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1.
Bone Joint J ; 102-B(7_Supple_B): 33-40, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32600210

RESUMO

AIMS: The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions. METHODS: Finite element models of generic cobalt-chromium (CoCr) heads on a titanium stem taper were developed and driven using dynamic assembly loads collected from clinicians. To verify contact mechanics at the taper interface, comparisons of deformed microgroove characteristics (height and width of microgrooves) were made between model estimates with those measured from five retrieved implants. Additionally, these models were used to assess the role of assembly technique-one-hit versus three-hits-on the taper interlock mechanical behaviour. RESULTS: The model compared well to deformed microgrooves from the retrieved implants, predicting changes in microgroove height (mean 1.1 µm (0.2 to 1.3)) and width (mean 7.5 µm (1.0 to 18.5)) within the range of measured changes in height (mean 1.4 µm (0.4 to 2.3); p = 0.109) and width (mean 12.0 µm (1.5 to 25.4); p = 0.470). Consistent with benchtop studies, our model found that increasing assembly load magnitude led to increased taper engagement, contact pressure, and permanent deformation of the stem taper microgrooves. Interestingly, our model found assemblies using three hits at low loads (4 kN) led to decreased taper engagement, contact pressures and microgroove deformations throughout the stem taper compared with tapers assembled with one hit at the same magnitude. CONCLUSION: These findings suggest additional assembly hits at low loads lead to inferior taper interlock strength compared with one firm hit, which may be influenced by loading rate or material strain hardening. These unique models can estimate microgroove deformations representative of real contact mechanics seen on retrievals, which will enable us to better understand how both surgeon assembly techniques and implant design affect taper interlock strength. Cite this article: Bone Joint J 2020;102-B(7 Supple B):33-40.


Assuntos
Artroplastia de Quadril/instrumentação , Simulação por Computador , Prótese de Quadril , Ajuste de Prótese , Ligas de Cromo , Análise de Elementos Finitos , Humanos , Desenho de Prótese , Estresse Mecânico , Propriedades de Superfície , Titânio
2.
Bone Joint J ; 102-B(7_Supple_B): 105-111, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32600211

RESUMO

AIMS: The purpose of this study is to examine six types of bearing surfaces implanted at a single institution over three decades to determine whether the reasons for revision vary among the groups and how long it takes to identify differences in survival. METHODS: We considered six cohorts that included a total of 1,707 primary hips done between 1982 and 2010. These included 223 conventional polyethylene sterilized with γ irradiation in air (CPE-GA), 114 conventional polyethylene sterilized with gas plasma (CPE-GP), 116 crosslinked polyethylene (XLPE), 1,083 metal-on-metal (MOM), 90 ceramic-on-ceramic (COC), and 81 surface arthroplasties (SAs). With the exception of the COC, all other groups used cobalt-chromium (CoCr) femoral heads. The mean follow-up was 10 (0.008 to 35) years. Descriptive statistics with revisions per 100 component years (re/100 yr) and survival analysis with revision for any reason as the endpoint were used to compare bearing surfaces. RESULTS: XLPE liners demonstrated a lower cumulative incidence of revision at 15 years compared to the CPE-GA and CPE-GP groups owing to the absence of wear-related revisions (4% for XLPE vs 18%, p = 0.02, and 15%, p = 0.003, respectively). Revisions for adverse local tissue reactions occurred exclusively among the MOM (0.8 re/100 year) and SA groups (0.1 re/100 year). The revision rate for instability was lower among hips with 36 mm and larger head sizes compared to smaller head sizes (0.2% vs 2%, p < 0.001). CONCLUSION: The introduction of XLPE has eliminated wear-related revisions through 15-year follow-up compared to CPE-GP and CPE-GA. Dislocation incidence has been reduced with the introduction of larger diameter heads but remains a persistent concern. The potential for adverse local tissue reactions with MOM requires continued follow-up. Cite this article: Bone Joint J 2020;102-B(7 Supple B):105-111.


Assuntos
Artroplastia de Quadril/instrumentação , Prótese de Quadril , Desenho de Prótese , Falha de Prótese/tendências , Adulto , Idoso , Cerâmica , Ligas de Cromo , Estudos de Coortes , Seguimentos , Humanos , Instabilidade Articular/cirurgia , Masculino , Próteses Articulares Metal-Metal , Pessoa de Meia-Idade , Polietileno , Reoperação/estatística & dados numéricos , Virginia
3.
Shanghai Kou Qiang Yi Xue ; 29(1): 40-45, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-32524119

RESUMO

PURPOSE: To study the change of ion precipitation and surface roughness of three dental alloys'coexisting in standard electrolyte solution, in order to provide a reference for the selection of clinical alloy materials. METHODS: Standard samples of Ni-Cr alloy, Co-Cr alloy and Au-Ag-Pd alloy were prepared and divided into 5 groups: Ni-Cr alloy(group N), Co-Cr alloy(group C), Au-Ag-Pd alloy(Group A), Ni-Cr alloy contact with Au-Ag-Pd alloy(group NA), Ni-Cr alloy contact with Co-Cr alloy(group NC). All groups of alloys were soaked in standard electrolyte solution (T=37 ℃, pH=2.31) for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the amount of ions released from each group. The surface morphology of each group was observed and the surface roughness(Ra) was measured using atomic force microscope(AFM). SPSS 18.0 software package was used for statistical analysis. RESULTS: The amount of nickel ions released from group N, NA, NC was (1.32±0.03) µg/cm2, (2.13±0.07) µg/cm2, (1.53±0.08) µg/cm2, respectively. Nickel ions of group NA and NC was significantly more than that of group N(P<0.05), nickel ions of group NA was significantly more than that of group NC(P<0.05). The amount of chromium ions released from group N, NA, NC was (0.06±0.01) µg/cm2, (0.08±0.01) µg/cm2, (0.05±0.01) µg/cm2, respectively, the amount of chromium ions of group NA was significantly more than that of group NC(P<0.05). The surface roughness of Ni-Cr alloy in group N, NA, NC was (4.60±0.16) nm, (5.37±0.08) nm, (5.04±0.15) nm, respectively. The surface roughness of Ni-Cr alloy in group NA and group NC was significantly larger than that in group N (P<0.05). When contact with Au-Ag-Pd alloy or Co-Cr alloy, the amount of nickel ions released and the surface roughness of Ni-Cr alloy both significantly increased. Compared with Co-Cr alloy, Au-Ag-Pd alloy caused Ni-Cr alloy to release more nickel, chromium ions and formed a rougher surface.


Assuntos
Ligas de Cromo , Ligas Dentárias , Íons , Teste de Materiais , Níquel , Propriedades de Superfície
4.
Int J Comput Dent ; 23(1): 49-56, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32207461

RESUMO

AIM: Evaluation of appropriate models for computer-aided design/computer-aided manufacturing (CAD/CAM) in vitro studies by investigation of different model materials regarding suitability for intraoral scanners and dimensional stability. MATERIALS AND METHODS: A typodont model was prepared to accommodate a 10-unit prosthesis. The model was duplicated using six different materials: class IV die stone (DS), cobalt-chrome molybdenum (CoCrMo), epoxy resin (EPOX), polyurethane (PU), titanium (TI), and zirconia (ZI). An intraoral scanner was used to obtain three scans of each model. Reference datasets were generated using micro-computed tomography (micro-CT). The first scan was compared with the corresponding reference micro-CT dataset to assess its trueness. The precision was measured by comparing all scans within one test group. For the evaluation of dimensional stability, micro-CT was used to generate three-dimensional (3D) datasets of the models at different time intervals over a 6-week period. The models were kept under constant conditions during the study. All datasets were analyzed with software that determined the deviation of two datasets by alignment using a best-fit algorithm. RESULTS: The criterion of trueness was fulfilled by CoCrMo, EPOX, PU, and the typodont model. Scans of CoCrMo and ZI showed the best precision. PU and the typodont model did not meet the requirement of dimensional stability, whereas EPOX and gypsum were stable only for a period of 10 days. CONCLUSION: The CoCrMo model was the only one that met all the criteria for an appropriate model for CAD/CAM in vitro studies. The other investigated materials either lacked dimensional stability or could not be scanned accurately and reproducibly.


Assuntos
Desenho Assistido por Computador , Adaptação Marginal Dentária , Ligas de Cromo , Técnica de Moldagem Odontológica , Modelos Dentários , Humanos , Imageamento Tridimensional , Titânio , Microtomografia por Raio-X
5.
J Prosthet Dent ; 123(6): 874.e1-874.e7, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32147253

RESUMO

STATEMENT OF PROBLEM: Laser sintering has several processing parameters, typically under the control of dental laboratory technicians. Laser scan speed is an important parameter, which has a significant effect on manufacturing time but may also affect the adaptation of restorations. However, limited information is available regarding its impact. PURPOSE: The purpose of this in vitro study was to evaluate the intaglio surface adaptation of laser-sintered cobalt-chromium single-crown frameworks sintered at laser scanning speeds of 1, 3, and 6 m/s. MATERIAL AND METHODS: A master bronze metal die was prepared and scanned by using a laboratory scanner to fabricate the metal frameworks for 4 groups (n=10). In group C, the frameworks were fabricated by using the lost-wax method (control). In group L1, L3, and L6, the frameworks were fabricated by using direct metal laser melting (DMLM) at laser scanning speeds of 1, 3, and 6 m/s. After fabrication, 3 scanning data sets were used to evaluate the intaglio surface adaptation: the master die, the intaglio surface of each metal framework, and each metal framework seated on the master die. The intaglio surface adaptation of the metal frameworks was evaluated by using a metrology software program. The data were statistically analyzed by using a 1-way ANOVA, the Tukey honestly significant difference test, and the Tamhane T2 test (α=.05). RESULTS: The highest mean intaglio surface discrepancy value was obtained from group L6, and this was significantly different from the other 3 groups (P<.001). No significant intaglio surface discrepancy differences were found among the other groups. CONCLUSION: The amount of intaglio surface discrepancy increased when the laser scanning speed reached 6 m/s.


Assuntos
Coroas , Adaptação Marginal Dentária , Ligas de Cromo , Desenho Assistido por Computador , Planejamento de Prótese Dentária , Lasers
6.
J Prosthodont Res ; 64(4): 468-477, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32063534

RESUMO

PURPOSE: Laboratory and clinical assessment of cast titanium dentures were reported, little is known about additive manufacturing (AM) frameworks. This study evaluated in vitro AM titanium alloy clasps for clinical use. METHODS: After scanning the stainless steel dies to simulate the first molar, an Akers clasp was designed by CAD. AM clasp specimens were manufactured using laser sintering and AM machines from CP titanium grade 2 (CPTi), Ti-6Al-4V (Ti64), and Ti-6Al-7Nb (Ti67) powders. As controls, cast titanium clasps were conventionally made with same three titanium alloys. After nondestructive inspection and surface element analysis, surface roughness, fitness accuracy, initial retentive forces, and changes in retentive forces were measured. RESULTS: Although few porosities and little contamination of AM clasps were confirmed, the AM clasp arm and tip indicated slightly worse fitness accuracy as compared to cast clasps. The initial retentive forces of all titanium clasps showed appropriate retentive forces within the acceptable ranges, AM clasps tended to have lower decreases in retentive forces with up to 10,000 insertion/removal cycles as compared to those of the cast clasps. CONCLUSIONS: AM titanium clasps would be acceptable for clinical use similar to that of cast titanium clasps.


Assuntos
Grampos Dentários , Prótese Parcial Removível , Ligas de Cromo , Retenção de Dentadura , Teste de Materiais , Propriedades de Superfície , Titânio
7.
J Prosthodont Res ; 64(4): 490-497, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32063537

RESUMO

PURPOSE: Not all elements with ß-stabilizing properties in titanium alloys are suitable for biomaterial applications, because corrosion and wear processes release the alloying elements to the surrounding tissue. Chromium and molybdenum were selected as the alloying element in this work as to find balance between the strength and modulus of elasticity of ß-titanium alloys. This study aimed to investigate the effect of Titanium-10Molybdenum-10Chromium (Ti-10Mo-10Cr), Titanium-10Chromium (Ti-10Cr) and Titanium-10Molybdenum (Ti-10Mo) on the elemental leachability in tissue culture environment and their effect on the viability of human gingival fibroblasts (HGFs). METHODS: Each alloy was immersed in growth medium for 0-21 days, and the elution was analyzed to detect the released metals. The elution was further used as the treatment medium and exposed to seeded HGFs overnight. The HGFs were also cultured directly to the titanium alloy for 1, 3 and 7 days. Cell viability was then determined. RESULTS: Six metal elements were detected in the immersion of titanium alloys. Among these elements, molybdenum released from Ti-10Mo-10Cr had the highest concentration throughout the immersion period. Significant difference in the viability of fibroblast cells treated with growth medium containing metals and with direct exposure technique was not observed. The duration of immersion did not significantly affect cell viability. Nevertheless, cell viability was significantly affected after 1 and 7 days of exposure, when the cells were grown directly onto the alloy surfaces. CONCLUSIONS: Within the limitation of this study, the newly developed ß-titanium alloys are non-cytotoxic to human gingival fibroblasts.


Assuntos
Cromo , Titânio , Ligas de Cromo , Corrosão , Teste de Materiais , Molibdênio
8.
J Prosthodont ; 29(3): 251-260, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31782584

RESUMO

PURPOSE: A new type of diazonium-based adhesive has been recently developed by our team to bind dental alloys (Titanium, stainless steel, and cobalt chromium) to dental polymers. Here, we explored the endurance of the resulting adhesive after thermal-cycling and autoclave aging. MATERIALS AND METHODS: Polished samples of titanium (Ti), stainless steel (SS) and cobalt chromium (Co-Cr) were coated with a diazonium-based adhesive. Untreated samples served as controls (n = 12 per each condition). X-ray photoelectron spectroscopy (XPS) was performed to characterize the elemental compositions of the different surfaces. Biocompatibility of the coated alloys was assessed with human gingival fibroblasts (HGF). Inductively coupled plasma (ICP) and total organic carbon (TOC) analyses were used to quantify the ions and organic matters released from the diazonium coated alloys. Endurance of the adhesives was assessed by exposing the samples to autoclaving and thermal-cycling. The tensile strength of the poly(methylmethacrylate) (PMMA)-alloy bond was also tested. RESULTS: Results of mechanical testing demonstrated a higher endurance of the coated CoCr, Ti, and SS compared to the uncoated alloys. The human fibroblasts cultured on the substrates remained alive and metabolically active, and the coatings did not release significant amounts of toxic chemicals in solutions. CONCLUSIONS: The results further support the use of diazonium-based adhesives as new coupling agents for dental applications.


Assuntos
Ligas Dentárias , Cimentos Dentários , Ligas , Ligas de Cromo , Humanos , Teste de Materiais , Propriedades de Superfície , Titânio
9.
J Prosthodont Res ; 64(2): 120-127, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31248826

RESUMO

PURPOSE: To investigate the adhesion strength and bonding interface of layered porcelain to powdered cobalt-chromium (CoCr) processed by two different computer-aided manufacturing methods. METHODS: Sixteen specimens were manufactured from each of Three-dimensionally -printed/laser-sintered (LS) CoCr and milled pre-sintered (SM) CoCr. The specimens were layered with porcelain and 4-point bending was carried out. Nanoindentation was used to calculate changes in elastic modulus and hardness before and after porcelain firing along with adhesion energy. Fracture surface and microstructural changes were examined before and after porcelain firing observed using scanning electron microscopy. RESULTS: The adhesion energy of the LS specimens bonded porcelain were higher than the SM specimens (P<0.05). Analysis of the fracture surfaces showed a predominantly adhesive mode of failure. Elastic-modulus and hardness of the CoCr specimens increased post porcelain firing. Examination using electron-backscatter diffraction (EBSD) showed a fine grain structure for both manufacturing methods. Significant localized changes in the crystal structure post firing were only observed at the surface of the SM specimens. CONCLUSIONS: Both manufacturing methods showed regular microstructures prior to porcelain firing. Laser-sintered CoCr had stronger bonding to porcelain than milled pre-sintered CoCr and was also more stable microstructurally post-ceramic firing. However, both manufacturing methods were deemed to have satisfactory adhesion strength to porcelain. It was also found that increased hardness of CoCr had an inverse relationship with bonding strength. High strength porcelain bonding and stability following multiple ceramic firings indicate suitability for use of these CoCr materials with implant or tooth supported long-span frameworks.


Assuntos
Colagem Dentária , Porcelana Dentária , Cromo , Ligas de Cromo , Cobalto , Teste de Materiais , Ligas Metalo-Cerâmicas , Microscopia Eletrônica de Varredura , Impressão Tridimensional , Propriedades de Superfície
10.
J Prosthet Dent ; 123(1): 42-44, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31153612

RESUMO

A digital process for designing and manufacturing a cobalt-chromium (Co-Cr) surgical template for static computer-aided implant surgery (s-CAIS) is described. The use of Co-Cr provides the advantage of a material with improved mechanical properties to reduce the possibility of surgical template fracture during s-CAIS. The stronger material also allows for a thinner surgical template, which in turn allows better access when the interarch operative space is limited or a longer implant is inserted. Limitations of the technique include the need for computer-aided manufacturing technology and, with the use of Co-Cr, a higher overall cost.


Assuntos
Cobalto , Implantes Dentários , Cromo , Ligas de Cromo , Desenho Assistido por Computador , Planejamento de Prótese Dentária
11.
Chemosphere ; 243: 125205, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31726262

RESUMO

To determine whether the potential effects on liver and kidney caused by dental alloys could be reduced or terminated by the removal of nickel-chromium (Ni-Cr) alloy, cobalt-chromium (Co-Cr) alloy, and commercially pure titanium (CP-Ti), they were placed in the cheek pouches of Syrian hamsters according to ISO 10993-10. Then, the peak/plateau and end times of trace metals in the blood were determined with or without the removal of the dental alloys. Based on these time points, the trace metals and their effects on liver and kidney were examined. We found that trace metals released from these dental alloys and titanium were accumulated transiently in the blood, liver, and kidney but had no effect on the histopathology of the liver or kidney. Although the functions of the liver and kidney were compromised, the function of these tissues seemed to be clinically acceptable compared to those in control Syrian hamsters. In addition, the apoptotic effect on renal cells was terminated by removing the Ni-Cr and Co-Cr alloys, and that on hepatocytes was also eliminated by removing the Ni-Cr alloy. In contrast, the effect of the Co-Cr alloy on hepatocytes was temporary and recovered by itself. Taken together, Ni- and Co-based dental alloys and titanium have no effect on the histopathology or function of liver and kidney. Moreover, Ni-Cr and Co-Cr alloys induce transient trace metal accumulation and apoptotic effects in liver and kidney, which can be reduced or terminated by the removal of the alloys, while CP-Ti shows favorable biocompatibility.


Assuntos
Ligas de Cromo/química , Ligas Dentárias/química , Titânio/química , Ligas , Ligas de Cromo/toxicidade , Ligas Dentárias/toxicidade , Rim , Fígado , Teste de Materiais , Titânio/toxicidade
12.
J Prosthodont Res ; 64(2): 210-216, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31680054

RESUMO

PURPOSE: The purpose of this study was to evaluate internal porosities, retentive force values and survival of cobalt-chromium (Co-Cr) alloy clasps fabricated by direct metal laser-sintering (DMLS) and compare them to conventionally cast clasps. METHODS: Embrasure clasps were digitally designed fitting teeth 35 and 36 on identical metal models (N = 32). Sixteen clasps were fabricated using DMLS (group DMLS) and another sixteen clasps were additively manufactured from wax and then cast from a Co-Cr alloy (group CAST). Internal porosities were examined using micro-focus X-ray (micro-CT) and analyzed applying Kolmogorov-Smirnov test, Mann-Whitney test, and T test (significance level: p < 0.050). A universal testing machine was used to determine the retentive force values at baseline and after 1095, 5475, 10,950 and 65,000 cycles of simulated aging. Data were analyzed employing Kolmogorov-Smirnov test, one-way ANOVA, and Scheffé's post-hoc test (significance level: p < 0.050). Survival was estimated for 65,000 cycles of artificial aging using Kaplan-Meier analysis. RESULTS: Micro-CT analysis revealed a higher prevalence (p < 0.001), but a more homogeneous size and a significantly smaller mean (p = 0.009) and total volume (p < 0.001) of internal porosities for group DMLS. The groups showed mean initial retentive force values of 13.57 N (CAST) and 15.74 N (DMLS), which significantly declined over aging for group CAST (p = 0.003), but not for group DMLS (p = 0.107). Survival was considerably higher for group DMLS (93.8%) than for group CAST (43.8%) after 65,000 cycles of aging. CONCLUSIONS: Clasps made by laser-sintering could be an alternative to conventional cast clasps for the fabrication of removable partial denture frameworks.


Assuntos
Grampos Dentários , Prótese Parcial Removível , Ligas de Cromo , Retenção de Dentadura , Teste de Materiais , Porosidade
13.
Dent Mater J ; 39(1): 9-11, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31511476

RESUMO

The demand for titanium and titanium alloys in dentistry is high. A surveillance survey regarding the clinical and laboratory uses of titanium/titanium alloys in Japan was conducted in this study. The alloys used for casting demonstrated a decreasing tendency in quantity, whereas the use of non-casting titanium alloys increase in the market. This increasing trend is reflected the popularity of CAD/CAM devices. In Japan, the processing technologies of titanium alloys have been improved; therefore, the application of titanium and titanium alloys to dental procedures covered by the insurance is clearly worth considering.


Assuntos
Ligas , Titânio , Ligas de Cromo , Ligas Dentárias , Técnica de Fundição Odontológica , Japão
14.
J Prosthodont ; 29(2): 142-150, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30381847

RESUMO

PURPOSE: To compare the effect of solutions of effervescent tablets (ET), cetylpyridinium chloride (CPC), and experimental solutions of Ricinus communis on the surface of cobalt-chromium (Co-Cr) alloys. MATERIALS AND METHODS: Fifty-five specimens of Co-Cr were prepared by the lost-wax casting method using circular patterns (∅12 × 3 mm). The specimens were randomly divided into 5 groups: deionized water (control); 2% R. communis; 10% R. communis; ET, and CPC. The surface roughness of specimens (n = 10) was evaluated before immersion (baseline), and at simulated times of ½, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, µm) and profilometer (Ra, µm). The surface topography and chemical composition (n = 1) was qualitatively analyzed with scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Data were subjected to Kruskal-Wallis followed by Dunn tests, and Friedman followed by Wilcoxon tests (α = 0.05). RESULTS: For Sa, there was no difference for the solution factor. For the time factor a significant difference was found with 2% R. communis solution among baseline and ½, 2, 3, and 5 years (p < 0.001) and with 10% R. communis solution between 1 and 2 years (p = 0.007), with decreasing roughness over time. For Ra, cetylpyridinium chloride exhibited less roughness than 10% R. communis solution in ½ (p = 0.048) and 5 years (p = 0.013). In the SEM and EDS analysis the solutions did not present deleterious effects or changes in the chemical composition on the surfaces. CONCLUSIONS: Although a significant difference was found for the roughness, the results, below 0.2 µm, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.


Assuntos
Higienizadores de Dentadura , Prótese Parcial Removível , Ligas de Cromo , Teste de Materiais , Propriedades de Superfície
15.
Mater Sci Eng C Mater Biol Appl ; 106: 110156, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753375

RESUMO

The silver contained coatings on cast Cobalt Chrome (CoCr) alloys were prepared by vacuum plasma spraying technique. The Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), energy dispersive spectrometry (EDS), properties of corrosion resistance, wear resistance and effect of vitro antibacterial on the surface of silver contained coating were investigated. The cytotoxicity of the coatings was performed with L-929 fibroblasts by MTT assay. SEM showed that the surfaces of the coatings were dense, smooth, no obvious cracks except only a few pores. XRD analysis indicated that the contents of the surface were mainly Ag and Cr except a small amount of Ag2O, Cr2O3. EDS analysis indicated that the distributions of Cr and Ag were uniform without any large-scale clustering. The wear resistance of silver coatings is similar to that of CoCr alloys, and the corrosion resistance is slightly better than that of CoCr alloys. The Ag coating had no significant effect on the proliferation of L929 cells. The antibacterial results indicated that the number of S. mutans and C. albicans were significantly reduced on the surface of silver contained coating than that of CoCr alloys. All the results indicated that the silver contained coatings can be achieved by vacuum plasma spraying technique with good surface characteristic and antibacterial properties and have promising applications in biomedical area.


Assuntos
Ligas de Cromo/química , Gases em Plasma/química , Prata/química , Animais , Candida albicans/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Ligas de Cromo/farmacologia , Corrosão , Camundongos , Resistência ao Cisalhamento , Staphylococcus/efeitos dos fármacos , Propriedades de Superfície , Vácuo
16.
Biomed Res Int ; 2019: 3649838, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781613

RESUMO

Metal wear debris and released ions (CoCrMo), which are widely generated in metal-on-metal bearings of hip implants, are also found in patients with metal-on-polyethylene bearings due to the mechanically assisted crevice corrosion of modular taper junctions, including head-neck and neck-stem taper interfaces. The resulting adverse reactions to metal debris and metal ions frequently lead to early arthroplasty revision surgery. National guidelines have since been published where the blood metal ion concentration of patients must consistently be monitored after joint replacement to prevent serious complications from developing after surgery. However, to date, the effect of metal particles and metal ions on local biological reactions is complex and still not understood in detail; the present study sought to elucidate the complex mechanism of metal wear-associated inflammation reactions. The knee joints in 4 groups each consisting of 10 female BALB/c mice received injections with cobalt chrome ions, cobalt chrome particles, and ultra-high-molecular-weight polyethylene (UHMWPE) particles or PBS (control). Seven days after injection, the synovial microcirculation and knee joint diameter were assessed via intravital fluorescence microscopy followed by histological evaluation of the synovial layer. Enlarged knee diameter, enhanced leukocyte to endothelial cell interactions, and an increase in functional capillary density within cobalt chrome particle-treated animals were significantly greater than those in the other treatment groups. Subsequently, pseudotumor-like tissue formations were observed only in the synovial tissue layer of the cobalt chrome particle-treated animals. Therefore, these findings strongly suggest that the cobalt chrome particles and not metal ions are the cause for in vivo postsurgery implantation inflammation.


Assuntos
Artroplastia de Quadril/efeitos adversos , Ligas de Cromo/efeitos adversos , Prótese de Quadril/efeitos adversos , Metais/efeitos adversos , Animais , Ligas de Cromo/farmacologia , Corrosão , Modelos Animais de Doenças , Humanos , Inflamação/sangue , Inflamação/induzido quimicamente , Articulação do Joelho/cirurgia , Metais/uso terapêutico , Camundongos , Polietileno/farmacologia , Falha de Prótese/efeitos adversos , Reoperação , Líquido Sinovial/efeitos dos fármacos
17.
Mymensingh Med J ; 28(4): 862-865, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31599252

RESUMO

Although esthetic factors might limit by the presentation of materials used, all-metal complete cast crown should always be offered to patients requiring restoration of endodontically treated posterior tooth. The complete cast crown has the highest longevity of all fixed restorations. It could be used to rebuild a single tooth or a retainer for a fixed prosthesis. It involves all the axial walls as well as the occlusal surface of the tooth to be restored. All restorations are placed in the oral environment in contact with the gingival tissue. Thus clinicians must choose nontoxic or least toxic metal alloys, since any release of elements that might cause reactions. This study was designed to observe clinical responses of nickel chromium alloy and gold alloy cast crown and provide guidance to ascertain the best alloy for cast metal crown, which serves better functional restoration.


Assuntos
Ligas de Ouro , Níquel , Coroa do Dente , Cromo , Ligas de Cromo , Corrosão , Ouro , Humanos
18.
Colloids Surf B Biointerfaces ; 184: 110492, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31522026

RESUMO

The electrochemical properties of CoCrMo alloy immersed in different artificial saliva with or without Ca2+ and albumin were studied by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP), and meanwhile the microstructures features, phase identification and chemical composition of the alloy were analyzed by SEM, EDS, XRD and RA-IR to further understand the electrochemical behavior of the alloy. The results indicated that the self-passivation behavior of the alloy occurred universally and was obviously distinct with each other in different acidic artificial saliva. No phase transformation was observed and the oxide layer and corrosion products exhibited amorphous nature. There was an obvious complexation of the adsorbed albumin with the alloy, and the adsorption capacity of albumin increased with the prolongation of immersion time. The adsorbed albumin presenting black stripped spots had a certain inhibition to the formation of passivation film, and Ca2+ in saliva promoted the further adsorption of albumin as an intermediate bridge, going against the improvement of the corrosion resistance of passivation film/alloy system. In addition, the passivation state of the alloy surface was changed by different methods to investigate the adsorption behavior of albumin and its influence on the further passivation behavior in depth. Hitherto, we tried to propose a model to explain the dynamic adsorption process of albumin and its influencing mechanism on the growth behavior of passivation film.


Assuntos
Albuminas/química , Ligas de Cromo/química , Cobalto/química , Ligas Dentárias/química , Molibdênio/química , Saliva Artificial/química , Adsorção , Espectroscopia Dielétrica , Eletroquímica/métodos , Concentração de Íons de Hidrogênio , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Difração de Raios X
19.
Photobiomodul Photomed Laser Surg ; 37(7): 442-450, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31265379

RESUMO

Objective: This study compared the effects of different surface treatments on the surface roughness (Ra), and shear bond strength (SBS) of resin cement to yttria-stabilized tetragonal zirconia (Y-TZP) ceramic and nickel-chromium (Ni-Cr) base metal alloy, respectively. Materials and methods: Thirty disk-shaped specimens (3 mm height and 10 mm diameter) of each material (Y-TZP and Ni-Cr) were prepared. Both zirconia and metal specimens were randomly assigned to three equal groups, according to the surface treatments (n = 10): sandblasting, sandblasting + Er:YAG laser, and sandblasting + Nd:YAG laser. Resin cement cylinders (4 mm diameter and 3 mm thickness) were placed on each specimen. The SBS tests were performed at a 1 mm per minute crosshead speed through a knife-edge rod after 5000 thermal cycles. The Ra (µm) of the specimens was measured using a profilometer and evaluated topographically by atomic force microscopy and scanning electron microscopy. Analysis of variance, followed by Tukey's honestly significant difference, in addition to the Kruskal-Wallis test, followed by the Mann-Whitney U test, were used for statistical analysis (α = 0.05). Results: Combined sandblasting and laser treatment of the metal groups led to statistically higher Ra values than sandblasting alone (p < 0.05). For Y-TZP, there were no significant differences between the Ra values of the subgroups (p > 0.05). The SBS of the sandblasted metal group was significantly higher than the other two laser-irradiated groups, whereas the SBS of sandblasted zirconia was only significantly higher than the Nd:YAG laser-irradiated group (p < 0.05). Conclusions: Combined laser and sandblasting surface treatments resulted in rougher surfaces than sandblasting alone, especially for the metal specimens. Sandblasting, alone, improved the SBS of resin cement in both metal and zirconia, compared with the laser and sandblasting treatments, combined.


Assuntos
Ligas de Cromo/química , Ligas Dentárias/química , Colagem Dentária/métodos , Corrosão Dentária/métodos , Porcelana Dentária/química , Lasers de Estado Sólido , Cimentos de Resina/química , Ítrio/química , Zircônio/química , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento/efeitos da radiação , Propriedades de Superfície
20.
Int J Cardiovasc Imaging ; 35(11): 1979-1987, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31256285

RESUMO

The purpose of this study was to clarify a cut-off value for acute incomplete stent apposition (ISA) volume and maximum-depth to predict ISA resolution at 1- and 3-month follow-up in patients treated with cobalt-chromium everolimus-eluting stents. In total, 95 cases and 103 stents were registered in the MECHANISM-Elective sub-study. Acute ISA-volume was measured by the trapezoid rule. ISA resolution of cut-off value at 1- and 3-month was estimated by ISA-volume and maximum-depth using receiver operatorating characteristic curve analysis. The total number of analysed acute ISAs was 202 in the 1-month group and 225 in the 3-month group. A total of 123 ISAs at 1-month and a total of 169 ISAs at 3-month had been resolved. The cut-off value of ISA resolution by ISA-volume was 0.169 mm3 at 1-month (AUC: 0.725, sensitivity: 72.2%, specificity: 61.0%) and 0.295 mm3 at 3-month (AUC: 0.757, sensitivity: 75.0%, specificity: 60.4%). The cut-off value of ISA resolution by ISA maximum-depth demonstrated was 0.285 mm at 1-month (area under curve (AUC): 0.789, sensitivity: 70.9%, specificity: 69.9%) and 0.305 mm at 3-month (AUC: 0.663, sensitivity: 60.7%, specificity: 66.9%). Incidence of ISA resolution was significantly lower in combination with cut-off values of ISA-volume and maximum-depth (33%, p < 0.001, at 1-month; 56%, p = 0.003, at 3-month). Combining the cut-off value of ISA-volume with the maximum-depth might be helpful to consider the endpoint of the PCI procedure.


Assuntos
Fármacos Cardiovasculares/administração & dosagem , Ligas de Cromo , Doença da Artéria Coronariana/terapia , Vasos Coronários/diagnóstico por imagem , Stents Farmacológicos , Everolimo/administração & dosagem , Intervenção Coronária Percutânea/instrumentação , Tomografia de Coerência Óptica , Idoso , Fármacos Cardiovasculares/efeitos adversos , Doença da Artéria Coronariana/diagnóstico por imagem , Everolimo/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea/efeitos adversos , Valor Preditivo dos Testes , Estudos Prospectivos , Desenho de Prótese , Sistema de Registros , Reprodutibilidade dos Testes , Fatores de Tempo , Resultado do Tratamento
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