Beta-tricalcium Phosphate Research Articles

Pervasion of beta-tricalcium phosphate with nanodiamond particles yields efficient and safe bone replacement material amenable for biofunctionalization and application in large-size osseous defect healing

Biofunctionalization of scaffold materials can enable the healing of large bone defects. In case of minimally invasive guided-bone regeneration (GBR), limitations are however hard-to-control side effects related to the potential release of biofactors into the systemic environment. Biofactors can be stably bound to nanodiamond particles (ND) through physisorption. We therefore tested the biological and clinical effects of refining beta-tricalcium phosphate (βTCP) with ND in vitro and in vivo. In vitro, βTCP carrying 4% ND resulted in enhanced attachment of mesenchymal stem cells. When assessing GBR after lateral augmentation of the mandible in sheep showed that ND in βTCP resulted in a consistently steady bone formation when compared to pure βTCP, demonstrating the biological inert behavior and the potential clinical safety of ND.

Synergistically enhanced osteoconductivity and anti-inflammation of PLGA/β-TCP/Mg(OH)2 composite for orthopedic applications

Synthetic biodegradable polymers including poly(lactide-co-glycolide) (PLGA) have been widely used as alternatives to metallic implantable materials in the orthopedic field due to their superior biocompatibility and biodegradability. However, weak mechanical properties of the biodegradable polymers and inflammatory reaction caused by the acidic degradation products have limited their biomedical applications. In this study, we have developed a PLGA composite containing beta-tricalcium phosphate (β-TCP) and magnesium hydroxide (Mg(OH)2) as additives to improve mechanical, osteoconductivity, and anti-inflammation property of the biopolymer composite simultaneously. The β-TCP has an osteoconductive effect and the Mg(OH)2 has a pH neutralizing effect. The PLGA/inorganic composites were uniformly blended via a twin extrusion process. The mechanical property of the PLGA/β-TCP/Mg(OH)2 composite was improved compared to the pure PLGA. In particular, the addition of Mg(OH)2 suppressed the inflammatory reaction of normal human osteoblast (NHOst) cells and also inhibited the differentiation of pre-osteoclastic cells into osteoclasts. Moreover, synergistically upregulated late osteogenic differentiation of NHOst cells was observed on the PLGA/β-TCP/Mg(OH)2 composite. Taken all together, we believe that the use of β-TCP and Mg(OH)2 as additives with synthetic biodegradable polymers has great potential by the synergistic effect in orthopedic applications.

Synthesis and Characterization of Novel Crystalline Mesoporous Beta-Tricalcium Phosphate Nanoparticles

A nanosized magnesium substituted beta-tricalcium phosphate (Mg:β-TCP) was synthesized by an aqueous precipitation method, at room temperature, in one single step. In the present study, the novel and stable Mg:β-TCP resulted in a crystalline and spherical nanoparticles (diameter of approximately 20 nm) with mesoporous structures and a high specific surface area (about 574 m2/g). These special characteristics make this novel crystalline mesoporous Mg: β-TCP nanoparticles ideal candidates for drug delivery system and a promising non-viral vector for gene therapy.

Form and functional repair of long bone using 3D-printed bioactive scaffolds.

Injuries to the extremities often require resection of necrotic hard tissue. For large-bone defects, autogenous bone grafting is ideal but, similar to all grafting procedures, is subject to limitations. Synthetic biomaterial-driven engineered healing offers an alternative approach. This work focuses on three-dimensional (3D) printing technology of solid-free form fabrication, more specifically robocasting/direct write. The research hypothesizes that a bioactive calcium-phosphate scaffold may successfully regenerate extensive bony defects in vivo and that newly regenerated bone will demonstrate mechanical properties similar to native bone as healing time elapses. Robocasting technology was used in designing and printing customizable scaffolds, composed of 100% beta tri-calcium phosphate (β-TCP), which were used to repair critical sized long-bone defects. Following full thickness segmental defects (~11mm×full thickness) in the radial diaphysis in New Zealand white rabbits, a custom 3D-printed, 100% β-TCP, scaffold was implanted or left empty (negative control) and allowed to heal over 8, 12, and 24weeks. Scaffolds and bone, en bloc, were subjected to micro-CT and histological analysis for quantification of bone, scaffold and soft tissue expressed as a function of volume percentage. Additionally, biomechanical testing at two different regions, (a) bone in the scaffold and (b) in native radial bone (control), was conducted to assess the newly regenerated bone for reduced elastic modulus (Er ) and hardness (H) using nanoindentation. Histological analysis showed no signs of any adverse immune response while revealing progressive remodelling of bone within the scaffold along with gradual decrease in 3D-scaffold volume over time. Micro-CT images indicated directional bone ingrowth, with an increase in bone formation over time. Reduced elastic modulus (Er ) data for the newly regenerated bone presented statistically homogenous values analogous to native bone at the three time points, whereas hardness (H) values were equivalent to the native radial bone only at 24weeks. The negative control samples showed limited healing at 8weeks. Custom engineered β-TCP scaffolds are biocompatible, resorbable, and can directionally regenerate and remodel bone in a segmental long-bone defect in a rabbit model. Custom designs and fabrication of β-TCP scaffolds for use in other bone defect models warrant further investigation.

Periodontal regeneration with autologous periodontal ligament-derived cell sheets - A safety and efficacy study in ten patients.

BackgroundPeriodontitis results in the destruction of tooth-supporting periodontal tissues and does not have the ability to heal spontaneously. Various approaches have been introduced to regenerate periodontal tissues; however, these approaches have limited efficacy for treating severe defects. Cytotherapies combine stem cell biology and tissue engineering to form a promising approach for overcoming these limitations. In this study, we isolated periodontal ligament (PDL)-derived cells from patients and created cell sheets with “Cell Sheet Engineering Technology”, using temperature responsive culture dishes, in which all the cultured cells can be harvested as an intact transplantable cell sheet by reducing the temperature of the culture dish. Subsequently, the safety and efficacy of autologous PDL-derived cell sheets were evaluated in a clinical setting.MethodsA single-arm and single-institute clinical study was performed to verify the safety and efficacy of autologous PDL-derived cell sheets in patients with periodontitis. Wisdom teeth were extracted from patients diagnosed with chronic periodontitis, ranging in age from 33 to 63 years (mean [±SD], 46 ± 12), and periodontal tissues were scraped for cell sources. Three-layered PDL-derived cell sheets were constructed using temperature-responsive culture dishes and transplanted in an autologous fashion following standard flap surgeries. Bony defects were filled with beta-tricalcium phosphate granules. Clinical variables were evaluated at baseline, 3 months, and 6 months. Cone-beam computed tomography was performed at baseline and 6 months. Additionally, mid-long-term follow-up has been performed with patients’ agreements.ResultsOur method was found to be safe and no severe adverse events were identified. All the findings, including reduction of periodontal probing depth (mean ± SD, 3.2 ± 1.9 mm), clinical attachment gain (2.5 ± 2.6 mm), and increase of radiographic bone height (2.3 ± 1.8 mm), were improved in all 10 cases at 6 months after the transplantation. These therapeutic effects were sustained during a mean follow-up period of 55 ± 19 months, and there were no serious adverse events.ConclusionsThe results of this study validate the safety and efficacy of autologous PDL-derived cell sheets in severe periodontal defects, and the stability of this efficacy during mid-long-term follow up. This cytotherapeutic approach, based on cell sheet engineering, offers an innovative strategy to treat the recognized unmet need of treating severe periodontal defects.

Advantages of creation of holes and removal of air in artificial bone for early bone formation when used artificial bone as a gap filler in open wedge high tibial osteotomy.

Recently, many facilities perform open wedge high tibial osteotomy (OWHTO) using artificial bone as a gap filler. However, there are many cases in which artificial bone is used without a clear purpose. We recommend a surgical technique to promote early synostosis between artificial bone and recipient bone due to mechanical support especially in the early stage after OWHTO. At our hospital, beta-tricalcium phosphate (β-TCP) with 60% porosity is used in OWHTO. Initially, a wedge-shaped block-type β-TCP, as large as possible, was inserted into the gap. However, from the standpoint of initial mechanical support, we changed the artificial bone size and created intentional holes. Furthermore, we removed air bubbles from β-TCP. We evaluated the synostosis on the basis of clinical results and diagnostic imaging. As a result of creating holes and removing air from the artificial bone, a trend toward faster synostosis was noted, especially at the early stage. No adverse events such as tibial plateau fracture, lateral cortical fracture, plate and screw failure and correction loss due to reducing the size of the artificial bone occurred, but placement of the artificial bone in contact with cortical bone and surface contact installation with the recipient bone tissue was important. When using artificial bone in OWHTO, holes formation and removal of air from the artificial bone are recommended for faster synostosis between artificial bone and recipient bone in the early stage after surgery. Artificial bone should be used, with attention to its positioning and shape, for efficient mechanical support.

Use of a three-dimensional printed polylactide-coglycolide/tricalcium phosphate composite scaffold incorporating magnesium powder to enhance bone defect repair in rabbits

BackgroundThe repair of large bone defects remains challenging for orthopaedic surgeons. Bone grafting remains the method of choice; such grafts fill spaces and enhance bone repair. Therapeutic agents also aid bone healing. The objective of this study is to develop a composite bioactive scaffold composed of polylactide-coglycolide (PLGA) and tricalcium phosphate (TCP) (the basic carrier) incorporating osteogenic, bioactive magnesium metal powder (Mg). MethodPorous PLGA/TCP scaffolds incorporating Mg were fabricated using a low-temperature rapid-prototyping process. We term the PLGA/TCP/Mg porous scaffold (hereafter, PPS). PLGA/TCP lacking Mg served as the control material when evaluating the efficacy of PPS. A total of 36 New Zealand white rabbits were randomly divided into blank, PLGA/TCP (P/T) and PPS group, with 12 rabbits in each group. We established bone defects 15 mm in length in rabbit radii to evaluate the in vivo osteogenic potential of the bioactive scaffold in terms of the direct controlled release of osteogenic Mg ion during in vivo scaffold degradation. Radiographs of the operated radii were taken immediately after implantation and then at 2, 4, 8 and 12 weeks. Micro-computed tomography of new bone formation and remaining scaffold and histological analysis were performed at 4, 8, 12 weeks after operation. ResultsX-ray imaging performed at weeks 4, 8 and 12 post-surgery revealed more newly formed bone within defects implanted with PPS and PLGA/TCP scaffolds than blank group (p < 0.05). And micro-computed tomography performed at weeks 4 and 8 after surgery revealed more newly formed bone within defects implanted with PPS scaffolds than PLGA/TCP scaffolds (p < 0.05). Histologically, the PPS group had more newly mineralized bone than controls (p < 0.05). The increases in new bone areas (total implant regions) in the PPS and PLGA/TCP groups were 19.42% and 5.67% at week 4 and 48.23% and 28.93% at week 8, respectively. The percentages of remaining scaffold material in total implant regions in the PPS and PLGA/TCP groups were 53.30% and 7.65% at week 8 and 20.52% and 2.70% at week 12, respectively. ConclusionOur new PPS composite scaffold may be an excellent orthopaedic substitute; it exhibits good biocompatibility and may potentially have clinical utility. Translational potential of this articleMagnesium and beta-tricalcium phosphate had osteoinduction. It is significant to print a novel bone composite scaffold with osteoinduction to repair segmental bone defects. This study evaluated efficacy of PPS in the rabbit radius segmental bone defect model. The results showed that the novel scaffold with good biocompatibility may be an excellent graft and potentially have clinical utility.

Lithium-zirconium silicate glass-ceramics for restorative dentistry: Physicochemical analysis and biological response in contact with human osteoblast

The main aim of this study was to evaluate the physicochemical and biological behavior of (LZS) lithium-zirconium and (LZSA) lithium-zirconium-alumina silicate glass-ceramics. LZS and LZSA silicate glass-ceramics were produced from commercial raw materials by melting (1550 °C/2 h) followed by water-cooling casting. The obtained glass frits were milled by a two-step process (dry and wet milling) up to achieve 5–10 μm particles. The milled powder was uniaxially pressed (50 MPa) and later fired at 900 °C/2 h (LZS) and at 850 °C/2 h (LZSA). Specimens were characterized by physical, chemical, thermal, and cell culture assays. Crystalline phases such ZrSiO4 and residual quartz and lithium metasilicate (Li2SiO3) was found in the LZS group microstructure while LZSA showed a mixture of ZrSiO4 and β-spodumene (LiAlSi2O6). Materials showed different thermal behavior and mechanical properties. LZS silicate glass ceramics revealed higher fracture toughness and Young's modulus values than those recorded for LZSA silicate glass-ceramics. A higher percentage of osteoblast cell proliferation and mineralization was detected on LZS surfaces when compared to LZSA surfaces. The chemical composition, microstructure, thermal behavior, and mechanical strength of LZS and LZSA silicate glass-ceramic can be adjusted for manufacturing of prosthetic structures for oral rehabilitation. Also, the interaction of glass-ceramics with human cells and tissues can be enhanced by increasing the content of bioactive ceramic materials such as silica or by adding additional bioactive compounds such as beta-tricalcium phosphate.

Effect of Freezing Temperature on The Pore Formation of Beta Tricalcium Phosphate Scaffold

Beta-tricalcium phosphate (β-TCP) has been widely used for biomedical application due to its excellent mechanical strength, good tissue compatibility and outstanding chemical stability. There are several methods to fabricate porous scaffolds including solvent casting, phase separation, rapid prototyping and electrospinning methods. In the present study, β-TCP scaffolds were fabricated using freeze drying method. β-TCP slurry was frozen and freeze dried for 24 hours followed by sintering process to form β-TCP scaffolds. The porous β-TCP scaffold were fabricated at different percentages of β-TCP powder used (10 wt. %, 20 wt. % and 30 wt. %) and froze at different freezing temperature (-10°C, -20°C, -40°C and -80°C) in order to study the effect of these parameters on the pore formation of the scaffolds. Scanning electron microscopy (SEM) analysis for 30 wt. % β-TCP scaffold frozen at -10°C revealed acceptable pore size distribution with majority pore size within the range of 102.65 µm to 372.90 µm. Furthermore, this scaffold also possessed highest compressive strength of 0.31 MPa.

XRD Analysis of Calcined Magnesium Substituted Biphasic Calcium Phosphate (Mg-BCP)

The incorporation of magnesium (Mg) in biphasic calcium phosphate (BCP) was prepared through precipitation method. The concentration of added Mg was varied with respect to calcium (Ca) precursor molarity as such Mg/Ca molar ratio were 0.05 and 0.1, while the (Ca + Mg)/P ratio was maintained at 1.59 throughout the experiment to ensure that calcium deficient apatite was formed. Precipitate obtained was aged for 24 h in ambient condition followed by decantation, centrifugation and drying at 90°C overnight. The as-synthesized powders were calcined at 600°C and characterized by X-ray diffraction (XRD) via Rietveld refinement (X’Pert HighScore Plus software). Both as-synthesized and calcined Mg-BCP powder contains hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) phase with Mg in its lattice. The substitution of Mg in calcium-deficient apatite resulted in the formation of biphasic mixtures of β-TCP/HA after calcinations with shifted peaks β-TCP when compared to reference β-TCP peaks. High deficiency of calcium in apatite enables more substitution of magnesium thus stabilizing β-TCP phase when subjected to high temperature.

Fabrication and Characterisation of Gelatine/Hydroxyapatite Porous Scaffold

Hydroxyapatite (HAp) has been used as bone substitute materials due to its bone compatibility after implantation. However, major drawbacks of HAp typical of ceramic materials are its brittleness which limits its applications. Therefore, to introduce toughness in HAp scaffold, gelatine layer was coated on the surface of the HAp scaffold. In this research, porous HAp scaffolds coated with gelatine are fabricated via polymer reticulate method using polyurethane foam (PU) template. Initially, HAp powders were calcined at 1100°C to reduce its viscosity and agglomeration effect when formed into slurry. Preparation of HAp slurry with 40wt% of calcined HAp powders and 3 wt% of polyvinyl alcohol (PVA) powder were prepared before immersing the PU foams. The HAp coated PU foams were then heat treated at 650°C for an hour to burnout all PU, then sintering was done at 1100°C. Finally, the sintered HAp scaffold was coated with 10, 15 and 20wt% of gelatine. Additionally, the gelatine was crosslinked at 130°C and 160°C. Compressive strength analysis shows that as the wt% of gelatine increases the compressive strength of the gelatine/HAp scaffold increases. Highest compressive strength of 71.0 kPa was obtained for 20wt% of gelatine coated on the HAp scaffold. Higher crosslinking temperature also increases the compressive strength. The average compressive strength for gelatine/HAp scaffold crosslinked at 130 °C and 160 °C are 66.4 kPa and 72.3 kPa respectively. XRD analysis shows that 66% of HAp transformed into beta-tricalcium phosphate (β-TCP) after calcination while 71% transformed into β-TCP after sintering. FTIR and EDX analysis showed that the higher amount of gelatine content found in scaffolds with higher crosslinking temperature correlate to the increased in compressive strength. SEM analysis shows that the increased in the compressive strength is attributed to the covering of cracks on the strut of the HAp scaffolds by the gelatine.

Effect of chitosan concentration on the properties of PLA/β-TCP scaffold produced by combination of solvent casting and salt leaching techniques

Polylactic acid (PLA)/beta-tricalcium phosphate (β-TCP) porous scaffold was fabricated using solvent casting and salt leaching. This scaffold is facing problems such as relatively low compressive strength and high brittleness. In order to overcome this problem, natural polymer coated porous scaffold was introduced. In this study, PLA/β-TCP scaffold was coated with four different concentration of chitosan (0.5%, 1.0%, 1.5% and 2.0% w/v). It was found chitosan coated scaffold has higher compressive strength compared to that of uncoated scaffold. The compressive strength of PLA/β-TCP coated with 1.5% w/v of chitosan indicates the highest compressive strength (0.49 MPa), which is 35% increament compared to the uncoated scaffold. Morphological observation by scanning electron microscopy (SEM) revealed that highly porous three-dimensional scaffold with well interconnected porous structure could be achieved by coated and uncoated scaffolds. The results reveal that the scaffold coated with chitosan layer achieves a highly interpenetrated polymer and scaffold network, potentially leading to a porous scaffold with higher mechanical strength and toughness.

Effect of Composition and Temperature to the HA/ß-TCP Composite

The aim of this study is to fabricate hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) composite by varying the HA/β-TCP compositions (100% HA, 80% HA with 20% β-TCP, 60% HA with 40% β-TCP, and 50% HA with 50% β-TCP) and sintering temperatures (1000°C and 1200°C). The powders are mixed with ethanol by using agate mortar, dried in oven (80°C, 24 hours) and uniaxially pressed into 16 mm diameter pellets followed by sintering. Samples are characterized by bulk density testing, phase analysis using X-ray Diffraction (XRD) and Vickers hardness test. Pure HA powder sintered at 1200°C shows the highest density and hardness with 3.090 gcm−3 and 421.70 HV respectively. XRD phase analysis show decrease of HA phase at higher sintering temperature due to phase decomposition of HA into β-TCP and alpha-tricalcium phosphate (α-TCP). Both HA/β-TCP composition and sintering temperature are significant factors to the hardness with sintering temperature the more dominant factor.

Gel casting of β-TCP scaffolds: Effects of foaming time and polymer coating

Three-dimensional interconnected porous structure and ideal mechanical strength are essential for biological scaffold for bone tissue engineering application. However, ceramic scaffold is very brittle and exhibit low strength. The main aim of this study is to investigate the effect of foaming time on the microstructure and mechanical properties of porous beta tricalcium phosphate (β-TCP) scaffold. The effect of polymer coating on the β-TCP scaffold was also investigated. Porous β-TCP scaffolds were fabricated using the gel casting method by varying the foaming time (60s and 90s) followed by sintering at 1100°C. Porous β-TCP scaffold was coated with polymer coating by using dipping method. Results indicate that increased foaming time results in higher porosity and lower compression strength. It is observed that polymer coating improved around 116% compressive strength in comparison to that of uncoated scaffold. Fourier transform infrared (FTIR) confirm the presence of gelatin on scaffold walls. Based on the morphology observed by scanning electron microscope (SEM), it is found that the scaffold fabricated by gel casting method showed open pores characteristic.

In Vitro and In Vivo Characterization of N-Acetyl-L-Cysteine Loaded Beta-Tricalcium Phosphate Scaffolds.

Beta-tricalcium phosphate bioceramics are widely used as bone replacement scaffolds in bone tissue engineering. The purpose of this study is to develop beta-tricalcium phosphate scaffold with the optimum mechanical properties and porosity and to identify the effect of N-acetyl-L-cysteine loaded to beta-tricalcium phosphate scaffold on the enhancement of biocompatibility. The various interconnected porous scaffolds were fabricated using slurries containing various concentrations of beta-tricalcium phosphate and different coating times by replica method using polyurethane foam as a passing material. It was confirmed that the scaffold of 40 w/v% beta-tricalcium phosphate with three coating times had optimum microstructure and mechanical properties for bone tissue engineering application. The various concentration of N-acetyl-L-cysteine was loaded on 40 w/v% beta-tricalcium phosphate scaffold. Scaffold group loaded 5 mM N-acetyl-L-cysteine showed the best viability of MC3T3-E1 preosteoblastic cells in the water-soluble tetrazolium salt assay test.

3D-Plotted Beta-Tricalcium Phosphate Scaffolds with Smaller Pore Sizes Improve In Vivo Bone Regeneration and Biomechanical Properties in a Critical-Sized Calvarial Defect Rat Model.

Due to the difficulty in fabricating bioceramic scaffolds with smaller pore sizes by the current 3D printing technique, the effect of smaller pore sizes (below 400 µm) of 3D printed bioceramic scaffolds on the bone regeneration and biomechanical behavior is never studied. Herein beta-tricalcium phosphate (β-TCP) scaffolds with interconnected smaller pores of three different sizes (100, 250, and 400 µm) are fabricated by 3D plotting. The resultant scaffolds are then implanted into rat critical-sized calvarial defects without any seeded cells. A custom-designed device is developed to investigate the biomechanical properties of the scaffolds after surgical implantation for 4, 8, and 12 weeks. The scaffolds with the 100 µm pore size are found to present the highest maximum load and stiffness, comparable to those of the autogenous bone, after being implanted for 12 weeks. Micro-computed tomography (micro-CT) and histological analysis further indicate that the scaffolds with the 100 µm pore size achieve the highest percentage of new bone ingrowth, which correlates to their best in vivo biomechanical properties. This study demonstrates that tailoring the pore size of β-TCP scaffolds to a smaller range by 3D-plotting can be a facile and efficient approach to enhanced bone regeneration and biomechanical behaviors in bone repair.

The effect of endodontic filling agents on the activity of the regeneration processes of bone tissue in the experiment

Introduction. Highly important is to regenerate the inflammatory destructive processes of bone tissue outside the apical area of the tooth that would optimize reparative bone formation, mineralization of tooth tissues, restoration of periodontal function and stability of tooth to occlusive loads, especially with acquired extensive root apex. Low efficiency of endodontic treatment led to the searching of the new osteotropic drugs of osteoconductive action and biorevitalization to stimulate the repairing and regeneration of tissues outside the apical area and dense obturation of the apex of the tooth root.Aim. of our research was to determine the dynamics of reparative processes in the bone tissue under the influence of drugs and compositions for endodontic treatment based on an analysis of indicators of a mineral metabolism, marker enzymes and an activity of antioxidant system and lipid peroxidation.Material and Methods. An experiment was conducted on 120 white rats. It was created a bone defect, which was filled with studied biomaterials or left with a blood clot. From the experiment the rats were taken out on 14 and 90 day. In homogenates of bone tissue it was examined the activity of lysosomal enzymes — alkaline (ALP) and acid (AP) phosphatases and the content of microelements — calcium and phosphorus. In the blood of rats it was studied the concentration of general protein, lipid peroxidation products — malonic dialdehyde (MDA) and the enzyme activity of antioxidant system — catalase (CAT) and superoxide dismutase (SOD).Results and conclusions. Results of conducted experimental research of the effect of endodontic filling materials on the activity of the regeneration processes of bone tissue show that proposed compositions based on hydroxyapatite and beta-tricalcium phosphate, due to their osteoconductive and biorevitalization qualities, promote more active stimulation of bone tissue regeneration processes compared to generally accepted drugs.

A novel gradated zirconia implant material embedding bioactive ceramics: Osteoblast behavior and physicochemical assessment

Bioactive ceramic coatings have been proposed to improve the bioactivity of zirconia although the coating detachment can occur during implant placement. The main aim of this study was to enhance bioactivity and strength of the implant surface by using a gradated bioactive zirconia structure. Zirconia discs (8 × 3 mm) embedding gradual content of hydroxyapatite (YTZP-HA) or beta-tricalcium phosphate (YTZP-βTCP) were produced by hot-pressing technique. Specimens were initially studied regarding hardness, roughness, wettability, and shear bond strength of the gradated zone. Functionally gradated ceramic discs and zirconia (control group) were placed in contact with human osteoblast culture for 1, 3, 7, and 14 days. Field emission guns scanning electron microscopy (FEGSEM) was used to assess the morphology and adhesion of osteoblasts while cell viability was assessed by fluorometric method. The mineralization on the test and control discs was evaluated by Alkaline phosphatase (ALP) activity and fluorescent microscopy. Shear strength mean values of the outer layer bioactive ceramic and zirconia bulk were recorded at 150 MPa. Mechanical assays demonstrated that the novel design and manufacturing approach proposed for producing gradated zirconia embedding bioactive ceramics resulted in significantly higher mechanical strength as compared to monolithic zirconia. Also, cell viability and ALP levels increased on gradated zirconia containing HA or βTCP over time. Gradated zirconia containing hydroxyapatite revealed an increased viability, bioactivity, and mineralization of human osteoblasts when compared to conventional zirconia surface, without substantial loss of strength.

Effects of solidification cooling rate on the corrosion resistance of a biodegradable β-TCP/Mg-Zn-Ca composite

Biodegradable beta-tricalcium phosphate (β-TCP) particle reinforced magnesium metal matrix composites (Mg-MMC) have attracted increasing interest for application as implant materials. This investigation was conducted to study the effect of cooling rate on the microstructure and corrosion behavior of a biodegradable β-TCP/Mg-Zn-Ca composite. The composite was fabricated under a series of cooling rates using a wedge-shaped casting mold. The microstructure of the composite was examined by optical and scanning electron microscopy, and the corrosion behavior was investigated using an electrochemical workstation and immersion tests in a simulated body fluid (SBF). Faster cooling rates were shown to refine the secondary phase and grain size, and produce a more homogenous microstructure. The refined microstructure resulted in a more uniform distribution of β-TCP particles, which is believed to be beneficial in the formation of a stable and compact corrosion product layer, leading to improved corrosion resistance for the composite.

Budget impact analysis of demineralized bone matrix in combination with autograft in lumbar spinal fusion procedures for the treatment of lumbar degenerative disc disease in Spain

Objective: To estimate the budget impact (BI) of introducing local autograft (LA) combined with demineralized bone matrix (LA + DBM) in lumbar spinal fusion (LSF) procedures to treat lumbar degenerative disc disease (LDDD) in Spain.Methods: A decision tree model was developed to evaluate the 4-year BI associated with introducing LA + DBM putty to replace currently available grafting methods, including iliac crest bone graft (ICBG), LA alone, and LA combined with beta-tricalcium phosphate (LA + ceramics), with 30%, 40%, and 30% market shares, respectively. The analysis was conducted for a hypothetical cohort of 100 patients with LDDD receiving LSF, assuming LA + DBM would replace 100% of the standard of care mix. The fusion rates extracted from the literature were validated by an expert panel. Costs (€2017) were obtained from different Spanish sources. Budget impact and incremental cost per successful fusion were calculated from the perspective of the Spanish National Health System (NHS).Results: Over 4 years, replacing currently available options with LA + DBM for 100 patients resulted in an additional cost of €12,330 (€123/patient), and an additional 14 successful fusions, implying a cost of €881 per additional successful fusion. When costs of productivity loss were included, the introduction of LA + DBM resulted in cost savings of €70,294 (€703/patient).Limitations: The lack of high-quality, homogeneous, head-to-head research studying the efficacy of grafting procedures available to patients undergoing LSF, in addition to a lack of long-term follow-up in existing studies. Therefore, the number of fusions occurring within the model’s time horizon may be underestimated.Conclusions: Acquisition costs of DBM were partially offset by costs of failed fusions, adverse events and reoperation when switching 100 hypothetical LDDD patients undergoing LSF procedures from standard of care grafting methods to LA + DBM from the perspective of the Spanish NHS. DBM cost was entirely offset when costs of lost productivity were considered.