Hydroxyapatite Bioactive Glass Research Articles

Efficacy of autologous platelet rich fibrin (PRF) and hydroxyapatite bioactive glass (HABG) in the management of intra bony defects -A randomized controlled trial

The ultimate aim of periodontal therapy is regeneration. Traditionally, many techniques and agents were used. The therapeutic outcome in treatment of intra bony defects can be augmented with the use of growth factors alongside bone grafts. The present clinical trial was designed to assess the efficacy of an alloplastic composite graft and the combination of autologous platelet rich fibrin with the graft in the management of intra bony defects. A total of 45 systemically healthy patients with intra bony defects indicated for flap surgery were selected from the outpatient department of periodontics. The patients were divided into three groups with the help of a computer generated random number table. Age, sex, and periodontal parameters (probing pocket depth, clinical attachment level, gingival marginal level, plaque index, modified sulcus bleeding index) and presence of intra bony defects were recorded. The defects in group I patients were treated with autologous PRF along with the graft, group II with graft, and group III with open flap debridement alone. All the patients were recalled at 3, 6, 9 months after surgery, and the periodontal parameters were recorded in each recall. The baseline parameters were compared with 9 month post op periodontal parameters by non parametric test for ANOVA (Kruskal Wallis). Maximum pocket depth reduction (5.86±1.03) maximum gain in attachment (4.64± 1.08), reduction in modified sulcus bleeding index were seen in group I, which is statistically significant between the groups. Though change in gingival marginal level is minimum for group I (1.21± 0.42), it was not statistically significant. Group I showed the maximum percentage of sites with bone fill (92.9%) which was also statistically significant when analyzed by the chi-square test. The Combination of autologous PRF with the hydroxy apatite bioglass graft in the management of intra bony defects showed improved clinical and radiographic outcome.

Evaluation of human amnion denuded derived mesenchymal stem cell on 3D porous hydroxyapatite composite scaffolds for osteogenic differentiation: Prolonged in vitro study

Recent studies using composite porous scaffolds have globally demonstrated the biocompatibility of mesenchymal stem cell sources. It is especially important in hard tissue bioengineering due to its desirable features and stemness effectivity. This study has emphasized primarily the evaluation of the morphological aspects of human amnion-denuded derived mesenchymal stem cells (hAMMSC) in combination with the fabrication of three-dimensional (3D) porous hydroxyapatite (Hap) composite scaffolds for bone tissue engineering based on the principal component of bone mineralization. We presented a novel combination of hAMMSC and nano-crystalline powder hydroxyapatite/bioactive glass (Hap/BG) composite scaffolds fabricated through the hydrothermal method via a novel formulation method from a previous study of stem cell in vitro prolonged culture. The 3D porous scaffold, 6 mm in size, was fabricated from 70 nm nanocrystalline powder and interacted with hAMMSC cultured in osteo-inductive conditions for 30 days. The characterization of 3D porous scaffolds was analyzed via Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) to explore the particle structure, morphology, bioactivity, and porosity of the composite powder and scaffolds in contact with hAMMSCs culture. Furthermore, biocompatibility was assessed using the PrestoBlueTM viability assay and scanning electron microscopy observation (SEM), which revealed the attachment, morphology, and spreading of hAMMSCs on the 3D porous scaffolds of Hap/BG by showing spindle-like morphology and forming the spreading filopodia bridge-like structure within the scaffolds. Subsequently, the secondary objective is the characterization of human AMMSC differentiation capacity assessed by early osteoblast differentiation and mineralization behaviour investigated by early detected assay via alkaline phosphatase activity (ALP) activity marker and energy dispersive X-ray (EDX) analysis simultaneously of the mineralization within bone matrix elements. It was comparatively evaluated via ALP and EDX for calcium quantification elements. Immunomodulatory properties were analyzed via ELISA kits. In conclusion, our findings indicate that 3D porous scaffolds made of Hap/BG composites could be great candidates for future regenerative medicine applications due to their support towards stem cell growth and enhancement of bone cell capacity.

Recent advances on innovative bioactive glass-hydroxyapatite composites for bone tissue applications: Processing, mechanical properties, and biological performance

New Hydroxyapatite-Bioactive Glass composites, xHA-(1-x)BG (x = 25, 50, and 75 wt %), are developed using HA and BGMS10 glass powders co-milled up to 2 h prior to Spark Plasma Sintering (SPS). Ball milling (BM) promoted the consolidation of HA-rich powders, whereas hindered the densification of 25HA-75BG samples. HA crystallite size is reduced from > 200 nm (unmilled) to 60 (x = 25 %) or 88 nm (x = 75 %) when using 2 h milled mixtures. Glass crystallization occurred in 75HA-25BG samples processed by SPS at 950 °C: a negligeable effect in the amount of the residual amorphous phase (12.3–13.3 wt %) is produced by BM, while changes are observed in the relative content of crystalline phases, with SiO2 increases from 8.5 to 13.1 wt %, whereas α- and β-CaSiO3 correspondingly decrease. Superior Young’s modulus and Vickers hardness (130 GPa and 726, respectively) are obtained in HA rich products. Biological tests evidenced that the milling treatment does not determine negative consequences on cells viability.

Mechanical Properties and In Vitro Biocompatibility of Hybrid Polymer-HA/BAG Ceramic Dental Materials

The aim of this study is to prepare hybrid polymer–ceramic dental materials for chairside computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The hybrid polymer–ceramic materials were fabricated via infiltrating polymerizable monomer mixtures into sintered hydroxyapatite/bioactive glass (HA/BAG) ceramic blocks and thermo-curing. The microstructure was observed by scanning electron microscopy and an energy-dispersive spectrometer. The phase structure was analyzed by X-ray diffraction. The composition ratio was analyzed by a thermogravimetric analyzer. The hardness was measured by a Vickers hardness tester. The flexural strength, flexural modulus, and compressive strength were measured and calculated by a universal testing machine. The growth of human gingival fibroblasts was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and immunofluorescence staining. The results showed that the sintering temperature and BAG content affected the mechanical properties of the hybrid polymer–ceramic materials. The X-ray diffraction analysis showed that high-temperature sintering promoted the partial conversion of HA to β-tricalcium phosphate. The values of the hardness, flexural strength, flexural modulus, and compressive strength of all the hybrid polymer–ceramic materials were 0.89–3.51 GPa, 57.61–118.05 MPa, 20.26–39.77 GPa, and 60.36–390.46 MPa, respectively. The mechanical properties of the hybrid polymer–ceramic materials were similar to natural teeth. As a trade-off between flexural strength and hardness, hybrid polymer–ceramic material with 20 wt.% BAG sintered at 1000 °C was the best material. In vitro experiments confirmed the biocompatibility of the hybrid polymer–ceramic material. Therefore, the hybrid polymer–ceramic material is expected to become a new type of dental restoration material.

Evaluation of antibacterial properties of hydroxyapatite/bioactive glass and fluorapatite/bioactive glass nanocomposite foams as a cellular scaffold of bone tissue.

AIMS AND OBJECTIVES:Infection is a serious problem for patients after implantation surgery, which is difficult to treat with antibiotic therapy. The present study was developed to evaluate and compare the antibacterial properties of hydroxyapatite/bioactive glass (HA/BG) and fluorapatite/bioactive glass (FA/BG) nanocomposite foams as a cellular scaffold for use in bone defects by two macrodilution and disk diffusion methods.MATERIALS AND METHODS:Staphylococcus aureus, Enterococcus faecalis, and Streptococcus mutans were cultured in brain heart infusion broth medium with nanocomposite powder for 5 days, and their bioactivity levels were evaluated by daily culturing on solid agar medium plates. To carry out the disk diffusion test, a disc form of nanocomposite foams was used on agar medium with 48 h incubation.RESULTS:None of two nanocomposites even at their highest concentration (200 mg/mL) did not prevent the growth of two Staphylococcus aureus and Enterococcus faecalis microorganisms. However, HA/BG nanocomposite on the 3rd day at a concentration of 200 mg/mL and on 4th and 5th day at a concentration of 100 mg/mL and FA/BG nanocomposite on the 4th day at a concentration of 100 mg/mL and on the 5th day at a concentration of 50 mg/mL could be able to kill Streptococcus mutans microorganism. In the disc diffusion test, none of the nanocomposites could create a nongrowth zone. Both tested biomaterials showed increased antibacterial properties over time and concentration increase.CONCLUSION:HA/BG and FA/BG nanocomposites, due to their biocompatibility and antimicrobial properties, are good choices for implantation instead of damaged bone tissue in tissue engineering.

Histopathological, histomorphometrical, and radiological evaluations of hydroxyapatite/bioactive glass and fluorapatite/bioactive glass nanocomposite foams as cell scaffolds in rat tibia: an in vivo study

Bone defects are common and persistent problems in clinical orthopedics and dentistry. The development of synthetic reconstruction materials is essential owing to the restricted access to natural bone grafts, disease transmission risks, surgical costs, donor-site morbidity, infections, and immune response-related complications. The present study was done to evaluate the histopathological, histomorphometrical, and radiological characteristics of composite foams containing hydroxyapatite/bioactive glass (HA/BG) and fluorapatite/bioactive glass (FA/BG) as cell scaffolds in rat tibia reconstruction. A total of 60 rats were divided into four equal groups, of which three groups were implanted with HA/BG, FA/BG, and CenoBone® biomaterials, and the fourth group served as the implant-free controls. Five rats from each group were sacrificed at 15, 30, or 60 days after implantation, and radiological, histopathological, and histomorphometrical assessments were carried out. Based on the findings, no foreign body reaction was present in the rats. Additionally, bone–biomaterial contact occurred directly without the involvement of connective tissues. The number of osteoblasts was reduced in the implant groups, whereas the trabecular thickness and rate of new bone formation were increased in all groups, where the increase in the FA/BG group was the most prominent. The mean percentage difference in bone density between the implant site and the host bone was greater in the FA/BG group at all three time points of the study. Based on the results of the present study and the positive characteristics of these nanocomposite foams, they can be suitable options for implantation in damaged tissues in tissue engineering.

Effect of forming condition on compressive strength of hydroxyapatite-bioactive glass compact rod

With rising concerns regarding alloy implants, alternative biomaterials are currently studied, to avoid the adverse effects of metal on the human body such as irritation and inflammation. Hydroxyapatite (HA) and Bioactive glass (BG) are two bio-ceramics, which have been implemented in medical applications such as bone implants and fixation parts due to their biocompatibility and close resemblance to the mineralized phase of human bone. Furthermore, these materials can be synthesized from natural sources. In this study, M8 screws rod which are commonly implemented for bone fixation was selected as a case study to investigate an effect of forming conditions on the mechanical property of the composite structure. HA and BG were synthesized and formed into a composite specimen using a hydraulic pressing machine. Full factorial experimental design was employed to solve for an optimal forming condition. 3 factors consisting of mixing ratio, pressure and holding time for pressing were investigated for their impacts on the specimen’s compressive strength. The result revealed that the BG ratio and pressure have a significant effect on the structural strength. The maximum compressive strength of 32.20 MPa was obtained from the specimen with 7.5 wt% of BG, 120 kg/cm2of pressure and 30 second of holding time.

Appropriate Forming Conditions for Hydroxyapatite-Bioactive Glass Compact Scaffold

Biomaterials, such as Hydroxyapatite (HA) and Bioactive glass (BG) have been increasingly implemented in bone substitution due to their biocompatibility and close resemblance to the mineralized phase of human bone. Furthermore, biomaterials can be synthesized from natural sources with calcium-based skeletal structures. In this study, HA and BG were synthesized from bovine bone and mollusk shell, and mixed together to form HA-BG composite biomaterial. Then, the mixtures were compressed into a compact scaffold with dimension of 8×6×8 mm 3 , sintered at 1,000 ˚C for 3 hours and cooled down to room temperature. The compressive strengths of all specimens were evaluated using a universal testing machine. Experimental design was implemented to evaluate the significant factors of forming conditions on the mechanical property of the scaffold. The results revealed that all forming parameters have a significant effect on the mechanical property of the composite scaffolds. Consequently, the highest compressive strength (136.92 MPa) was obtained from the scaffold with a 5.85 wt% of BG, 23.41 MPa of pressure and 65.64 seconds of holding time. In addition, simulations of impact force behavior were performed using Finite Element Analysis which validated the application of the composite scaffold under development.

Modification of electrophoretic deposition of chitosan–bioactive glass–hydroxyapatite nanocomposite coatings for orthopedic applications by changing voltage and deposition time

This article presents electrophoretic depositions of chitosan (CS), bioactive glass (BG), and hydroxyapatite (HA) applied on titanium (Ti) substrate from ethanol-based suspension. The strategy was utilized to modify the deposition of particles with different values of sizes and Zeta potentials, and consequently obtain desirable nanocomposite coating. SEM studies showed that uniform distribution of particles was obtained on isolated substrate at pH 4.5. Moreover, modified deposition of BG microparticles (<37µm) and HA nanoparticles (<150nm) in chitosan matrix was reached by changing voltage and deposition time. The results of X-ray diffraction (XRD) revealed a composite with high content of HA was fabricated at pH 4.5, V=20V, and t=15min. The deposition mechanism at the initial and final times was significantly related to self-assembly of HA nanoparticles that chelated by cationic macromolecular chains and located on BG microparticles, and CS-coated particulates of HA nanoparticles, respectively. The results of potentiodynamic polarization and electrochemical impedance spectroscopy studies demonstrated that the CS–BG–HA composite coating acts as a barrier layer in corrected simulated body fluid (C-SBF).

Effect of different sol-gel synthesis processes on microstructural and morphological characteristics of hydroxyapatite-bioactive glass composite nanopowders

The aim of this work was to study the influence of the different synthesis processes on microstructural and morphological characteristics and distribution of hydroxyapatite-bioactive glass (HAp-BG) composite nanopowders obtained by sol-gel method. HAp-BG composite nanopowders with 20 wt% bioactive glass were prepared using a sol-gel method via four routes: (I) mixing the prepared HAp solution with BG solution before aging time; (II) mixing the prepared BG solution with the prepared HAp gel after gelation; (III) mixing the calcined BG nanopowders with the prepared HAp solution; and (IV) mixing the two prepared calcined nanopowders by mechanochemical activation. The prepared nanopowders were evaluated and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Fourier transform infrared (FTIR), transmission electron diffraction (TEM) and Brunauer-Emmet-Teller (BET) method to investigate the phase structure, microstructure and morphology, functional groups, and the size and distribution of nanopowders. Results indicated that morphology, crystallinity, crystallite size and specific surface area (SSA) of the powders are highly correspondent to the process and type of synthesis method. These findings suggest that the modified sol-gel derived HAp-BG composite nanopowders are expected to efficiently provide a possibility to produce a good candidate to use for fabrication of a bulk nanostructured HAp-BG composite for bone tissue engineering.

A clinical study on the efficacy of hydroxyapatite - Bioactive glass composite granules in the management of periodontal bony defects.

Background:In periodontal regeneration, several alloplastic materials are being used with a goal to reconstruct new osseous tissue in the infrabony defect sites. The present study was undertaken to evaluate the efficacy of hydroxyapatite–bioactive glass (HA:BG) composite granules in the management of periodontal bony defects.Materials and Methods:A randomized control study was conducted. Subjects with infrabony defects were divided into three groups. Test Group 1 (n = 10): Defect site was treated with HA:BG, with a biodegradable membrane. Test Group 2 (n = 10): Defect site was treated with HAP, with a biodegradable membrane. Control group (n = 10): Defect site was treated with open flap debridement with a biodegradable membraneResults:The healing of defects was uneventful and free of any biological complications. The gain in clinical attachment level, reduction of probing pocket depth, and defect fill were statistically significant in all three groups. TG1 sites showed significant defect fill than TG2 and CG sites.Conclusion:The performance of HA:BG was better compared to HAP and open flap debridement for the reconstruction of infrabony defects.

New Approach to Bone Tissue Engineering: Simultaneous Application of Hydroxyapatite and Bioactive Glass Coated on a Poly(l-lactic acid) Scaffold

A combination of bioceramics and polymeric nanofibers holds promising potential for bone tissue engineering applications. In the present study, hydroxyapatite (HA), bioactive glass (BG), and tricalcium phosphate (TCP) particles were coated on the surface of electrospun poly(L-lactic acid) (PLLA) nanofibers, and the capacity of the PLLA, BG-PLLA, HA-PLLA, HA-BG-PLLA, and TCP-PLLA scaffolds for bone regeneration was investigated in rat critical-size defects using digital mammography, multislice spiral-computed tomography (MSCT) imaging, and histological analysis. Electrospun scaffolds exhibited a nanofibrous structure with a homogeneous distribution of bioceramics along the surface of PLLA nanofibers. A total of 8 weeks after implantation, no sign of complication or inflammation was observed at the site of the calvarial bone defect. On the basis of imaging analysis, a higher level of bone reconstruction was observed in the animals receiving HA-, BG-, and TCP-coated scaffolds compared to an untreated control group. In addition, simultaneous coating of HA and BG induced the highest regeneration among all groups. Histological staining confirmed these findings and also showed an efficient osseointegration in HA-BG-coated nanofibers. On the whole, it was demonstrated that nanofibrous structures could serve as an appropriate support to guide the healing process, and coating their surface with bioceramics enhanced bone reconstruction. These bioceramic-coated scaffolds can be used as new bone-graft substitutes capable of efficiently inducing osteoconduction and osseointegration in orthopedic fractures and defects.

Can Iliac Crest Reconstruction Reduce Donor Site Morbidity?

Prospective study. To prospectively validate the hypothesis that iliac crest donor site morbidity may be a structural issue and by reconstructing the crest its incidence might be reduced. The study also evaluates the efficacy of Chitra hydroxyapatite-bioactive glass ceramic composite (Chitra-HABG) as a material for reconstructing the iliac crest. Tricortical iliac crest bone graft harvesting is associated with significant donor site morbidity, varying from 3% to 61%. Reconstruction of the defect has been shown to reduce this morbidity, but the only materials which have been shown to be useful and readily available are bioactive apatite-wollastonite glass ceramic and morcellized beta-tricalcium phosphate. Twenty-six patients in whom tricortical graft was harvested from the iliac crest and defect reconstructed with an indigenously developed and tested graft substitute-Chitra HABG-were followed up to duration of 1 year. Outcome measures were donor site morbidity as assessed clinically and radiologic assessment for ceramic incorporation, dissolution, fragmentation, and migration. At the end of 1 year from surgery, 25 of the 26 patients (96.15%) had no pain at the donor site, which had been reconstructed. Radiologic evaluation showed that in 21 cases the ceramic incorporation was complete, partial in 3, and absent in 2. Partial dissolution of ceramic was noticed in 3 patients and migration in 1. This study validates our hypothesis that the donor site morbidity after tricortical iliac crest graft harvesting is probably a structural issue and it can be reduced by reconstruction of the defect. It also highlights the fact that the Chitra-HABG block is an excellent material for reconstruction of the iliac crest defect, as it gets incorporated into the surrounding bone without adverse effects.

Electrophoretic deposition of bioactive glass/polymer composite coatings with and without HA nanoparticle inclusions for biomedical applications

Electrophoretic deposition (EPD) methods have been developed for the fabrication of composite bioactive glass–hydroxyapatite (HA)–chitosan and bioactive glass–HA–alginate composite coatings. Two different strategies have been utilized, which are based on the use of cationic chitosan and anionic alginate biopolymers. The mechanism of cathodic deposition of chitosan is based on the pH increase at the cathode surface, whereas the pH decrease at the anode surface enabled the deposition of alginate coatings. The use of chitosan and alginate enabled the electrosteric stabilization and deposition of bioactive glass and HA particles. Composite coatings were obtained on various conductive substrates and studied by thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composition of the coatings can be varied by variation of bioactive glass and HA concentrations in the suspensions. The proposed method offers the advantages of room temperature fabrication of bioactive composite coatings that are suitable for biomedical applications.

Hydroxyapatite-Bioactive Glass Ceramic Composite as Stand-alone Graft Substitute for Posterolateral Fusion of Lumbar Spine: A Prospective, Matched, and Controlled Study

Prospective, matched, and controlled study. To evaluate the efficacy of hydroxyapatite-bioactive glass ceramic composite (Chitra-HABg) as a stand-alone graft substitute in promoting posterolateral fusion in the lumbar spine as compared with autologous bone. The use of ceramics as stand-alone graft substitutes in posterolateral fusion remains controversial. The Chitra-HABg is a new composite that has undergone clinical trials in various orthopedic applications with excellent clinical and radiologic outcomes. Twenty-four patients underwent instrumented posterolateral fusion, with Chitra-HABg laid on the left intertransverse bed and autogenous graft on the right side. The primary outcome measure was radiologic consolidation of the graft, and secondary outcome measures were the work status and the Modified Oswestry Disability index. The McNamara and Student chi test were applied for statistical analysis. Although the study was prematurely terminated owing to the high incidence of resorption of Chitra-HABg, 22 of the 24 subjects were followed-up for a minimum of 1 year. At the end of 1-year, excellent radiologic outcome was seen on the right side (autogenous graft) in all the cases, whereas 95% (21/22) of the cases had poor consolidation on the left side (Chitra-HABg). The clinical outcome was rated as good in 16/22 (73%) patients, fair in 5, and poor in only 1 patient, but this had no statistically significant association with the consolidation of the fusion mass. This study clearly demonstrates that hydroxyapatite-bioactive glass ceramic composites (Chitra-HABg) has no role as stand-alone bone graft substitutes in posterolateral fusion of the lumbar spine, as the composite undergoes resorption without the formation of bridging callus. Level 1.

Bioactive Glass Hydroxyapatite in Fronto-Orbital Defect Reconstruction

Synthetic bioactive ceramics and glasses have osteoconductive properties. These materials are capable of chemically bonding to the bone tissue. In addition, special bioactive glasses do not favor microbial growth. In this study, the clinical outcome of bioactive glass and hydroxyapatite in head and neck surgery was evaluated. In a retrospective series of 150 patients, 62 patients underwent reconstruction with frontal sinus obliteration after chronic frontal sinusitis, 65 patients were operated on for fronto-orbital traumas, and 23 patients underwent reconstruction after fronto-orbital tumor resections. These patients were evaluated for surgical procedures, reconstruction materials, complications, and functional outcomes. Three of the 62 frontal sinus occlusions underwent operation (4.8 percent) during the follow-up of 5 years. The reoperations were caused by a new mucocele. In fronto-orbital reconstructions, we have reoperated on the orbital floor in four cases (7 percent). All 12 benign tumor patients and six of 11 malignant tumor patients survived during a follow-up of 3 years. Two of the 23 (9 percent) complicated tumor and trauma patients underwent reoperation because of a local mucocele. Treatment of severe head and neck defects with biomaterial is a suitable alternative to conventional methods. Bioactive materials seem to be stable and reliable at clinical follow-up. The reconstructions with bioactive glass and hydroxyapatite are associated with good functional and aesthetic results without donor-site morbidity. However, more long-term outcomes of studied biomaterials are needed to determine whether they are capable of competing with traditional tissue grafts.

Production of Hydroxyapatite/Bioactive Glass Biomedical Composites by the Hot‐Pressing Technique

Biomedical composites of hydroxyapatite (HA) and bioactive glass (BG) have been difficult to obtain as a dense body without the undesirable occurrence of thermal reactions and phase degradation. Herein, HA–BG dense composites were produced by the hot‐pressing technique. A range of HA–BG powder mixtures (30–50 wt% BG) was fully densified by hot pressing at temperatures as low as ∼700°–800°C. On the other hand, the HA–BG composites could not be densified by pressureless sintering because their composition was degraded due to a severe thermal reaction. The hot‐pressed composites had significantly improved flexural strengths (∼60 MPa) as compared with those subjected to pressureless sintering (∼30 MPa) or the pure HA control (∼40 MPa). The hot‐pressed HA–BG composites showed significantly enhanced bioactivity in a simulated body fluid, as well as osteoblast cell activity with respect to the pure HA, confirming their excellent in vitro biocompatibility.

Characterization of immersed hydroxyapatite-bioactive glass coatings in Hank’s solution

Monolithic HA and hydroxyapatite-bioactive glass (HA–BG) coatings have been plasma-sprayed on Ti–6A1–4V substrate using sinter-granulated HA and HA–BG powders. The immersion behavior of these coatings in Hank’s physiological solution was investigated. The results showed that sinter-granulated monolithic HA powder was irregularly-shaped and appeared quite dense. When 5 wt.% or more BG was added in HA, the powder became rough and porous. X-ray diffraction patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powder. The plasma spray process itself also enhanced the decomposition of apatite. Surface morphology of the present HA–BG coatings was not much different from that of monolithic HA coating, that comprised patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. Reasonably high bond strengths were obtained from all as-plasma-sprayed coatings. When immersed in Hank’s solution, these bond strengths largely declined.

Morphology and immersion behavior of plasma-sprayed hydroxyapatite/bioactive glass coatings.

A series of hydroxyapatite/bioactive glass (HA/BG) coatings have been plasma-sprayed on Ti6Al-4V substrate using HA/BG powders that were prepared by both sinter-granulation and direct mixing methods. The morphology and immersion behavior of these coatings in a simulated body fluid (SBF) were investigated. The results showed that in-house fabricated BG and sinter-granulated HA powders were irregularly shaped and dense. When 5 wt % or more BG was added in HA, the powder became rough and porous. X-ray diffraction (XRD) patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powders. Reasonably high bond strengths were obtained from all coatings. The granulated type HA/BG coatings showed no significant differences in bond strength from the mixed type HA/BG coatings. The plasma spray process itself and the presence of BG enhanced the decomposition of apatite. Surface morphology of all sinter-granulated type coatings was similar to that of monolithic HA coating, that was comprised of patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. The dissolution depth of plasma-sprayed coatings immersed in SBF was largely dependent on the type and composition of the coating. Granulated type HA/BG coatings were much less dissolvable than monolithic HA or mixed type HA/BG coatings. It seems that the presently used granulation method for the preparation of HA/BG powders plays a predominant role in determining the dissolution behavior of the plasma-sprayed coatings.

Structural analysis of hydroxyapatite/bioactive glass composite coatings obtained by plasma spray processing

Bioactive materials such as hydroxyapatite (HA) are used as coatings on metallic implants, producing a conjugate with better performance. The coatings are in general obtained by a plasma spray process. In this work the structural properties of composite coatings hydroxyapatite/bioactive glass (HA/BG) as well as coatings of the pure materials are measured. The coatings were obtained by plasma spraying mixtures of the powders Bioglass® and HA, in different proportions. The process parameters, arc current and primary/secondary gas ratios, were also varied. X-ray diffraction (XRD), infrared spectroscopy and scanning electron microscopy (SEM) measurements were made of the coatings. The in vitro bioactivity of the different coatings was also evaluated. The results showed that Bioglass® addition to the coating powders increased the dissolution rates and rate of formation of a HA film on the surface of the coatings, thus increasing its in vitro bioactivity compared to pure HA coatings.