, so the gingival tissue is more strongly attached to sol-gel derived TiO -coated zirconia than uncoated zirconia. Immunohistochemical staining showed that TiO coating may enhance the synthesis and deposition of Ln-332 in the epithelial attachment to the implant surface. 10.1002/JPER.19-0323
    Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process. Seo Dong Seok,Chae Hak Cheol,Lee Jong Kook Journal of nanoscience and nanotechnology Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation. 10.1166/jnn.2015.10440
    Influence of Zirconia-Coated Bioactive Glass on Gingival Fibroblast Behavior. Barros Suelen Aline de Lima,Soares Diana Gabriela,Leite Maria Luísa,Basso Fernanda Gonçalves,Costa Carlos Alberto de Souza,Adabo Gelson Luís Brazilian dental journal The objective of this study was the development of a bioactive glass coating on zirconia (Zr) to modulate the gingival fibroblast phenotype. For this purpose, Biosilicate® (BS) particles in a water/isopropyl alcohol (1:1) vehicle (6 mg/mL) were applied to zirconia discs followed by thermal treatment at 1100 °C for 20 min. The surface topography (SEM), chemical composition (EDX), surface roughness (Ra; confocal microscopy), surface free energy (goniometry), and color alteration (UV-vis spectrophotometry) were assessed (n=6). Thereafter, L929 fibroblasts were seeded onto Zr and Zr+BS discs, and cell proliferation (Alamar Blue; n=6), morphology (SEM; n=2), migration (wound healing; n=4), and collagen synthesis (Sirius Red; n=6) were evaluated up to 7 days. Data were analyzed by ANOVA/Tukey tests (a=5%). A homogeneous coating consisting of Si, Na, O, and Ca was detected on the Zr surface after thermal treatment with BS, which led to a significant increase in surface roughness and free energy (p<0.05). No change in color parameters was observed (p>0.05). Cells seeded on the Zr+BS surface featured increased proliferation, collagen expression, and migration capability in comparison with those cultured on plain Zr (p<0.05). SEM images revealed that cell spreading occurred faster in the presence of BS. Therefore, it was concluded that thermal treatment of the Zr surface with BS led to the deposition of a bioactive coating, which induced gingival fibroblast spread, proliferation, migration, and collagen expression in vitro. 10.1590/0103-6440201902417
    Development of novel zirconia implant's materials gradated design with improved bioactive surface. Faria D,Pires J M,Boccaccini A R,Carvalho O,Silva F S,Mesquita-Guimarães J Journal of the mechanical behavior of biomedical materials Zirconia implants are becoming a preference choice for different applications such as knee, dental, among others. In order to improve osseointegration, implant's surfaces are usually coated with bioactive materials like hydroxyapatite (HAp) and beta-tricalcium phosphate (β-TCP) that are very similar to the calcium phosphates found in bones. However, due to the implantation process, these coatings can be detached from the zirconia surface, leading to implant premature failure. In this work, a new component materials design aiming to avoid this coating detachment problem is proposed. It is based on the use of a bioactive zirconia-calcium phosphate composite outer layer onto the zirconia bulk, where the zirconia bulk provides mechanical strength and the outer layer provides biological performance. In order to assess the potential of this new materials design, two types of bioactive zirconia outer composite layers (zirconia reinforced by 10 vol% of HAp and by 10 vol% of β-TCP) were produced by press and sinter process and the gradated samples were fully characterized concerning materials, mechanical resistance, fatigue resistance, and biological performance, as measured by different approaches. Results showed that the novel component materials design and the manufacturing process proposed for producing the bioactive zirconia samples with outer composite layers on zirconia bulk substrates are a promising solution for implants, with improved biological performance without substantially compromising their overall mechanical and fatigue properties. 10.1016/j.jmbbm.2019.02.022
    Bioactive-hybrid-zirconia implant surface for enhancing osseointegration: an in vivo study. Mostafa Dawlat,Aboushelib Moustafa International journal of implant dentistry BACKGROUND:Zirconia is characterized by a hard, dense, and chemically inert surface which requires additional surface treatments in order to enhance osseointegration. The proposed hypothesis of the study was that combination of a nano-porous surface infiltrated with a bioactive material may enhance osseointegration of zirconia implants. METHODS:Custom-made zirconia implants (3.7 mm × 8 mm) were designed, milled, and sintered according to manufacturer recommendations. All implants received selective infiltration etching (SIE) technique to produce a nano-porous surface. Surface porosities were either filled with nano-hydroxy apatite particle- or platelet-rich plasma while uncoated surface served as a control (n = 12, α = 0.05). New surface properties were characterized with mercury porosimetry, XRD analysis, SEM, and EDX analysis. Implants were inserted in femur head of rabbits, and histomorphometric analysis was conducted after healing time to evaluate bone-implant contact percentage (BIC%). RESULTS:Selective infiltration etching produced a nano-porous surface with interconnected surface porosities. Mercury porosimetry revealed a significant reduction in total porosity percent after application of the two coating materials. XRD patterns detected hexagonal crystal structure of HA superimposed on the tetragonal crystal phase of zirconia. Histomorphometric analysis indicated a significantly higher (F = 14.6, P < 0.001) BIC% around HA-bioactive-hybrid surface (79.8 ± 3%) and PRP-coated surface (71 ± 6 %) compared to the control (49 ± 8%). CONCLUSIONS:Bioactive-hybrid-zirconia implant surface enhanced osseointegration of zirconia implants. 10.1186/s40729-018-0129-3
    Ag nanoparticle-coated zirconia for antibacterial prosthesis. Yamada Risa,Nozaki Kosuke,Horiuchi Naohiro,Yamashita Kimihiro,Nemoto Reina,Miura Hiroyuki,Nagai Akiko Materials science & engineering. C, Materials for biological applications Bacterial adhesion to dental materials is a major cause of caries and periodontitis, necessitating the development of compounds such as yttria-stabilized zirconia (YSZ) and silver nanoparticles (AgNPs), which are widely employed in medicine due to their high antimicrobial activity and low cytotoxicity. The main goal of this study is the synthesis of the broad antimicrobial activity of AgNP-coated YSZ with facile methods. The bactericidal AgNPs were immobilized on the surface of YSZ and tested for bactericidal activity against Staphylococcus aureus, Streptococcus mutans, Escherichia coli, and Aggregatibacter actinomycetemcomitans based on ISO 22196:2007. The loading of AgNPs was optimized by culturing mouse fibroblast cells on AgNP-coated YSZ with cell viability test based on ISO 10993-5. In addition, the silver release profile of AgNP-coated YSZ in artificial saliva was determined using an accelerated aging test. Antibacterial activity, and cell viability test revealed optimum performance with no cytotoxicity at a level of 32 μg/cm. Accelerated aging test showed that the AgNP-coated surface was extremely stable, exhibiting a total silver leaching level of only 1% and confirming the effectiveness of this coating method for retaining AgNPs while exerting an antibacterial effect against oral pathogens. This finding also implies that the bactericidal action of AgNP-coated YSZ is not mediated by the released Ag ions, but rather corresponds to contact killing. ABBREVIATIONS:Yttria-stabilized zirconia, YSZ; silver nanoparticles, AgNPs; field emission scanning electron microscopy, FE-SEM; X-ray photoelectron spectroscopy, XPS; grazing incidence X-ray diffraction, GIXRD; ultraviolet-visible, UV-vis; inductively coupled plasma atomic emission spectrometry, ICP-AES. 10.1016/j.msec.2017.04.149
    TiO-Modified Zirconia Surface Improves Epithelial Cell Attachment. Riivari Sini,Shahramian Khalil,Kangasniemi Ilkka,Willberg Jaana,Närhi Timo O The International journal of oral & maxillofacial implants PURPOSE:Good cell adhesion is an important prerequisite for soft tissue attachment on implant abutment or crown surfaces. The aim of this study was to evaluate the adhesion and proliferation of human epithelial cells on sol-gel-derived TiO-coated and noncoated zirconia. MATERIALS AND METHODS:Altogether, 56 zirconia disks (Z-CAD, Metoxit) were fabricated for this study. Half of the disks were coated with a sol-gel-derived TiO coating (MetAlive, ID Creations). The rest of the disks were noncoated and formed the control group. Surface properties of the disks were characterized by contact angle measurements and surface free energy (SFE) calculation. The cell adhesion was tested by cultivating epithelial cells (20,000 cells/cm) on the experimental disks for 1, 3, 6, and 24 hours, after which the fluorescence of the samples was measured (BioTek synergy HT). The amount of cells was detected by comparing the fluorescence value to the standard curve. In addition, the proliferation was studied by growing epithelial cells (25,000 cells/cm) for 1, 3, and 7 days. The number of cells was calculated by defining the absorbance of the samples (Multiskan EX, Thermo Labsystems), followed by a comparison with the standard curve. Finally, the samples were processed for light microscopy. RESULTS:TiO-coated disks were significantly more hydrophilic with higher total SFE than noncoated disks (P < .05). The amount of epithelial cells was greater on TiO-coated disks than on controls after 24 hours (P < .05). Regarding cell proliferation, the difference was statistically significant (P < .05) on days 3 and 7. Light microscope evaluation confirmed viable cells, which were in immediate close contact with both substrate surfaces. The cell layers on the coated disks appeared to be more uniform and cell rich than the layers on noncoated disks. CONCLUSION:This study indicated that TiO coating improves epithelial cell attachment and proliferation on zirconia surfaces. This has good potential to enhance formation of the epithelial junction to the coated zirconia surfaces. 10.11607/jomi.6862
    Influence of thin carbonate-containing apatite coating with molecular precursor method to zirconia on osteoblast-like cell response. Kaneko Hajime,Sasaki Hodaka,Honma Shinya,Hayakawa Tohru,Sato Mitsunobu,Yajima Yasutomo,Yoshinari Masao Dental materials journal The influence of a thin carbonate-containing hydroxyapatite (CA) coating to tetragonal zirconia polycrystal (TZP) on osteoblastlike cell response was investigated. TZP disks were subjected to blasting and acid etching. Thin CA coatings were deposited by the molecular precursor method (TZP-CA). Initial cell adhesion of mouse osteoblast-like cells MC3T3-E1 was enhanced, and marked progress of actin filaments was observed on TZP-CA compared to on TZP. After 3, 5 or 7 days, cell proliferation on TZP-CA was significantly higher than that on TZP. Alkaline phosphatase activity was slightly lower on TZP-CA than on TZP at 7 days, and no difference was observed at 14 or 21 days. At 28 days incubation, collagenous fibers with mineral precipitants accompanied by phosphorous and amino groups were observed. These results indicate that thin CA coating with molecular precursor method offers promise as a means of enhancing cell response, particularly initial adhesion and proliferation of MC3T3-E1 cells.
    Surface Characteristics of Bioactive Glass-Infiltrated Zirconia with Different Hydrofluoric Acid Etching Conditions. Oh Gye-Jeong,Yoon Ji-Hye,Vu Van Thi,Ji Min-Kyung,Kim Ji-Hyun,Kim Ji-Won,Yim Eun-Kyung,Bae Jung-Chan,Park Chan,Yun Kwi-Dug,Lim Hyun-Pil,Park Sang-Won Journal of nanoscience and nanotechnology The purpose of this study was to examine the surface characteristics of bioactive glass-infiltrated zirconia specimens that underwent different hydrofluoric acid (HF) etching conditions. Specimens were classified into the following six groups: Zirconia, Zirliner, Porcelain, Bioactive glass A1, Bioactive glass A2, and Bioactive glass A3. Zirliner and porcelain were applied to fully sintered zirconia followed by heat treatment. Bioactive glass was infiltrated into presintered zirconia using a spin coating method followed by complete sintering. All the specimens were acid-etched with 10% or 20% HF, and surface roughness was measured using a profiler. The surface roughness of the zirconia group was not affected by the etching time or the concentration of the acid. The roughness of the three bioactive glass groups (A1, A2, and A3) was slightly increased up until 10 minutes of etching. After 1 hour of etching, the roughness was considerably increased. The infiltrated bioactive glass and acid etching did not affect the adhesion and proliferation of osteoblasts. This study confirmed that surface roughness was affected by the infiltration material, etching time, and acid concentration. For implant surfaces, it is expected that the use of etched bioactive glass-infiltrated zirconia with micro-topographies will be similar to that of machined or sand-blasted/acid-etched (SLA) titanium.
    Magnesium-containing mixed coatings on zirconia for dental implants: mechanical characterization and in vitro behavior. Pardun Karoline,Treccani Laura,Volkmann Eike,Streckbein Philipp,Heiss Christian,Gerlach Juergen W,Maendl Stephan,Rezwan Kurosch Journal of biomaterials applications An important challenge in the field of dental and orthopedic implantology is the preparation of implant coatings with bioactive functions that feature a high mechanical stability and at the same time mimic structural and compositional properties of native bone for a better bone ingrowth. This study investigates the influence of magnesium addition to zirconia-calcium phosphate coatings. The mixed coatings were prepared with varying additions of either magnesium oxide or magnesium fluoride to yttria-stabilized zirconia and hydroxyapatite. The coatings were deposited on zirconia discs and screw implants by wet powder spraying. Microstructure studies confirm a porous coating with similar roughness and firm adhesion not hampered by the coating composition. The coating morphology, mechanical flexural strength and calcium dissolution showed a magnesium content-dependent effect. Moreover, the in vitro results obtained with human osteoblasts reveal an improved biological performance caused by the presence of Mg(2+) ions. The magnesium-containing coatings exhibited better cell proliferation and differentiation in comparison to pure zirconia-calcium phosphate coatings. In conclusion, these results demonstrate that magnesium addition increases the bioactivity potential of zirconia-calcium phosphate coatings and is thus a highly suitable candidate for bone implant coatings. 10.1177/0885328215572428
    Investigation of surface structure and biocompatibility of chitosan-coated zirconia and alumina dental abutments. Kalyoncuoglu Ulku Tugba,Yilmaz Bengi,Koc Serap Gungor,Evis Zafer,Arpaci Pembegul Uyar,Kansu Gulay Clinical implant dentistry and related research BACKGROUND:For long-term success of dental implants, it is essential to maintain the health of the surrounding soft tissue barrier, which protects the bone-implant interface from the microorganisms. Although implants based on titanium and its alloys still dominate the dental implant market, alumina (Al O ) and zirconia (ZrO ) implant systems are widely used in the area. However, they provide smooth and bioinert surfaces in the transmucosal region, which poorly integrate with the surrounding tissues. OBJECTIVE:The main aim of this research was to investigate the surface characteristics and biocompatibility of chitosan-coated alumina and zirconia surfaces. MATERIALS AND METHODS:The substrates were coated via solution casting technique. Additionally, an aging process with a thermocycle apparatus was applied on the coated materials to mimic the oral environment. To define the morphology and chemical composition of the surfaces of untreated, chitosan-coated, and chitosan-coated-aged samples, scanning electron microscopy and energy dispersive X-ray spectrometry were used. The phases and bonds characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The human gingival fibroblast cells were used to evaluate cytocompatibility by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium salt assay. RESULTS:It was observed that both substrates were successfully coated with chitosan and the aging process did not significantly affect the integrity of the coating. The attachment and proliferation of human gingival fibroblast cells were shown to be good on both kinds of chitosan-coated surfaces. CONCLUSION:Coating zirconia and alumina surfaces with chitosan is an efficient surface modification for increasing biocompatibility and bioactivity of these materials in vitro. 10.1111/cid.12665
    Osteogenic responses to zirconia with hydroxyapatite coating by aerosol deposition. Cho Y,Hong J,Ryoo H,Kim D,Park J,Han J Journal of dental research Previously, we found that osteogenic responses to zirconia co-doped with niobium oxide (Nb2O5) or tantalum oxide (Ta2O5) are comparable with responses to titanium, which is widely used as a dental implant material. The present study aimed to evaluate the in vitro osteogenic potential of hydroxyapatite (HA)-coated zirconia by an aerosol deposition method for improved osseointegration. Surface analysis by scanning electron microscopy and x-ray diffraction proved that a thin as-deposited HA film on zirconia showed a shallow, regular, crater-like surface. Deposition of dense and uniform HA films was measured by SEM, and the contact angle test demonstrated improved wettability of the HA-coated surface. Confocal laser scanning microscopy indicated that MC3T3-E1 pre-osteoblast attachment did not differ notably between the titanium and zirconia surfaces; however, cells on the HA-coated zirconia exhibited a lower proliferation than those on the uncoated zirconia late in the culture. Nevertheless, ALP, alizarin red S staining, and bone marker gene expression analysis indicated good osteogenic responses on HA-coated zirconia. Our results suggest that HA-coating by aerosol deposition improves the quality of surface modification and is favorable to osteogenesis. 10.1177/0022034514566432
    Surface modification of zirconia with polydopamine to enhance fibroblast response and decrease bacterial activity in vitro: A potential technique for soft tissue engineering applications. Liu Mingyue,Zhou Jianfeng,Yang Yang,Zheng Miao,Yang Jianjun,Tan Jianguo Colloids and surfaces. B, Biointerfaces The quality of soft-tissue integration plays an important role in the short- and long-term success of dental implants. The aim of the present study was to provide a surface modification approach for zirconia implant abutment materials and to evaluate its influence on fibroblast behavior and oral bacteria adhesion, which are the two main factors influencing the quality of peri-implant soft-tissue seal. In this study, polydopamine (PDA)-coated zirconia was prepared and the surface characteristics were evaluated using scanning electron microscopy, atomic force microscopy, a contact-angle-measuring device, X-ray photoelectron spectroscopy, and Raman spectroscopy. The responses of human gingival fibroblasts (HGFs) to PDA-coated zirconia; i.e., adhesion, proliferation, morphology, protein synthesis, and gene expression, were analyzed. Additionally, the adhesion of Streptococcus gordonii and Streptococcus mutans to zirconia after PDA coating was assessed by scanning electron microscopy and live/dead staining. The material surface analyses suggested the successful coating of PDA onto the zirconia surface. The PDA coating significantly increased cell adhesion and proliferation compared with pristine zirconia. HGFs exhibited a high degree of spreading and secreted a high level of collagen type I on PDA-modified disks. Upregulation of integrin α5, β1, β3 and fibronectin was noted in HGFs cultured on PDA-coated zirconia. The number of adherent bacteria decreased significantly on zirconia after PDA coating. In summary, our result suggest that PDA is able to modify the surface of zirconia, influence HGFs' behavior and reduce bacterial adhesion. Therefore, this surface modification approach holds great potential for improving soft-tissue integration around zirconia abutments in clinical application. 10.1016/j.colsurfb.2015.06.047
    Bioactive and thermally compatible glass coating on zirconia dental implants. Kirsten A,Hausmann A,Weber M,Fischer J,Fischer H Journal of dental research The healing time of zirconia implants may be reduced by the use of bioactive glass coatings. Unfortunately, existing glasses are either bioactive like Bioglass 45S5 but thermally incompatible with the zirconia substrate, or they are thermally compatible but exhibit only a very low level of bioactivity. In this study, we hypothesized that a tailored substitution of alkaline earth metals and alkaline metals in 45S5 can lead to a glass composition that is both bioactive and thermally compatible with zirconia implants. A novel glass composition was analyzed using x-ray fluorescence spectroscopy, dilatometry, differential scanning calorimetry, and heating microscopy to investigate its chemical, physical, and thermal properties. Bioactivity was tested in vitro using simulated body fluid (SBF). Smooth and microstructured glass coatings were applied using a tailored spray technique with subsequent thermal treatment. Coating adhesion was tested on implants that were inserted in bovine ribs. The cytocompatibility of the coating was analyzed using L929 mouse fibroblasts. The coefficient of thermal expansion of the novel glass was shown to be slightly lower (11.58 · 10(-6) K(-1)) than that of the zirconia (11.67 · 10(-6) K(-1)). After storage in SBF, the glass showed reaction layers almost identical to the bioactive glass gold standard, 45S5. A process window between 800 °C and 910 °C was found to result in densely sintered and amorphous coatings. Microstructured glass coatings on zirconia implants survived a minimum insertion torque of 60 Ncm in the in vitro experiment on bovine ribs. Proliferation and cytotoxicity of the glass coatings was comparable with the controls. The novel glass composition showed a strong adhesion to the zirconia substrate and a significant bioactive behavior in the SBF in vitro experiments. Therefore, it holds great potential to significantly reduce the healing time of zirconia dental implants. 10.1177/0022034514559250
    Bone Tissue Responses to Zirconia Implants Modified by Biomimetic Coating Incorporated with BMP-2. Teng Fei,Zheng Yuanna,Wu Gang,Beekmans Bart,Wismeijer Daniel,Lin Xingnan,Liu Yuelian The International journal of periodontics & restorative dentistry This study aimed to histologically investigate the bone tissue response to zirconia implants functionalized with a biomimetic calcium phosphate (CaP) coating incorporated with bone morphogenetic protein-2 (BMP-2). Zirconia implants coated with biomimetic CaP were prepared with and without BMP-2. Untreated zirconia implants served as a control. These three groups of implants were placed randomly in the mandibles of six beagle dogs (n = 6). Three months later, samples were harvested for histomorphometric analysis. The present study showed that the application of a biomimetic CaP coating incorporated with BMP-2 enhanced the peri-implant osteogenesis for zirconia implants. 10.11607/prd.3980
    Enhancement of the Surface Roughness by Powder Spray Coating on Zirconia Substrate. Kim Hyeong-Jin,Kim Jeong-Jun,Lee Jong Kook Journal of nanoscience and nanotechnology Highly surface-roughened zirconia substrates were obtained from additive zirconia powder coating by room temperature spray processing. Homogeneous and dense zirconia coatings were deposited on sintered zirconia substrates with strong bonding by a powder spray coating method. The thickness and surface roughness of the coating layers on zirconia substrates increased with increasing coating cycles, which was confirmed from atomic force microscopy (AFM) and roughness analyses. The tetragonal phase and chemical composition of the zirconia coating layers were similar to those of the raw 3Y-TZP powder used as a raw material, indicating that no phase or composition changes occurred during the spray process. 10.1166/jnn.2019.17040
    Effects of Silica Coating by Physical Vapor Deposition and Repeated Firing on the Low-Temperature Degradation and Flexural Strength of a Zirconia Ceramic. Cakir-Omur Tutku,Gozneli Rifat,Ozkan Yasemin Journal of prosthodontics : official journal of the American College of Prosthodontists PURPOSE:To examine the application of physical vapor deposition (PVD) silica coating as an approach to retard low temperature degradation (LTD) for dental applications. Accelerated aging characteristics of heat- and surface-treated zirconia material were also investigated by exposing specimens to hydrothermal treatment. MATERIALS AND METHODS:The specimens (90 disc-shaped specimens [15 mm ×1.2 mm]) were divided into 9 groups (n = 10) according to the test protocol: Ctrl, control (no surface treatment); Ag, autoclave aging; GrAg, grinding + aging; SiAg, silica coating + aging; GrSiAg, grinding + silica coating + aging; 3FAg, 3-time firing + aging; Gr3FAg, grinding + 3-time firing + aging; 5FAg, 5-time firing + aging; Gr5FAg, grinding + 5-time firing + aging. Accelerated aging was performed in a steam autoclave (134°C, 2 bars) for 12 hours. Following each treatment protocol, X-ray diffraction (XRD) analysis was used to estimate the relative amount of monoclinic phase and corresponding transformed zone depth (TZD). Additionally, a biaxial flexure test was used to calculate the flexural strength. Statistical analysis was conducted with one-way ANOVA and Fisher's LSD test (p < 0.05). RESULTS:The tetragonal-to-monoclinic transformation was retarded by PVD silica coating only on ground surfaces. Ground and heat-treated specimens exhibited the lowest monoclinic content after aging. The biaxial flexural strength value of the GrAg group was significantly higher than the values in all of the other groups except the SiAg group. The flexural strength value of the GrSiAg group was significantly higher than that of the 3FAg group. There was no statistically significant difference between the other groups (p > 0.05). CONCLUSIONS:Grinding decreased the susceptibility of zirconia to LTD and increased the flexural strength. PVD silica coating and repeated firing decreased the monoclinic content only in ground specimens during aging. 10.1111/jopr.12618
    [Effect of SiO₂-ZrO₂slurry coating on surface performance of zirconia ceramic]. Du Qiao,Niu Guangliang,Lin Hong,Jiang Ruodan Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology OBJECTIVE:To evaluate the effect of SiO₂-ZrO₂slurry coating on surface performance of zirconia ceramic. METHODS:Seventy pre-sintered zirconia discs were randomly divided into seven groups with 10 discs per group. Sample discs in each group received one of the following seven different surface treatments, namely, sintered (group AS), sand blasting after sintered (group SB), coated with slurry of mole ratio of SiO₂to ZrO₂2:1 (group 2SiO₂-1ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:1 (group 1SiO₂-1ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:2 (group 1SiO₂-2ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:3 (group 1SiO₂-3ZrO₂), coated with slurry of mole ratio of SiO₂to ZrO₂1:4 (group 1SiO₂-4ZrO₂). Profilometer, X-ray diffractometer (XRD), energy dispersive spectrometer, scanning electron microscopy (SEM) were used to analyze surface performance. RESULTS:The surface roughness of the discs in group AS was lower than those in the other groups [(0.33 ± 0.03) µm] (P < 0.05), there was no statistically significant difference (P > 0.05) among group 2SiO₂-1ZrO₂[(3.85 ± 0.38) µm], group 1SiO₂-1ZrO₂[(3.78 ± 0.56) µm] and group 1SiO₂-2ZrO₂[(4.06 ± 0.48) µm], and no difference (P > 0.05) was observed between group 1SiO₂-3ZrO₂[(1.02 ± 0.09) µm] and group 1SiO₂-4ZrO₂[(1.53 ± 0.23) µm] either. However, surface roughness in all coating groups was higher than those in group SB [(0.86 ± 0.05) µm] (P < 0.05). According to the XRD pattern, group AS and all coating groups consisted of 100% tetragonal airconia and monoclinic zirconia was detected at surface of group SB. Contents of surface silicon of coating groups increased significantly, however, no silicon was detected at sample surface of group AS and group SB. SEM showed that zirconia grains of coating exposed since part of silicon was etched by hydrofluoric acid, a three-dimensional network of intergrain nano-spaces was created. CONCLUSIONS:SiO₂-ZrO₂slurry coating could make surface of zirconia rough and increase Si content without creating monoclinic zirconia.
    Mixed zirconia calcium phosphate coatings for dental implants: tailoring coating stability and bioactivity potential. Pardun Karoline,Treccani Laura,Volkmann Eike,Streckbein Philipp,Heiss Christian,Li Destri Giovanni,Marletta Giovanni,Rezwan Kurosch Materials science & engineering. C, Materials for biological applications Enhanced coating stability and adhesion are essential for long-term success of orthopedic and dental implants. In this study, the effect of coating composition on mechanical, physico-chemical and biological properties of coated zirconia specimens is investigated. Zirconia discs and dental screw implants are coated using the wet powder spraying (WPS) technique. The coatings are obtained by mixing yttria-stabilized zirconia (TZ) and hydroxyapatite (HA) in various ratios while a pure HA coating served as reference material. Scanning electron microscopy (SEM) and optical profilometer analysis confirm a similar coating morphology and roughness for all studied coatings, whereas the coating stability can be tailored with composition and is probed by insertion and dissections experiments in bovine bone with coated zirconia screw implants. An increasing content of calcium phosphate (CP) resulted in a decrease of mechanical and chemical stability, while the bioactivity increased in simulated body fluid (SBF). In vitro experiments with human osteoblast cells (HOB) revealed that the cells grew well on all samples but are affected by dissolution behavior of the studied coatings. This work demonstrates the overall good mechanical strength, the excellent interfacial bonding and the bioactivity potential of coatings with higher TZ contents, which provide a highly interesting coating for dental implants. 10.1016/j.msec.2014.12.031
    Improvement of mechanical properties of Y-TZP by thermal annealing with monoclinic zirconia nanoparticle coating. Okada Masahiro,Taketa Hiroaki,Hara Emilio Satoshi,Torii Yasuhiro,Irie Masao,Matsumoto Takuya Dental materials : official publication of the Academy of Dental Materials OBJECTIVE:To assess whether a thermal annealing with a monoclinic zirconia (mZrO) nanoparticle coating can improve the reliability of sandblasted yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and maintain its mechanical strength. METHODS:Commercially available Y-TZP (Lava Frame, 3M Dental Products) disks were sintered and surface-treated as follows: AS (as sintered, with no treatment); SB (sandblasting); SB-TA (sandblasting followed by thermal annealing at 1000 °C); and SB-mZr-TA (sandblasting followed by thermal annealing at 1000 °C with the mZrO nanoparticle coating). The mZrO nanoparticles of 21 nm in size were prepared by a hydrothermal method, and coated onto Y-TZP sintered disks as a 5 g/L ethanol dispersion. Biaxial flexural strength (S) was measured using the piston-on-three-ball test, and reliability was evaluated by the Weibull modulus (m). RESULTS:Biaxial flexural tests showed a significant increase in the strength of Group SB (S = 1445 ± 191 MPa) compared with Group AS (S = 1071 ± 112 MPa). The thermal annealing improved the reliabilities of the sandblasted Y-TZP (m = 20.14 and m = 21.33), as compared with Group SB (m = 7.77). However, the conventional thermal annealing without the mZrO coating caused a significant decrease in the strength of sandblasted Y-TZP (S = 1273 ± 65 MPa). Importantly, the mZrO coating prevented the decrease in the strength caused by conventional thermal annealing (S = 1379 ± 65 MPa). SIGNIFICANCE:The thermal annealing with the mZrO nanoparticle coating can improve the reliability of sandblasted Y-TZP and maintain its mechanical strength, which would otherwise be decreased by the conventional annealing process. 10.1016/j.dental.2019.04.002
    Characterization of wet powder-sprayed zirconia/calcium phosphate coating for dental implants. Pardun Karoline,Treccani Laura,Volkmann Eike,Li Destri Giovanni,Marletta Giovanni,Streckbein Philipp,Heiss Christian,Rezwan Kurosch Clinical implant dentistry and related research PURPOSE:Yttria-stabilized zirconia (TZ) is used for dental applications because of its low toxicity and beneficial mechanical properties, but it does not stimulate bone regeneration around the implant due to its bioinertness. Therefore, hydroxyapatite (HA) coatings are often utilized to increase the surface bioactivity and to achieve a better osseointegration. These coatings, however, are chemically nonstable and provide a weak bonding to the substrate surface. MATERIALS AND METHODS:In this study, zirconia substrates were coated with a calcium phosphate/zirconia mixture to achieve ceramic coatings with a high bioactivity potential and a good mechanical stability. The coatings were obtained by wet powder spraying (WPS). Pure HA and TZ coatings were employed as reference materials. The coatings were characterized with regard to microstructure, surface roughness, and phase composition. Scratch tests were carried out to investigate the coating adhesion. The influence of the coating on the mechanical strength was evaluated with the ball on three balls test (B3B). In addition, zirconia dental implant screws were also coated and inserted in a biomechanical test block and bovine rip bone. RESULTS:After sintering, the mixed coating exhibited a porous morphology with a surface roughness of about 4 μm and a total porosity of 17%. Phase analysis showed a transformation from TZ and HA to calcium zirconium oxide and tricalcium phosphate. Investigations of the bond strength confirmed a strong adhesion of the mixed coating to the substrate, while the biaxial fracture strength was only slightly affected. Insertion experiments confirmed the scratch test results and evidenced an intact mixed coating on the zirconia screw. CONCLUSIONS:The present study revealed a higher stability and firm adhesion of the mixed coating compared with a pure calcium phosphate coating. We also successfully demonstrate the particular versatility of the WPS technique for dental implants by coating a complex curved surface. 10.1111/cid.12071
    Influence of bioactive glass-coating of zirconia implant surfaces on human osteoblast behavior in vitro. Rohr Nadja,Nebe J Barbara,Schmidli Fredy,Müller Petra,Weber Michael,Fischer Horst,Fischer Jens Dental materials : official publication of the Academy of Dental Materials OBJECTIVE:The recently developed bioactive glass PC-XG3, which is suitable to coat zirconia implant surfaces with high adhesion strength may reduce the time of osseointegration and the marginal bone loss following implantation. The glass composition has been previously evaluated for cytotoxicity on fibroblast cells, and will now be used to evaluate the cell behavior of osteoblast cells. METHODS:Three different surface morphologies were created with PC-XG3 on zirconia discs. A clinically tested zirconia implant surface as well as polished and machined zirconia served as a reference. Cell viability after 24 h, cell spreading after 30 min and 24 h and the respective morphology of human osteoblasts using scanning electron microscopy were evaluated. Additionally, the corrosive process of PC-XG3 in cell culture medium up to 7 d was measured. RESULTS:Initial cell behavior of human osteoblasts was not accelerated by the PC-XG3 surface when compared to zirconia. Additionally, it was found that a decreased surface roughness promoted initial cell spreading. Storage in cell culture medium resulted in the accumulation of C and N on the bioglass surface while Mg, Si, K and Ca were decreased and crack formation was observed. SIGNIFICANCE:Since initial spreading quality to a biomaterial is a crucial factor that will determine the subsequent cell function, proliferation, differentiation, and viability it can be assumed that a coating of zirconia implants with this bioactive glass will unlikely reduce osseointegration time. 10.1016/j.dental.2019.02.029
    [Effects of zirconia micron coating on the proliferation and differentiation of osteoblasts]. Wang Y F,Niu G L,Han J M Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology To investigate the effects of zirconia micro coating on the proliferation and differentiation of osteoblasts on the surface of zirconia ceramic, and to provide a strategy for zirconia implant surface treatment. Forty tablets of zirconia ceramic, with the diameter of 15 mm and the thickness of 1.5 mm, were prepared. Then, twenty tablets polished by water sandpaper were taken as the control group, and 20 pieces of the zirconia coating after sintering micron were taken as the experimental group. The micromorphology of the surface of the two groups were observed by scanning electron microscope. The cell morphology after inoculation with MC3T3-E1 of osteoblasts on the surface of the material was investigated for 1, 3, and 5 days by scanning electron microscope. The cell proliferation was detected at 1 and 3 days by methyl thiazolyl tetrazolium. The cell differentiation ability was detected at 3 and 7 days by real-time quantitative PCR. Statistical analysis was conducted by independent sample test. After coating with zirconia micron particles, pores with the diameter of 1-20 μm could be observed on the surface of the test group of tiles through high temperature sintering. The growth of osteoblasts on the surface of the ceramic chip in the test group and control group exhibited the similar cell morphology. As they were cultured for 1 day, the experimental group exhibited a similar quality of cells as those in the test group (>0.05). After 3 days incubation, comparing with the cell quality of the test group (1.067 ± 0.077) (<0.05), the quality of osteoblasts on the surface of zirconia ceramics coating increased to 1.763±0.165, and the expression of mRNA in alkaline phosphatase (ALP), osteopotin (OPN) and osteocalcin (OCN) also increased with the amount of 1.63±0.28, 1.99±0.41 and 1.60±0.30, respectively, compared with the test group (1.00± 0.00) (<0.05). Seven days later, the expression of mRNA in Runt-related transcription factor-2 (RNUX2) (1.33±0.19), special AT-rich sequence binding protein-2 (SATB2) (1.64 ± 0.36), as well as alkaline phosphatase (ALP) (1.78±0.40), OPN (2.25±0.36), and OCN (1.88±0.21), showed a remarkably increase compared with the test group (1.00±0.00) (<0.05). Zirconia micro coating on the surface of zirconia ceramics promoted the proliferation and differentiation of osteoblasts adhered. 10.3760/cma.j.issn.1002-0098.2018.05.010
    Evaluation of silk fibroin electrogel coating for zirconia material surface. Qu Yinying,Hong Guang,Liu Lin,Sasaki Keiichi,Chen Xiaodong Dental materials journal Zirconia is commonly used in dental applications. It has been reported that surface-modified zirconia implants showed better performance in vivo than machined zirconia implants. Silk fibroin electrogel is a good candidate for controlled drug delivery; however, the use of silk fibroin electrogel on zirconia implants has not previously been reported. The aim of this study was to investigate a method to coat zirconia implants with silk fibroin electrogel and evaluate the mechanical and biological properties of the coating. The results show that the wettability of the coating was close to that of sand-blasted and acid-etched (SLA)-treated zirconia, and the bond strength was larger than that of the coating prepared from silk fibroin aqueous solution. ATR-FTIR spectra provided evidence that the secondary structure changed during the electrogelation process. Culturing cells on the coating revealed its nontoxicity to osteoblast-like cells. Thus, it can be suggested that a silk fibroin electrogel coating is a promising biocompatible and degradable drugdelivery material for zirconia implants. 10.4012/dmj.2018-228
    Bioactive glass coating on zirconia by vacuum sol-dipping method. Yamada Mao,Valanezhad Alireza,Egoshi Takafumi,Tashima Yumiko,Watanabe Ikuya,Murata Hiroshi Dental materials journal In order to the preparation of biodegradable, bioactive and strongly adhered coating layer to the bioinert zirconia substrate, a bioactive glass (BG) was successfully coated on the zirconia plates. To achieve this goal, the zirconia plates dipped into the 45S5 BG sol in the vacuum chamber (vacuum sol-dipping method) followed by sintering to fabricate a strongly adhered BG coating on the zirconia plates. The parameters such as surface morphology and BG coating coverage ability on the zirconia plates have been assessed before and after coating with 45S5 BG. Phase structure of the BG coating based on the X-ray diffraction (XRD) result could be indexed as NaCa(SiO). The interfacial adhesive strength between the zirconia substrate and BG coating layer was higher than the measured adhesive strength (55±7 MPa). The viability results approved the satisfying conclusion for the offered coating method on the zirconia substrates. 10.4012/dmj.2018-222