Bioactive Calcium Phosphate-Based Composites for Bone Regeneration

3D printing of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(lactide-co-glycolide) blend loaded with β-tricalcium phosphate for the development of scaffolds to support human mesenchymal stromal cell proliferation

Polyhydroxyalkanoates (PHAs) are microbially produced aliphatic polyesters investigated for tissue engineering thanks to their biocompatibility, processability, and suitable mechanical properties. Taking advantage of these properties, the present study investigates the development by 3D printing of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffolds loaded with β-tricalcium phosphate (β-TCP) for bone tissue regeneration. PHBV blending with poly(lactide-co-glycolide) (PLGA) (30 wt%) was exploited to enhance material processability via an optimized computer-aided wet-spinning approach. In particular, PHBV/PLGA blends were loaded with different β-TCP percentages (up to 15 wt%) by suspending the ceramic particles into the polymeric solution. The composite materials were successfully fabricated into 3D scaffolds with a fully interconnected porous architecture, as demonstrated by scanning electron microscopy. The ceramic phase had a significant effect on PHBV crystallization as shown by differential scanning calorimetry, as well as on scaffold mechanical properties with a significant increase of compressive modulus in the case of 5 wt% β-TCP loading. In addition, in vitro cell culture experiments demonstrated that β-TCP loading led to a significant increase of the viability of human mesenchymal stem/stromal cells grown on the scaffolds. Taken together, our data suggest that microbial PHBV processability, biomechanical performance, and bioactivity can be improved through combined PLGA blending and β-TCP loading.

Macroporous coating of silver-doped hydroxyapatite/silica nanocomposite on dental implants by EDTA intermediate to improve osteogenesis, antibacterial, and corrosion behavior

Coating a titanium (Ti) implant with hydroxyapatite (HA) increases its bioactivity and biocompatibility. However, implant-related infections and biological corrosion have restricted the success of implant. To address these issues, a modified HA nanocomposite (HA/silica-EDTA-AgNPs nanocomposite) was proposed to take advantage of the sustained release of silver nanoparticles (AgNPs) and silicate ions through the silica-EDTA chelating network. As a result, a uniform layer of nanocomposite, compared to HA as the gold standard, was formed on Ti implants without fracture and with a high level of adhesion, using plasma electrolytic oxidation (PEO). Bioactivity assessment evidenced a shift in the surface phase of the Ti implant to generation of beta-tricalcium phosphate, a more bioresorbable material than HA. Metabolic activity assessments using human dental pulp stem cells revealed that Ti surfaces modified by the new nanocomposite are superior to bare and HA-modified Ti surfaces for cell attachment and proliferationin vitro. In addition, it successfully inhibited bacterial growth and induced osteogenesis on the implant surface. Finally, potentiodynamic polarization behavior of Ti implants before and after coating confirmed that a thick oxide interface layer on the modified Ti surface acts as an electrical barrier and protects the substrate layer from corrosion. Therefore, the HA/silica-EDTA/Ag nanocomposite presented here, compared to HA, can better coat Ti dental implants due to its good biocompatibility and osteoinductive activity, along with improved biological stability.

3D-Printed PCL-Based Scaffolds with High Nanosized Synthetic Smectic Clay Content: Fabrication, Mechanical Properties, and Biological Evaluation for Bone Tissue Engineering

Background

The 3D printing of macro- and mesoporous biomimetic grafts composed of polycaprolactone (PCL) infused with nanosized synthetic smectic clay is a promising innovation in biomaterials for bone tissue engineering (BTE). The main challenge lies in achieving a uniform distribution of nanoceramics across low to high concentrations within the polymer matrix while preserving mechanical properties and biological performance essential for successful osseointegration.

Methods

This study utilized 3D printing to fabricate PCL scaffolds enriched with nanosized synthetic smectic clay (LAP) to evaluate its effects on structural, chemical, thermal, mechanical, and degradative properties, with a focus on in vitro biological performance and non-toxicity. Scaffolds were created with varying proportions of PCL and LAP. Comprehensive characterization included scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), mechanical testing, swelling analysis, and degradation studies. Biological performance was assessed through MTT assays (cell viability), alkaline phosphatase activity, histological analysis, and Raman spectroscopy, highlighting the scaffolds' biocompatibility and potential applications in regenerative medicine.

Results

The developed inks demonstrated excellent injectability, and the 3D-printed PCL/LAP scaffolds exhibited a microporous and rough structure, good structural fidelity, low degradability, thermal stability, and sufficient mechanical strength across all formulations. Intrinsic properties of the scaffolds revealed no cytotoxicity while enhancing bioactivity and promoting in vitro mineralization when cultured with mesenchymal stem cells in all analyzed groups. Notably, the high concentration of LAP within the PCL matrices did not induce in vitro cytotoxicity but rather stimulated in vitro mineralization and differentiation.

Conclusion

This study demonstrated the feasibility of 3D printing PCL/LAP scaffolds with high concentrations of nanoceramics. Both in vitro and in vivo assays validated the regenerative potential of these scaffolds, emphasizing their efficacy as a promising approach for developing advanced biomimetic grafts.

3D printing of strontium-enriched biphasic calcium phosphate scaffolds for bone regeneration

Calcium phosphate (CaP) scaffolds doping with therapeutic ions are one of the focuses of recent bone tissue engineering research. Among the therapeutic ions, strontium stands out for its role in bone remodeling. This work reports a simple method to produce Sr-doped 3D-printed CaP scaffolds, using Sr-doping to induce partial phase transformation from β-tricalcium phosphate (β-TCP) to hydroxyapatite (HA), resulting in a doped biphasic calcium phosphate (BCP) scaffold. Strontium carbonate (SrCO3) was incorporated in the formulation of the 3D-printing ink, studying β-TCP:SrO mass ratios of 100:0, 95:5, and 90:10 (named as β-TCP, β-TCP/5-Sr, and β-TCP/10-Sr, respectively). Adding SrCO3 in the 3D-printing ink led to a slight increase in viscosity but did not affect its printability, resulting in scaffolds with a high printing fidelity compared to the computational design. Interestingly, Sr was incorporated into the lattice structure of the scaffolds, forming hydroxyapatite (HA). No residual SrO or SrCO3 were observed in the XRD patterns of any composition, and HA was the majority phase of the β-TCP/10-Sr scaffolds. The addition of Sr increased the compression strength of the scaffolds, with both β-TCP/5-Sr and β-TCP/10-Sr performing better than the β-TCP. Overall, β-TCP/5-Sr presented higher mineralized nodules and mechanical strength, while β-TCP scaffolds presented superior cell viability. The incorporation of SrCO3 in the ink formulation is a viable method to obtain Sr-BCP scaffolds. Thus, this approach could be explored with other CaP scaffolds aiming to optimize their performance and the addition of alternative therapeutic ions.

Progress in Dentin-Derived Bone Graft Materials: A New Xenogeneic Dentin-Derived Material with Retained Organic Component Allows for Broader and Easier Application

The optimal repair of rigid mineralized tissues, such as bone, in cases of fracture, surgical resection, or prosthetic placement, is a complex process often necessitating the use of bone graft materials. Autogenous bone from the patient is generally the gold standard in terms of outcomes but also has disadvantages, which have resulted in extensive research in the field of tissue engineering to develop better and more convenient alternatives. In the dental field, several initiatives have demonstrated that the dentin material derived from extracted teeth produces excellent results in terms of repairing bone defects and supporting dental implants. Dentin is acellular and thus, in contrast to autogenous bone, cannot provide osteoblasts or other cellular elements to the grafted region, but it does contain growth and differentiation factors, and has other properties that make it an impressive material for bone repair. In this review, the beneficial properties of dentin and the ways it interacts with the host bone are described in the context of bone graft materials. Autogenous tooth material has limitations, particularly in terms of the need for tooth extraction and the limited amount available, which currently restrict its use to particular dental procedures. The development of a xenograft dentin-derived material, which retains the properties of autogenous dentin, is described. Such a material could potentially enable the use of dentin-derived material more widely, particularly in orthopedic indications where its properties may be advantageous.

Navigating the combinations of platelet-rich fibrin with biomaterials used in maxillofacial surgery

Platelet-rich fibrin (PRF) is a protein matrix with growth factors and immune cells extracted from venous blood via centrifugation. Previous studies proved it a beneficial biomaterial for bone and soft tissue regeneration in dental surgeries. Researchers have combined PRF with a wide range of biomaterials for composite preparation as it is biocompatible and easily acquirable. The results of the studies are difficult to compare due to varied research methods and the fact that researchers focus more on the PRF preparation protocol and less on the interaction of PRF with the chosen material. Here, the literature from 2013 to 2024 is reviewed to help surgeons and researchers navigate the field of commonly used biomaterials in maxillofacial surgeries (calcium phosphate bone grafts, polymers, metal nanoparticles, and novel composites) and their combinations with PRF. The aim is to help the readers select a composite that suits their planned research or medical case. Overall, PRF combined with bone graft materials shows potential for enhancing bone regeneration both in vivo and in vitro. Still, results vary across studies, necessitating standardized protocols and extensive clinical trials. Overviewed methods showed that the biological and mechanical properties of the PRF and material composites can be altered depending on the PRF preparation and incorporation process.

Materials for 3D printing in healthcare sector: A review

Additive Manufacturing (AM) encompasses various techniques creating intricate components from digital models. The aim of incorporating 3D printing (3DP) in the healthcare sector is to transform patient care by providing personalized solutions, improving medical procedures, fostering research and development, and ultimately optimizing the efficiency and effectiveness of healthcare delivery. This review delves into the historical beginnings of AM's 9 integration into medical contexts exploring various categories of AM methodologies and their roles within the medical sector. This survey also dives into the issue of material requirements and challenges specific to AM's medical applications. Emphasis is placed on how AM processes directly enhance human well-being. The primary focus of this paper is to highlight the evolution and incentives for cross-disciplinary AM applications, particularly in the realm of healthcare by considering their principle, materials and applications. It is designed for a diverse audience, including manufacturing professionals and researchers, seeking insights into this transformative technology's medical dimensions.

Regenerative treatment of canine osteogenic lesions with Platelet-Rich Plasma and hydroxyapatite: a case report

Introduction

This study examined the efficacy of a therapy based on a combination of Platelet Rich Plasma and hydroxyapatite nanoparticles in a severe clinical case involving a young Rottweiler with a complex spiral fracture of the tibia.

Method

Following a worsening of the lesion after traditional surgical intervention, the subject was treated with the combined therapy. X-rays were taken at the following stages: immediately post-surgery, four weeks post-surgery, and 10 days post-treatment. Fracture gap and callus density measurements were obtained using ImageJ analysis, allowing for a detailed quantitative assessment of bone regeneration over time.

Results

Post-operative radiographs indicated a clinical worsening of the fracture, revealing an increased fracture gap due to bone loss. However, significant improvements were observed ten days following the treatment, with a marked reduction in fracture gaps and increased callus density. These results demonstrated a notable acceleration in bone healing and callus formation compared to typical recovery times for similar lesions.

Conclusion

The method showed potential for enhancing osteogenic regeneration, facilitating faster healing of serious orthopedic injuries compared to traditional methods.

Evaluation of Mechanical and Elemental Properties of Bioceramic-Coated Orthodontic Brackets and Enamel Surface

OBJECTIVE

 The aim is to coat orthodontic brackets with two different bioactive materials and to compare the mechanical and morphological properties of coated brackets and tooth surfaces.

MATERIALS AND METHODS

 A total of 120 stainless steel brackets were divided equally into three groups, that is, the uncoated brackets and nanohydroxyapatite (nHA)-coated, and nanobioactive glass (nBG)-coated brackets using a spin coater machine. The brackets were bonded on the enamel surface and underwent remineralization/demineralization cycles for days 1, 7, 14, and 30. At each time interval, the bond strength of the brackets was assessed using mechanical loading. An optical and scanning electron microscope (SEM) were used for surface evaluation, and the adhesive remanent index (ARI) values were obtained and quantified.

STATISTICAL ANALYSIS

 One-way analysis of variance using Tukey's test was used to compare the differences among the groups.

RESULTS

 A uniform distribution of nanoparticles occurred on the surfaces of brackets. The shear bond strength (SBS) showed no significant differences in any tested groups on days 1, 7, and 14. However, control and nBG showed a significant difference from nHA at day 30. On days 7, 14, and 30, the nHA group showed the highest SBS values among the groups. For ARI, most samples showed an adhesive nature of failure at the enamel-brackets interface. The images confirmed the presence of coated particles on brackets and remnants of adhesives after SBS.

CONCLUSION

 This study confirmed that the nHA- and nBG-coated brackets have a high potential for application in orthodontics regarding structural and mechanical properties.

Dual-functional Hydroxyapatite scaffolds for bone regeneration and precision drug delivery

Addressing infected bone defects remains a significant challenge in orthopedics, requiring effective infection control and bone defect repair. A promising therapeutic approach involves the development of dual-functional engineered biomaterials with drug delivery systems that combine antibacterial properties with osteogenesis promotion. The Hydroxyapatite composite scaffolds offer a one-stage treatment, eliminating the need for multiple surgeries and thereby streamlining the process and reducing treatment time. This review delves into the impaired bone repair mechanisms within pathogen-infected and inflamed microenvironments, providing a theoretical foundation for treating infectious bone defects. Additionally, it explores composite scaffolds made of antibacterial and osteogenic materials, along with advanced drug delivery systems that possess both antibacterial and bone-regenerative properties. By offering a comprehensive understanding of the microenvironment of infectious bone defects and innovative design strategies for dual-function scaffolds, this review presents significant advancements in treatment methods for infectious bone defects. Continued research and clinical validation are essential to refine these innovations, ensuring biocompatibility and safety, achieving controlled release and stability, and developing scalable manufacturing processes for widespread clinical application.

Biomimetic Scaffolds of Calcium-Based Materials for Bone Regeneration

Calcium-based materials, such as calcium carbonate, calcium phosphate, and calcium silicate, have attracted significant attention in biomedical research, owing to their unique physicochemical properties and versatile applications. The distinctive characteristics of these materials, including their inherent biocompatibility and tunable structures, hold significant promise for applications in bone regeneration and tissue engineering. This review explores the biomedical applications of calcium-containing materials, particularly for bone regeneration. Their remarkable biocompatibility, tunable nanostructures, and multifaceted functionalities make them pivotal for advancing regenerative medicine, drug delivery system, and biomimetic scaffold applications. The evolving landscape of biomedical research continues to uncover new possibilities, positioning calcium-based materials as key contributors to the next generation of innovative biomaterial scaffolds.

In vitro antifungal and physicochemical properties of polymerized acrylic resin containing strontium-modified phosphate-based glass

Acrylic resins are widely used as the main components in removable orthodontic appliances. However, poor oral hygiene and maintenance of orthodontic appliances provide a suitable environment for the growth of pathogenic microorganisms. In this study, strontium-modified phosphate-based glass (Sr-PBG) was added to orthodontic acrylic resin at 0% (control), 3.75%, 7.5%, and 15% by weight to evaluate the surface and physicochemical properties of the novel material and its in vitro antifungal effect against Candida albicans (C. albicans). Surface microhardness and contact angle did not vary between the control and 3.75% Sr-PBG groups (p > 0.05), and the flexural strength was lower in the experimental groups than in the control group (p < 0.05), but no difference was found with Sr-PBG content (p > 0.05). All experimental groups showed an antifungal effect at 24 and 48 h compared to that in the control group (p < 0.05). This study demonstrated that 3.75% Sr-PBG exhibits antifungal effects against C. albicans along with suitable physicochemical properties, which may help to minimize the risk of adverse effects associated with harmful microbial living on removable orthodontic appliances and promote the use of various materials.

Preliminary osteogenic and antibacterial investigations of wood derived antibiotic-loaded bone substitute for the treatment of infected bone defects

Introduction: The development of reliable treatments for infected or potentially infected bone loss resulting from open fractures and non-unions is extremely urgent, especially to reduce the prolonged courses of antimicrobial therapy to which affected patients are subjected. Numerous bone graft substitutes have been used over the years, but there are currently no effective solutions to treat critical bone loss, especially in the presence of infection. The present study evaluated the use of the biomorphic calcium phosphate bone scaffold b. Bone™, based on a next-generation resorbable biomimetic biomaterial, in bone reconstruction surgery in cases of infection. Methods: Using an "in vitro 3D bone fracture model" to predict the behavior of this drug delivery system during critical bone loss at an infected (or potentially infected) site, the effects of scaffolds loaded with gentamicin or vancomycin on the viability and differentiation capacity of human mesenchymal stem cells (hMSCs) were evaluated. Results: This scaffold, when loaded with gentamicin or vancomycin, exhibits a typical drug release curve that determines the inhibitory effects on the growth of Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, as well as relative biofilm formation. Discussion: The study demonstrates that b.bone scaffolds can effectively address key challenges in orthopedic surgery and patient care by inhibiting bacterial growth and biofilm formation through rapid, potent antibiotic release, reducing the risk of treatment failure due to resistance, and providing a promising solution for bone infections and improved patient outcomes. Future studies could explore the combination of different antibiotics on these scaffolds for more tailored and effective treatments against post-traumatic osteomyelitis pathogens.

Influence of physicochemical characteristics of calcium phosphate-based biomaterials in cranio-maxillofacial bone regeneration. A systematic literature review and meta-analysis of preclinical models

Objectives

Calcium phosphate-based biomaterials (CaP) are the most widely used biomaterials to enhance bone regeneration in the treatment of alveolar bone deficiencies, cranio-maxillofacial and periodontal infrabony defects, with positive preclinical and clinical results reported. This systematic review aimed to assess the influence of the physicochemical properties of CaP biomaterials on the performance of bone regeneration in preclinical animal models.

Methods

The PubMed, EMBASE and Web of Science databases were searched to retrieve the preclinical studies investigating physicochemical characteristics of CaP biomaterials. The studies were screened for inclusion based on intervention (physicochemical characterization and in vivo evaluation) and reported measurable outcomes.

Results

A total of 1532 articles were retrieved and 58 studies were ultimately included in the systematic review. A wide range of physicochemical characteristics of CaP biomaterials was found to be assessed in the included studies. Despite a high degree of heterogeneity, the meta-analysis was performed on 39 studies and evidenced significant effects of biomaterial characteristics on their bone regeneration outcomes. The study specifically showed that macropore size, Ca/P ratio, and compressive strength exerted significant influence on the formation of newly regenerated bone. Moreover, factors such as particle size, Ca/P ratio, and surface area were found to impact bone-to-material contact during the regeneration process. In terms of biodegradability, the amount of residual graft was determined by macropore size, particle size, and compressive strength.

Conclusion

The systematic review showed that the physicochemical characteristics of CaP biomaterials are highly determining for scaffold's performance, emphasizing its usefulness in designing the next generation of bone scaffolds to target higher rates of regeneration.

Strategies for Improving Impaired Osseointegration in Compromised Animal Models

Implant osseointegration is reduced in patients with systemic conditions that compromise bone quality, such as osteoporosis, disuse syndrome, and type 2 diabetes. Studies using rodent models designed to mimic these compromised conditions demonstrated reduced bone-to-implant contact (BIC) or a decline in bone mineral density. These adverse effects are a consequence of disrupted intercellular communication. A variety of approaches have been developed to compensate for the altered microenvironment inherent in compromised conditions, including the use of biologics and implant surface modification. Chemical and physical modification of surface properties at the microscale, mesoscale, and nanoscale levels to closely resemble the surface topography of osteoclast resorption pits found in bone has proven to be a highly effective strategy for improving implant osseointegration. The addition of hydrophilicity to the surface further enhances osteoblast response at the bone-implant interface. These surface modifications, applied either alone or in combination, improve osseointegration by increasing proliferation and osteoblastic differentiation of osteoprogenitor cells and enhancing angiogenesis while modulating osteoclast activity to achieve net new bone formation, although the specific effects vary with surface treatment. In addition to direct effects on surface-attached cells, the communication between bone marrow stromal cells and immunomodulatory cells is sensitive to these surface properties. This article reports on the advances in titanium surface modifications, alone and in combination with novel therapeutics in animal models of human disease affecting bone quality. It offers clinically translatable perspectives for clinicians to consider when using different surface modification strategies to improve long-term implant performance in compromised patients. This review supports the use of surface modifications, bioactive coatings, and localized therapeutics as pragmatic approaches to improve BIC and enhance osteogenic activity from both structural and molecular standpoints.

Lamellar Septa-like Structured Carbonate Apatite Scaffolds with Layer-by-Layer Fracture Behavior for Bone Regeneration

Generally, ceramics are brittle, and porosity is inversely correlated with strength, which is one of the challenges of ceramic scaffolds. Here, we demonstrate that lamellar septum-like carbonate apatite scaffolds have the potential to overcome these challenges. They were fabricated by exploiting the cellular structure of the cuttlebone, removing the organic components from the cuttlebone, and performing hydrothermal treatment. Scanning electron microscopy revealed that the scaffolds had a cellular structure with walls between lamellar septa. The interwall and interseptal sizes were 80-180 and 300-500 μm, respectively. The size of the region enclosed by the walls and septa coincided with the macropore size detected by mercury intrusion porosimetry. Although the scaffold porosity was extremely high (93.2%), the scaffold could be handled without disintegration. The compressive stress-strain curve demonstrated that the scaffolds showed layer-by-layer fracture behavior, which seemed beneficial for avoiding catastrophic failure under impact. When the scaffolds were implanted into rabbit femurs, new bone and blood vessels formed within the scaffold cells at 4 weeks. At 12 weeks, the scaffolds were almost entirely replaced with new bone. Thus, the lamellar septum-like cellular-structured carbonate apatite is a promising scaffold for achieving early bone regeneration and compression resistance.

Model-Based Design to Enhance Neotissue Formation in Additively Manufactured Calcium-Phosphate-Based Scaffolds

In biomaterial-based bone tissue engineering, optimizing scaffold structure and composition remains an active field of research. Additive manufacturing has enabled the production of custom designs in a variety of materials. This study aims to improve the design of calcium-phosphate-based additively manufactured scaffolds, the material of choice in oral bone regeneration, by using a combination of in silico and in vitro tools. Computer models are increasingly used to assist in design optimization by providing a rational way of merging different requirements into a single design. The starting point for this study was an in-house developed in silico model describing the in vitro formation of neotissue, i.e., cells and the extracellular matrix they produced. The level set method was applied to simulate the interface between the neotissue and the void space inside the scaffold pores. In order to calibrate the model, a custom disk-shaped scaffold was produced with prismatic canals of different geometries (circle, hexagon, square, triangle) and inner diameters (0.5 mm, 0.7 mm, 1 mm, 2 mm). The disks were produced with three biomaterials (hydroxyapatite, tricalcium phosphate, and a blend of both). After seeding with skeletal progenitor cells and a cell culture for up to 21 days, the extent of neotissue growth in the disks' canals was analyzed using fluorescence microscopy. The results clearly demonstrated that in the presence of calcium-phosphate-based materials, the curvature-based growth principle was maintained. Bayesian optimization was used to determine the model parameters for the different biomaterials used. Subsequently, the calibrated model was used to predict neotissue growth in a 3D gyroid structure. The predicted results were in line with the experimentally obtained ones, demonstrating the potential of the calibrated model to be used as a tool in the design and optimization of 3D-printed calcium-phosphate-based biomaterials for bone regeneration.

Strontium-Substituted Nanohydroxyapatite-Incorporated Poly(lactic acid) Composites for Orthopedic Applications: Bioactive, Machinable, and High-Strength Properties

Traditional metal-alloy bone fixation devices provide structural support for bone repair but have limitations in actively promoting bone healing and often require additional surgeries for implant removal. In this study, we focused on addressing these challenges by fabricating biodegradable composites using poly(lactic acid) (PLA) and strontium-substituted nanohydroxyapatite (SrHAP) via melt compounding and injection molding. Various percentages of SrHAP (5, 10, 20, and 30% w/w) were incorporated into the PLA matrix. We systematically investigated the structural, morphological, thermal, mechanical, rheological, and dynamic mechanical properties of the prepared composites. Notably, the tensile modulus, a critical parameter for orthopedic implants, significantly improved from 2.77 GPa in pristine PLA to 3.73 GPa in the composite containing 10% w/w SrHAP. The incorporation of SrHAP (10% w/w) into the PLA matrix led to an increased storage modulus, indicating a uniform dispersion of SrHAP within the PLA and good compatibility between the polymer and nanoparticles. Moreover, we successfully fabricated screws using PLA composites with 10% (w/w) SrHAP, demonstrating their formability at room temperature and radiopacity when observed under X-ray microtomography (micro-CT). Furthermore, the water contact angle decreased from 93 ± 2° for pristine PLA to 75 ± 3° for the composite containing SrHAP, indicating better surface wettability. To assess the biological behavior of the composites, we conducted in vitro cell-material tests, which confirmed their osteoconductive and osteoinductive properties. These findings highlight the potential of our developed PLA/SrHAP10 (10% w/w) composites as machinable implant materials for orthopedic applications. In conclusion, our study presents the fabrication and comprehensive characterization of biodegradable composites comprising PLA and strontium-substituted nanohydroxyapatite (SrHAP). These composites exhibit improved mechanical properties, formability, and radiopacity while also demonstrating desirable biological behavior. Our results suggest that these PLA/SrHAP10 composites hold promise as machinable implant materials for orthopedic applications.

Fabrication of injectable antibiotic-loaded apatitic bone cements with prolonged drug delivery for treating post-surgery infections

Antibiotic-loaded bioactive bone substitutes are widely used for treating various orthopedic diseases and prophylactically to avoid post implantation infection. Calcium deficient hydroxyapatite (also known as apatitic bone cement) is a potential bioactive bone substitute in orthopedics due to its chemical composition similar to that of natural bone minerals. In this study, fabrication of mannitol (a solid porogen) incorporated injectable synthetic (Syn) and eggshell derived (ESD) apatitic bone cements loaded with antibiotics (gentamicin/meropenem/ rifampicin/vancomycin) was investigated. The release kinetics of the antibiotics were studied by fitting them with different kinetic models. All the antibiotics-loaded apatitic bone cements set within clinically accepted setting time (20 ± 2 min) and with good injectability (>70%). The antibiotics released from these bone cements were found to be controlled and sustained throughout the study time. Weibull and Gompertz (applies in least initial burst and sustain drug release rate models) were the best models to predict the release behavior. They cements had acceptable compressive strength (6-10 MPa; in the range of trabecular bone) and were biodegradable (21%-27% within 12 weeks of incubation) in vitro in simulated body fluids at physiological conditions. These bone cements showed excellent antibacterial activity from day 1 onwards and no bacterial colony was found from day 3 onwards. The viability of MG63 cells in vitro after 72 h was significantly higher after 24 h (i.e., ~110%). The cells were well attached and spread over the surface of the cements with extended morphology. The ESD antibiotic-loaded apatitic bone cements showed better injectability, degradation and cytocompatibility compared when compared to Syn antibiotic-loaded apatitic bone cements. Thus, we believe that the ESD antibiotic-loaded apatitic bone cements are suitable as potential injectable bone substitutes to avoid post-operative implant associated and other acute or chronic bone infections.

A better roadmap for designing novel bioactive glasses: effective approaches for the development of innovative revolutionary bioglasses for future biomedical applications

The introduction of bioactive glasses (BGs) precipitated a paradigm shift in the medical industry and opened the path for the development of contemporary regenerative medicine driven by biomaterials. This composition can bond to live bone and can induce osteogenesis by the release of physiologically active ions. 45S5 BG products have been transplanted effectively into millions of patients around the world, primarily to repair bone and dental defects. Over the years, many other BG compositions have been introduced as innovative biomaterials for repairing soft tissue and delivering drugs. When research first started, many of the accomplishments that have been made today were unimaginable. It appears that the true capacity of BGs has not yet been realized. Because of this, research involving BGs is extremely fascinating. However, to be successful, it requires interdisciplinary cooperation between physicians, glass chemists, and bioengineers. The present paper gives a picture of the existing clinical uses of BGs and illustrates key difficulties deserving to be faced in the future. The challenges range from the potential for BGs to be used in a wide variety of applications. We have high hopes that this paper will be of use to both novice researchers, who are just beginning their journey into the world of BGs, as well as seasoned scientists, in that it will promote conversation regarding potential additional investigation and lead to the discovery of innovative medical applications for BGs.

Polysaccharide-bioceramic composites for bone tissue engineering: A review

Limitations associated with conventional bone substitutes such as autografts, increasing demand for bone grafts, and growing elderly population worldwide necessitate development of unique materials as bone graft substitutes. Bone tissue engineering (BTE) would ensure therapy advancement, efficiency, and cost-effective treatment modalities of bone defects. One way of engineering bone tissue scaffolds by mimicking natural bone tissue composed of organic and inorganic phases is to utilize polysaccharide-bioceramic hybrid composites. Polysaccharides are abundant in nature, and present in human body. Biominerals, like hydroxyapatite are present in natural bone and some of them possess osteoconductive and osteoinductive properties. Ion doped bioceramics could substitute protein-based biosignal molecules to achieve osteogenesis, vasculogenesis, angiogenesis, and stress shielding. This review is a systemic summary on properties, advantages, and limitations of polysaccharide-bioceramic/ion doped bioceramic composites along with their recent advancements in BTE.

Optimization of the Composition of Mesoporous Polymer-Ceramic Nanocomposite Granules for Bone Regeneration

Difficult-to-treat bone damage resulting from metabolic bone diseases, mechanical injuries, or tumor resection requires support in the form of biomaterials. The aim of this research was to optimize the concentration of individual components of polymer-ceramic nanocomposite granules (nanofilled polymer composites) for application in orthopedics and maxillofacial surgery to fill small bone defects and stimulate the regeneration process. Two types of granules were made using nanohydroxyapatite (nanoHA) and chitosan-based matrix (agarose/chitosan or curdlan/chitosan), which served as binder for ceramic nanopowder. Different concentrations of the components (nanoHA and curdlan), foaming agent (sodium bicarbonate-NaHCO₃), and chitosan solvent (acetic acid-CH₃COOH) were tested during the production process. Agarose and chitosan concentrations were fixed to be 5% w/v and 2% w/v, respectively, based on our previous research. Subsequently, the produced granules were subjected to cytotoxicity testing (indirect and direct contact methods), microhardness testing (Young's modulus evaluation), and microstructure analysis (porosity, specific surface area, and surface roughness) in order to identify the biomaterial with the most favorable properties. The results demonstrated only slight differences among the resultant granules with respect to their microstructural, mechanical, and biological properties. All variants of the biomaterials were non-toxic to a mouse preosteoblast cell line (MC3T3-E1), supported cell growth on their surface, had high porosity (46-51%), and showed relatively high specific surface area (25-33 m²/g) and Young's modulus values (2-10 GPa). Apart from biomaterials containing 8% w/v curdlan, all samples were predominantly characterized by mesoporosity. Nevertheless, materials with the greatest biomedical potential were obtained using 5% w/v agarose, 2% w/v chitosan, and 50% or 70% w/v nanoHA when the chitosan solvent/foaming agent ratio was equal to 2:2. In the case of the granules containing curdlan/chitosan matrix, the most optimal composition was as follows: 2% w/v chitosan, 4% w/v curdlan, and 30% w/v nanoHA. The obtained test results indicate that both manufactured types of granules are promising implantable biomaterials for filling small bone defects that can be used in maxillofacial surgery.

Calcium Phosphate Cements as Carriers of Functional Substances for the Treatment of Bone Tissue

Interest in calcium phosphate cements as materials for the restoration and treatment of bone tissue defects is still high. Despite commercialization and use in the clinic, the calcium phosphate cements have great potential for development. Existing approaches to the production of calcium phosphate cements as drugs are analyzed. A description of the pathogenesis of the main diseases of bone tissue (trauma, osteomyelitis, osteoporosis and tumor) and effective common treatment strategies are presented in the review. An analysis of the modern understanding of the complex action of the cement matrix and the additives and drugs distributed in it in relation to the successful treatment of bone defects is given. The mechanisms of biological action of functional substances determine the effectiveness of use in certain clinical cases. An important direction of using calcium phosphate cements as a carrier of functional substances is the volumetric incorporation of anti-inflammatory, antitumor, antiresorptive and osteogenic functional substances. The main functionalization requirement for carrier materials is prolonged elution. Various release factors related to the matrix, functional substances and elution conditions are considered in the work. It is shown that cements are a complex system. Changing one of the many initial parameters in a wide range changes the final characteristics of the matrix and, accordingly, the kinetics. The main approaches to the effective functionalization of calcium phosphate cements are considered in the review.

Clindamycin-Loaded Nanosized Calcium Phosphates Powders as a Carrier of Active Substances

Bioactive calcium phosphate ceramics (CaPs) are one of the building components of the inorganic part of bones. Synthetic CaPs are frequently used as materials for filling bone defects in the form of pastes or composites; however, their porous structure allows modification with active substances and, thus, subsequent use as a drug carrier for the controlled release of active substances. In this study, four different ceramic powders were compared: commercial hydroxyapatite (HA), TCP, brushite, as well as HA obtained by wet precipitation methods. The ceramic powders were subjected to physicochemical analysis, including FTIR, XRD, and determination of Ca/P molar ratio or porosity. These techniques confirmed that the materials were phase-pure, and the molar ratios of calcium and phosphorus elements were in accordance with the literature. This confirmed the validity of the selected synthesis methods. CaPs were then modified with the antibiotic clindamycin. Drug release was determined on HPLC, and antimicrobial properties were tested against Staphylococcus aureus. The specific surface area of the ceramic has been demonstrated to be a factor in drug release efficiency.

In vitro hemocompatibility studies on small-caliber stents for cardiovascular applications

The doping of biologically meaningful ions into biphasic calcium phosphate (BCP) bioceramics, which exhibit biocompatibility with human body parts, has led to their effective use in biomedical applications in recent years. Doping with metal ions while changing the characteristics of the dopant ions, an arrangement of various ions in the Ca/P crystal structure. In our work, small-diameter vascular stents based on BCP and biologically appropriate ion substitute-BCP bioceramic materials were developed for cardiovascular applications. The small-diameter vascular stents were created using an extrusion process. FTIR, XRD, and FESEM were used to identify the functional groups, crystallinity, and morphology of the synthesized bioceramic materials. In addition, investigation of the blood compatibility of the 3D porous vascular stents was carried out via hemolysis. The outcomes indicate that the prepared grafts are appropriate for clinical requirements.

New Series of Red-Light Phosphor Ca9-xZnxGd0.9(PO4)7:0.1Eu3+ (x = 0-1)

In this study, a new series of phosphors, Ca9−xZnxGd0.9(PO4)7:0.1Eu3+ (x = 0.00−1.00, step dx 0.05), was synthesized, consisting of centro- and non-centrosymmetric phases with β-Ca3(PO4)2-type structure. Crystal structures with space groups R3c (0.00 ≤ x < 0.35) and R3¯c (x > 0.8) were determined using X-ray powder diffraction and the method of optical second harmonic generation. In the region 0.35 ≤ x ≤ 0.75, phases R3c and R3¯c were present simultaneously. Refinement of the Ca8ZnGd(PO4)7 crystal structure with the Rietveld method showed that 71% of Gd3+ ions are in M3 sites and 29% are in M1 sites. A luminescent spectroscopy study of Ca9−xZnxGd0.9(PO4)7:0.1Eu3+ indicated the energy transfer from the crystalline host to the Gd3+ and Eu3+ luminescent centers. The maximum Eu3+ luminescence intensity corresponds to the composition with x = 1.

The Use of Newly Synthesized Composite Scaffolds for Bone Regeneration - A Review of Literature

Bone tissue engineering is a multidisciplinary concept that combines biological and engineering principles to repair bone defects. Three elements that have a fundamental role in bone tissue engineering are scaffolds, stem cells, and bioactive components. Scaffolds mimic extracellular matrix functions and provide mechanical support for the new tissue formation. They are made of different natural and synthetic materials that can be categorized into three main groups: ceramics, metals, and polymers. Among them, synthetic polyesters and their combination with bioceramics, have been the most frequently used for scaffold fabrication. They could be potentially applied in clinical practice in the future as an alternative to the standard use of bone grafts but more studies are needed to assess their performance in the challenging conditions of human bone defects.

Nanohydroxyapatite/Titanate Nanotube Composites for Bone Tissue Regeneration

Strategies for the production of new nanocomposites that promote bone tissue regeneration are important, particularly those that enhance the osteoinduction of hydroxyapatite in situ. Here, we studied and report the synthesis of nanohydroxyapatite and titanate nanotube (nHAp/TiNT) composites formulated at different concentrations (1, 2, 3, and 10 wt % TiNT) by means of a wet aqueous chemical reaction. The addition of TiNT affects the morphology of the nanocomposites, decreasing the average crystallite size from 54 nm (nHAp) to 34 nm (nHAp/TiNT10%), while confirming its interaction with the nanocomposite. The crystallinity index (CI) calculated by Raman spectroscopy and XRD showed that the values decreased according to the increase in TiNT concentration, which confirmed their addition to the structure of the nanocomposite. SEM images showed the presence of TiNTs in the nanocomposite. We further verified the potential cytotoxicity of murine fibroblast cell line L929, revealing that there was no remarkable cell death at any of the concentrations tested. In vivo regenerative activity was performed using oophorectomized animal (rat) models organized into seven groups containing five animals each over two experimental periods (15 and 30 days), with bone regeneration occurring in all groups tested within 30 days; however, the nHAp/TiNT10% group showed statistically greater tissue repair, compared to the untreated control group. Thus, the results of this study demonstrate that the presently formulated nHAp/TiNT nanocomposites are promising for numerous improved bone tissue regeneration applications.

Strontium-doped apatitic bone cements with tunable antibacterial and antibiofilm ability

Injectable calcium phosphate cements (CPCs) represent promising candidates for the regeneration of complex-shape bone defects, thanks to self-hardening ability, bioactive composition and nanostructure offering high specific surface area for cell attachment and conduction. Such features make CPCs also interesting for functionalization with various biomolecules, towards the generation of multifunctional devices with enhanced therapeutic ability. In particular, strontium-doped CPCs have been studied in the last years due to the intrinsic antiosteoporotic character of strontium. In this work, a SrCPC previously reported as osteointegrative and capable to modulate the fate of bone cells was enriched with hydroxyapatite nanoparticles (HA-NPs) functionalized with tetracycline (TC) to provide antibacterial activity. We found that HA-NPs functionalized with TC (NP-TC) can act as modulator of the drug release profile when embedded in SrCPCs, thus providing a sustained and tunable TC release. In vitro microbiological tests on Escherichia coli and Staphylococcus aureus strains proved effective bacteriostatic and bactericidal properties, especially for the NP-TC loaded SrCPC formulations. Overall, our results indicate that the addition of NP-TC on CPC acted as effective modulator towards a tunable drug release control in the treatment of bone infections or cancers.

Standardized and axially vascularized calcium phosphate-based implants for segmental mandibular defects: A promising proof of concept

The reconstruction of massive segmental mandibular bone defects (SMDs) remains challenging even today; the current gold standard in human clinics being vascularized bone transplantation (VBT). As alternative to this onerous approach, bone tissue engineering strategies have been widely investigated. However, they displayed limited clinical success, particularly in failing to address the essential problem of quick vascularization of the implant. Although routinely used in clinics, the insertion of intrinsic vascularization in bioengineered constructs for the rapid formation of a feeding angiosome remains uncommon. In a clinically relevant model (sheep), a custom calcium phosphate-based bioceramic soaked with autologous bone marrow and perfused by an arteriovenous loop was tested to regenerate a massive SMD and was compared to VBT (clinical standard). Animals did not support well the VBT treatment, and the study was aborted 2 weeks after surgery due to ethical and animal welfare considerations. SMD regeneration was successful with the custom vascularized bone construct. Implants were well osseointegrated and vascularized after only 3 months of implantation and totally entrapped in lamellar bone after 12 months; a healthy yellow bone marrow filled the remaining space. STATEMENT OF SIGNIFICANCE: Regenerative medicine struggles with the generation of large functional bone volume. Among them segmental mandibular defects are particularly challenging to restore. The standard of care, based on bone free flaps, still displays ethical and technical drawbacks (e.g., donor site morbidity). Modern engineering technologies (e.g., 3D printing, digital chain) were combined to relevant surgical techniques to provide a pre-clinical proof of concept, investigating for the benefits of such a strategy in bone-related regenerative field. Results proved that a synthetic-biologics-free approach is able to regenerate a critical size segmental mandibular defect of 15 cm³ in a relevant preclinical model, mimicking real life scenarii of segmental mandibular defect, with a full physiological regeneration of the defect after 12 months.

Radiopaque Crystalline, Non-Crystalline and Nanostructured Bioceramics

Radiopacity is sometimes an essential characteristic of biomaterials that can help clinicians perform follow-ups during pre- and post-interventional radiological imaging. Due to their chemical composition and structure, most bioceramics are inherently radiopaque but can still be doped/mixed with radiopacifiers to increase their visualization during or after medical procedures. The radiopacifiers are frequently heavy elements of the periodic table, such as Bi, Zr, Sr, Ba, Ta, Zn, Y, etc., or their relevant compounds that can confer enhanced radiopacity. Radiopaque bioceramics are also intriguing additives for biopolymers and hybrids, which are extensively researched and developed nowadays for various biomedical setups. The present work aims to provide an overview of radiopaque bioceramics, specifically crystalline, non-crystalline (glassy), and nanostructured bioceramics designed for applications in orthopedics, dentistry, and cancer therapy. Furthermore, the modification of the chemical, physical, and biological properties of parent ceramics/biopolymers due to the addition of radiopacifiers is critically discussed. We also point out future research lacunas in this exciting field that bioceramists can explore further.

Strontium Substituted β-Tricalcium Phosphate Ceramics: Physiochemical Properties and Cytocompatibility

Sr²⁺-substituted β-tricalcium phosphate (β-TCP) powders were synthesized using the mechano-chemical activation method with subsequent pressing and sintering to obtain ceramics. The concentration of Sr²⁺ in the samples was 0 (non-substituted TCP, as a reference), 3.33 (0.1SrTCP), and 16.67 (0.5SrTCP) mol.% with the expected Ca₃(PO₄)₂, Ca_2.9Sr_0.1(PO₄)₂, and Ca_2.5Sr_0.5(PO₄)₂ formulas, respectively. The chemical compositions were confirmed by the energy-dispersive X-ray spectrometry (EDX) and the inductively coupled plasma optical emission spectroscopy (ICP-OES) methods. The study of the phase composition of the synthesized powders and ceramics by the powder X-ray diffraction (PXRD) method revealed that β-TCP is the main phase in all compounds except 0.1SrTCP, in which the apatite (Ap)-type phase was predominant. TCP and 0.5SrTCP ceramics were soaked in the standard saline solution for 21 days, and the phase analysis revealed the partial dissolution of the initial β-TCP phase with the formation of the Ap-type phase and changes in the microstructure of the ceramics. The Sr²⁺ ion release from the ceramic was measured by the ICP-OES. The human osteosarcoma MG-63 cell line was used for viability, adhesion, spreading, and cytocompatibility studies. The results show that the introduction of Sr²⁺ ions into the β-TCP improved cell adhesion, proliferation, and cytocompatibility of the prepared samples. The obtained results provide a base for the application of the Sr²⁺-substituted ceramics in model experiments in vivo.

Effects of Scaffold Shape on Bone Regeneration: Tiny Shape Differences Affect the Entire System

Although studies on scaffolds for tissue generation have mainly focused on the chemical composition and pore structure, the effects of scaffold shape have been overlooked. Scaffold shape determines the scaffold surface area (SA) at the single-scaffold level (i.e., microscopic effects), although it also affects the amount of interscaffold space in the tissue defect at the whole-system level (i.e., macroscopic effects). To clarify these microscopic and macroscopic effects, this study reports the osteogenesis abilities of three types of carbonate apatite granular scaffolds with different shapes, namely, irregularly shaped dense granules (DGs) and two types of honeycomb granules (HCGs) with seven hexagonal channels (∼255 μm in length between opposite sides). The HCGs possessed either 12 protuberances (∼75 μm in length) or no protuberances. Protuberances increased the SA of each granule by 3.24 mm2 while also widening interscaffold spaces and increasing the space percentage in the defect by ∼7.6%. Interscaffold spaces were lower in DGs than HCGs. On DGs, new bone formed only on the surface, whereas on HCGs, bone simultaneously formed on the surface and in intrascaffold channels. Interestingly, HCGs without protuberances formed approximately 30% more new bone than those with protuberances. Thus, even tiny protuberances on the scaffold surface can affect the percentage of interscaffold space, thereby exerting dominant effects on osteogenesis. Our findings demonstrate that bone regeneration can be improved by considering macroscopic shape effects beyond the microscopic effects of the scaffold.

Design Strategies and Biomimetic Approaches for Calcium Phosphate Scaffolds in Bone Tissue Regeneration

Bone is a complex biologic tissue, which is extremely relevant for various physiological functions, in addition to movement, organ protection, and weight bearing. The repair of critical size bone defects is a still unmet clinical need, and over the past decades, material scientists have been expending efforts to find effective technological solutions, based on the use of scaffolds. In this context, biomimetics which is intended as the ability of a scaffold to reproduce compositional and structural features of the host tissues, is increasingly considered as a guide for this purpose. However, the achievement of implants that mimic the very complex bone composition, multi-scale structure, and mechanics is still an open challenge. Indeed, despite the fact that calcium phosphates are widely recognized as elective biomaterials to fabricate regenerative bone scaffolds, their processing into 3D devices with suitable cell-instructing features is still prevented by insurmountable drawbacks. With respect to biomaterials science, new approaches maybe conceived to gain ground and promise for a substantial leap forward in this field. The present review provides an overview of physicochemical and structural features of bone tissue that are responsible for its biologic behavior. Moreover, relevant and recent technological approaches, also inspired by natural processes and structures, are described, which can be considered as a leverage for future development of next generation bioactive medical devices.

Granular honeycomb scaffolds composed of carbonate apatite for simultaneous intra- and inter-granular osteogenesis and angiogenesis

Granular porous calcium phosphate scaffolds are used for bone regeneration in dentistry. However, in conventional granules, the macropore interconnectivity is poor and has varying size. Herein, we developed a productive method for fabricating carbonate apatite honeycomb granules with uniformly sized macropores based on extrusion molding. Each honeycomb granule possesses three hexagonal macropores of ∼290 ​μm along its diagonal. Owing to these macropores, honeycomb granules simultaneously formed new and mature bone and blood vessels in both the interior and exterior of the granules at 4 weeks after implantation. The honeycomb granules are useful for achieving rapid osteogenesis and angiogenesis.

Editorial for the Special Issue on Bioceramic Composites

This Special Issue on bioceramic composites and its published papers, addressing a number of current topics from industry and academia, are intended to be a reference for students and scholars in the field of biomaterials science, giving an insight into challenges and research topics in the field bioceramic composites [...]

The Application of Beta-Tricalcium Phosphate in Implant Dentistry: A Systematic Evaluation of Clinical Studies

The demand for synthetic graft materials in implant dentistry is rising. This systematic review aims to evaluate the survival rate of dental implants placed simultaneously with bone regeneration procedures using the material β-tricalcium phosphate, one of the most promising synthetic graft materials. The electronic search was conducted in PubMed, Scielo, and the Cochrane Central Register of Controlled Trials. Five randomized clinical trials, one non-randomized controlled clinical trial and four observational studies without control group were include. Implant survival rate and other clinical, radiographic, and histological parameters did not differ from those of implants placed simultaneously with another type of graft material, or placed in blood clots or natural alveolar ridges. Based on the available literature, β-tricalcium phosphate seems to be a promising graft material in implant dentistry. Nevertheless, more randomized clinical trials, with long follow-up periods, preoperative and postoperative CBCT, and histological analysis, are necessary to assess its long-term behavior.

Toughening of Bioceramic Composites for Bone Regeneration

Bioceramics are widely considered as elective materials for the regeneration of bone tissue, due to their compositional mimicry with bone inorganic components. However, they are intrinsically brittle, which limits their capability to sustain multiple biomechanical loads, especially in the case of load-bearing bone districts. In the last decades, intense research has been dedicated to combining processes to enhance both the strength and toughness of bioceramics, leading to bioceramic composite scaffolds. This review summarizes the recent approaches to this purpose, particularly those addressed to limiting the propagation of cracks to prevent the sudden mechanical failure of bioceramic composites.