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Biphasic Calcium Phosphate (BCP) bioceramics were prepared in physiological pH. Salts of Calcium and Phosphate with initial molar ratio of Ca/P=1.67, similar to Hydroxyapatite (HA) stoichiometry, were precipitated by the addition of NH4HCO3 1 M. XRD results of the as prepared materials show that high crystalline CaHPO4 center dot 2H(2)O (DCPD) was produced, resulting a decrease of the initial Ca/P ratio. However ageing of the slurry under continuous stirring for 1 and 2 days time, lead to the gradual hydrolysis of dicalcium phosphate dihydrate (DCPD) to low crystalline HA producing biphasic HA/DCPD particles. Ageing time affects also the morphology of the materials. SEM images show that the initial lath-like DCPD particles with HA during the ageing were transformed firstly into bigger particles and flake like particles afterwards. The above mentioned are in accordance to the results of TG/DTA analysis. The morphology and the phase composition of the yielding materials depend on the initial concentration of HCO3- and ageing time. Hydrolysis of NH4HCO3, affects the precipitation of both Ca2+ and PO43- on the starting material, under physiological pH and thus has to be manipulated properly in order to achieve the desirable results in a possible hard tissue evaluation of in vitro bioactivity. (C) 2012 Elsevier Ltd and Techna Group S.r.l All rights reserved. Ceramics International

U ovom radu je izvršeno nanošenje hidroksiapatitnih (HA) prevlaka primenom visokoenergetskog laminarnog plazma sprej postupka. Glavni ciljevi rada su bili: (i) da se ispita uticaj nekoliko parametara procesa nanošenja na hemijska, strukturna i morfološka svojstva HA prevlaka i (ii) da se ispita uticaj ljudskih proteina albumin i gama globulin na početni stadijum procesa biomineralizacije koji se javlja na površini dobijenih HA prevlaka u modifikovanim Kokubo rastvorima (simulirane telesne tečnosti) u kojima je vrednost pH bila aktivno regulisana pomoću CO2... In the present work, hydroxyapatite coatings (HACs) were deposited by using the high power laminar plasma spray process. Major objectives were: (i) to estimate effects of several deposition parameters on chemical, structural, and morphological properties of HACs and (ii) to evaluate effects of human proteins albumin and gamma globulin on the early stage of the biomineralization process on the surface of HACs in modified Kokubo solutions (simulated body fluids) in which the pH value was actively regulated using CO2.

Introdução: A osteointegração de um implante é essencial para garantir êxito clínico. Vários tratamentos de superfície foram introduzidos para melhorar a osseointegração e a biocompatibilidade de um implante. Objectivos: O objectivo de esta revisão bibliográfica é explorar as diferentes propriedades de Titanio e como á modifica-las, depois de introduzir um implante de Titanio num tecido de osso vivo, a osteointrgração, a resposta celular e a biocompatibilidade do implante podem ser afectadas. Materiais e métodos: Para esta revisão bibliográfica, 96 artigos foram usados, tombados das seguintes bases de dados: Pubmed, Science direct and Scielo. Através das seguintes palavras chave: "Surface treatments", "Titanium dental implants", "osseointegration", "anodization", "anodic oxidation", "plasma spraying", "HA coatings", "hydroxyapatite coatings", "acid etching", "grit blasting”, “tribocorrosion" AND “biotribocorrosion”. Conclusão: Foi concluído que a superfície ideal deve presentear uma rugosidade de superfície e 1-2μm, exibir aumentada hidrofilicidade e apresentar uma grossa camada de óxido. Deve também carecer de contaminastes citototòxicos a fim de promover um ambiente biológico favorável e finalmente, foi demonstrado que uma carga negativa promove resposta celular. Introduction: The osseointegration of an implant is essential in order to achieve clinical success. Various surface treatments have been introduced in order to achieve a better osseointegration and biocompatibility of the implant. Objectives: The objective of this review was to explore the different properties of titanium and how by changing them, after a titanium implant being introduced to living bone tissue, osseointegration, cellular response and biocompatibility of the implant can be affected. By this it can be understood what to look for in an implant surface, concluding to the ideal surface characteristics a Ti implant should possess. Materials and Methods: For this review, they were used 96 articles, retrieved from the following search engines: Pubmed, Science direct and Scielo. Through the following key words: "Surface treatments", "Titanium dental implants", "osseointegration", "anodization", "anodic oxidation", "plasma spraying", "HA coatings", "hydroxyapatite coatings", "acid etching", "grit blasting”, “tribocorrosion" AND “biotribocorrosion”. Conclusion: It was concluded that the ideal surface should present a surface roughness of 1-2μm, have increased hydrophilicity and present a thick oxide layer. It should also lack of any cytotoxic contaminants in order to promote a favorable biologic environment and finally, a negative charge has been shown to promote cell response.

The aim of this work was to examine the dependence of the local surface structure (surface structural heterogeneity) on the local thickness (thickness uniformity) and structure properties along the thickness of hydroxyapatite coatings (HACs) deposited by using the high power (52 kW) laminar plasma jet. For the deposition process, a relatively small size of the feedstock hydroxyapatite powder (HAP) (33 mu m) was used. The HACs were deposited at different stand-off distances (SODs) (80, 100, and 150 mm) without preheating of substrates. The thickness measurements were performed by using the calibrated micrometer and light microscopy (LM). The surface micro-structure was analyzed by using the micro-Raman spectroscopy (MRS), whereas the micro-structure along the thickness of HACs was studied by using the MRS, X-ray powder diffractometry (XRPD), and LM (combined with chemical etching). The results showed a heterogeneous phase distribution on the surface of each HAC analyzed as well as the non-uniform thickness of HACs. Apparently, a correlation existed between the local surface structure and the local thickness of HACs. However, the MRS, XRPD, and LM analyses of micro-structure along the thickness of HACs indicated that the differences in the local surface structure could be related to the different recrystallization established during the plasma deposition process in the different parts along the thickness of each HAC analyzed. (C) 2016 Elsevier B.V. All rights reserved.

TiO2 coating offers excellent corrosion resistance and the bone mineral hydroxyapatite (HA) offers very good biocompatibility. A suitable combination of these coatings is expected to produce good corrosion resistance as well as biocompatibility of an implant. Functionally graded coatings containing TiO2 and HA were produced on Ti-6Al-4V. Three sets of coatings were produced. The bare alloy is heated for 2 h at 800 �C to get TiO2 layer to get the first coating. The next coating consists of two layers, namely, (a) TiO2 produced by heat-treatment and (b) a second layer containing 50% TiO2 and 50% HA. The third sample contains three layers, namely, (a) TiO2 produced by heat-treatment as the first layer, followed by (b) a layer containing 50% TiO2 and 50% HA and (c) third layer of HA electrochemically deposited above the second layer. These three samples were subjected to corrosion tests in Simulated Body Fluid (SBF). It was found that coating 1 containing the oxide alone had the highest corrosion resistance followed by coatings 2 and 3. Coating 2 provides corrosion resistance and will show better implant-bone bonding. � 2007 Elsevier B.V. All rights reserved.

The water absorption behavior of bone-cements of PMMA reinforced with 1.5 wt.%, 2.5 wt.%, and 3.5 wt.% silane-treated powders of hydroxyapatite (synthetic, or derived from bovine bones, or teeth enamel), beta-tricalcium phosphate (TCP), bioactive glass (45S5), and zirconia, was investigated. The experimental results showed that addition of calcium phosphate in the polymeric matrix favors water absorption except in the case of enamel hydroxyapatite. Water uptake is also suppressed when 45S5-bioglass or zirconia is added. The solubility is not affected by addition of hydroxyapatite or 45S5-bioglass but it increases when beta-TCP or zirconia is added. A superior behavior of bone-cements reinforced with bioglass-45S5 and enamel hydroxyapatite can be suggested. (c) 2006 Elsevier B.V. All rights reserved. Materials Letters

Composites of titanium and calcium–phosphorus phases were developed by powder metallurgy processing and evaluated for bioactivity. Titanium hydride powder and precursors of calcium and phosphorus in the form of calcium carbonate and di-ammonium hydrogen orthophosphate were mixed in different proportions, compacted and calcined in different atmospheres. The calcined compacts were subsequently crushed, recompacted and sintered in vacuum. In situ formation of bioactive phases like hydroxylapatite, tricalcium phosphate and calcium titanate during the calcination and sintering steps was studied using X-ray diffraction. The effect of calcination atmosphere on density, interconnected porosity, phase composition and modulus of rupture of sintered composites was examined. The sintered composites were immersed in simulated body fluid for 7 days to observe their in vitro behaviour with XRD and FTIR spectroscopic identification of deposits. Composites with 10 wt% precursors sintered from vacuum calcined powder gave the best results in terms of bioactive phases, density and strength.

Item does not contain fulltext The use of endosseous implants is firmly established in skeletal reconstructive surgery, with rapid and permanent fixation of prostheses being a highly desirable feature. Implant coatings composed of hydroxyapatite (HA) have become the standard and have been used with some success in prolonging the time to revision surgery, but aseptic loosening remains a significant issue. The development of a new generation of more biologically active coatings is a promising approach for tackling this problem. Bioactive glasses are an ideal candidate material due to the osteostimulative properties of their dissolution products. However, to date, they have not been formulated with stability to devitrification or thermal expansion coefficients (TECs) that are suitable for stable coating onto metal implants while still retaining their bioactive properties. Here, we present a strontium-substituted bioactive glass (SrBG) implant coating which has been designed to encourage peri-implant bone formation and with a TEC similar to that of HA. The coating can be successfully applied to roughened Ti6Al4V and after implantation into the distal femur and proximal tibia of twenty-seven New Zealand White rabbits for 6, 12, or 24 weeks, it produced no adverse tissue reaction. The glass dissolved over a 6 week period, stimulating enhanced peri-implant bone formation compared with matched HA coated implants in the contralateral limb. Furthermore, superior mechanical fixation was evident in the SrBG group after 24 weeks of implantation. We propose that this coating has the potential to enhance implant fixation in a variety of orthopedic reconstructive surgery applications.

Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuous scanning. The melted structure displayed a multi-layered porous structure. The size range of these pores was about 30-150 mu m. These pores have the propensity to promote osseo-induction. However, when the spot size was increased to 3 mm, the coating was found to display melted structure at energy levels of >6 J. XRD results for the laser treated coating showed increased crystallinity of the HA phase. Favourable amount of crystalline HA was found when the laser pulse energy

Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuous scanning. The melted structure displayed a multi-layered porous structure. The size range of these pores was about 30-150 mu m. These pores have the propensity to promote osseo-induction. However, when the spot size was increased to 3 mm, the coating was found to display melted structure at energy levels of >6 J. XRD results for the laser treated coating showed increased crystallinity of the HA phase. Favourable amount of crystalline HA was found when the laser pulse energy

El objetivo de este trabajo de investigación se basó en el estudio de los parámetros del proceso de deposición de recubrimientos de hidroxiapatita sobre substratos de acero inoxidable implantable mediante el proceso de proyección térmica con plasma atmosférico, que pueden afectar de forma significativa la calidad de los recubrimientos, en cuanto a su cristalinidad y adherencia al substrato. Como parámetros a evaluar se tomaron el tamaño de grano de la hidroxiapatita, el espesor del recubrimiento y la rugosidad superficial del substrato, encontrando que el tamaño de grano de la hidroxiapatita y la rugosidad superficial del substrato son factores significativos, afectando el primero la cristalinidad y el segundo la adherencia, haciendo que estas características mejoren con el aumento de sus valores. Se encuentra también que aunque el espesor no es un factor significativo, puede influir en las características físicas del recubrimiento, afectando su desempeño mecánico. Abstract. El objetivo de este trabajo de investigación se basó en el estudio de los parámetros del proceso de deposición de recubrimientos de hidroxiapatita sobre substratos de acero inoxidable implantable mediante el proceso de proyección térmica con plasma atmosférico, que pueden afectar de forma significativa la calidad de los recubrimientos, en cuanto a su cristalinidad y adherencia al substrato. Como parámetros a evaluar se tomaron el tamaño de grano de la hidroxiapatita, el espesor del recubrimiento y la rugosidad superficial del substrato, encontrando que el tamaño de grano de la hidroxiapatita y la rugosidad superficial del substrato son factores significativos, afectando el primero la cristalinidad y el segundo la adherencia, haciendo que estas características mejoren con el aumento de sus valores. Se encuentra también que aunque el espesor no es un factor significativo, puede influir en las características físicas del recubrimiento, afectando su desempeño mecánico. Maestría

Various surface modifications have been applied to titanium and titanium alloys implants to improve their corrosion resistance and biocompatibility1. In this work Nitinol surface was modified with bioactive, bone-like hydroxyapatite coatings(HA), obtained by two deposition steps: electrochemical and chemical. Each of them has individual formation mechanism and deposited films posses different protection and biocompatible (bioactive) properties. The kinetics of the first step, nucleation of HA precursor film, was studied in situ using chronoamperometry (CA) and cyclic voltammetry (CV). The morphology, microstructure and barrier properties of HA coatings were characterized by field emission scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The chemical composition was examined using energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR).

The physical, chemical and biological properties of the bioglass reinforced yttria-stabilized composite layer on Ti6Al4V titanium substrates were investigated. The Ti6Al4V substrate was deposited with yttria stabilized zirconia - YSZ as the base layer of thickness approximate to 4-5 mu m, to inhibit metal ion leach out from the substrate and bioglass zirconia reinforced composite as the second layer of thickness approximate to 15 mu m, which would react with surrounding bone tissue to enhance bone formation and implant fixation. The deposition of these two layers on the substrate was carried out using the most viable electrophoretic deposition (EPD) technique. Biocompatible yttria-stabilized zirconia (YSZ) in the form of nano-particles and sol gel derived bioglass in the form of micro-particles were chosen as precursors for coating. The coatings were vacuum sintered at 900 degrees C for 3 h. The biocompatibility and corrosion resistance property were studied in osteoblast cell culture and in simulated body fluid (SBF) respectively. Analysis showed that the zirconia reinforced bioglass bilayer system promoted significant bioactivity, and it exhibited a better corrosion resistance property and elevated mechanical strength under load bearing conditions in comparison with the monolayer YSZ coating on Ti6Al4V implant surface. (C) 2013 Elsevier B.V. All rights reserved.

Calcium phosphate based materials of natural origin with photocatalytic properties were produced. Bones of Atlantic cod fish were treated in appropriate solutions (either Ca- or Ti-containing salts) and successively annealed. Results showed multiphasic materials (hydroxyapatite, beta-tricalcium phosphate and anatase titania) with excellent photocatalytic performance under both UV and visible light, with an anatase concentration of only about 2 mol%. Results with such a low amount of anatase have never been reported before for a calcium phosphate-based material; this is attributed to the presence of anatase being mainly on the surface. Single-phase hydroxyapatite (Ca-10(PO4)(6)(OH)(2) or HAp) also showed some photocatalytic properties and antibacterial activity.

W artykule przedstawiono wyniki oceny procesu natryskiwania plazmowego z zawiesin hydroksyapatytu (HA). Zawiesina proszku HA została wytworzona na bazie alkoholu etylowego i wody. Powłoki natryskiwano plazmowo na podłoża tytanowe. Proces nanoszenia powłok badano przy zmiennej odległości natryskiwania i mocy palnika. Do badań powłok zastosowano mikroskop skaningowy. Skład fazowy powłok określono na podstawie dyfraktogramów rentgenowskich. Stosując metodę mikroindentacji, zbadano twardość i moduł sprę- żystości natryskiwanych powłok. Mechanical properties of suspension plasma sprayed hydroxyapatite coatings Abstract The paper presents the results of the evaluation of process of suspension plasma spraying of hydroxyapatite (HA). The suspension of HA powder is produced based on etanol and water. Coatings were plasma sprayed on titanium substrates. The coating was analyzed at varying distances and power of spray gum. To study of coatings used scanning electron microscope. Phase composition of coatings was determined on the basis of X-ray diffraction patterns. Hardness and modulus of elasticity of sprayed coatings were examined using a microindentation method.

This paper reports on the response of hydroxyapatite (HA) coatings, fabricated using two deposition technologies, to immersion in simulated body fluid (SBF). The deposition methods used were: plasma spray, a commercial standard, and CoBlast, a novel low temperature microblast technique. In the case of the latter, HA coatings are deposited by simultaneous blasting HA and abrasive powders concentrically at a metallic substrate, resulting in a thin layer of HA (approx. 2.5 μm thick). Groups of the CoBlast and plasma spray HA coatings were immersed in 7 ml of SBF solution for 1, 2, 4, 7, 14 and 28 days, and were subsequently removed and examined for any alterations caused by the SBF solution. It was noted from this study that the CoBlast HA coatings appeared to undergo a two step calcium phosphate recrystallisation process; initial homogenous nucleation and subsequent heterogeneous nucleation. Conversely recrystallisation on the plasma spray coatings appeared to proceed largely through a heterogeneous nucleation process. Two factors that may influence the differences in HA recrystallisation is the presence of amorphous HA resulting in rapid dissolution, and/or the significantly lower surface area (roughness) offered to the SBF solution by the CoBlast coatings. The interpretation of recrystallisation mechanisms from this preliminary study is limited however by the differences in coating morphology and thickness (27 versus 2 μm) for the plasma spray and CoBlast HA coatings respectively. Science Foundation Ireland Deposited by bulk import kpw3/10/13

Hydroxyapatite (HA) thin-film coatings grown biomimetically using simulated body fluid (SBF) are desirable for a range of applications such as improved fixation of fine- and complex-shaped orthopedic and dental implants, tissue engineering scaffolds and localized and sustained drug delivery. There is a dearth of knowledge on two key aspects of SBF-grown HA coatings: (i) the growth kinetics over short deposition periods, hours rather than weeks; and (ii) possible difference between the coatings deposited with and without periodic SBF replenishment. A study centred on these aspects is reported. X-ray photoelectron spectroscopy (XPS) has been used to study the growth kinetics of SBF-grown HA coatings for deposition periods ranging from 0.5 h to 21 days. The coatings were deposited with and without periodic replenishment of SBF. The XPS studies revealed that: (i) a continuous, stable HA coating fully covered the titanium substrate after a growth period of 13 h without SBF replenishment; (ii) thicker HA coatings about 1 μm in thickness resulted after a growth period of 21 days, both with and without SBF replenishment; and (iii) the Ca/P ratio at the surface of the HA coating was significantly lower than that in its bulk. No significant difference between HA grown with and without periodic replenishment of SBF was found. The coatings were determined to be carbonated, a characteristic desirable for improved implant fixation. The atomic force and scanning electron microscopies results suggested that heterogeneous nucleation and growth are the primary deposition mode for these coatings. Primary osteoblast cell studies demonstrated the biocompatibility of these coatings, i.e., osteoblast colony coverage of approximately 80%, similar to the control substrate (tissue culture polystyrene). Refereed/Peer-reviewed

International audience; The plasma spraying process of hydroxyapatite (HA) suspension was optimized in order to obtain possibly dense and well adherent coatings onto aluminum and titanium alloy substrates. The process variables included the suspension liquid (water, ethanol or their mixture), the pneumatic pressure applied to inject the suspension (0.2 to 0.8 bar), type of injection (nozzle or atomizer), geometry of suspension injection to plasma (internal or external), electric power input to the arc (30 or 40 kW), and spray distance (50, 60 or 80 mm). The screening of spray parameters was made in 23 experimental runs consisting of suspension spraying during a few passes of plasma torch onto aluminum substrate. The microscopic morphology of obtained splats was analyzed using scanning electron microscope (SEM). The analysis enabled to select the optimal parameters of processing used, thereafter, to obtain the coatings. The microstructural observations of the coatings, made using SEM and electron probe microanalysis (EPMA), revealed two zones microstructure: well molten big lamellae and very fine nanometric and submicrometric grains. The phase analysis, made using X-ray diffraction (XRD) and EMPA showed the presence of HA crystal and the phases of its decomposition: tricalcium phosphate (β-TCP), tetracalcium phosphate (TTCP) and calcium oxide (CaO). The mechanical properties, such as critical load, scratch hardness and friction coefficient, of the deposits were characterized using scratch test under a load of 3 to 9 N. The properties were depending on the coatings' substrate. The coatings sprayed onto titanium alloy indicated critical load of 12.3 N and the ones onto aluminum substrate were lower and equal to 10.5 N.

The influence of bond-coating on the mechanical properties of plasma-spray coatings of hydroxyatite on Ti was investigated. Plasma-spray powder was produced from human teeth enamel and dentine. Before processing the main apatite coating, a very thin layer of Al2O3/TiO2 was applied on super clean and roughened, by Al2O3 blasting, Ti surface as bond-coating. The experimental results showed that bond-coating caused significant increase of the mechanical properties of the coating layer: In the case of the enamel powder from 6.66 MPa of the simple coating to 9.71 MPa for the bond-coating and in the case of the dentine powder from 6.27 MPa to 7.84 MPa, respectively. Both tooth derived powders feature high thermal stability likely due to their relatively high content of fluorine. Therefore, F-rich apatites, such those investigated in this study, emerge themselves as superior candidate materials for calcium phosphate coatings of producing medical devices. The methods of apatite powder production and shaping optimization of powder particles are both key factors of a successful coating. The methods used in this study can be adopted as handy, inexpensive and reliable ways to produce high quality of powders for plasma spray purposes. © 2006 Springer Science + Business Media, LLC., Centro de Investigação em Materiais Cerâmicos e Compósitos Fuel Cell Technologies Program, Acknowledgements The authors gratefully acknowledge the assistance of Yasar C¸ elik and Turgut Halamoglu from Senkron Ceramic Coating Inc. for the plasma-coating process, Prof. Dr. Hadi Ozbal from the Chemistry Department of Bogazici University for powder-preparation, and Prof. Dr. Nuri Akkas for the tensile strength tests. The financial support of the Portuguese FCT and CICECO are also gratefully acknowledged.