In Situ Characterization of Degradation Behavior of Plasma-Sprayed Coatings on Orthopedic and Dental Implants

2006 ◽  
Vol 49 ◽  
pp. 203-211 ◽  
Author(s):  
Racquel Z. LeGeros ◽  
John P. LeGeros
Keyword(s):  
Calcium Phosphate ◽  
Dental Implants ◽  
Calcium Phosphates ◽  
Interfacial Strength ◽  
Precipitation Method ◽  
Calcium Phosphate Coating ◽  
Implant Surface ◽  
Ha Coating ◽  
Plasma Sprayed

Plasma-sprayed ‘HA’ coatings on commercial orthopedic and dental implants were developed to combine the strength of the metal (Ti or Ti alloy) and the bioactivity of the hydroxyapatite (HA). Several studies have shown that ‘HA’-coated implants provided greater amount of bone attachment, higher bone-implant interfacial strength and accelerated skeletal attachment. However, some reports on implant failures have been attributed to coating delamination and coating early resorption of the plasma sprayed ‘HA’ coating. This paper reviews studies on characterization and degradation of plasma-sprayed ‘HA’ coatings on orthopedic and dental implants and offers alternatives to plasma-spray method of providing calcium phosphate coating. X-ray diffraction analyses showed that plasma-sprayed HA coating consists principally of HA and amorphous calcium phosphate (ACP) with minor amounts of other resorbable calcium phosphates (α- or β-tricalcium phosphates, tetracalcium phosphate), sometimes calcium oxide. The HA/ACP ratios were found to range from 20HA/80ACP to 70HA/30ACP in coated implants from different manufacturers. In vitro initial dissolution rates in acidic buffer (pH 6, 37oC) increased with decreasing HA/ACP ratios in the coating because of the preferential dissolution of the ACP phase. These results suggest that coating with very low HA/ACP ratio may result in the premature resorption of the coating before the bone can attach to the implant thus causing loosening and eventual failure of the implant. Alternatives to plasma-sprayed ‘HA’ are implant surface modifications and low temperature calcium phosphate coatings using electrochemical deposition method or precipitation method.

scholarly journals Mineralization of Titanium Surfaces: Biomimetic Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2879
Author(s):  
Javier Gil ◽  
Jose Maria Manero ◽  
Elisa Ruperez ◽  
Eugenio Velasco-Ortega ◽  
Alvaro Jiménez-Guerra ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Dental Implants ◽  
Early Stage ◽  
Calcium Phosphates ◽  
Biological Fixation ◽  
Biomimetic Surfaces ◽  
Titanium Surfaces ◽  
Deposition Processes ◽  
Fast Dissolution ◽  
Plasma Sprayed

The surface modification by the formation of apatitic compounds, such as hydroxyapatite, improves biological fixation implants at an early stage after implantation. The structure, which is identical to mineral content of human bone, has the potential to be osteoinductive and/or osteoconductive materials. These calcium phosphates provoke the action of the cell signals that interact with the surface after implantation in order to quickly regenerate bone in contact with dental implants with mineral coating. A new generation of calcium phosphate coatings applied on the titanium surfaces of dental implants using laser, plasma-sprayed, laser-ablation, or electrochemical deposition processes produces that response. However, these modifications produce failures and bad responses in long-term behavior. Calcium phosphates films result in heterogeneous degradation due to the lack of crystallinity of the phosphates with a fast dissolution; conversely, the film presents cracks, which produce fractures in the coating. New thermochemical treatments have been developed to obtain biomimetic surfaces with calcium phosphate compounds that overcome the aforementioned problems. Among them, the chemical modification using biomineralization treatments has been extended to other materials, including composites, bioceramics, biopolymers, peptides, organic molecules, and other metallic materials, showing the potential for growing a calcium phosphate layer under biomimetic conditions.

Growth of Calcium Phosphate Coating on Ti-7.5Mo Alloy after Anodic Oxidation

2013 ◽  
Vol 334-335 ◽  
pp. 297-302 ◽  
Author(s):  
A.L.A. Escada ◽  
João Paulo Barros Machado ◽  
Roberto Zenhei Nakazato ◽  
Ana Paula Rosifini Alves Claro
Keyword(s):  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Calcium Phosphates ◽  
Sodium Titanate ◽  
Ammonium Fluoride ◽  
Biological Properties ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. Among the various materials for implants, calcium phosphates and hydroxyapatite are widely used clinically. In this work, titanium nanotubes were fabricated on the surface of Ti-7.5Mo alloy by anodization. The samples were anodized for 20 V in an electrolyte containing glycerol in combination with ammonium fluoride (NH4F, 0.25%), and the anodization time was 24 h. After being anodized, specimens were heat treated at 450 °C and 600°C for 1 h to crystallize the amorphous TiO2 nanotubes and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. Surface morphology and coating chemistry were obtained respectively using, field-emission scanning electron microscopy (FEG-SEM), AFM and X-ray diffraction (XRD). It was shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent in-vitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nanodimensioned calcium phosphate. It was possible to observe the formation of TiO2 nanotubes on the surface of Ti-7.5Mo. Calcium phosphate coating was greater in the samples with larger nanotube diameter. These findings represent a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications.

In Vitro Dissolution of Amorphous Calcium Phosphate (ACP) Increased the Wear Particle Generation of Plasma-Sprayed HA Coatings

2007 ◽  
Vol 330-332 ◽  
pp. 561-564
Author(s):  
Wei Dong Tong ◽  
Pan Jian Li
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Morphological Changes ◽  
Wear Particle ◽  
In Vitro Dissolution ◽  
Wear Particles ◽  
Particle Generation ◽  
Ha Coating ◽  
Plasma Sprayed

Hydroxyapatite (HA) coated total hip joint device has caused concerns of generating wear particles after long-term implantation. We designed a pin-on-disk (POD) test to examine the morphological changes and wear particle generation of plasma sprayed HA coating in vitro. HA coatings were immersed in supplemented α-calf bovine serum for 48 hours. Serum soaked HA coating exhibited significant amount of weight loss due to dissolution of amorphous calcium phosphate (ACP). POD test demonstrated the serum soaked HA coatings presented many micronsized particles on the surface while the as-received HA coatings maintained good integrity. The generation of wear particles of the serum soaked HA coatings is related to the reduction of the cohesion/adhesion of HA coatings due to the preferential dissolution of ACP.

Electrochemically Deposited Calcium Phosphate Coating on Titanium Alloy Substrates

2005 ◽  
Vol 284-286 ◽  
pp. 247-250 ◽  
Author(s):  
John P. LeGeros ◽  
Shu Jie Lin ◽  
Dindo Q. Mijares ◽  
Fred Dimaano ◽  
Racquel Z. LeGeros
Keyword(s):  
Calcium Phosphate ◽  
Electric Fields ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Calcium Phosphate Coating ◽  
Pulse Time ◽  
Uniform Coating ◽  
Spray Method ◽  
Electrochemically Deposited ◽  
Plasma Sprayed

Plasma-sprayed HA coating combines the strength of the metal and the bioactivity of the HA. However, this method has several disadvantages. Alternatives to the plasma-spray method such as electrochemical deposition (ECD) and biomimetic or precipitation methods are being explored. The purpose of this study was to develop an ECD method for coating Ti alloy substrate with different calcium phosphates (octacalcium phosphate, calcium deficient apatite, carbonatesubstituted apatite, fluoride-substituted apatite). Pairs of Ti6Al4V plates that have been mechanically polished, ultrasonically cleaned, acid etched, rinsed and dried were used as anodes and cathodes. ECD was carried out using programmed pulse time electric fields. Results showed that uniform coating with only the desired calcium phosphate can be obtained using metastable calcium phosphate solutions at different pH and temperature conditions and different electrolyte concentrations. Coating thickness varied with the duration of coating deposition. Crystal size varied with other ECD conditions (e.g., pulse time, current density). This method can be used to obtain uniform coating of the desired calcium phosphate composition at low temperatures (25 to 80oC) on substrates of any type of geometry.

scholarly journals Macrophagic Inflammatory Response Next to Dental Implants with Different Macro- and Micro-Structure: An In Vitro Study

2021 ◽  
Vol 11 (12) ◽  
pp. 5324
Author(s):  
Maria Menini ◽  
Francesca Delucchi ◽  
Domenico Baldi ◽  
Francesco Pera ◽  
Francesco Bagnasco ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Dental Implants ◽  
In Vitro Study ◽  
Titanium Implants ◽  
Implant Surface ◽  
Bone Implant ◽  
Optimal Outcomes ◽  
Negative Controls ◽  
Inflammatory Effect

(1) Background: Intrinsic characteristics of the implant surface and the possible presence of endotoxins may affect the bone–implant interface and cause an inflammatory response. This study aims to evaluate the possible inflammatory response induced in vitro in macrophages in contact with five different commercially available dental implants. (2) Methods: one zirconia implant NobelPearl® (Nobel Biocare) and four titanium implants, Syra® (Sweden & Martina), Prama® (Sweden & Martina), 3iT3® (Biomet 3i) and Shard® (Mech & Human), were evaluated. After 4 h of contact of murine macrophage cells J774a.1 with the implants, the total RNA was extracted, transcribed to cDNA and the gene expression of the macrophages was evaluated by quantitative PCR (qPCR) in relation to the following genes: GAPDH, YWHAZ, IL1β, IL6, TNFα, NOS2, MMP-9, MMP-8 and TIMP3. The results were statistically analyzed and compared with negative controls. (3) Results: No implant triggered a significant inflammatory response in macrophages, although 3iT3 exhibited a slight pro-inflammatory effect compared to other samples. (4) Conclusions: All the samples showed optimal outcomes without any inflammatory stimulus on the examined macrophagic cells.

scholarly journals Amorphous–Crystalline Calcium Phosphate Coating Promotes In Vitro Growth of Tumor-Derived Jurkat T Cells Activated by Anti-CD2/CD3/CD28 Antibodies

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3693
Author(s):  
Yurii P. Sharkeev ◽  
Ekaterina G. Komarova ◽  
Valentina V. Chebodaeva ◽  
Mariya B. Sedelnikova ◽  
Aleksandr M. Zakharenko ◽  
...  
Keyword(s):  
T Cells ◽  
Calcium Phosphate ◽  
Biological Effects ◽  
Electrical Potential ◽  
Biological Properties ◽  
Modern Trend ◽  
Calcium Phosphate Coating ◽  
Jurkat T Cells ◽  
Micro Arc Oxidation

A modern trend in traumatology, orthopedics, and implantology is the development of materials and coatings with an amorphous–crystalline structure that exhibits excellent biocopatibility. The structure and physico–chemical and biological properties of calcium phosphate (CaP) coatings deposited on Ti plates using the micro-arc oxidation (MAO) method under different voltages (200, 250, and 300 V) were studied. Amorphous, nanocrystalline, and microcrystalline statesof CaHPO4 and β-Ca2P2O7were observed in the coatings using TEM and XRD. The increase in MAO voltage resulted in augmentation of the surface roughness Ra from 2.5 to 6.5 µm, mass from 10 to 25 mg, thickness from 50 to 105 µm, and Ca/P ratio from 0.3 to 0.6. The electrical potential (EP) of the CaP coatings changed from −456 to −535 mV, while the zeta potential (ZP) decreased from −53 to −40 mV following an increase in the values of the MAO voltage. Numerous correlations of physical and chemical indices of CaP coatings were estimated. A decrease in the ZP magnitudes of CaP coatings deposited at 200–250 V was strongly associated with elevated hTERT expression in tumor-derived Jurkat T cells preliminarily activated with anti-CD2/CD3/CD28 antibodies and then contacted in vitro with CaP-coated samples for 14 days. In turn, in vitro survival of CD4+ subsets was enhanced, with proinflammatory cytokine secretion of activated Jurkat T cells. Thus, the applied MAO voltage allowed the regulation of the physicochemical properties of amorphous–crystalline CaP-coatings on Ti substrates to a certain extent. This method may be used as a technological mechanism to trigger the behavior of cells through contact with micro-arc CaP coatings. The possible role of negative ZP and Ca2+ as effectors of the biological effects of amorphous–crystalline CaP coatings is discussed. Micro-arc CaP coatings should be carefully tested to determine their suitability for use in patients with chronic lymphoid malignancies.

Calcium Phosphate Coating on Blast-Treated Titanium Implants by RF Magnetron Sputtering

2009 ◽  
Vol 631-632 ◽  
pp. 211-216 ◽  
Author(s):  
Kyosuke Ueda ◽  
Takayuki Narushima ◽  
Takashi Goto ◽  
T. Katsube ◽  
Hironobu Nakagawa ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Magnetron Sputtering ◽  
Bonding Strength ◽  
Rf Magnetron Sputtering ◽  
Titanium Implants ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating ◽  
Coating Films

Calcium phosphate coating films were fabricated on Ti-6Al-4V plates and screw-type implants with a blast-treated surface using radiofrequency (RF) magnetron sputtering and were evaluated in vitro and in vivo. Amorphous calcium phosphate (ACP) and oxyapatite (OAp) films obtained in this study could cover the blast-treated substrate very efficiently, maintaining the surface roughness. For the in vitro evaluations of the calcium phosphate coating films, bonding strength and alkaline phosphatase (ALP) activity were examined. The bonding strength of the coating films to a blast-treated substrate exceeded 60 MPa, independent of film phases except for the film after post-heat-treatment in silica ampoule. When compared with an uncoated substrate, the increase in the ALP activity of osteoblastic SaOS-2 cells on a calcium phosphate coated substrate was confirmed by a cell culture test. The removal torque of screw-type Ti-6Al-4V implants with a blast-treated surface from the femur of Japanese white rabbit increased with the duration of implantation and it was statistically improved by coating an ACP film 2 weeks after implantation. The in vitro and in vivo studies suggested that the application of the sputtered ACP film as a coating on titanium implants was effective in improving their biocompatibility with bones.

Hydrothermal Growth of Nano-Hydroxyapatite Coating Formed on Fluorinated Magnesium Alloy and Its Corrosion Behaviour

2021 ◽  
Vol 13 (1) ◽  
pp. 10-19
Author(s):  
Chun-Yan Zhang ◽  
Hao-Lan Fang ◽  
Xin-Peng Liu ◽  
Fan-Cheng Meng ◽  
Zhong-Qing Tian ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Calcium Phosphate ◽  
Hydrothermal Treatment ◽  
Treatment Time ◽  
Electrochemical Impedance ◽  
Hydrothermal Growth ◽  
Crystal Phase ◽  
Calcium Phosphate Coating ◽  
Phosphate Coating ◽  
Ha Coating

In order to explore the hydrothermal growth mechanism of hydroxyapatite (HA) coating on fluorinated magnesium alloy, the changes of morphology, composition and crystal phase of the calcium phosphate coating during the hydrothermal treatment were studied. And the change of electrochemical impedance spectroscopy (EIS) of the coating specimen of different hydrothermal treatment time was discussed to further understanding the change of the coating structure. The results demonstrated that calcium phosphate could rapidly nucleate on fluorinated AZ31 magnesium alloy. The crystal phase of calcium phosphate coating was mainly octacalcium phosphate (OCP) at the early stage of hydrothermal treatment. Then the content of OCP decreased and the content of HA increased with hydrothermal time. The coating consisted of only HA after hydrothermal treatment for about 4h. The HA coating composed of rod-like crystals exhibited an obvious double layer structure. The rod-like crystals of inner layer arranged into dense bundles and the rod-like crystals of outer layer arranged into loose chrysanthemum-like clusters. Fluoride conversion layer acted as an intermediate transition layer to connect magnesium alloy and HA coating into a whole. The results of immersion test in simulated body fluid demonstrated that HA crystals dissolved slowly. No peeling occurred of HA coating during the 12 days' immersion. Pitting corrosion was still the mainly corrosion mode of magnesium alloy substrate due to the electrolyte infiltration during the immersion.

scholarly journals Organic/Inorganic bioactive materials Part III: in vitro bioactivity of gelatin/silicocarnotite hybrids

2009 ◽  
Vol 7 (4) ◽  
pp. 721-730 ◽  
Author(s):  
Lachezar Radev ◽  
Maria Fernandes ◽  
Isabel Salvado ◽  
Daniela Kovacheva
Keyword(s):  
Calcium Phosphate ◽  
Hybrid Materials ◽  
Calcium Phosphates ◽  
Ceramic Powder ◽  
Structure Evolution ◽  
In Vitro Test ◽  
In Vitro Bioactivity ◽  
Bioactive Materials ◽  
Vitro Test

AbstractIn this work we present our experimental results on synthesis, structure evolution and in vitro bioactivity assessment of new gelatin/silicocarnotite hybrid materials. The hybrids were obtained by diluting gelatin (G) and silicocarnotite (S) ceramic powder with G:S ratios of 75:25 and 25:75 wt.% in hot (40°C) water. The hybrids were characterized using XRD, FTIR, SEM/EDS and XPS. FTIR depicts that the “red shift” of amide I and COO− could be attributed to the fact that the gelatin prefers to chelate Ca2+ from S. The growth of calcium phosphates on the surface of the hybrids synthesized and then immersed in 1.5 SBF for 3 days was studied by using of FTIR, XRD and SEM/EDS. According to FTIR results, after an immersion of 3 days, A and B-type CO3HA can be observed on the surface. XRD results indicate the presence of hydroxyapatite with well defined crystallinity. SEM/EDS of the precipitated layers show the presence of CO3HA and amorphous calcium phosphate on the surface of samples with different G/S content when immersed in 1.5 SBF. XPS of the G/S hybrid with 25:75 wt.% proved the presence of Ca-deficient hydroxyapatite after an in vitro test for 3 days.

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