Quantitative rates of in vivo bone generation for Bioglass and hydroxyapatite particles as bone graft substitute

Guttapercha Improves In Vitro Bioactivity and Dentin Remineralization Ability of a Bioglass Containing Polydimethylsiloxane-Based Root Canal Sealer

Guttapercha (GP, trans-1,4-polyisoprene) is the most used tooth root filling material, and it must be used with an appropriate cement (typically a polydimethylsiloxane (PDMS)-based sealer) to ensure an adequate canal obturation. This study aimed to assess the bioactivity and dentin remineralization ability of a bioglass containing PDMS commercial endodontic sealer, BG-PDMS (GuttaFlow Bioseal), and to evaluate the possible influence of a GP cone (Roeko GP point) on the mineralization process. To this end, BG-PDMS disks were aged alone or in the presence of a GP cone in Hank's Balanced Salt Solution (28 d, 37 °C). Dentin remineralization experiments were carried out under the same conditions. Micro-Raman and IR analyses demonstrated that BG-PDMS is bioactive, thanks to the formation of a silica-rich layer with nucleation sites for B-type carbonated apatite deposition. This phase was thicker when BG-PDMS was aged in the presence of GP. The two materials influenced each other because GP, which alone did not show any bioactivity, nucleated a calcium phosphate phase under these conditions. Analogously, dentin remineralization experiments showed that BG-PDMS is able to remineralize dentin, especially in the presence of GP. Under the experimental conditions, GP acted as a templating agent for calcium phosphate deposition.

Effects of La2O3contents on microstructure and properties of laser-cladded 5wt%CaB6/HA bioceramic coating

In the present work, 5wt%CaB6/HA bioceramic coatings with different La2O3contents (0-0.6wt%) have been fabricated by a laser cladding technique on Ti-6Al-4V. The effects of La2O3 contents on microstructure and properties of the laser-cladded 5wt%CaB6/HA coatings have been carefully investigated. The results show that the microstructure is obviously refined, and the structure is relatively uniform after doping 0.2-0.4 wt% La2O3. As the La2O3 content increases, the corrosion resistance are found to increase firstly and then gradually decrease. The XRD analysis confirms that the amount of HA and TCP in the coating reaches maximum after doping 0.2wt% La2O3. The La2O3-doped coatings show a significantly higher bone-like apatite precipitation after immersion in SBF compared with La2O3-free coating. In vitro experiment also shows that 5wt%CaB6/HA bioceramic coatings with 0.2-0.4wt% La2O3 are more suitable for the attachment and proliferation of MG63 cells, exhibiting superior bioactivity and biocompatibility.

Controlling the bone regeneration properties of bioactive glass: Effect of particle shape and size

The ability of particulate bioactive glass to function as an effective bone graft material is directly related to its in vivo dissolution, ion release, and interparticle spacing (area associated with bone in‐growth). A spherical shape represents an optimal geometry to control bioactive glass bone formation properties. Spherical particles were fabricated from 45S5 bioactive glass with unimodal (90–180, 180–355, and 355–500 μm) and bimodal size ranges (180–355/355–500 and 90–180/355–500 μm). Particles were formed into bone graft putties and compared to a commercially available product composed of irregular 45S5 bioactive glass particles (32–710 μm). Scanning electron microscopy characterization of spherical particles showed a relatively uniform sphere shape and smooth surfaces. Irregular particles were characterized by random shapes with flat surfaces and sharp edges. X‐ray fluorescence and X‐ray diffraction indicated that the spheroidization process maintained the properties of 45S5 bioactive glass. Cross‐sectional micro‐computed tomography imaging of the putty samples demonstrated that smaller spheres and irregular particles resulted denser packing patterns compared to the larger spheres. Isolated particles were immersed in simulated body fluid for 14 days to measure silicon ion release and bioactivity. Inductively coupled plasma spectroscopy showed faster ion release from smaller particles due to increased surface area. Bioactivity characterization of 14‐day simulated body fluid exposed particle surfaces showed the presence of a hydroxycarbanoapatite mineral layer (characteristic of 45S5 bioactive glass) on all bioactive glass particles. Results demonstrated that spherical particles maintained the properties of the starting 45S5 bioactive glass, and that particle shape and size directly affected short‐term glass dissolution, ion release, and interparticle spacing.

Advances in Filament Structure of 3D Bioprinted Biodegradable Bone Repair Scaffolds

Conventional bone repair scaffolds can no longer meet the high standards and requirements of clinical applications in terms of preparation process and service performance. Studies have shown that the diversity of filament structures of implantable scaffolds is closely related to their overall properties (mechanical properties, degradation properties, and biological properties). To better elucidate the characteristics and advantages of different filament structures, this paper retrieves and summarizes the state of the art in the filament structure of the three-dimensional (3D) bioprinted biodegradable bone repair scaffolds, mainly including single-layer structure, double-layer structure, hollow structure, core-shell structure and bionic structures. The eximious performance of the novel scaffolds was discussed from different aspects (material composition, ink configuration, printing parameters, etc.). Besides, the additional functions of the current bone repair scaffold, such as chondrogenesis, angiogenesis, anti-bacteria, and anti-tumor, were also concluded. Finally, the paper prospects the future material selection, structural design, functional development, and performance optimization of bone repair scaffolds.

[Effects of bioactive glass on proliferation, differentiation and angiogenesis of human umbilical vein endothelial cells]

OBJECTIVE

To investigate the effects of phytic acid derived bioactive P₂O₅-SiO₂-CaO gel-glasses (PSC) on the proliferation, differentiation and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro.

METHODS

HUVECs were cultured in PSC extracts, which were prepared with endothelial cell medium (ECM) at a gradient concentration of 0.01, 0.1, 1 and 2 g/L. Cells cultured in ECM were used as the control. The effect of PSC on HUVECs proliferation was assessed on the 1st, 3rd, 5th, 7th and 10th days with (4, 5-dimethylthiazol-2-yl) 2, 5-diphenyltetrazolium bromide assay (MTT), and the optimum PSC concentration for HUVECs proliferation was used in the following experiments. The subsequent experiments were divided into two groups. The experimental group used PSC extracts to culture HUVECs (PSC group) and the control group used ECM to culture HUVECs (ECM group). Gene expression of angiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), was detected on the 2nd, 4th and 7th days by real-time reverse transcription-polymerase chain reaction (real-time RT-PCR). The morphology and number of tubules formation were observed at the 4th and 10th hours. Image J software was used for counting and quantitative analysis.

RESULTS

The results of MTT assay showed that 0.1 g/L PSC group had the most significant effect on promoting HUVECs proliferation. The optical density values of 0.1 g/L PSC group on the 5th and 7th days were significantly higher than those of the other PSC groups and the control group (P < 0.05). The result of real-time RT-PCR showed that 0.1 g/L PSC extract up-regulated the mRNA expression of VEGF and bFGF significantly (P < 0.05). On the 4th day, the gene expressions of VEGF and bFGF in PSC group were 1.59 and 1.45 times higher than those in ECM group respectively, and on the 7th day, the gene levels of VEGF and bFGF in PSC group were 1.98 and 1.37 times higher than those in ECM group respectively. The tubule formation assay showed that the maturity and density of the tubules in 0.1 g/L PSC group was much better than that in the ECM group at the 10th hour. The quantitative analysis by Image J indicated that the tubules number in PSC group (29.63±2.29) was higher than in the ECM group (20.13±2.36), with statistical significance (P < 0.05).

CONCLUSION

PSC showed significant promoting effects on HUVECs' proliferation, differentiation and angiogenesis in vitro.

MagnetOs, Vitoss, and Novabone in a Multi-endpoint Study of Posterolateral Fusion: A True Fusion or Not?

STUDY DESIGN

This study was a multi-endpoint analysis of bone graft substitutes implanted as a standalone graft in a clinically relevant Ovine model of instrumented posterolateral spinal fusion (PLF).

OBJECTIVE

The objective of this study was to obtain high-quality evidence on the efficacy of commercial bone graft substitutes compared with autograft in instrumented PLF using a state-of-the-art model with a complete range of assessment techniques.

SUMMARY OF BACKGROUND DATA

Preclinical and clinical data on the quality of spinal fusions obtained with bone graft substitutes are often limited. Calcium phosphates with submicron topography have shown promising results in PLF, as these are able to induce bone formation in tissues distant from the host bone, which facilitates bony union.

METHODS

Nine female, skeletally mature sheep (4-5 y) underwent posterior pedicle screw/rods instrumented PLF at L2-L3 and L4-L5 using the following bone graft materials as a standalone graft per spinal segment: (1) biphasic calcium phosphate with submicron topography (BCP<µm), (2) 45S5 Bioglass (BG), and (3) collagen-β-tricalcium phosphate with a 45S5 Bioglass adjunct (TCP/BG). Autograft bone (AB) was used as a positive control treatment. Twelve weeks after implantation, the spinal segments were evaluated by fusion assessment (manual palpation, x-ray, micro-computed tomography, and histology), fusion mass volume quantification (micro-computed tomography), range of motion (ROM) testing, histologic evaluation, and histomorphometry.

RESULTS

Fusion assessment revealed equivalence between AB and BCP<µm by all fusion assessment methods, whereas BG and TCP/BG led to significantly inferior results. Fusion mass volume was highest for BCP<µm, followed by AB, BG, and TCP/BG. ROM testing determined equivalence for spinal levels treated with AB and BCP<µm, while BG and TCP/BG exhibited higher ROM. Histologic evaluation revealed substantial bone formation in the intertransverse regions for AB and BCP<µm, whereas BG and TCP/BG grafts contained fibrous tissue and minimal bone formation. Histologic observations were supported by the histomorphometry data.

CONCLUSIONS

This study reveals clear differences in efficacy between commercially available bone graft substitutes, emphasizing the importance of clinically relevant animal models with multiendpoint analyses for the evaluation of bone graft materials. The results corroborate the efficacy of calcium phosphate with submicron topography, as this was the only material that showed equivalent performance to autograft in achieving spinal fusion.

A Clinical and Radiographic Evaluation of the Efficacy of Nanohydroxyapatite (Sybograf™) versus Bioactive Calcium Phosphosilicate Putty (Novabone®) in the Treatment of Human Periodontal Infrabony Defects: A Randomized Clinical Trial

Aim:

The aim of this study is to compare and to evaluate clinically and radiographically the bone regeneration and the amount of bone fill (BL) between nanocrystalline hydroxyapatite (Nc-HA) (Sybograf™) and bioactive synthetic NovaBone Putty in the treatment of intrabony component of periodontal osseous defects.

Materials and Methods:

Twenty sites in 20 patients, within the age range of 25–55 years, showing intrabony defects were selected and divided into Group I (Nc-HA) and Group II (Bioactive synthetic NovaBone Putty). All the selected sites were assessed with the clinical and radiographic parameters such as plaque index, gingival index, sulcus bleeding index, probing pocket depth, clinical attachment level, gingival recession, and radiographic BL. All the clinical and radiographic parameter values obtained at different intervals (baseline, 3, and 6 and 9 months) were subjected to statistical analysis.

Results:

A statistically significant reduction in pocket depth of 4.400 ± 0.843 mm (Group I), 3.800 ± 0.789 mm (Group II) and gain in clinical attachment level of 6.2 mm (Group I), 5.9 mm (Group II) were recorded at the end of the study. A slight increase in gingival recession was observed. The mean percentage changes in the amount of radiographic BL of Group II and Group I were significant, However, when compared between the groups, there is no significant difference in BL observed.

Conclusion:

Both the graft materials appear to have nearly comparable effects, with nanocrystalline hydroxyapatite (Sybograf™), displaying slightly superior effect over bioactive glass especially in relation to clinical parameters. However, long-term, controlled clinical trials are required to confirm these findings.

Biomechanical Evaluation of a Novel Apatite-Wollastonite Ceramic Cage Design for Lumbar Interbody Fusion: A Finite Element Model Study

Objectives

Cage design and material properties play a crucial role in the long-term results, since interbody fusions using intervertebral cages have become one of the basic procedures in spinal surgery. Our aim is to design a novel Apatite-Wollastonite interbody fusion cage and evaluate its biomechanical behavior in silico in a segmental spinal model.

Materials and Methods

Mechanical properties for the Apatite-Wollastonite bioceramic cages were obtained by fitting finite element results to the experimental compression behavior of a cage prototype. The prototype was made from hydroxyapatite, pseudowollastonite, and frit by sintering. The elastic modulus of the material was found to be 32 GPa. Three intact lumbar vertebral segments were modelled with the ANSYS 12.0.1 software and this model was modified to simulate a Posterior Lumbar Interbody Fusion. Four cage designs in different geometries were analyzed in silico under axial loading, flexion, extension, and lateral bending.

Results

The K2 design had the best overall biomechanical performance for the loads considered. Maximum cage stress recorded was 36.7 MPa in compression after a flexion load, which was within the biomechanical limits of the cage.

Conclusion

Biomechanical analyses suggest that K2 bioceramic cage is an optimal design and reveals essential material properties for a stable interbody fusion.

Hydroxylapatite nanoparticles: fabrication methods and medical applications

Hydroxylapatite (or hydroxyapatite, HAp) exhibits excellent biocompatibility with various kinds of cells and tissues, making it an ideal candidate for tissue engineering, orthopedic and dental applications. Nanosized materials offer improved performances compared with conventional materials due to their large surface-to-volume ratios. This review summarizes existing knowledge and recent progress in fabrication methods of nanosized (or nanostructured) HAp particles, as well as their recent applications in medical and dental fields. In section 1, we provide a brief overview of HAp and nanoparticles. In section 2, fabrication methods of HAp nanoparticles are described based on the particle formation mechanisms. Recent applications of HAp nanoparticles are summarized in section 3. The future perspectives in this active research area are given in section 4.

Osteoconductivity and osteoinductivity of NanoFUSE(®) DBM

Bone graft substitutes have become an essential component in a number of orthopedic applications. Autologous bone has long been the gold standard for bone void fillers. However, the limited supply and morbidity associated with using autologous graft material has led to the development of many different bone graft substitutes. Allogeneic demineralized bone matrix (DBM) has been used extensively to supplement autograft bone because of its inherent osteoconductive and osteoinductive properties. Synthetic and natural bone graft substitutes that do not contain growth factors are considered to be osteoconductive only. Bioactive glass has been shown to facilitate graft containment at the operative site as well as activate cellular osteogenesis. In the present study, we present the results of a comprehensive in vitro and in vivo characterization of a combination of allogeneic human bone and bioactive glass bone void filler, NanoFUSE(®) DBM. NanoFUSE(®) DBM is shown to be biocompatible in a number of different assays and has been cleared by the FDA for use in bone filling indications. Data are presented showing the ability of the material to support cell attachment and proliferation on the material thereby demonstrating the osteoconductive nature of the material. NanoFUSE(®) DBM was also shown to be osteoinductive in the mouse thigh muscle model. These data demonstrate that the DBM and bioactive glass combination, NanoFUSE(®) DBM, could be an effective bone graft substitute.

Enhanced osteocalcin expression by osteoblast-like cells (MC3T3-E1) exposed to bioactive coating glass (SiO2-CaO-P2O5-MgO-K2O-Na2O system) ions

This study tested the hypothesis that bioactive coating glass (SiO(2)-CaO-P(2)O(5)-MgO-K(2)O-Na(2)O system), used for implant coatings, enhanced the induction of collagen type 1 synthesis and in turn enhanced the expression of downstream markers alkaline phosphatase, Runx2 and osteocalcin during osteoblast differentiation. The ions from experimental bioactive glass (6P53-b) and commercial Bioglass(TM) (45S5) were added to osteoblast-like MC3T3-E1 subclone 4 cultures as a supplemented ion extract (glass conditioned medium (GCM)). Ion extracts contained significantly higher concentrations of Si and Ca (Si, 47.9+/-10.4 ppm; Ca, 69.8+/-14.0 for 45S5; Si, 33.4+/-3.8 ppm; Ca, 57.1+/-2.8 ppm for 6P53-b) compared with the control extract (Si<0.1 ppm, Ca 49.0 ppm in alpha-MEM) (ANOVA, p<0.05). Cell proliferation rate was enhanced (1.5x control) within the first 3 days after adding 45S5 and 6P53-b GCM. MC3T3-E1 subclone 4 cultures were then studied for their response to the addition of test media (GCM and control medium along with ascorbic acid (AA; 50 ppm)). Each GCM+AA treatment enhanced collagen type 1 synthesis as observed in both gene expression results (day 1, Col1alpha1, 45S5 GCM+AA: 3x control+AA; 6P53-b GCM+AA: 4x control+AA; day 5, Col1alpha2, 45S5 GCM+AA: 3.15x control+AA; 6P53-b GCM+AA: 2.35x control+AA) and in histological studies (Picrosirius stain) throughout the time course of early differentiation. Continued addition of each GCM and AA treatment led to enhanced expression of alkaline phosphatase (1.4x control+AA after 5 days, 2x control+AA after 10 days), Runx2 (2x control+AA after 7 days) and osteocalcin gene (day 3, 45S5 GCM+AA: 14x control+AA; day 5, 6P53-b GCM+AA: 19x control+AA) and protein expression (40x-70x control+AA after 6 days). These results indicated the enhanced effect of bioactive glass ions on key osteogenic markers important for the bone healing process.

Orthopedic coating materials: considerations and applications

The host response to titanium and its alloys is not always favorable, as a fibrous layer may form at the skeletal tissue-device interface, causing aseptic loosening. Therefore, a great deal of current orthopedic research is focused on developing implants with improved osseointegration properties in order to increase their clinical success. Promising new studies have been reported regarding coating the currently available implants with various coating materials and techniques so as to improve the long-term stability of implants. This article will discuss various coating materials developed, their advantages and disadvantages as coating materials and their biological performance.

Osteoblast proliferation and maturation on bioactive fiber-reinforced composite surface

The objective of this study was to evaluate the proliferation and osteogenic potential of bone-marrow derived osteoblast-like cells on fiber-reinforced composite (FRC) substrates with and without bioactive glass surface modification. Three FRC materials were fabricated for the study: (a) grit-blasted FRC, (b) grit-blasted FRC with bidirectional net reinforcement and (c) FRC with bioactive glass (BAG) coating. Rat bone-marrow derived osteoblast-like cells were harvested and cultured on experimental material plates and on cp. titanium plates (control) for 21 days. The materials' surfaces were characterized by roughness testing and scanning electron microscopy. Cell growth and differentiation kinetics were subsequently investigated by evaluating proliferation, alkaline phosphatase (ALP) activity, osteocalcin (OC) and bone sialoprotein (BSP) production. On day 14, the cell proliferation was significantly lower (P<0.05) on FRC-BAG than on titanium and FRC. The proliferation on the other three materials was equal throughout the experiment. The maximal ALP activities on FRC, FRC-Net, and titanium were observed on day 21, whereas FRC-BAG had already reached the maximal level on day 14. Expression of osteoblastic markers (OC, BSP) indicates that the fastest osteogenic differentiation takes place on FRC after 7 days. In contrast, a slower differentiation process was observed on titanium than on any other tested material (P<0.015) at 21 days, as was confirmed by increased mRNA expression of OC and BSP. It can be concluded that the proliferation and maturation of osteoblast-like cells on FRC appears to be comparable to titanium. Presence of BAG enhances cell maturation.

Poly(3- hydroxybutyrate)/Bioglass(®) composite films containing carbon nanotubes

Poly(3hydroxybutyrate) (P(3HB))/Bioglass(®) composites incorporating multiwalled carbon nanotubes (MWCNTs) have been successfully prepared by the solvent casting technique. The microstructure, electrical properties and bioactivity of the composites were characterized using scanning electron microscopy, x-ray diffraction and current-voltage measurements. Different concentrations of MWCNTs were used to determine their effect on the electrical properties of the composites. MWCNTs and Bioglass(®) particles were found to be homogeneously dispersed throughout the P(3HB) matrix. The electrical resistance of the composite samples decreased on increasing the MWCNT concentration, as expected. An in vitro degradation study in simulated body fluid (SBF) was carried out on composite samples. The formation of hydroxyapatite on the surfaces of P(3HB)/Bioglass(®)/MWCNT composite films was confirmed after two months of immersion in SBF. This hydroxyapatite layer was not formed on the neat polymeric films and on composites containing MWCNTs only (without Bioglass(®)). It was found that the presence of MWCNTs did not hinder the bioactivity of the Bioglass(®) particles, as confirmed by SEM and XRD studies on composite samples.

Gene activation by bioactive glasses

Bioactive glasses have been shown to regulate gene expression in both hard and soft tissue repair. New resorbable bioactive glass constructs are now being developed that can influence gene expression in the local environment by manipulating material properties such as the surface chemistry, topography and the release of dissolution ions. The success of these scaffolds, however, may depend upon a greater understanding of the bioactive glass stimulated gene expression pathways. This will allow the construction of tissue specific scaffolds with tailored surface chemistry, topography and ion release rates. This paper summarises the advances made in understanding gene expression in response to bioactive glasses and discusses the future steps required for further insights into these molecular mechanisms.

Histomorphometric Analysis of Tissue Responses to Bioactive Glass Implants in Critical Defects in Rat Calvaria

The aim of this study was to evaluate the osteogenic behavior of two chemically similar bioactive glass products (Biogranand Perioglas) implanted in critical bone defects in rat calvaria. Thirty-six transfixed bone defects of 8 mm diameter were made surgically in adult male Wistar rats. The animals were distributed equally into three groups: Biogran (GI), Perioglas (GII) and without implant material (control; GIII). The morphology and composition of both bioactive glasses were analyzed by scanning electron microscopy and energy-dispersive spectrometry. Tissue specimens were analyzed at the biological time points of 15, 30 and 60 days by optical microscopy and morphometry, demonstrating biocompatibility for the tested materials with moderate chronic inflammation involving their particles. Bone neoformation resulted only as a reparative reaction to an intentionally produced defect and was limited to the defect's edges. No statistically significant differences among the groups were observed. At the scar interstice, abundant deposits of collagenous fibers enveloping the particles were noted. The present results indicated that the bioactive glasses, under the experimental conditions analyzed, did not show osteogenic behavior.

Cancellous bone repair using bovine trabecular bone matrix particulates

At 5 and 15 weeks post-surgery, biomechanical and histological analyses of cancellous bone defects filled with the bovine trabecular bone matrix (BBM) and hydroxyapatite (Hap) particulates of dimensions 106-150 microm were investigated. It was observed that at 5 weeks post-surgery the stiffness properties of the BBM filled defects were significantly higher than those observed in the Hap filled defects (p < 0.01) but comparable to those recorded in intact cancellous bone from the same anatomical position. Histologically, no significant differences were observed in the percentage of new bone contact with the particles. The biomechanical properties of the Hap filled defects mirrored those in intact cancellous bone only at 15 weeks post-surgery. BBM particles thus appeared to accelerate the early healing of osteotomies. It is therefore suggested that particles of this bioceramic be the subject of intense research for more usage in both periodontal osseous defects and orthopaedic fractures.