Beta-tricalcium Phosphate Research Articles

Finite element analysis of the effect of boron nitride nanotubes in beta tricalcium phosphate and hydroxyapatite elastic modulus using the RVE model

A numerical study was carried out to determine the effect of the boron nitride nanotubes (BNNTs) as a reinforcement element for two different implant materials. Random distribution of the BNNTs was reconstructed using the random sequential adsorption algorithm in the beta tricalcium phosphate (β-TCP) and hydroxyapatite (HA) matrixes. A representative volume element (RVE) with 4% wt. of the BNNTs in β-TCP and HA matrixes was prepared. The predicted elastic moduli of the β-TCP-BNNTs and HA-BNNTs composites showed 24.1% and 26.3% enhancement, respectively, compared with the pure β-TCP and HA. To validate our finite element method (FEM) analysis results, we used a modified Halpin–Tsai (H-T) approach to calculate the elastic modulus of the models. The results showed that the FEM and H-T were in good agreement, with 1.5% and 2.7% deviations for the β-TCP-BNNTs and HA-BNNTs composites, respectively. In contrast, a major gap was found between our theoretical approaches and experimental results for the HA-BNNTs composite that is available in the literature. This deviation was probably a consequence of the manufacturing method of the composite, which was not considered in the RVE model.

Periodontal tissue engineering by nano beta-tricalcium phosphate scaffold and fibroblast growth factor-2 in one-wall infrabony defects of dogs.

Nanoparticle bioceramics are being investigated for biomedical applications. We fabricated a regenerative scaffold comprising type I collagen and beta-tricalcium phosphate (β-TCP) nanoparticles. Fibroblast growth factor-2 (FGF-2) is a bioeffective signaling molecule that stimulates cell proliferation and wound healing. This study examined the effects, on bioactivity, of a nano-β-TCP/collagen scaffold loaded with FGF-2, particularly on periodontal tissue wound healing. Beta-tricalcium phosphate was pulverized into nanosize particles (84 nm) and was then dispersed. A nano-β-TCP scaffold was prepared by coating the surface of a collagen scaffold with a nanosize β-TCP dispersion. Scaffolds were characterized using scanning electron microscopy, compressive testing, cell seeding and rat subcutaneous implant testing. Then, nano-β-TCP scaffold, nano-β-TCP scaffold loaded with FGF-2 and noncoated collagen scaffold were implanted into a dog one-wall infrabony defect model. Histological observations were made at 10 d and 4 wk postsurgery. Scanning electron microscopy images show that TCP nanoparticles were attached to collagen fibers. The nano-β-TCP scaffold showed higher compressive strength and cytocompatibility compared with the noncoated collagen scaffold. Rat subcutaneous implant tests showed that the DNA contents of infiltrating cells in the nano-β-TCP scaffold and the FGF-2-loaded scaffold were approximately 2.8-fold and 3.7-fold greater, respectively, than in the collagen scaffold. Histological samples from the periodontal defect model showed about five-fold greater periodontal tissue repair following implantation of the nano-β-TCP scaffold loaded with FGF-2 compared with the collagen scaffold. The β-TCP nanoparticle coating strongly improved the collagen scaffold bioactivity. Nano-β-TCP scaffolds containing FGF-2 are anticipated for use in periodontal tissue engineering.

Structural and mechanical characterization of boron doped biphasic calcium phosphate produced by wet chemical method and subsequent thermal treatment

In the current study, boron doped biphasic calcium phosphate bioceramics consisting of a mixture of boron doped hydroxyapatite (BHA) and beta tricalcium phosphate (β-TCP) of varying BHA/β-TCP ratios were obtained after sintering stage. The effects of varying boron contents and different sintering temperatures on the BHA/β-TCP ratios and on the sinterability of the final products were investigated. Particle sizes and morphologies of the obtained precipitates were determined using SEM. XRD and FTIR investigation were conducted to detect the boron formation in the structure of HA and quantitative analysis was performed to determine the BHA/β-TCP ratio before and after sintering stage. In order to determine the sinterability of the obtained powders, pellets were prepared and sintered; the rates of densification were calculated and obtained results were correlated by SEM images. Also Vickers microhardness values of the sintered samples were determined. The experimental results verified that boron doped hydroxyapatite powders were obtained after sintering stage and the structure consists of a mixture of BHA and β-TCP. As the boron content used in the precipitation stage increases, β-TCP content of the BHA/β-TCP ratio increases but sinterability, density and microhardness deteriorate. As the sintering temperature increases, β-TCP content, density and microhardness of the samples increase and sinterability improves.

Effect of biphasic calcium phosphate scaffold porosities on odontogenic differentiation of human dental pulp cells.

Calcium phosphates (CaP) of different porosities have been widely and successfully used as scaffolds with osteoblast cells for bone tissue regeneration. However, the effects of scaffold porosities on cell viability and differentiation of human dental pulp cells for dentin tissue regeneration are not well known. In this study, biphasic calcium phosphate (BCP) scaffolds of 20/80 hydroxyapatite to beta tricalcium phosphate ratio with a mean pore size of 300 μm were prepared into BCP1, BCP2, BCP3, and BCP4 of 25%, 50%, 65%, and 75% of total porosities, respectively. The extracts of these scaffolds were assessed with regard to cell viability, proliferation, and differentiation of human dental pulp cells. The high alkalinity, and more calcium and phosphate ions release that were exhibited by BCP3 and BCP4 decreased the viability and proliferation of human dental pulp cells as compared to BCP1 and BCP2. BCP2 significantly increased both cell viability and cell proliferation. However, the cells cultured with BCP3 extract revealed high alkaline phosphatase (ALP) activity and high expression of odontoblast related genes, collagen type I alpha 1, dentin matrix protein-1, and dentin sialophosphoprotein as compared to that cultured with BCP1, BCP2, and BCP4 extracts. The results highlight the effect of different scaffold porosities on the cell microenvironment and demonstrate that BCP3 scaffold of 65% porosity can support human dental pulp cells differentiation for dentin tissue regeneration.

Coating and surface treatments enhance scaffold degradation

Coating and surface treatments enhance scaffold degradation

Strontium folate loaded biohybrid scaffolds seeded with dental pulp stem cells induce in vivo bone regeneration in critical sized defects.

Strontium folate (SrFO) is a recently developed bone promoting agent with interest in medical and pharmaceutical fields due to its improved features in comparison to current strontium based therapies for osteoporosis and other bone diseases. In this work SrFO derivative was synthesized and loaded into biohybrid scaffolds obtained through lyophilisation of semi-interpenetrating networks of chitosan polyethylene glycol dimethacrylate and beta tri-calcium phosphate (βTCP) fabricated using free radical polymerization. The scaffolds were seeded with pluripotent stem cells obtained from human dental pulp and their potential to regenerate bone tissues were assessed using a critical sized defect model of calvaria in rats and compared with those obtained without SrFO. The results obtained both in vitro and in vivo demonstrated excellent cyto-compatibility with resorption of scaffolds in 4-6 weeks and a total regeneration of the defect, with a more rapid and dense bone formation in the group with SrFO. Thus, the use of stem cells sourced from human dental pulp in combination with SrFO are very promising systems for their application in compromised osseous tissue regeneration.

Bone augmentation in sinus floor elevation by octacalcium phosphate collagen composite

Event Abstract Back to Event Bone augmentation in sinus floor elevation by octacalcium phosphate collagen composite Tadashi Kawai1*, Keiko Matsui1, Yushi Ezoe1, Yuji Tanuma1*, Hidenori Tanaka2*, Fumihiko Kajii2, 3*, Atsushi Iwai2*, Osamu Suzuki4*, Shinji Kamakura3* and Tetsu Takahashi1 1 Tohoku University, Graduate School of Dentistry, Oral and Maxillofacial Surgery, Japan 2 TOYOBO CO., LTD, Japan 3 Tohoku University Graduate School of Biomedical Engineering, Bone Regenerative Engineering, Japan 4 Tohoku University, Graduate School of Dentistry, Craniofacial Function Engineering, Japan Introduction: Synthetic octacalcium phosphate (OCP) has become recognized as a highly osteoconductive bone substitute material based on in vitro and vivo studies [1],[2]. OCP enhances osteoblastic cell differentiation in vitro in a dose-dependent manner [3]. Furthermore, the dose-dependent stimulatory capacity of OCP was confirmed in vivo implantation with collagen matrix in rat critical sized calvaria defect [4]. OCP has higher solubility than be-ta tricalcium phosphate (be-ta TCP) therefore more resorbable than be-ta TCP in vivo [5]. It has been shown that OCP combined with collagen (OCP/Collagen) facilitates bone regeneration in comparison with OCP itself [6]. The osteoconductivity of OCP/Collagen has been demonstrated also in critical-sized bone defect of dog [7]. After that, we examined the effect of OCP/Collagen on bone regeneration in human small bone defect and confirmed the healing at the defect[8]. In this study, we performed sinus floor elevation for bone augmentation by OCP/Collagen as a preparation for dental implant treatment in clinical patient. Experimental methods: OCP was prepared according to a method of synthesis by mixing calcium nad phosphate solution [1]. Particle size of OCP was 300 - 500 micrometer in diameter. OCP/Collagen was molded in the shape of a disc, 9 mm diameter, and 1.5 mm thick. Then OCP/Collagen was sterilized using electron beam irradiation at 15kGy. The protocol of the clinical trial was submitted and approved by the research ethics commitee of the Tohoku University Graduate School of Dentistry. In this study, we performed sinus floor elevation in a 41-years old man at left sinus under local anesthesia. 19 OCP/Collagen discs (approximately 1.8 cc) were used in this surgery. We observed the healing at operative region and confirmed having infection or allergy, or not and radiographic examination or CT scan was performed at 3 or 6 months after operation. Furthermore, we performed bone biopsy at the same time of placement of dental implant and we examined the newly formed bone histologically. Result: There was no abnormality for healing, no infection and no allergic reaction for the entire period. OCP or OCP/Collagen does not have radiopacity under normal X-ray condition. However, radiopacity of OCP/Collagen implanted in sinus increased with time. CT scan showed radiopacity at 3 months after implantation. At 6 months, the radiopacity of that was almost same as surrounding bone of that in cancellous bone. Histological analysis showed the normal bone tissue including a little remaining impants. Discussion: These results showed that OCP/Collagen could convert to bone tissue in clinical use of sinus floor elevation. It was suggested that OCP/Collagen could be a suitable material for bone augmentation.

Alveolar ridge preservation using autogenous tooth graft versus beta-tricalcium phosphate alloplast: A randomized, controlled, prospective, clinical pilot study.

Background:A randomized, prospective clinical, radiographical, and histological study was conducted to evaluate healing after alveolar ridge preservation technique using two different graft materials, namely, a novel autogenous graft material i. e., autogenous tooth graft (ATG) and beta-tricalcium phosphate (β-TCP) alloplast.Materials and Methods:Fifteen patients undergoing extraction of at least three teeth were selected. Atraumatic extractions were performed. Of the three extraction sockets, one was grafted with ATG, other with β-TCP, and the third was left ungrafted. Cone-beam computed tomography scans were taken immediately after grafting and 4 months postoperatively to check the changes in alveolar crest height and width at all the sites. Three patients in whom implant placement was done after complete healing; bone samples were harvested using a 3 mm diameter trephine during osteotomy preparation from both the ridge preserved sites and studied histologically.Results:There was a statistically significant difference when the changes in width and height of alveolar crest were compared within all the three groups (P < 0.05). Among three sites, ATG-grafted sites showed the most superior results with a minimal reduction in alveolar crest height and width. Histological analysis also showed the same trend with more new bone formation at ATG-grafted sites as compared to β-TCP-grafted sites.Conclusion:Postextraction, ridge preservation leads to more predictable maintenance of alveolar ridge height and width. ATG as compared to β-TCP provided superior results. Based on this, we conclude that ATG material can serve as a better alternative to conventional bone graft materials.

Histomorphometric evaluation of bone regeneration using autogenous bone and beta-tricalcium phosphate in diabetic rabbits.

The mechanism of impaired bone healing in diabetes mellitus includes different tissue and cellular level activities due to micro- and macrovascular changes. As a chronic metabolic disease with vascular complications, diabetes affects a process of bone regeneration as well. The therapeutic approach in bone regeneration is based on the use of osteoinductive autogenous grafts as well as osteoconductive synthetic material, like a β-tricalcium phosphate. The aim of the study was to determine the quality and quantity of new bone formation after the use of autogenous bone and β-tricalcium phosphate in the model of calvarial critical-sized defect in rabbits with induced diabetes mellitus type I. The study included eight 4-month-old Chincilla rabbits with alloxan-induced diabetes mellitus type I. In all animals, there were surgically created two calvarial bilateral defects (diameter 12 mm), which were grafted with autogenous bone and β-tricalcium phosphate (n = 4) or served as unfilled controls (n = 4). After 4 weeks of healing, animals were sacrificed and calvarial bone blocks were taken for histologic and histomorphometric analysis. Beside descriptive histologic evaluation, the percentage of new bone formation, connective tissue and residual graft were calculated. All parameters were statistically evaluated by Friedman Test and post hock Wilcoxon Singed Ranks Test with a significance of p < 0.05. Histology revealed active new bone formation peripherally with centrally located connective tissue, newly formed woven bone and well incorporated residual grafts in all treated defects. Control samples showed no bone bridging of defects. There was a significantly more new bone in autogeonous graft (53%) compared with β-tricalcium phosphate (30%), (p < 0.030) and control (7%), (p < 0.000) groups. A significant difference was also recorded between β-tricalcium phosphate and control groups (p < 0.008). In the present study on the rabbit grafting model with induced diabetes mellitus type I, the effective bone regeneration of critical bone defects was obtained using autogenous bone graft. [Projekat Ministarstva nauke Republike Srbije, br. 175021].

Effect of Alendronate with β - TCP Bone Substitute in Surgical Therapy of Periodontal Intra-Osseous Defects: A Randomized Controlled Clinical Trial.

Alendronate (ALN), an aminobisphosphonate, inhibits osteoclastic bone resorption and also stimulates osteogenesis. Beta-Tricalcium Phosphate (β-TCP) is an osteoconductive graft material which provides a scaffold for bone formation and also a widely used drug delivery vehicle for growth factors and antibiotics. Drug delivery vehicles, like β-TCP, improve the potency of the drugs by specific local site delivery of the drug, optimal release characteristics and easy handling. The aim of the this study was to evaluate the bone formation potential of 400μg ALN delivered in β-TCP in the treatment of periodontal intra-osseous defects. Thirty patients with periodontal defects were randomly assigned to 400μg ALN + β-TCP + Saline (test) group and β-TCP + Saline (active-control) group. Clinical parameters like Clinical Attachment Level (CAL) gain, Probing Depth (PD) reduction, post-operative Gingival Recession (GR) were assessed from the baseline, 3 months and 6 months recordings. Radiographic parameters like Linear Bone Growth (LBG), Percentage Bone Fill (%BF), and change in alveolar crest height (ACH) were assessed from baseline and 6 months radiographs. Mean measurements in the ALN test group for CAL gain (3.4 ± 0.74 mm), PD reduction (4.33 ± 0.82 mm), LBG (2.88 ± 0.88 mm), and %BF (51.98 ± 15.84%) were significantly greater with a p-value <0.05 compared to the mean measurements of CAL gain (2.20 ± 0.86 mm), PD reduction (3.20 ± 1.15 mm), LBG (1.70 ± 0.39 mm), and %BF (30.35 ± 6.88%) of the control group. There was mild alveolar crestal apposition (0.32 ± 0.68 mm) in the ALN test group and mild alveolar crestal resorption (-0.24 ± 0.40 mm) in the control group. 400μg ALN combined with β-TCP bone graft material was effective in improving soft tissue parameters, inhibiting alveolar crestal resorption and enhancing bone formation, compared to β-TCP alone.

Regulation and Biological Significance of Formation of Osteoclasts and Foreign Body Giant Cells in an Extraskeletal Implantation Model.

The implantation of biomaterials induces a granulomatous reaction accompanied by foreign body giant cells (FBGCs). The characterization of multinucleated giant cells (MNGCs) around bone substitutes implanted in bone defects is more complicated because of healing with bone admixed with residual bone substitutes and their hybrid, and the appearance of two kinds of MNGCs, osteoclasts and FBGCs. Furthermore, the clinical significance of osteoclasts and FBGCs in the healing of implanted regions remains unclear. The aim of the present study was to characterize MNGCs around bone substitutes using an extraskeletal implantation model and evaluate the clinical significance of osteoclasts and FBGCs. Beta-tricalcium phosphate (β-TCP) granules were implanted into rat subcutaneous tissue with or without bone marrow mesenchymal cells (BMMCs), which include osteogenic progenitor cells. We also compared the biological significance of plasma and purified fibrin, which were used as binders for implants. Twelve weeks after implantation, osteogenesis was only detected in specimens implanted with BMMCs. The expression of two typical osteoclast markers, tartrate-resistant acid phosphatase (TRAP) and cathepsin-K (CTSK), was analyzed, and TRAP-positive and CTSK-positive osteoclasts were only detected beside bone. In contrast, most of the MNGCs in specimens without the implantation of BMMCs were FBGCs that were negative for TRAP, whereas the degradation of β-TCP was detected. In the region implanted with β-TCP granules with plasma, FBGCs tested positive for CTSK, and when β-TCP granules were implanted with purified fibrin, FBGCs tested negative for CTSK. These results showed that osteogenesis was essential to osteoclastogenesis, two kinds of FBGCs, CTSK-positive and CTSK-negative, were induced, and the expression of CTSK was plasma-dependent. In addition, the implantation of BMMCs was suggested to contribute to osteogenesis and the replacement of implanted β-TCP granules to bone.

Novel high-strength bioabsorbable bone adhesives

Event Abstract Back to Event Novel high-strength bioabsorbable bone adhesives Antony Bou-Francis1 and Amyl Ghanem1 1 Dalhousie University, Department of Process Engineering & Applied Science, Canada The idea of being able to glue bone fragments with a suitable bicompatible adhesive remains highly attractive to orthopaedic surgeons[1]. Despite decades of research, no suitable system that fully satisfies all the many requirements for such an adhesive has yet been identified[2]. We propose novel high-strength bioabsorbable bone adhesives based on polycaprolactone (PCL), polyglycolide (PGA) and beta-tricalcium phosphate (β-TCP) blends. Figure 1. The polymer blends tested for adhesive strength and water uptake. All materials used to prepare the blends were medical grade. PCL and PGA were obtained from Purac, The Netherlands. β-TCP was obtained from Berkeley Advanced Biomaterials, USA. Five polymer blends (Figure 1) were prepared and mixed manually in a vial then molded into glue-stick cylinders using injection molding (Arburg Polytronica, Germany). All blends were comparatively tested for adhesive strength and water uptake. Bovine bone samples were obtained from a local abattoir and cut into 50 mm x 15 mm x 10 mm (L x W x D) rectangular sections. A glue gun (Ad Tech, China) was then used to apply the blends and adhere the samples as per the configurations shown in Figure 2. The adhered samples were cured at 37°C for 24 hours then loaded in tension (Instron, USA) at a crosshead control rate of 1.3 mm/min until failure[3]. The maximum shear stress was calculated by dividing the maximum force by the shear area. Experiments were repeated three times and the shear stress was reported as mean ± standard deviation. Water uptake tests were performed according to ASTM D570. The glue sticks of the different polymer blends were cut into circular pieces, dried overnight at 40°C, then immersed in distilled water at room temperature. Water uptake for different swelling times was measured as percent uptake = [(mwet - mdry) / mdry] x 100. Six samples were tested for each blend and the percent water uptake versus immersion time was reported as mean ± standard deviation. Figure 2. The test configurations for assessing the adhesive strength of the polymer blends. A) Lateral view showing the position of the samples based on lap shear strength assessment with a 300 mm2 adhesion area. B) Top view showing the position of the samples based on assessing tissue-adhesive strength under tension with a 150 mm2 adhesion area. The bond strength experiments revealed that, independent of the test configuration, blend 1 and blend 2 exhibited the lowest and highest maximum shear stress, respectively. The measured shear stress for blends 1 to 5 were 1.63 ± 0.39, 3.31 ± 0.36, 2.53 ± 0.42, 1.95 ± 0.35, and 2.37 ± 0.38 MPa, respectively. The water uptake experiments (Figure 3) revealed that, for all the swelling times tested, blend 1 and blend 4 had the lowest and highest water absorption rates, respectively. After 24 hours of immersion in distilled water, the percent water uptake for blends 1 to 5 were 0.34 ± 0.05, 0.48 ± 0.04, 0.58 ± 0.03, 1.17 ± 0.07, and 0.61 ± 0.05 %, respectively. Figure 3. Moisture absorption of different polymer blends for up to 72 hours of immersion in distilled water. This study shows that the incorporation of PGA and TCP with PCL seems to improve the adhesive strength and water absorption properties of the polymer blends. More experiments are needed to elucidate this hypothesis and help determine the suitability of such polymer blends as high-strength bioabsorbable bone adhesives. Mitacs; Dartmouth Medical Research Limited

Blood vessel count and bone formation after maxillary sinus augmentation

Event Abstract Back to Event Blood vessel count and bone formation after maxillary sinus augmentation Christoph Brochhausen1, 2, Volker H. Schmitt1, Sebastian Kuehl3, Christine Schmitt1, Andreas Mamilos1, 2, Andreas Filippi3, Matthias Kreisler3 and C James Kirkpatrick1 1 University Medical Centre Mainz, REPAIR-lab, Institute of Pathology, Germany 2 University Hospital Regensburg, REPAIR-lab, Institute of Pathology, Germany 3 Univeristy Basel, Clinic for Oral Surgery, Switzerland Introduction: Maxillary sinus augmentation (MSA) represents a valuable technique to successfully graft severe atrophic maxillary bone prior to implant placement. For this purpose, autologous bone, bone substitute materials or mixtures of both can be used. The aim is to obtain a maximum amount of bone. Angiogenesis is a crucial step in bone formation. However, there are no studies which have evaluated the correlation between blood vessel count and the amount of bone after MSA. In this study, the correlation between the number of blood vessels and the percentage distribution of bone as well as soft tissue was investigated after MSA with bone and bone substitute materials in ex vivo samples. Materials and Methods: 35 trephine samples were retrieved five months after grafting the maxillary sinus either with autologous bone (control, n=8), composites of autologous bone and beta-tricalcium phosphate (n=15, group A) or autologous bone and beta-tricalcium phosphate/hydroxyapatite (n=11, group B). The samples were processed according to standardized methods for histological (HE, Goldner) and immunohistochemical (anti-CD31 stain) examination. The vessel count per sample was determined as well as the distribution of bone, substitute biomaterial and soft tissue. The data were plotted against the percentage distribution of bone and soft tissue and correlations were evaluated by means of a Spearman test. Results: The mean distribution of soft tissue was the highest in group A (42.3 %) and lowest in group B (32.2 %). The mean distribution of bone was the highest in the control (27.8 %), followed by group A (mean=24.2%). The lowest amount of bone was seen in group B (mean=23.5 %). The control group gave the highest number of blood vessels (mean=53.8 vessels per sample). Group A revealed 47.1 vessels per sample, while the lowest number (26.9 vessels per sample) was detected in group B. Discussion: In this study, blood vessel count correlated significantly with the amount of soft tissue. No correlation could be found between the number of blood vessels and the percentage distribution of bone. In addition, angiogenesis occurred mainly in soft tissue independent of the grafted material used after MSA. Further studies are necessary to investigate the mechanisms of bone formation and the role of the blood supply in MSA. Keywords: Bone Regeneration, Biomimetic Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Bone substitutes in clinics Citation: Brochhausen C, Schmitt VH, Kuehl S, Schmitt C, Mamilos A, Filippi A, Kreisler M and Kirkpatrick C (2016). Blood vessel count and bone formation after maxillary sinus augmentation. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02955 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Christoph Brochhausen Volker H Schmitt Sebastian Kuehl Christine Schmitt Andreas Mamilos Andreas Filippi Matthias Kreisler C James Kirkpatrick Google Christoph Brochhausen Volker H Schmitt Sebastian Kuehl Christine Schmitt Andreas Mamilos Andreas Filippi Matthias Kreisler C James Kirkpatrick Google Scholar Christoph Brochhausen Volker H Schmitt Sebastian Kuehl Christine Schmitt Andreas Mamilos Andreas Filippi Matthias Kreisler C James Kirkpatrick PubMed Christoph Brochhausen Volker H Schmitt Sebastian Kuehl Christine Schmitt Andreas Mamilos Andreas Filippi Matthias Kreisler C James Kirkpatrick Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Surface Modification of β-TCP with Stearic Acid and Its Effects on β-TCP/PLLA Biodegradable Composite Nanofibers

In order to improve interfacial compatibility between beta-tricalcium phosphate (β-TCP) with poly-L-lactide (PLLA) to prepare bone tissue engineering (TE) scaffold material, a surface modification of β-TCP with stearic acid was investigated. Interfacial interaction between β-TCP particles with stearic acid was studied using Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA) and X-ray Photoelectron Spectra (XPS). The unmodified β- TCP/PLLA and modified β-TCP/PLLA composite nanofiber membranes with different quality ratios were prepared by electrospinning. Morphology of these composite nanofiber membranes was observed by using scanning electron microscope (SEM). Mechanical properties of these composites were also tested. The results indicated that hydrogen ions of stearic acid produced protonation reaction with oxygen ions in phosphate of β-TCP and then generated hydroxyls. The β-TCP particles modified by stearic acid reduced the agglomeration of β-TCP particles in matrix and obtained continuous and uniform nanofibers. The mechanical properties of the modified β- TCP/PLLA composite nanofiber membranes were significantly improved than those of unmodified β-TCP/ PLLA composite nanofiber membranes.

Multifunctional polymeric composites: Bioactive, biodegradable, antithrombogenic and antimicrobial

Event Abstract Back to Event Multifunctional polymeric composites: Bioactive, biodegradable, antithrombogenic and antimicrobial Nesrin Hasirci1 1 Middle East Technical University, Chemistry, Türkiye Introduction: Polymers are the preferable materials for production of medical devices since they have broad versatility, ease of fabrication and economic availability. In the cases where the properties are not enough for a certain application, either the bulk or the surface can easily be modified. In this way high mechanical strength, antibacterial and antithrombogenic affinity, and enhanced cell and tissue integration can be obtained. Method: In this study different polymers were modified. Polycaprolactone (PCL) was modified with gelatin microparticles containing beta-tricalcium phosphate (b-TCP) and Gentamicin. Antibacterial activities against Escherichia coli and Staphylococcus aureus were investigated[1],[2]. Second polymer is polylactide (PLLA) which was modified with supercritical carbondioxide treatment to obtain porous structures for local delivery of bioactive agents. These systems can be affective in hard tissue treatments. Third polymer is polyurethane (PU) which was synthesized and modified with heparin and chitosan immobilization[3]. These samples were incubated with plasma proteins and whole blood to investigate protein attachment and cell agglomeration. Also, PU samples were treated with Gram positive (Staphylococcus aureus and Staphylococcus epidermidis) and Gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Antibacterial activities were determined by colony counting method. Results: Modified PCL samples demonstrated high affinity for Saos-2 cells and antimicrobial activity against Escherichia coli and Staphylococcus aureus (Figure 1). PLLA samples modified with super scritical conditions exhibited porous structure and fast release of a model antibiotic. PU samples modified with heparin and chitosan demonstrated high antithrombogenic activity for blood cells and antimicrobial activity against all types of bacteria. The most effective surfaces were the ones having both chitosan and heparin. Figure 1: PCL samples. a) modified PCL with microparticles, b) antimicrobial effect of PCL films, c) Saos-2 cells on PCL scaffold. Conclusion: Blending, grafting and immobilizations applications to polymers change their properties and enhance their chemical, physical, mechanical properties as well as their affinity against cells and bacteria. We gratefully acknowledge the support to BIOMATEN through the Ministry of Development funds and by METU; Characterization analyses were carried out by Central Lab of METU

The histological study of osseous regeneration following implantation of various bone graft biomaterials.

While various biomaterials are used for bone regeneration, the relative comparative efficiency of them has not been thoroughly investigated. This study evaluated histopathological events during osseous healing after implantation of following bone grafts: Demineralized freeze-dried cortical bone powder (DFDB), natural coral implants, calcium sulfate-based putty containing demineralized bone matrix (CaS-DBM), and pure-phase beta tricalcium phosphate ceramic granules (β-TCP). Fifty-six Wistar Albino rats were used for this study. The postimplantation osseous healing was evaluated at 3rd, 6th weeks after the operation. DFDB did not induce bone formation in 3 weeks period, but it showed a highly osteoinductive effect at the end of 6th week period. The effects of coral implants on bone formation both at 3 and 6 weeks period were much higher than the DFDB. CaS-DBM showed higher bone formation than β-TCP at 3rd, 6th weeks. It was found that coral and CaS-DBM had a more beneficial impact on early bone healing compared to β-TCP and DFDB. All these graft biomaterials are useable in human bone defects. The main difference in the ossous healing properties of these materials is observed early postimplantation with the delayed healing outcome being similar.

Histological Evaluation of Effect of Beta-Tricalcium Phosphate on Bone Healing in Alloxan-Induced Diabetes

Histological Evaluation of Effect of Beta-Tricalcium Phosphate on Bone Healing in Alloxan-Induced Diabetes

Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series.

Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques.

Effect of Cell Seeding Conditions on the Efficiency of In Vivo Bone Formation.

To optimize methods for seeding cells on granular-type beta-tricalcium phosphate (β-TCP). Bone marrow stromal cells were obtained from rat long bones and cultured in flasks with Minimum Essential Medium, Alpha Modification (αMEM) supplemented with 10% fetal bovine serum (FBS), dexamethasone, ascorbic acid, β -glycerophosphate, and antibiotics. The influence of differential cell seeding densities and dynamic cell seeding conditions (rotation) was investigated using different sizes of β -TCP granules and a subcutaneous implantation model. Higher cell seeding densities contributed to efficient in vivo bone formation. The rotational seeding did not affect the efficiency but contributed to the uniformity. Although the granule size did not affect the efficiency under the conditions used in this study, large granules showed more uniform distribution of bone regeneration, while small granules showed nonuniform but dense bone formation. Mixtures of relatively large and small granules may be beneficial for both uniform and efficient bone regeneration. These findings may contribute to stable bone tissue engineering with bone marrow stromal cells and β -TCP granules as a scaffold.

Innovative manufacture of hard tissue scaffold using tailored bioresorbable composite filaments for promoting bone regeneration

Event Abstract Back to Event Innovative manufacture of hard tissue scaffold using tailored bioresorbable composite filaments for promoting bone regeneration Hannah Little1, Eoin Cunnigham1, Susan A. Clarke2, Nagitha Wijayathunga3 and Fraser Buchanan1 1 Queen's University, School of Mechanical and Aerospace Engineering, United Kingdom 2 Queen's University, School of Nursing and Midwifery, United Kingdom 3 University of Leeds, School of Mechanical Engineering, United Kingdom Introduction: Limitations in current procedures such as secondary trauma for autografts and disease transmission in allografts have resulted in an increased push to develop synthetic tissue scaffolds[1]. Additive manufacturing (AM) provides precise control over scaffold morphology. Complex internal architectures can be predesigned with specific properties. However challenges include the limited number of AM compatible biomaterials[2]. This work aims to investigate AM techniques to understand process-structure-performance relationships for clinically relevant bioresorbable polymers in order to tailor degradation rates and optimise release kinetics of incorporated bioactive agents. Particular attention was focused on identifying degradation effects throughout the manufacturing process, determining implant performance. Materials and Methods: Poly(L-lactic acid) (PLLA) (4043D Natureworks) was cryogenically ground before being processed into filament using a Haake twin-screw extruder (Thermo Fisher Scientific). An extruder temperature of 170oC-175oC, draw off speed of 0.11 m/s, feed rate of 12% and screw speed of 300 rpm were applied. An air ring and chilled air ring were positioned alongside rollers to control draw down and stabilise extrudate. Composites of PLLA incorporating 0.2µm beta-tricalcium phosphate (β-TCP) (Plasma Biotal Ltd) were mixed in weight percentages of 5 and 20% and extruded into filament. A RepRap Tricolour Mendel (RepRapPro) fused deposition modelling technique was used to produce scaffolds. Various 3-D structures with porous geometries were created using computer aided design (Solidworks). To evaluate print performance scaffolds were manufactured from the tailored filament using optimised RepRap parameters. A 0.3mm nozzle extruded filament at 190oC onto a 60oC heated bed at 30mm/s. Scanning electron microscopy (Oxford Instruments) and Micro CT analysis (Scanco) were used to examine the structure of printed scaffolds. Results and Discussion: Optimisation of the extrusion process produced FDM compatible filament at 1.75 (+0.15/-0.08) mm. Processing of composite β-TCP filaments required minor adjustments of the draw off speed to maintain consistency of diameter. FDM demonstrated suitable processing capability, parameter adaptability, and material compatibility. The ability to print a range of different morphologies compatible with the deposition technique has been demonstrated, maintaining pore geometry within the recommended range for hard tissue[3]. Initial results in processing 0/90o laydown patterns provided clear pore channels. Controlled adaptation of RepRap parameters allowed the equipment to be functionalised towards the manufacture of scaffolds with improved control over pore geometry, creating pores >200µm. Scaffolds manufactured from all three tailored filaments produced accurate and repeatable results (Fig.1) with minimal morphology variation. Micro CT revealed micropore inclusions of 130µm typical diameter throughout the structure (Fig.2) suggesting void formation through extrusion or FDM processes. Conclusion: Work completed highlights the potential of this innovative approach for manufacturing bioresorbable hard tissue scaffolds. With the aim of developing scaffolds with clinically relevant resorption rates, this study has provided the foundation for processing other resorbable polymers.