Development of cobalt (Co)-doped monetites for bone regeneration.

Cobalt-doped monetite powders were synthesized by coprecipitation method under a cobalt nominal content between 2 and 20 mol % of total cation. Structural characterization of samples was performed by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. XRD results indicated that the Co-doped samples exhibited a monetite single-phase with the cell parameters and crystallite size dependent on the amount of substitutional element incorporated into the triclinic crystalline structure. Cell viability and adhesion assays using pre-osteoblastic cells showed there is no toxicity and the RTqPCR analysis showed significant differences in the expression for osteoblastic phenotype genes, showing a potential material for the bone regeneration.

Targeting Biomechanical Endurance of Dental-Implant Abutments Using a Diamond-Like Carbon Coating.

Abutment components (i.e., fixtures associated with oral implants) are essentially made of titanium (Ti), which is continuously exposed to the hash oral environment, resulting in scratching. Thus, such components need to be protected, and surface treatments are viable methods for overcoming long-term damage. Diamond-like carbon (DLC), an excellent protective material, is an alternative surface-treatment material for Ti abutments. Here, we demonstrate that a silicon interlayer for DLC film growth and the pulsed-direct current plasma-enhanced chemical vapor deposition (DC-PECVD) method enables the deposition of an enhanced protective DLC film. As a result, the DLC film demonstrated a smooth topography with a compact surface. Furthermore, the DLC film enhanced the mechanical (load-displacement, hardness, and elastic modulus) and tribological properties of Ti as well as increased its corrosion resistance (16-fold), which surpassed that of a bare Ti substrate. The biofilm formed (Streptococcus sanguinis) after 24 h exhibited an equal bacterial load (∼7 Log colony-forming units) for both the groups (Ti and DLC). In addition, the DLC film exhibited good cytocompatibility, owing to its noncytotoxicity toward human gingival fibroblast cells. Therefore, DLC deposition via DC-PECVD can be considered to be a promising protective and cytocompatible alternative for developing implant abutments with enhanced mechanical, tribological, and electrochemical properties.

Effect of Plasma Excitation Power on the SiOxCyHz/TiOx Nanocomposite.

Titanium dioxide has attracted a great deal of attention in the field of environmental purification due to its photocatalytic activity under ultraviolet light. Photocatalytic efficiency and the energy required to initiate the process remain the drawbacks that hinder the widespread adoption of the process. Consistently with this, it is proposed here the polymerization of hexamethyldisiloxane fragments simultaneously to TiO2 sputtering for the production of thin films in low-pressure plasma. The effect of plasma excitation power on the molecular structure and chemical composition of the films was evaluated by infrared spectroscopy. Wettability and surface energy were assessed by a sessile drop technique, using deionized water and diiodomethane. The morphology and elemental composition of the films were determined using scanning electron microscopy and energy dispersive spectroscopy, respectively. The thickness and roughness of the resulting films were measured using profilometry. Organosilicon-to-silica films, with different properties, were deposited by combining both deposition processes. Titanium was detected from the structures fabricated by the hybrid method. It has been observed that the proportion of titanium and particles incorporated into silicon-based matrices depends on the plasma excitation power. In general, a decrease in film thickness with increasing power has been observed. The presence of Ti in the plasma atmosphere alters the plasma deposition mechanism, affecting film deposition rate, roughness, and wettability. An interpretation of the excitation power dependence on the plasma activation level and sputtering yield is proposed. The methodology developed here will encourage researchers to create TiO2 films on a range of substrates for their prospective use as sensor electrodes, water and air purification systems, and biocompatible materials.

Antimicrobial behavior of titanium coating with chlorhexidine-doped thin film exposed to a biofilm supplemented with nicotine.

Because nicotine upregulates the growth of most oral bacteria, this in vitro study investigated the antimicrobial effect of chlorhexidine-doped thin film on commercially pure titanium against Fusobacterium nucleatum (F. nucleatum) biofilm supplemented with different concentrations of nicotine (0, 1, and 2 mg/mL). Biofilms were formed on a chlorhexidine-doped thin film on commercially-pure-titanium discs and compared to the control groups. Biofilm viability, total biofilm growth using a spectrophotometer, extracellular polysaccharide content, and pH variations were assessed as dependent variables. Data were submitted to ANOVA and Tukey honest significant difference tests (α=0.05). F. nucleatum biofilm growth was inhibited when exposed to chlorhexidine-doped thin film (p<0.05). Biofilm supplemented with nicotine did not impact the synthesis of EPS on the same type of treatment (p>0.05). The pH values were significantly increased with the increase of nicotine concentration (p<0.05). Chlorhexidine-doped thin film was effective in reducing F. nucleatum biofilm supplemented with nicotine.

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.

Sputtered crystalline TiO2 film drives improved surface properties of titanium-based biomedical implants.

Different crystalline phases in sputtered TiO2 films were tailored to determine their surface and electrochemical properties, protein adsorption and apatite layer formation on titanium-based implant material. Deposition conditions of two TiO2 crystalline phases (anatase and rutile) were established and then grown on commercially pure titanium (cpTi) by magnetron sputtering to obtain the following groups: A-TiO2 (anatase), M-TiO2 (anatase and rutile mixture), R-TiO2 (rutile). Non-treated commercially pure titanium (cpTi) was used as a control. Surfaces characterization included: chemical composition, topography, crystalline phase and surface free energy (SFE). Electrochemical tests were conducted using simulated body fluid (SBF). Albumin adsorption was measured by bicinchoninic acid method. Hydroxyapatite (HA) precipitation was evaluated after 28 days of immersion in SBF. MC3T3-E1 cell adhesion, morphology and spreading onto the experimental surfaces were evaluated by scanning electron microscopy. Sputtering treatment modified cpTi topography by increasing its surface roughness. CpTi and M-TiO2 groups presented the greatest SFE. In general, TiO2 films displayed improved electrochemical behavior compared to cpTi, with M-TiO2 featuring the highest polarization resistance. Rutile phase exhibited a greater influence on decreasing the current density and corrosion rate, while the presence of a bi-phasic polycrystalline condition displayed a more stable passive behavior. M-TiO2 featured increased albumin adsorption. HA morphology was dependent on the crystalline phase, being more evident in the bi-phasic group. Furthermore, M-TiO2 displayed normal cell adhesion and morphology. The combination of anatase and rutile structures to generate TiO2 films is a promising strategy to improve biomedical implants properties including greater corrosion protection, higher protein adsorption, bioactivity and non-cytotoxicity effect.

Effect of handling material on mechanical and optical properties of feldspathic porcelain.

OBJECTIVE: To evaluate the optical, chemical, and mechanical properties of feldspathic porcelain after handling with different instrument materials. MATERIAL AND METHODS: Feldspathic porcelain was manipulated with different spatula compositions: metal spatula (MS), plastic spatula (PS), and glass spatula (GS) for the fabrication of 30 (n = 10) disks. Contrast ratio (CR), translucency parameter (TP), and surface Knoop microhardness (KHN) were measured. The color change (ΔE00 ) was evaluated using the CIEDE2000 system. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used for surface analysis. Data were analyzed using one-way ANOVA and Tukey test (P < 0.05). RESULTS: All groups presented different morphological surfaces with higher presence of Al on the MS. PS group presented lower Al, Si, K than MS, and GS. Higher CR was observed for PS (0.734; P < 0.043), followed by MS (0.696; P < 0.043) and GS (0.65; P < 0.011). The highest TP (13.06) and KHN (386.27) were presented by GS (P < 0.001). MS and PS presented similar KHN results. The higher ΔE00 were found for plastic/metal comparison. Also, the L* values for the MS group (67.49) were lower than the other groups. CONCLUSION: The use of metal spatula promoted higher color alteration during feldspathic porcelain manipulation than did the other materials. Handling with glass instrument promoted higher microhardness than other spatula materials. CLINICAL SIGNIFICANCE: The effect of the material used for ceramic handling on feldspathic porcelain properties is often ignored. This study shows that the handling spatula material must be carefully chosen to avoid inadvertent changes to the feldspathic porcelain restoration.

Analysis of physical properties of facial silicones with different pigmentations submitted to nonthermal plasma treatment and accelerated aging.

STATEMENT OF PROBLEM: Exposure of silicone prostheses to environmental factors can alter their properties, affecting longevity. However, whether nonthermal plasma (NTP) can prevent these alterations is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the surface roughness (Ra), sorption, solubility, and color stability (ΔE00) of the MDX4-4210 and A-120 silicones, with and without NTP treatment in accordance with an independent analysis of the use of 2 pigmentations. MATERIAL AND METHODS: One hundred sixty specimens were fabricated and distributed into 16 groups (n=10) as per the silicone, pigmentation, and NTP coating. The NTP was applied, and the Ra, sorption, solubility, and ΔE00 were evaluated before and after accelerated aging. ANOVA was used, and the HSD Tukey test was applied (α=.05). RESULTS: NTP generated an increase in roughness after aging, regardless of pigmentation or silicone. A-120 silicone without NTP showed a reduction in roughness after aging, regardless of pigmentation. For sorption and solubility, the bronze pigmentation (for A-120 and MDX4-4210) presented the smallest results after NTP treatment. For MDX4-4210 with pink pigmentation and NTP, sorption decreased and solubility increased. For A-120 with pink pigmentation and NTP, sorption and solubility increased. Sorption was reduced in all situations, except for A-120 with pink pigmentation, which increased. Regardless of the silicone used, solubility was reduced after NTP for bronze pigmentation. For A-120 and MDX4-4210 with pink pigmentation and NTP, the solubility increased. For both pigmentations, the NTP treatment promoted lower color alteration only for the A-120 silicone after accelerated aging (within the acceptability threshold). CONCLUSIONS: The NTP protocol of this study, which was applied to facial silicones, generated inconsistent results between the evaluated properties. Therefore, the NTP protocol used does not seem to be ideal for the treatment of silicone surfaces after aging.

The Effect of Different Plasma Treatments on the Surface Properties and Bond Strength between Lithium Disilicate and Resin Cement.

PURPOSE: To evaluate the roughness, surface energy, and the bond strength of lithium disilicate yielded by two different types of nonthermal plasma (NTP), oxygen- or argon-based, compared to the conventional method. MATERIALS AND METHODS: Ninety-three lithium disilicate (IPS e.max Press) samples were divided into 3 groups: HF (hydrofluoric acid group); ONTP (oxygen-based NTP group); ANTP (argon-based NTP group). Surface energy and roughness analyses were performed before and after surface treatment, and bond strength testing was performed before and after 5000 thermocycles. Scanning electron microscopy (SEM) was used to characterize the surface treatments. Data were submitted to ANOVA and Bonferroni's test with statistical significance set at 5%. RESULTS: The ONTP group presented the highest surface energy values, followed by ANTP and HF. In addition, the ONTP group had higher surface roughness. SEM revealed exposed lithium disilicate crystals in the HF group, but a homogeneous film coverage in both NTP groups. Regarding bond strength, ANTP presented statistically significantly higher values than the other groups before thermocycling, and statistically significantly lower values than the other groups after thermocycling. The HF and ONTP groups presented statistically similar values after thermocycling. CONCLUSION: The bond strength of resin cement to lithium disilicate obtained after oxygen-based NTP was comparable with that obtained after conventional hydrofluoric acid treatment.

Synthesis of multifunctional chlorhexidine-doped thin films for titanium-based implant materials.

Our goal was to create bio-functional chlorhexidine (CHX)-doped thin films on commercially pure titanium (cpTi) discs using the glow discharge plasma approach. Different plasma deposition times (50, 35 and 20 min) were used to create bio-functional surfaces based on silicon films with CHX that were compared to the control groups [no CHX and bulk cpTi surface (machined)]. Physico-chemical and biological characterizations included: 1. Morphology, roughness, elemental chemical composition, film thickness, contact angle and surface free energy; 2. CHX-release rate; 3. Antibacterial effect on Streptococcus sanguinis biofilms at 24, 48 and 72 h; 4. Cytotoxicity and metabolic activity using fibroblasts cell culture (NIH-F3T3 cells) at 1, 2, 3 and 4 days; 5. Protein expression by NIH-F3T3 cells at 1, 2, 3 and 4 days; and 6. Co-culture assay of fibroblasts cells and S. sanguinis to assess live and dead cells on the confocal laser scanning microscopy, mitochondrial activity (XTT), membrane leakage (LDH release), and metabolic activity (WST-1 assay) at 1, 2 and 3 days of co-incubation. Data analysis showed that silicon films, with or without CHX coated cpTi discs, increased surface wettability and free energy (p < 0.05) without affecting surface roughness. CHX release was maintained over a 22-day period and resulted in a significant inhibition of biofilm growth (p < 0.05) at 48 and 72 h of biofilm formation for 50 min and 20 min of plasma deposition time groups, respectively. In general, CHX treatment did not significantly affect NIH-F3T3 cell viability (p > 0.05), whereas cell metabolism (MTT assay) was affected by CHX, with the 35 min of plasma deposition time group displaying the lowest values as compared to bulk cpTi (p < 0.05). Moreover, data analysis showed that films, with or without CHX, significantly affected the expression profile of inflammatory cytokines, including IL-4, IL-6, IL-17, IFN-y and TNF-α by NIH-F3T3 cells (p < 0.05). Co-culture demonstrated that CHX-doped film did not affect the metabolic activity, cytotoxicity and viability of fibroblasts cells (p > 0.05). Altogether, the findings of the current study support the conclusion that silicon films added with CHX can be successfully created on titanium discs and have the potential to affect bacterial growth and inflammatory markers without affecting cell viability/proliferation rates.

Antimicrobial and protective effects of non-thermal plasma treatments on the performance of a resinous liner.

OBJECTIVE: Overcoming substantial shortcomings of soft liners as physico-chemical changes and liner-biofilm-related infections remains a challenge in the rehabilitation treatment. In this study, protective non-thermal plasma (NTP) treatments were developed on the soft liner surface to improve its surface and physico-chemical properties and to reduce fungal colonization after biofilm inhibition challenge. METHODS: Resinous liner specimens (Coe-Soft) were prepared and distributed in 3 groups according to the surface treatments: (1) untreated (control); (2) treated with sulfur hexafluoride-based NTP (SF6); and (3) treated with hexamethyldisiloxane-based NTP (HMDSO). To test the NTP stability and their protective and antimicrobial effect on the liner surface over time, the morphology, chemical composition, roughness, water contact angle, shore A hardness, sorption and solubility were evaluated before and after the specimens were exposed to dual-species biofilm of Candida albicans and Streptococcus oralis for 14 days. Colony forming units and biofilm structure were assessed. Data were submitted to ANOVA and Tukey tests (α = 0.05). RESULTS: Both treatments modified the surface morphology, increased hydrophobicity and roughness of the liner, and were effective to reduce C. albicans adhesion without affecting the commensal health-associated S. oralis. HMDSO presented chemical stability and lower hardness in both periods, whereas SF6 exhibited higher initial hardness than control and the highest sorption; contrarily, similar solubility was noted for all groups. CONCLUSION: HMDSO-based film showed improved physico-chemical properties and inhibited C. albicans biofilm. Thus, it has potential for use to control candida-related stomatitis and improve liner's stability even after being exposed to biofilm inhibition challenge.

Bond strength of lithium disilicate after cleaning methods of the remaining hydrofluoric acid.

BACKGROUND: Different ceramic surface cleaning methods have been suggested after the acid conditioning. The aim was to evaluate the effect of different protocols used to remove the remaining hydrofluoric acid on the shear bond strength (SBS) between lithium disilicate and resin cement. MATERIAL AND METHODS: Forty-four specimens of lithium disilicate (IPS e.max Press) were divided in 4 groups (n=11): group C (control, no treatment); group HF+S (5% hydrofluoric acid + silane); group HF+US+S (5% hydrofluoric acid + ultrasound cleaning + silane); group HF+PH+S (5% hydrofluoric acid + 37% phosphoric acid + silane). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were performed to characterize the surface morphology. The SBS test was performed on the resin/ceramic interface, and the failure mode was characterized. SBS values were submitted to 1-way ANOVA and the Tukey test (α=.05). The relation between surface treatment and failure modes was analyzed using the chi-squared test (α=.05). RESULTS: The surface treatment type interfered in the shear strength (p<.001) and higher SBS values were observed for the groups HF+US+S (17.87 MPa) and HF+PH+S (16.37 MPa). The surface treatment did not influence the failure mode (p=.713). No fluorsilicate salts were observed after ultrasound cleaning. CONCLUSIONS: The utilization of ultrasound cleaning was an effective procedure to remove remaining fluorsilicate salts, promoting the highest SBS values. Key words:Bond strength, ceramics, fluorsilicate, lithium disilicate, resin cement.

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.

Tailoring the synthesis of tantalum-based thin films for biomedical application: Characterization and biological response.

The aim of this study was to tailor the deposition parameters of magnetron sputtering to synthetize tantalum oxide (TaxOy) films onto commercially pure titanium (cpTi) surface. The structural and optical properties, morphology, roughness, elemental chemical composition and surface energy were assessed. The impact of TaxOy films on initial Streptococcus sanguinis adhesion was investigated. The morphology and spreading of pre-osteoblastic (MC3T3-E1) cells on a crystalline tantalum oxide film were evaluated. TaxOy films with estimated thickness of 600 nm and different structures (amorphous or crystalline) were produced depending on the various oxygen flow rates and parameters used. X-ray diffraction analysis revealed that the 8 O2 sccm (600 °C/400 W) group showed crystallization corresponding to the ß-Ta2O5 phase. Optical analysis showed that the 4 O2 sccm (200 °C 300 W) to 8 O2 sccm (600 °C 300 W) groups and 10 O2 sccm (200 °C 300 W) group presented regular and large-amplitude interference oscillations, suggesting high optical homogeneity of the films. The crystalline ß-Ta2O5 coating showed higher roughness and surface energy values than the other groups (P < .05) and was biocompatible. Compared with cpTi, the amorphous and crystalline tantalum oxide films did not increase bacterial adhesion (P > .05). By tailoring the deposition parameters, we synthetized a crystalline ß-Ta2O5 coating that improved titanium surface properties and positively affected cell spreading and morphology, making it a promising surface treatment for titanium-based implants.

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.

Surface characterization of polymers used in fabrication of interim prostheses after treatment with photopolymerized glaze.

The material used for interim prostheses fabrication must present excellent physical properties for greater longevity in the face of environmental conditions, which can occur in the oral cavity. The purpose of this study was to evaluate the effect of a photopolymerized glaze on the physical and mechanical properties of polymers used for the fabrication of interim prostheses, before and after thermocycling and immersion in staining solutions. One hundred samples of composite and acrylic resins were fabricated: Dencor chemically activated acrylic resin (CAAR) (n=20) and heat-polymerized acrylic resin (HPAR) (n=20), Charisma (n=20), Structur (n=20), and Protemp (n=20). A mechanical polishing was performed on half of the samples, and a chemical polishing was performed on the remaining samples. Subsequently, all samples were submitted to thermocycling and immersion in coffee staining solution for 21days. Analysis of color and microhardness, as well as atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive x-ray spectrometry (EDS) were performed. The data were submitted to repeated-measures analysis of variance (ANOVA), followed by the Tukey test (α=0.05) and the Student t-test (α=0.05). It was verified that the glaze decreased the chromatic alteration values, and increased the microhardness values of the samples, with the exception of the Charisma resin. The samples that did not receive chemical polishing had the greatest number of surface irregularities. This study concluded that the groups with glaze presented less color alteration. In addition, Charisma and Structur resins exhibited the greatest chromatic stability. As to the microhardness, the values were greater when the samples were treated with the glaze, with the exception of the Charisma group.

Surface analysis and shear bond strength of zirconia on resin cements after non-thermal plasma treatment and/or primer application for metallic alloys.

There is no established protocol for bonding zirconia (Y-TZP) with resin cements. Non-thermal plasma (NTP) may be an alternative for the clinical problems related to adhesion. The purpose of the present study was to characterize the surface of Y-TZP exposed to methane (CH4) NTP or coated with a layer of primer for metal alloys and the association between the two methods and to evaluate the effect of NTP treatment on bond strength between Y-TZP and two resin cements. A total of 235 Y-TZP discs (8×2mm) were distributed into five groups: Co (no surface treatment), Pr (primer), NTP (methane plasma), Pr+NTP and NTP+Pr. The effect of the treatment type on the surface free energy, morphology, topography and chemical composition of the Y-TZP discs was investigated. The discs were cemented to composite resin substrates using Panavia F2.0 or RelyX U200. Shear bond strength (n=10) analyses were performed (1mm/min) before and after thermocycling (5-55°C, 2000cycles) on the bonded specimens. The data were analyzed with one and three-way ANOVAs and Bonferroni tests (α=0.05). NTP reduced the surface energy and roughness of the Y-TZP discs. SEM-EDS and XPS analyses showed the presence of the organic thin film, which significantly improved the bond strength results when Rely X U200 was used, whereas the primer treatment was more effective with Panavia F2.0. Thermocycling significantly reduced the bond strength results of the NTP and Pr+NTP groups cemented with Rely X U200 and the Pr and NTP+Pr groups cemented with Panavia F2.0. Nonthermal plasma improves the bond strength between Rely X U200 and Y-TZP and also seems to have water-resistant behavior, whereas Panavia F2.0 showed better results when associated with primer.

Deciphering the preservation of fossil insects: a case study from the Crato Member, Early Cretaceous of Brazil.

Exceptionally well-preserved three-dimensional insects with fine details and even labile tissues are ubiquitous in the Crato Member Konservat Lagerstätte (northeastern Brazil). Here we investigate the preservational pathways which yielded such specimens. We employed high resolution techniques (EDXRF, SR-SXS, SEM, EDS, micro Raman, and PIXE) to understand their fossilisation on mineralogical and geochemical grounds. Pseudomorphs of framboidal pyrite, the dominant fossil microfabric, display size variation when comparing cuticle with inner areas or soft tissues, which we interpret as the result of the balance between ion diffusion rates and nucleation rates of pyrite through the originally decaying carcasses. Furthermore, the mineral fabrics are associated with structures that can be the remains of extracellular polymeric substances (EPS). Geochemical data also point to a concentration of Fe, Zn, and Cu in the fossils in comparison to the embedding rock. Therefore, we consider that biofilms of sulphate reducing bacteria (SRB) had a central role in insect decay and mineralisation. Therefore, we shed light on exceptional preservation of fossils by pyritisation in a Cretaceous limestone lacustrine palaeoenvironment.

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.

Toxicity analysis of ocular prosthesis acrylic resin with or without pigment incorporation in human conjunctival cell line.

The aim of this study was to evaluate the influence of pigment incorporation on the cytotoxicity of ocular prosthesis N1 color acrylic resin. Nine samples were manufactured by heat-polymerization in water bath and divided into 3 groups: acrylic resin without pigment incorporation (group R), acrylic resin with pigment incorporation (group RP), and acrylic pigment (group P). Eluates formed after 72h of sample immersion in medium were incubated with conjunctival cell line (Chang conjunctival cells) for 72h. The negative control group consisted in medium without samples (group C). The cytotoxic effect from the eluates was evaluated using MTT assay (cell proliferation), ELISA assay (quantification of IL1ß, IL6, TNF α and CCL3/MIP1α) and RT-PCR assay (mRNA expression of COL IV, TGF ß and MMP9). Data were submitted to ANOVA with Bonferroni post-tests (p<0.05). All groups were considered non-cytotoxic based on cell proliferation. However, resin with pigment incorporation showed significant IL6 quantity increase. Resin without pigment incorporation exhibited higher mRNA expression of COL IV, MMP9 and TGF ß, however it was also observed for the negative control group. The materials exhibited divergent biological behavior. Despite the pigment incorporation that resulted in an increase of IL6, no cytotoxicity was observed based on cell proliferation.