Glass-reinforced Hydroxyapatite Research Articles

Dextrin hydrogel loaded with a macroporous Bonelike® scaffold and dental pulp stem cells for critical-sized defect repair

Regeneration of severe bone defects remains a challenge. A formulation of synthetic glass-reinforced hydroxyapatite bone substitute, Bonelike® Poro (BL®P), 250–500 µm-diameter, with a dextrin-based hydrogel (HG), further loaded with human dental pulp stem cells (hDPSCs) with osteogenic differentiation ability, was tested for the management of critical-sized defects in an ovine model.Morphology, calcium release, and mechanical strength of HG + BL®P were analyzed. Then, BL®P, HG + BL®P, and 106 hDPSCs-loaded HG + BL®P were implanted in ovine critical-sized 14 mm-diameter calvaria defects. Bone samples were collected after 3 and 6 weeks for histological and micro-CT analysis.BL®P exhibits a suitable porous size for cell ingrowth, from the nm (>200 nm) to the µm (5 µm) range. The addition of BL®P granules to the HG resulted in increased compressive elastic modulus and ultimate tensile strength. The mildly acidic nature of the HG contributed to a faster dissolution of granules. In vivo results confirmed the HG suitability as a carrier, providing better defect filling, easy handling, and injectability of BL®P without compromising new bone formation nor biocompatibility. The HG + BL®P formulations can successfully regenerate critical-sized defects; however, addition of hDPSCs did not significantly enhance new bone formation under these conditions.Granular BL®P provides an effective alternative to autologous grafts. The HG acts as a biocompatible carrier of granular bone substitutes and cells, conferring injectability and cohesivity.

Randomized clinical study of injectable dextrin-based hydrogel as a carrier of a synthetic bone substitute

ObjectivesThis study aimed to improve the performance and mode of administration of a glass-reinforced hydroxyapatite synthetic bone substitute, Bonelike by Biosckin® (BL®), by association with a dextrin-based hydrogel, DEXGEL, to achieve an injectable and moldable device named DEXGEL Bone.MethodsTwelve participants requiring pre-molar tooth extraction and implant placement were enrolled in this study. BL® granules (250–500 µm) were administered to 6 randomized participants whereas the other 6 received DEXGEL Bone. After 6 months, a bone biopsy of the grafted area was collected for histological and histomorphometric evaluation, prior to implant placement. The performance of DEXGEL Bone and BL® treatments on alveolar preservation were further analyzed by computed tomography and Hounsfield density analysis. Primary implant stability was analyzed by implant stability coefficient technique.ResultsThe healing of defects was free of any local or systemic complications. Both treatments showed good osseointegration with no signs of adverse reaction. DEXGEL Bone exhibited increased granule resorption (p = 0.029) accompanied by a tendency for more new bone ingrowth (although not statistically significant) compared to the BL® group. The addition of DEXGEL to BL® granules did not compromise bone volume or density, being even beneficial for implant primary stability (p = 0.017).ConclusionsThe hydrogel-reinforced biomaterial exhibited an easier handling, a better defect filling, and benefits in implant stability.Clinical relevanceThis study validates DEXGEL Bone safety and performance as an injectable carrier of granular bone substitutes for alveolar ridge preservation.Trial registrationEuropean Databank on Medical Devices (EUDAMED) No. CIV-PT-18–01-02,705; Registo Nacional de Estudos Clínicos, RNEC, No. 30122.

Application of Bonelike\xae as synthetic bone graft in orthopaedic and oral surgery in veterinary clinical cases

Autologous bone remains the gold standard grafting substrate for bone fusions used for small gaps and critical defects. However, significant morbidity is associated with the harvesting of autologous bone grafts and, for that reason, alternative bone graft substitutes have been developed. In the present case series, a glass-reinforced hydroxyapatite synthetic bone substitute, with osteoinductive and osteoconductive proprieties, was applied. This synthetic bone substitute comprises the incorporation of P2O5-CaO glass-based system within a hydroxyapatite matrix, moulded into spherical pellets with 250-500 μm of diameter. A total of 14 veterinary clinical cases of appendicular bone defects and maxillary / mandibular bone defects are described. In all clinical cases, the synthetic bone substitute was used to fill bone defects, enhancing bone regeneration and complementing the recommended surgical techniques. Results demonstrated that it is an appropriate synthetic bone graft available to be used in veterinary patients. It functioned as a space filler in association with standard orthopaedic and odontological procedures of stabilization, promoting a faster bone fusion without any local or systemic adverse reactions. This procedure improves the animals’ quality of life, decreasing pain and post-operative recovery period, as well as increasing bone stability improving positive clinical outcomes.

Incorporation of glass-reinforced hydroxyapatite microparticles into poly(lactic acid) electrospun fibre mats for biomedical applications

Tissue engineering is constantly evolving towards novel materials that mimic the properties of the replaced injured tissue or organ. A hybrid electrospun membrane of electroactive poly(l-acid lactic) (PLLA) polymer with glass reinforced hydroxyapatite (Bonelike®) microparticles placed among the polymer fibres in a morphology like “islands in the sea” was processed. The incorporation of 60 to 80wt% Bonelike® bone grafts granules with ≤150μm into the polymer solution lead to an amorphous polymeric fibre membranes, and a decrease of the average polymer fibre diameter from 550±150nm for neat PLA down to 440±170nm for the hybrid composite. The presence of Bonelike® in the polymer mats reduced the activation energy for thermal degradation from 134kJ·mol−1, obtained for the neat PLLA membranes down to 71kJ·mol−1, calculated for the hybrid composite membranes. In vitro cell culture results suggest that the developed processing method does not induce cytotoxic effects in MG 63 osteoblastic cells, and creates an environment that enhances cell proliferation, when compared to the neat PLLA membrane. The simplicity and scalability of the processing method suggests a large application potential of this novel hybrid polymer-microparticles fibre membranes for bone regenerative medicine.

Novel cerium doped glass-reinforced hydroxyapatite with antibacterial and osteoconductive properties for bone tissue regeneration

The aim of this work was to develop a bioactive bone substitute with an effective antibacterial ability based on a cerium (Ce) doped glass-reinforced hydroxyapatite (GR-HA) composite. Developed composites were physicochemically characterized, using x-ray diffraction (XRD) analysis, SEM, energy dispersive x-ray spectroscopy (EDS), and flexural bending strength (FBS) tests. X-ray photoelectron spectroscopy (XPS) analysis was performed to analyze the oxidation state of Ce in the prepared doped glass. The antimicrobial activity of the composites was evaluated against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa; whether the cytocompatibility profile was assayed with human osteoblastic-like cells (Mg-63 cell line).The results revealed that the Ce inclusion in the GR-HA matrix induced the antimicrobial ability of the composite. In addition, Ce-doped materials reported an adequate biological behavior following seeding of osteoblastic populations, by inducing cell adhesion and proliferation. Developed materials were also found to enhance the expression of osteoblastic-related genes.Overall, the developed GR-HA_Ce composite is a prospective candidate to be used within the clinical scenario with a successful performance due to the effective antibacterial properties and capability of enhancing the osteoblastic cell response.

Microanalysis of Bioactive Samarium Doped Glass-Reinforced Hydroxyapatite

Microanalysis of Bioactive Samarium Doped Glass-Reinforced Hydroxyapatite

Morphology effect of bioglass-reinforced hydroxyapatite (Bonelike(®) ) on osteoregeneration.

In the last decades, the well-known disadvantages of autografts and allografts have driven to the development of synthetic bone grafts for bone regeneration. Bonelike(®) , a glass-reinforced hydroxyapatite (HA) composite was developed and registered for bone grafting. This biomaterial is composed by a modified HA matrix, with α- and β-tricalcium phosphate secondary phases. Aiming to improve the biological characteristics of Bonelike(®) , new spherical pelleted granules, of different shape and size, were developed with controlled micro and macrostructure. In the present study, it was compared the physicochemical properties and in vivo performance of different Bonelike(®) granule presentations-Bonelike(®) polygonal (500-1000 µm size) and Bonelike spherical (250-500 µm; 500-1000 µm size). For the in vivo study, Bonelike(®) was implanted on sheep femurs, with various implantation times (30 days, 60 days, 120 days, and 180 days). X-ray diffraction analysis revealed that the phase composition of different granules presentations was similar. Bonelike(®) spherical 500-1000 µm was the most porous material (global porosity and intraporosity) and Bonelike(®) polygonal 500-1000 µm the less porous. Considering the in vivo study, both polygonal and spherical granules presented osteoconductive proprieties. The spherical granules showed several advantages, including easier medical application through syringe and improved osteointegration, osteoconduction, and degradation, by the presence of larger pores, controlled micro- and macrosctructure and suitable particle format that adapts to bone growth. Bonelike(®) spherical 500-1000 µm showed improved new bone invasion throughout the material's structure and Bonelike(®) spherical 250-500 µm appeared to induce faster bone regeneration, presenting less unfilled areas and less lacunae in the histological analysis.

Samarium doped glass-reinforced hydroxyapatite with enhanced osteoblastic performance and antibacterial properties for bone tissue regeneration.

A novel bioactive bone substitute with improved osteoblastic performance and effective antibacterial activity was developed, using a completely new approach based on samarium (Sm3+) doped P2O5 glass-reinforced hydroxyapatite composites (GR-HA). The composites were prepared by adding 2.5% (w/w) of the P2O5 glass to 97.5% (w/w) of HA. Four composites were developed, i.e. one non-doped composite, and three Sm3+ doped composites prepared with the P2O5 glass containing 0.5, 1 and 2 (mol%) of Sm2O3. The composites were labeled as GR-HA_control, GR-HA_0.5Sm, GR-HA_1Sm and GR-HA_2Sm. The composites were physicochemical and mechanically characterized, namely performing SEM, EDS and XRD analysis and flexural bending strength (FBS) assessment. The incorporation of Sm3+ in the GR-HA matrix resulted in the presence of a residual Sm3+ containing phase besides HA, β-TCP and α-TCP phases, increased surface hydrophilicity and slightly higher FBS. Sm3+ doped composites exhibited improved osteoblastic cell response, as evidenced by a better F-actin cytoskeleton organization and higher cell proliferation and expression of relevant osteoblastic genes. In addition, adhesion of Staphylococcus aureus and Staphylococcus epidermidis was greatly reduced on these composites. The improved osteoblastic behavior and the antibacterial effects were dependent on the amount of Samarium in the composite, this being particularly evident in the composite with a higher Sm3+ content. Therefore, the developed composite GR-HA_2Sm appears as a successful bone substitute with osteoconductive and antibacterial properties.

Treatment of a Large Cystic Lesion in Anterior Maxilla Using Glass Reinforced Hydroxyapatite – A Case Report

Jaw cysts are common lesions in the maxillofacial area. Their treatment varies from surgical enucleation alone to enucleation followed by bone grafting depending on the size of the lesion. Various bone substitutes ranging from autografts, allografts, xenografts and alloplasts have been tried and tested with varying degrees of success. Here, the author present a case report of large cystic lesion of anterior maxilla and its treatment using a glass reinforced hydroxyapatite composite (Bonelike®) following enucleation. One year follow up demonstrated satisfactory clinical and radiological treatment outcomes.Keywords: Jaw cyst, enucleation, defect filling, alloplast, Bonelike®, bone grafts.

Guided Bone Regeneration Using Glass-Reinforced Hydroxyapatite and Collagen Membrane in the Treatment of Peri-Implantitis

Implant therapy has provided the clinician a wide variety of treatment options with respect to the replacement of missing natural teeth. With more number of dentists practicing implant dentistry, one is likely to be presented with peri-implantitis and implant related failures in day to day practice. Peri-impant mucositis can be reversed by elimination of the biofilm but peri-implantitis which results in bone loss and subsequent exfoliation of the implant if left unattended have to be treated using a regenerative approach in addition to conventional non surgical therapy. The present case demonstrates the guided bone regeneration procedure using a glass-reinforced HA and collagen membrane in the treatment of an intrabony defect around the implant. Nine months post operative radiograph revealed complete resolution of the defect. This novel composite alloplast shows promise in treating such lesions.Keywords: Peri-implantitis, Guided bone regeneration, Alloplast, Dental implant, Bone graft, Collagen membrane, Implant decontamination.

Characterization and preliminary in vivo evaluation of a novel modified hydroxyapatite produced by extrusion and spheronization techniques

A glass-reinforced hydroxyapatite (HA) composite, recently registered as Bonelike®, was developed for bone grafting. This biomaterial is composed of a modified HA matrix with α- and β-tricalcium phosphate secondary phases and ionic species that mimic the chemical composition of human bone. Several in vitro and in vivo studies have confirmed the benefits of these properties. However, these studies were all executed with Bonelike® polygonal granules obtained by crushing. In this study, Bonelike® pellets were produced through a patented process, which required the use of techniques such as extrusion and spheronization. The final product presented a homogeneous size, a 55.1% global porosity and a spherical shape. This spherical shape permitted a better adaptation to the implantation site and improved injectability. Additionally, it also may contribute to formation of macropores as pellets packaging leaves open spaces. After implantation of Bonelike® polygonal granules and Bonelike® pellets in monocortical defects in sheep for 8 and 12 weeks, light microscopy and scanning electron microscopy showed extensive osteointegration simultaneously with bone regeneration for both presentations. Histomorphometric analysis did not reveal statistically significant differences between defects treated with Bonelike® polygonal granules and Bonelike® pellets, which suggests similar in vivo performances.

A glass-reinforced hydroxyapatite and surgical-grade calcium sulfate for bone regeneration:In vivobiological behavior in a sheep model

A glass-reinforced hydroxyapatite (HA) composite (Bonelike®) was developed for bone grafting. This biomaterial is composed of a modified HA matrix with α- and β-tricalcium phosphate secondary phases, resulting in higher solubility than single HA type of materials. Several invitro and invivo studies demonstrated that Bonelike® has a highly bioactive behavior, which was also confirmed by employing granular forms of this biomaterial in orthopedics and dental applications. However, a fast consolidation vehicle was needed to promote the fixation of Bonelike® granules if applied in larger defects or in unstable sites. Surgical-grade calcium sulfate (CS), which is widely recognized as a well-tolerated and inexpensive bone graft material, was the chosen vehicle to improve the handling characteristics of Bonelike® as it can be used in the form of a powder that is mixed with a liquid to form a paste that sets in situ. After application in non-critical monocortical defects in sheep, histological, and scanning electron microscopy evaluations demonstrated that Bonelike® associated to CS functioned as a very satisfactory scaffold for bone regeneration as it achieved synchronization of the ingrowing bone with biomaterial resorption and subsequent preservation of the bone graft initial volume. Therefore, our results indicate that CS is an effective vehicle for Bonelike® granules as it facilitates their application and does not interfere with their proven highly osteoconductive properties. In the opposite way, the incorporation of Bonelike® improves the bone regeneration capabilities of CS.

Application of Glass Reinforced Hydroxyapatite Composite in the Treatment of Human Intrabony Periodontal Angular Defects – Two Case Reports

Bony defects caused by periodontitis are often treated by regenerative therapy using autografts and/or allografts. Alloplasts such as hydroxyapatite or ceramics and bioactive glasses are used as osteoconductive materials that serve as scaffold for new bony ingrowth. The purpose of this study was to ascertain the possible regenerative capability of glass reinforced hydroxyapatite (Bonelike¬)¬¬¬ an osteoconductive synthetic graft in the treatment of human periodontal intrabony angular defects. The material was placed in 2 defects in 2 individual patients and clinical parameters such as probing depth (PD) and clinical attachment level (CAL) have been included. Bone fill was determined using an intra oral periapical radiograph (IOPA) and Autocad Software. After 3 months implantation period, there was an improvement in CAL and reduction in PD along with bone fill was observed.

Growth and phenotypic expression of human endothelial cells cultured on a glass-reinforced hydroxyapatite

Glass-reinforced hydroxyapatite composites (GR-HA) are bone regenerative materials that are characterized by their increased mechanical properties, when compared to synthetic hydroxyapatite. Bonelike is a GR-HA that is a result of the addition of a CaO-P(2)O(5) based glass to a HA matrix. This biomaterial has been successfully applied in clinical bone regenerative applications. This work aims to evaluate the ability of Bonelike to support the adhesion, proliferation and phenotypic expression of human endothelial cells, aiming to establish new bone tissue engineering pre-endothelialization strategies. Bonelike discs, regardless of being submitted to a pre-immersion treatment with culture medium, were seeded with first passage human umbilical vein endothelial cells, and characterized regarding proliferation and differentiation events. Pre-immersed Bonelike allowed the adhesion, proliferation and phenotype expression of endothelial cells. Seeded materials presented positive immunofluorescent staining for PECAM-1 and a tendency for the formation of cord-like arrangements under angiogenesis-stimulating conditions, although, compared to standard culture plates, a slight decreased cell growth was observed. In this way, Bonelike may be a suitable candidate for pre-endothelialization approaches in bone tissue engineering applications.

Clinical applications of Titanium dental implants coated with glass-reinforced Hydroxyapatite composite (Bonelike®)

Commercially pure titanium dental implants were coated with glass-reinforced hydroxyapatite composites (Bonelike?) using the plasma spraying technique. A total of 27 Bonelike? coated 3.75 mm diameter and 10 mm length implants were placed in the maxilla (18) and mandible (9) of seven patients. Pre and post-operative radiological examination was performed by orthopantomogram according to the standard follow-up protocols. After a 3-month healing period, one patient's implant from the mandible was surgically removed due to bad positioning and was then assessed by light and scanning electron microscopy for histological analysis. The reported Bonelike? coated dental implants proved to be highly bioactive with extensive new bone formation and attachment.

Dissolution of Hydroxyapatite Reinforced Grain Boundary by Glassy Phases

Several sintering additives for hydroxyapatite have been tested in order to enhance its sinterability without decomposing the hydroxyapatite(Ca10(PO4)6(OH)2) and without decreasing the bioactivity and/or biocompatibility. In case of sintered pure hydroxyapatites significant dissolution was occurred after immersion in distilled water or in simulated body fluid. At first the dissolution was iniciated at grain boundary creating the nano-size defects such as small pores and grew up to micro scale by increasing the immersion time. This dissolution resulted in grain separation at the surfaces and finally in fracture. And the dissolution was concentrated on those grains adjacent to pores rather than those in the dense region. So glass-reinforced hydroxyapatite(GR-HA) ceramics were prepared to strengthening the grain boundary to prevent dissolution. Several glasses were added at 0 to 10wt.% and sintered at 1200 °C for 2h in air with moisture protection. Glass phase was incorporated into hydroxyapatite to act as the sintering aids followed by crystallization in order to improve the mechanical properties without reducing the biocompatibility. From dissolution test, significant damage was reduced even more than 7days. X-ray diffraction and SEM showed no decomposition of hydroxyapatite to secondary phases and fracture toughness was increased more than pure hydroxyapatite.

Mechanical Properties of Glass Reinforced Hydroxyapatite

Hydroxyapatite (HA) has been increasingly used in biomedical applications due to its biocompatibility with living tissues. However, its use is limited to low load bearing areas due to the poor mechanical properties compared to bone. The aim of this project is to improve the mechanical properties of synthetic HA by optimising the processing method and also by using a phosphate based glass as a sintering aid to develop Glass Reinforced Hydroxyapatite (GR-HA). A phosphate based glass containing CaO, P2O5 and CaF2 was incorporated into HA at 2.5wt% and 5wt% additions during the milling process prior to sintering at 1300°C. The flexural strength mean values for GR-HA ranged from 80MPa to 110MPa. Pure HA exhibited a much lower flexural strength mean value ranging from 66MPa to 79MPa. The improved mechanical properties were associated with the occurrence of residual stress as a result of decomposition of HA to b-Tricalcium Phosphate (TCP) and in 5wt% GRHA to a-Tricalcium Phosphate (TCP).

Development of a system to adsorb drugs onto calcium phosphate materials

Several studies were carried out in order to reduce the systemic use of antibiotics due to the high concentration required to provide the minimum inhibitory concentration (MIC) at infected sites. The aim of this study was to develop a system of drug adsorption onto commercial hydroxyapatite (HA, Ca10(PO4)6(OH)2) and glass reinforced hydroxyapatite (GR-HA) granules. The drug will then be released for the local treatment of periodontitis. The antibiotics used in this study were metronidazole, a specific antibiotic indicated for the systemic treatment of periodontitis, and ampicillin, a wide spectrum antibiotic. UV spectroscopy was used to measure the amount of drug adsorbed onto HA and GR-HA granules. Results showed that metronidazole was unable to adsorb on the material's surface, as opposed to ampicillin which adsorbed both onto HA and GR-HA. Preliminary release kinetics studies were carried out using a flow through dissolution system. Results are discussed in terms of the influence of the different surface characteristics of the materials on the adsorption processes.

Laser surface modification of hydroxyapatite and glass-reinforced hydroxyapatite

Surface treatment of materials with excimer laser radiation often results in the formation of a rough columnar or cone-shaped surface topography, which leads to a considerable increase in the surface area. As a result, the search for a non-porous bioactive material with adequate mechanical properties and a high surface to volume ratio, similar to porous materials, which could be used for drug delivery in the treatment of periodontitis, justified assessing excimer laser surface treatment to promote controlled roughning of hydroxyapatite (HA) and glass-reinforced hydroxyapatite (GR-HA). A KrF excimer laser with 248 nm radiation wavelength and 30 ns pulse duration was used for surface modification. The laser treatment was carried out in air, using wide ranges of radiation fluence and number of laser pulses. In order to identify the physico-chemical changes induced by the laser treatment and the column formation mechanisms in these materials, the treated surfaces were characterised by laser profilometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infra-red spectroscopy (FTIR). Laser processing induced the formation of a surface topography consisting of cone-shaped features. The constitution of the surface layer was also modified, as revealed by FTIR, XPS and XRD. This work has shown that laser surface modification increases the surface area of HA and GR-HA and is a promising technique to increase the reactivity and drug delivery capability of both materials.

Porous Hydroxyapatite and Glass Reinforced Hydroxyapatite for Controlled Release of Sodium Ampicillin

Porous Hydroxyapatite and Glass Reinforced Hydroxyapatite for Controlled Release of Sodium Ampicillin