Surface characterization of different surface treatments associations with plasma and bonding analysis of Y-TZP and the veneering ceramic.

OBJECTIVES: To characterize the surface of zirconia (Y-TZP) submitted to different surface treatments (with and without plasma associations) and to evaluate the shear bond strength (SBS) between veneering ceramic (VC) and Y-TZP after different aging methods. METHODS: 301 Y-TZP specimens were fabricated and distributed into 7 groups: C (control): no treatment; Al: airborne abrasion with 27 µm Al2O3 particle; L: liner; P: plasma; Al + L: airborne + liner; Al + P: airborne + plasma; P + L: plasma + liner. The Y-TZP surface was characterized by SEM, EDS, AFM, surface profilometry, surface-free energy (SFE), and XRD. SBS between Y-TZP and VC was verified after three aging protocols: initial, after hydrothermal aging (autoclave for 5 h), or thermal fatigue (30,000 baths - 5-55 °C). One- (profilometry, SFE) and two-way ANOVA (SBS), and Tukey's HSD test were used. RESULTS: For the plasma groups, a full globular surface coverage was observed (SEM, AFM). Si was found for Al, L, Al + L, and P + L. Roughness was lower for C, P, and Al + P. For SFE, the highest values were found when the liner was applied (>74.59 nm/Nm). The highest monoclinic content was observed for Al + L (6.96%) and Al + P (5.86%). For the initial period, Al and P + L presented the lowest SBS values (<5.85 MPa; P > 0.331). The highest SBS values were found for L, P, and P + L (hydrothermal aging) and for P, L, Al + L, and Al + P (thermal fatigue). SIGNIFICANCE: Changes in Y-TZP topography and the SBS with the VC were found, according to treatments performed. Plasma treatment improved SBS and did not cause phase transformation.

Is an anodizing coating associated to the photobiomodulation able to optimize bone healing in ovariectomized animal model?

This in vivo study investigated whether the bioactivity of anodizing coating, produced by plasma electrolytic oxidation (PEO), on mini-plate in femur fracture could be improved with the association of photobiomodulation (PBM) therapy. From the 20 ovariectomized Wistar female rats, 8 were used for model characterization, and the remaining 12 were divided into four groups according to the use of PBM therapy by diode laser (808 nm; power: 100 mW; energy: 6.0 J; energy density: 212 J/cm2; power density: 3.5 W/cm2) and the type of mini-plate surface (commercially pure titanium mini-plate -cpTi- and PEO-treated mini-plate) as follow: cpTi; PEO; cpTi/PBM; and PEO/PBM. After 60 days of surgery, fracture healing underwent microstructural, bone turnover, histometric, and histologic adjacent muscle analysis. Animals of groups with PEO and PBM showed greater fracture healing than cpTi control group under histometric and microstructural analysis (P < 0.05); however, bone turnover was just improved in PBM's groups (P < 0.05). there was no difference between cpTi and PEO without PBM (P > 0.05). Adjacent muscle analysis showed no metallic particles or muscle alterations in all groups. PEO and PBM are effective strategies for bone repair in fractures, however their association does not provide additional advantages.

Miniplates coated by plasma electrolytic oxidation improve bone healing of simulated femoral fractures on low bone mineral density rats.

The treatment of polytrauma patients represents a great challenge in the maxillofacial and orthopedic surgery fields. Therefore, this study tested the hypothesis that the use of a bioactive coating (by plasma electrolytic oxidation, PEO) on titanium microplates could improve the fracture healing of low bone mineral density (BMD) rats. Thirty female rats underwent bilateral ovariectomy surgery (OVX), and 35 rats underwent fake surgery (SHAM). Three months later, animals were subjected to femoral fracture simulation and were fixed with either non-coated (CONV) or coated (PEO) titanium miniplates. Eight weeks postoperatively, microplate/bone complexes were analyzed through computed microtomography, histometric, confocal microscopy, molecular, and biomechanical analysis. Bioactive elements (Ca and P) were incorporated on the PEO microplate and the surface was modified in a volcano-like structure. In the microCT analysis the OVX/PEO group had greater values for Tb.Th (bone trabecular thickness), Tb.Sp (separation of bone trabeculae) and Tb.N (number of trabeculae) parameters compared to the OVX/CONV group. According to histometric analysis, the OVX/PEO group showed significantly higher new bone formation than the OVX/CONV group (P < 0.05). For the fluorochrome area, the OVX groups (PEO and CONV) showed greater values for calcein precipitation (old bone) than alizarin red (new bone). Molecular results showed greater values for proteins related to the final phase of bone formation (P < 0.05) in the OVX/PEO group. The OVX/PEO group showed higher bone/miniplate system resilience compared to the others (P < 0.05). It was concluded that PEO coating optimizes bone healing on simulated femoral fractures in low bone mineral density rats. This sheds new light in the treatment of osteoporotic patients with bone fractures.

Author Correction: Plasma Electrolytic Oxidation as a Feasible Surface Treatment for Biomedical Applications: an in vivo study.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Plasma Electrolytic Oxidation as a Feasible Surface Treatment for Biomedical Applications: an in vivo study.

OBJECTIVES: In this in vivo animal study, we evaluated the effect of plasma electrolytic oxidation (PEO) coating on the topographic and biological parameters of implants installed in rats with induced osteoporosis and low-quality bones. MATERIALS AND METHODS: In total 44 Wistar rats (Rattus novergicus), 6 months old, were submitted to ovariectomy (OXV group) and dummy surgery (SHAM group). After 90 days, the ELISA test was performed and the ovariectomy effectiveness was confirmed. In each tibial metaphysis, an implant with PEO coating containing Ca2+ and P5+ molecules were installed, and the other tibia received an implant with SLA acid etching and blasting (AC) (control surface). After 42 days, 16 rats from each group were euthanized, their tibias were removed for histological and immunohistochemical analysis (OPG, RANKL, OC and TRAP), as well as reverse torque biomechanics. Data were submitted to One-way ANOVA or Kruskal-Wallis tests, followed by a Tukey post-test; P < 0.05. Histological analyses showed higher bone neoformation values among the members of the PEO group, SHAM and OVX groups. Immunohistochemical analysis demonstrated equilibrium in all groups when comparing surfaces for TRAP, OC and RANKL (P > 0.05), whereas OPG showed higher PEO labeling in the OVX group (P < 0.05). Biomechanical analysis showed higher reverse torque values (N.cm) for PEO, irrespective of whether they were OVX or SHAM groups (P < 0.05). CONCLUSION: The results indicated that the PEO texturing method favored bone formation and showed higher bone maturation levels during later periods in osteoporotic rats.

Comparison between Plasma Electrolytic Oxidation Coating and Sandblasted Acid-Etched Surface Treatment: Histometric, Tomographic, and Expression Levels of Osteoclastogenic Factors in Osteoporotic Rats.

Plasma electrolytic oxidation (PEO) has been a promising surface coating with better mechanical and antimicrobial parameters comparing to conventional treatment surfaces. This study evaluated the peri-implant bone repair using (PEO) surface coatings compared with sandblasted acid (SLA) treatment. For this purpose, 44 Wistar rats were ovariectomized (OVX-22 animals) or underwent simulated surgery (SS-22 animals) and received implants in the tibia with each of the surface coatings. The peri-implant bone subsequently underwent molecular, microstructural, bone turnover, and histometric analysis. Real-time PCR showed a higher expression of osteoprotegerin (OPG), receptor activator of nuclear kappa-B ligand (RANKL), and osteocalcin (OC) proteins in the SLA/OVX and PEO/SS groups (p < 0.05). Computed microtomography, confocal microscopy, and histometry showed similarity between the PEO and SLA surfaces, with a trend toward the superiority of PEO in OVX animals. Thus, PEO surfaces were shown to be promising for enhancing peri-implant bone repair in ovariectomized rats.

Can Nonthermal Plasma Improve the Adhesion between Acrylic Resin for Ocular Prostheses and Silicone-Based Relining Material?

PURPOSE: To investigate the influence of nonthermal plasma (NTP) treatment on the tensile bond strength between heat-polymerized acrylic resin for ocular prostheses and silicone reliner, with and without the use of an adhesive primer. MATERIALS AND METHODS: One-hundred and sixty-four acrylic resin specimens were fabricated and randomly distributed into four groups according to the type of surface treatment: Sofreliner Primer, NTP, Sofreliner Primer + NTP, and NTP + Sofreliner Primer. Two specimens interposed with relining material (Sofreliner) formed one test sample to perform the tensile bond strength tests, before (initial) and after storage (final) in saline solution (37°C, 90 days, n = 10). Surface characterization was performed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The failure type was classified as cohesive, adhesive, or mixed. The data were analyzed statistically using the two-way ANOVA and Tukey test, as well as the chi-squared test (α = 0.05), Bonferroni correction (α = 0.005), and Spearman correlation coefficient (α = 0.05). RESULTS: The SEM and EDS analyses showed the presence of a thin, homogenous organic film in the groups treated with NTP. The NTP + Sofreliner Primer group presented the largest bond strength mean values in the initial period (p < 0.05). Sofreliner Primer and NTP + Sofreliner Primer groups presented the first and second largest tensile bond strength mean values in the final period (p < 0.05), respectively. NTP + Sofreliner Primer group also had the largest number of cohesive (70%, initial) and mixed (90%, final) failures. CONCLUSIONS: The NTP treatment performed before the primer application enhanced the bond between the acrylic resin ocular prosthesis and the Sofreliner silicone-based reliner, even after 90 days of immersion in saline solution.

Effect of nonthermal plasma on the properties of a resinous liner submitted to aging.

STATEMENT OF PROBLEM: The properties, such as softness and viscoelasticity, of a resinous reliner can deteriorate and extrinsic elements can become incorporated, making surface protection of the reliner material essential. PURPOSE: The purpose of this in vitro study was to evaluate the effect of low temperature plasma on Coe-Soft resinous reliner, submitted to aging in artificial saliva for up to 180 days. Sorption, solubility, Shore A hardness, surface energy, and topographic characteristics were analyzed by scanning electronic microscopy (SEM) and energy-dispersive spectroscopy (EDS). MATERIAL AND METHODS: Forty-four specimens were fabricated and distributed in 2 groups: nonplasma reliner (control group) and reliner with plasma (plasma group). The plasma was applied with a mixture of 70% hexamethyldisiloxane, 20% O, and 10% Ar. Total work pressure was maintained at a constant 20 Pa for 30 minutes of deposition. The specimens were analyzed before and after aging in an incubator with immersion in artificial saliva for 30, 90, and 180 days. The quantitative data were submitted to 2-way ANOVA and the Tukey test (α=.05), while qualitative data were compared visually. RESULTS: The control group presented lower Shore A hardness values only in the initial period, and surface energy increased with aging for both groups until 90 days. Greater sorption percentage values were encountered at 180 days in the plasma group. Greater solubility values were encountered in the control group in all periods. CONCLUSIONS: Plasma is an option for the protection of the material studied because the deposited film remained on the surface of the reliner material after aging.

Effects of negatively and positively charged Ti metal surfaces on ceramic coating adhesion and cell response.

This manuscript reports an evaluation of the effects of simple chemical-heat treatments on the deposition of different ceramic coatings, i.e., TiO2, CaTiO3 and CaP, on commercially pure titanium (cp-Ti) and Ti6Al4V and the influence of the coatings on cells interaction with the surfaces. The ceramic materials were prepared by the sol-gel method and the coating adhesion was analyzed by pull-off bending tests. The wettability of positively or negatively charged surfaces was characterized by contact angle measurements, which also enabled the calculation of the surface free energy through the polar-apolar liquids approach. Both acid and alkaline treatments activated the cp-Ti, whereas Ti6Al4V was only activated by the alkaline treatment. Such treatment led to increased hydrophilicity with inhibition of the fibroblastic response on Ti6Al4V. On the other hand, osteoblastic cells adhered to and proliferated on the positively and negatively charged surfaces. The maximum adhesion strength (~ 3400 N) was obtained with a negative Ti6Al4V-CaTiO3-CaP multilayer surface.

Achieving surface chemical and morphologic alterations on tantalum by plasma electrolytic oxidation.

BACKGROUND: Search for materials that may either replace titanium dental implants or constitute an alternative as a new dental implant material has been widely studied. As well, the search for optimum biocompatible metal surfaces remains crucial. So, the aim of this work is to develop an oxidized surface layer on tantalum using plasma electrolytic oxidation (PEO) similar to those existing on oral implants been marketed today. METHODS: Cleaned tantalum samples were divided into group 1 (control) and groups 2, 3, and 4 (treated by PEO for 1, 3, and 5 min, respectively). An electrolytic solution diluted in 1-L deionized water was used for the anodizing process. Then, samples were washed with anhydrous ethyl alcohol and dried in the open air. For complete anodic treatment disposal, the samples were immersed in acetone altogether, taken to the ultrasonic tank for 10 min, washed again in distilled water, and finally air-dried. For the scanning electron microscopy (SEM) analysis, all samples were previously coated with gold; the salt deposition analysis was conducted with an energy-dispersive X-ray spectroscopy (EDS) system integrated with the SEM unit. RESULTS: SEM images confirmed the changes on tantalum strips surface according to different exposure times while EDS analysis confirmed increased salt deposition as exposure time to the anodizing process also increased. CONCLUSIONS: PEO was able to produce both surface alteration and salt deposition on tantalum strips similar to those existing on oral implants been marketed today.

In vitro analysis of different properties of acrylic resins for ocular prosthesis submitted to accelerated aging with or without photopolymerized glaze.

The effect of a photopolymerized glaze on different properties of acrylic resin (AR) for ocular prostheses submitted to accelerated aging was investigated. Forty discs were divided into 4 groups: N1 AR without glaze (G1); colorless AR without glaze (G2); N1 AR with glaze (G3); and colorless AR with glaze (G4). All samples were polished with sandpaper (240, 600 and 800-grit). In G1 and G2, a 1200-grit sandpaper was also used. In G3 and G4, samples were coated with MegaSeal glaze. Property analysis of color stability, microhardness, roughness, and surface energy, and assays of atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were performed before and after the accelerated aging (1008h). Data were submitted to the ANOVA and Tukey Test (p<0.05). Groups with glaze exhibited statistically higher color change and roughness after aging. The surface microhardness significantly decreased in groups with glaze and increased in groups without glaze. The surface energy increased after the aging, independent of the polishing procedure. All groups showed an increase of surface irregularities. Photopolymerized glaze is an inadequate surface treatment for AR for ocular prostheses and it affected the color stability, roughness, and microhardness. The accelerated aging interfered negatively with the properties of resins.

Layer-by-layer assembly of functionalized reduced graphene oxide for direct electrochemistry and glucose detection.

We report an electrochemical glucose biosensor made with layer-by-layer (LbL) films of functionalized reduced graphene oxide (rGO) and glucose oxidase (GOx). The LbL assembly using positively and negatively charged rGO multilayers represents a simple approach to develop enzymatic biosensors. The electron transport properties of graphene were combined with the specificity provided by the enzyme. rGO was obtained and functionalized using chemical methods, being positively charged with poly(diallyldimethylammonium chloride) to form GPDDA, and negatively charged with poly(styrene sulfonate) to form GPSS. Stable aqueous dispersions of GPDDA and GPSS are easily obtained, enabling the growth of LbL films on various solid supports. The use of graphene in the immobilization of GOx promoted Direct Electron Transfer, which was evaluated by Cyclic Voltammetry. Amperometric measurements indicated a detection limit of 13.4µmol·L(-1) and sensitivity of 2.47µA·cm(-2)·mmol(-1)·L for glucose with the (GPDDA/GPSS)1/(GPDDA/GOx)2 architecture, whose thickness was 19.80±0.28nm, as determined by Surface Plasmon Resonance (SPR). The sensor may be useful for clinical analysis since glucose could be detected even in the presence of typical interfering agents and in real samples of a lactose-free milk and an electrolyte solution to prevent dehydration.

Biomimetic coatings enhance tribocorrosion behavior and cell responses of commercially pure titanium surfaces.

Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (-0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (-0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces.

Production of a biofunctional titanium surface using plasma electrolytic oxidation and glow-discharge plasma for biomedical applications.

In this study, the authors tested the hypotheses that plasma electrolytic oxidation (PEO) and glow-discharge plasma (GDP) would improve the electrochemical, physical, chemical, and mechanical properties of commercially pure titanium (cpTi), and that blood protein adsorption on plasma-treated surfaces would increase. Machined and sandblasted surfaces were used as controls. Standard electrochemical tests were conducted in artificial saliva (pHs of 3.0, 6.5, and 9.0) and simulated body fluid. Surfaces were characterized by scanning electron microscopy, energy-dispersive spectroscopy, x-ray photoelectron spectroscopy, atomic force microscopy, x-ray diffraction, profilometry, Vickers microhardness, and surface energy. For biological assay, the adsorption of blood serum proteins (i.e., albumin, fibrinogen, and fibronectin) was tested. Higher values of polarization resistance and lower values of capacitance were noted for the PEO and GDP groups (p < 0.05). Acidic artificial saliva reduced the corrosion resistance of cpTi (p < 0.05). PEO and GDP treatments improved the surface properties by enrichment of the surface chemistry with bioactive elements and increased surface energy. PEO produced a porous oxide layer (5-µm thickness), while GDP created a very thin oxide layer (0.76-µm thickness). For the PEO group, the authors noted rutile and anatase crystalline structures that may be responsible for the corrosion barrier improvement and increased microhardness values. Plasma treatments were able to enhance the surface properties and electrochemical stability of titanium, while increasing protein adsorption levels.

Aging effect of atmospheric air on lithium disilicate ceramic after nonthermal plasma treatment.

STATEMENT OF PROBLEM: Nonthermal plasma (NTP) treatment is an alternative technique for promoting the adhesion of resin cement to lithium disilicate ceramic. However, no study has evaluated whether the surface modifications are affected by atmospheric air aging. PURPOSE: The purposes of this in vitro study were to characterize the lithium disilicate surface after depositing an organosilicon film with NTP treatment and to verify the surface energy before and after atmospheric air aging up to 30 days. MATERIAL AND METHODS: Sixteen lithium disilicate disks (10×3 mm) were prepared, and their surfaces were treated with a mixture of hexamethyldisiloxane and argon, followed by oxygen plasma treatment, both for 30 minutes. The lithium disilicate surface was characterized through scanning electron microscopy, energy-dispersive spectroscopy, and atomic force microscopy. Surface energy analysis was performed before (T0) and immediately after NTP treatment (T1) and after atmospheric air aging for 7 (T2), 15 (T3), and 30 days (T4). Data were submitted to analysis of variance followed by the Tukey HSD test (α=.05). RESULTS: Carbon, oxygen, and silicon were identified on the disilicate surface after NTP treatment, suggesting organosilicon film adhesion. Air aging did not modify the film morphology. At T1, the surface energy was significantly higher compared with other periods, and the water contact angle on the disilicate surface was reduced to 0 degrees. Similar surface energy was observed for T0, T2, T3, and T4. CONCLUSIONS: On the basis of the results of this in vitro study, NTP treatment can promote bonding to lithium disilicate surfaces because of its high surface wettability. However, after air aging, the wettability was not durable.

Effect of nonthermal plasma treatment on surface chemistry of commercially-pure titanium and shear bond strength to autopolymerizing acrylic resin.

The effect of nonthermal plasma on the surface characteristics of commercially pure titanium (cp-Ti), and on the shear bond strength between an autopolymerizing acrylic resin and cp-Ti was investigated. A total of 96 discs of cp-Ti were distributed into four groups (n=24): Po (no surface treatment), SB (sandblasting), Po+NTP and SB+NTP (methane plasma). Surface characterization was performed through surface energy, surface roughness, scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction tests. Shear bond strength test was conducted immediately and after thermocycling. Surface treatment affected the surface energy and roughness of cp-Ti discs (P<.001). SEM-EDS showed the presence of the carbide thin film. XRD spectra revealed no crystalline phase changes. The SB+NTP group showed the highest bond strength values (6.76±0.70 MPa). Thermocycling reduced the bond strength of the acrylic resin/cp-Ti interface (P<.05), except for Po group. NTP is an effective treatment option for improving the shear bond strength between both materials.

Aging Effect of Atmospheric Air on Zirconia Surfaces Treated by Nonthermal Plasma.

PURPOSE: The purpose of this study was twofold: 1) to characterize the zirconia (Y-TZP) surfaces through scanning electronic microscopy associated with energy-dispersive spectroscopy and atomic force microscopy after the deposition of a thin organosilicon film by nonthermal plasma (NTP) treatment, and 2) to determine the zirconia surface hydrophilicity, before and after aging, through surface energy analysis. MATERIALS AND METHODS: Surfaces of 16 zirconia disks (10 x 3 mm) were treated for 30 min each with hexamethyldisiloxane and argon plasmas, followed by oxygen plasma. Disks were analyzed before NTP treatment, immediately after NTP treatment, and after aging for 7, 15, and 30 days. The surface energy of the Y-TZP disks was measured with a goniometer. Quantitative data were submitted to statistical analysis using ANOVA and Tukey's test (p < 0.05). RESULTS: Immediately after NTP treatment, the surface energy of the zirconia disks was significantly higher than at any other tested period (p < 0.001), and the water contact angle on the zirconia disks was reduced to 0 degrees. Similar surface energy results were obtained before NTP treatment and after 15 or 30 days of aging (p > 0.05; Tukey's test). Energy-dispersive spectroscopy results revealed the presence of carbon, oxygen, and silicon on the surface after NTP treatment. CONCLUSION: NTP treatment was useful for treating the zirconia surface for cementation procedures, as it produced a high level of hydrophilicity on the zirconia surface. However, this high level of hydrophilicity did not persist after aging.

Incorporation of Ca, P, and Si on bioactive coatings produced by plasma electrolytic oxidation: The role of electrolyte concentration and treatment duration.

The objectives of the present study were to produce bioactive coatings in solutions containing Ca, P, and Si by plasma electrolytic oxidation (PEO) on commercially pure titanium, to investigate the influence of different electrolytes concentration and treatment duration on the produced anodic films and to evaluate biocompatibility properties. The anodic films were characterized using scanning electron microscopy, energy-dispersive spectroscopy, atomic force microscopy, and x-ray diffraction and x-ray photoelectron spectroscopies. The surface energy and roughness were also evaluated. PEO process parameters influenced the crystalline structure formation and surface topography of the anodic films. Higher Ca content produced larger porous (volcanolike appearance) and thicker oxide layers when compared to the lower content. Treatment duration did not produce any topography difference. The treatment modified the surface chemistry, producing an enriched oxide layer with bioactive elements in the form of phosphate compounds, which may be responsible for mimicking bone surface. In addition, a rough surface with increased surface energy was generated. Optimal spreading and proliferation of human mesenchymal stem cells was achieved by PEO treatment, demonstrating excellent biocompatibility of the surface. The main finding is that the biofunctionalization with higher Ca/P on Ti-surface can improve surface features, potentially considered as a candidate for dental implants.

Surface degradation of lithium disilicate ceramic after immersion in acid and fluoride solutions.

PURPOSE: To analyze whether immersion in sodium fluoride (NaF) solutions and/or common acidic beverages (test solutions) would affect the surface roughness or topography of lithium disilicate ceramic. METHODS: 220 ceramic discs were divided into four groups, each of which was subdivided into five subgroups (n = 11). Control group discs were immersed in one of four test beverages for 4 hours daily or in artificial saliva for 21 days. Discs in the experimental groups were continuously immersed in 0.05% NaF, 0.2% NaF, or 1.23% acidulated phosphate fluoride (APF) gel for 12, 73, and 48 hours, respectively, followed by immersion in one of the four test beverages or artificial saliva. Vickers microhardness, surface roughness, scanning electron microscopy (SEM) associated with energy dispersive spectroscopy, and atomic force microscopy (AFM) assessments were made. Data were analyzed by nested analysis of variance (ANOVA) and Tukey's test (α = 0.05). RESULTS: Immersion in the test solutions diminished the microhardness and increased the surface roughness of the discs. The test beverages promoted a significant reduction in the Vickers microhardness in the 0.05% and 0.2% NaF groups. The highest surface roughness results were observed in the 0.2% NaF and 1.23% APF groups, with similar findings by SEM and AFM. Acidic beverages affected the surface topography of lithium disilicate ceramic. Fluoride treatments may render the ceramic surface more susceptible to the chelating effect of acidic solutions.

Electrochemical behavior of bioactive coatings on cp-Ti surface for dental application.

The surface characteristics and electrochemical properties of bioactive coatings produced by plasma electrolytic oxidation (PEO) with calcium, phosphorous, silicon and silver on commercially pure titanium were evaluated. PEO treatment produced a porous oxide layer, which improved the surface topography, and enriched the surface chemistry with bioactive elements, responsible for mimicking bone surface. The surfaces with higher calcium concentration presented antibacterial and biocompability properties with better responses for corrosion and barrier properties, due to the presence of rutile crystalline structure. PEO may be a promising surface treatment option to improve the electrochemical behavior of dental implants mitigating treatment failures.