Simultaneous mechanical property and biodegradation improvement of wollastonite bioceramic through magnesium dilute doping

Tuning zinc content in wollastonite bioceramic endowing outstanding angiogenic and antibacterial functions beneficial for orbital reconstruction

Prosthetic eye is indispensable as filler after enucleation in patients with anophthalmia, whereas there are still many complications including postoperative infection and eye socket depression or extrusion during the conventional artificial eye material applications. Some Ca-silicate biomaterials showed superior bioactivity but their biological stability in vivo limit the biomedical application as long-term or permanent implants. Herein we aimed to understand the physicochemical and potential biological responses of zinc doping in wollastonite bioceramic used for orbital implants. The wollastonite powders with different zinc dopant contents (CSi-Znx) could be fabricated as porous implants with strut or curve surface pore geometries (cubic, IWP) via ceramic stereolithography. The experimental results indicated that, by increasing zinc-substituting-Ca ratio (up to 9%), the sintering and mechanical properties could be significantly enhanced, and meanwhile the bio-dissolution in vitro and biodegradability in vivo were thoroughly inhibited. In particular, an appreciable angiogenic activity and expected antibacterial efficacy (over 90 %) were synergistically achieved at 9 mol% Zn dopant. In the back-embedding and enucleation and implantation model experiments in rabbits, the superior continuous angiogenesis was corroborated from the 2D/3D fibrovascular reconstruction in the IWP-pore CSi-Zn9 and CSi-Zn13.5 groups within very short time stages. Totally, the present silicate-based bioceramic via selective Zn doping could produce outstanding structural stability and bifunctional biological responses which is especially valuable for developing the next-generation implants with vascular insertion and fixation in orbital reconstruction prothesis.

Dual-core-component multiphasic bioceramic granules with selective-area porous structures facilitating bone tissue regeneration and repair

Ca-phosphate/-silicate ceramic granules have been widely studied because their biodegradable fillers can enhance bone defect repair accompanied with bioactive ion release and material degradation; however, it is a challenge to endow bioceramic composites with time-dependent ion release and highly efficient osteogenesis in vivo. Herein, we prepared dual-core-type bioceramic granules with varying chemical compositions beneficial for controlling ion release and stimulating osteogenic capability. Core-shell-structured bioceramic granules (P8-Sr4@Zn3, P8-Sr4@TCP, and P8-Sr4@HAR) composed of 8% P- and 4% Sr-substituting wollastonite (P8, Sr4) dual core components and different shell components, such as 3% Zn-substituting wollastonite (Zn3), β-tricalcium phosphate (β-TCP), and hardystonite (HAR), were prepared by cutting extruded core-shell fibers through dual-core ternary nozzles, followed by high-temperature sintering post-treatment. The experimental results showed that nonstoichiometric wollastonite core components contributed to more biologically active ion release in Tris buffer in vitro, and the sparingly dissolvable shell component readily maintained the granule morphology in vivo; thus, such bioceramic implants can adjust new bone growth and material degradation over time. In particular, bioceramic granules encapsulated by the TCP shell exhibited the most appreciable osteogenic capacity and expected biodegradation, which was mostly favorable for bone repair in critical bone defects. It is reasonable to consider that this new multiphasic bioceramic granule design is versatile for developing next-generation implants for various bone damage repairs.

Appreciable biosafety, biocompatibility and osteogenic capability of 3D printed nonstoichiometric wollastonite scaffolds favorable for clinical translation

Background

Alveolar bone destruction due to periodontal disease often requires a bone graft substitute to reconstruct the anatomical structures and biological functions of the bone tissue. Despite significant advances in the development of foreign ion-doped nonstoichiometric wollastonite bioceramics (CaSiO3, nCSi) for alveolar bone regeneration over the past decade, the in vivo biosafety and osteogenesis of nCSi scaffolds remain uncertain. In this study, we developed a customized porous nCSi scaffold to investigate the in vivo biocompatibility and osteogenic properties of nCSi bioceramics.

Methods

Six percent Mg-doped nCSi bioceramic scaffolds were fabricated by digital light processing (DLP), and the scaffold morphology, pore architecture, compressive strength, in vitro biodegradation, and apatite-forming ability of the bioceramic scaffolds were investigated systematically. Subsequently, an alveolar bone defect rabbit model was used to evaluate the biocompatibility and osteogenic efficacy of the nCSi bioceramics. Animal weight, hematological test, blood biochemical test, wet weight of the main organs, and pathological examination of the main organs were conducted. Micro-CT and histological staining were performed to analyze the osteogenic potential of the personalized bioceramic scaffolds.

Results

The nCSi scaffolds exhibited appreciable initial compressive strength (>30 MPa) and mild mechanical decay over time during in vitro biodissolution. In addition, the scaffolds induced apatite remineralization in SBF. Bioceramic scaffolds have been proven to have good biocompatibility in vivo after implantation into the alveolar bone defect of rabbits. No significant effects on the hematological indices, blood biochemical parameters, organ wet weight, or organ histopathology were detected from 3 to 180 days postoperatively. The porous scaffolds exhibited strong bone regeneration capability in the alveolar bone defect model of rabbits. Micro-CT and histological examination showed effective maintenance of bone morphology in the bioceramic scaffold group; however, depressed bone tissue was observed in the control group.

Conclusions

Our results suggest that personalized nCSi bioceramic scaffolds can be fabricated using the DLP technique. These newly developed strong bioceramic scaffolds exhibit good biocompatibility and osteogenic capability in vivo and have excellent potential as next-generation oral implants.

The translational potential of this article

Tissue-engineered strategies for alveolar bone repair require a bone graft substitute with appreciable biocompatibility and osteogenic capability. This article provides a systematic investigation of the in vivo biosafety and osteogenic property of nCSi to further development of a silicate-based bioceramics materials for clinical applications.

Bioactive materials for in vivo sweat gland regeneration

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

Comparison of osteogenic capability of 3D-printed bioceramic scaffolds and granules with different porosities for clinical translation

Pore parameters, structural stability, and filler morphology of artificial implants are key factors influencing the process of bone tissue repair. However, the extent to which each of these factors contributes to bone formation in the preparation of porous bioceramics is currently unclear, with the two often being coupled. Herein, we prepared magnesium-doped wollastonite (Mg-CSi) scaffolds with 57% and 70% porosity (57-S and 70-S) via a 3D printing technique. Meanwhile, the bioceramic granules (57-G and 70-G) with curved pore topography (IWP) were prepared by physically disrupting the 57-S and 70-S scaffolds, respectively, and compared for in vivo osteogenesis at 4, 10, and 16 weeks. The pore parameters and the mechanical and biodegradable properties of different porous bioceramics were characterized systematically. The four groups of porous scaffolds and granules were then implanted into a rabbit femoral defect model to evaluate the osteogenic behavior in vivo. 2D/3D reconstruction and histological analysis showed that significant bone tissue production was visible in the central zone of porous granule groups at the early stage but bone tissue ingrowth was slower in the porous scaffold groups. The bone tissue regeneration and reconstruction capacity were stronger after 10 weeks, and the porous architecture of the 57-S scaffold was maintained stably at 16 weeks. These experimental results demonstrated that the structure-collapsed porous bioceramic is favorable for early-stage osteoconduction and that the 3D topological scaffolds may provide more structural stability for bone tissue growth for a long-term stage. These findings provide new ideas for the selection of different types of porous bioceramics for clinical bone repair.

Customized bioceramic scaffolds and metal meshes for challenging large-size mandibular bone defect regeneration and repair

Large-size mandible graft has huge needs in clinic caused by infection, tumor, congenital deformity, bone trauma and so on. However, the reconstruction of large-size mandible defect is challenged due to its complex anatomical structure and large-range bone injury. The design and fabrication of porous implants with large segments and specific shapes matching the native mandible remain a considerable challenge. Herein, the 6% Mg-doped calcium silicate (CSi-Mg6) and β- and α-tricalcium phosphate (β-TCP, α-TCP) bioceramics were fabricated by digital light processing as the porous scaffolds of over 50% in porosity, while the titanium mesh was fabricated by selective laser melting. The mechanical tests showed that the initial flexible/compressive resistance of CSi-Mg6 scaffolds was markedly higher than that of β-TCP and α-TCP scaffolds. Cell experiments showed that these materials all had good biocompatibility, while CSi-Mg6 significantly promoted cell proliferation. In the rabbit critically sized mandible bone defects (∼13 mm in length) filled with porous bioceramic scaffolds, the titanium meshes and titanium nails were acted as fixation and load bearing. The results showed that the defects were kept during the observation period in the blank (control) group; in contrast, the osteogenic capability was significantly enhanced in the CSi-Mg6 and α-TCP groups in comparison with the β-TCP group, and these two groups not only had significantly increased new bone formation but also had thicker trabecular and smaller trabecular spacing. Besides, the CSi-Mg6 and α-TCP groups showed appreciable material biodegradation in the later stage (from 8 to 12 weeks) in comparison with the β-TCP scaffolds while the CSi-Mg6 group showed much outstanding mechanical capacity in vivo in the early stage compared to the β-TCP and α-TCP groups. Totally, these findings suggest that the combination of customized strength-strong bioactive CSi-Mg6 scaffolds together with titanium meshes is a promising way for repairing the large-size load-bearing mandible defects.

The design of strut/TPMS-based pore geometries in bioceramic scaffolds guiding osteogenesis and angiogenesis in bone regeneration

The pore morphology design of bioceramic scaffolds plays a substantial role in the induction of bone regeneration. Specifically, the effects of different scaffold pore geometry designs on angiogenesis and new bone regeneration remain unclear. Therefore, we fabricated Mg/Sr co-doped wollastonite bioceramic (MS-CSi) scaffolds with three different pore geometries (gyroid, cylindrical, and cubic) and compared their effects on osteogenesis and angiogenesis in vitro and in vivo. The MS-CSi scaffolds were fabricated by digital light processing (DLP) printing technology. The pore structure, mechanical properties, and degradation rate of the scaffolds were investigated. Cell proliferation on the scaffolds was evaluated using CCK-8 assays while angiogenesis was assessed using Transwell migration assays, tube formation assays, and immunofluorescence staining. The underlying mechanism was explored by western blotting. Osteogenic ability of scaffolds was evaluated by alkaline phosphatase (ALP) staining, western blotting, and qRT-PCR. Subsequently, a rabbit femoral defect model was prepared to compare differences in the scaffolds in osteogenesis and angiogenesis in vivo. Cell culture experiments showed that the gyroid pore scaffold downregulated YAP/TAZ phosphorylation and enhanced YAP/TAZ nuclear translocation, thereby promoting proliferation, migration, tube formation, and high expression of CD31 in human umbilical vein endothelial cells (HUVECs) while strut-based (cubic and cylindrical pore) scaffolds promoted osteogenic differentiation in bone marrow mesenchymal stem cells and upregulation of osteogenesis-related genes. The gyroid pore scaffolds were observed to facilitate early angiogenesis in the femoral-defect model rabbits while the strut-based scaffolds promoted the formation of new bone tissue. Our study indicated that the pore geometries and pore curvature characteristics of bioceramic scaffolds can be precisely tuned for enhancing both osteogenesis and angiogenesis. These results may provide new ideas for the design of bioceramic scaffolds for bone regeneration.

Core-shell bioceramic fiber-derived biphasic granules with adjustable core compositions for tuning bone regeneration efficacy

Silicate-based biomaterials-clinically applied fillers and promising candidates-can act as a highly biocompatible substrate for osteostimulative osteogenic cell growth in vitro and in vivo. These biomaterials have been proven to exhibit a variety of conventional morphologies in bone repair, including scaffolds, granules, coatings and cement pastes. Herein, we aim to develop a series of novel bioceramic fiber-derived granules with core-shell structures which have a hardystonite (HT) shell layer and changeable core components-that is, the chemical compositions of a core layer can be tuned to include a wide range of silicate candidates (e.g., wollastonite (CSi)) with doping of functional ions (e.g., Mg, P, and Sr). Meanwhile, it is versatile to control the biodegradation and bioactive ion release sufficiently for stimulating new bone growth after implantation. Our method employs rapidly gelling ultralong core-shell CSi@HT fibers derived from different polymer hydrosol-loaded inorganic powder slurries through the coaxially aligned bilayer nozzles, followed by cutting and sintering treatments. It was demonstrated that the nonstoichiometric CSi core component could contribute to faster bio-dissolution and biologically active ion release in tris buffer in vitro. The rabbit femoral bone defect repair experiments in vivo indicated that core-shell bioceramic granules with an 8% P-doped CSi-core could significantly stimulate osteogenic potential favorable for bone repair. It is worth concluding that such a tunable component distribution strategy in fiber-type bioceramic implants may develop new-generation composite biomaterials endowed with time-dependent biodegradation and high osteostimulative activities for a range of bone repair applications in situ.

A triphasic biomimetic BMSC-loaded scaffold for osteochondral integrated regeneration in rabbits and pigs

Osteochondral tissue involves cartilage, calcified cartilage and subchondral bone. These tissues differ significantly in chemical compositions, structures, mechanical properties and cellular compositions. Therefore, the repairing materials face different osteochondral tissue regeneration needs and rates. In this study, we fabricated an osteochondral tissue-inspired triphasic material, which was composed of a poly(lactide-co-glycolide) (PLGA) scaffold loaded with fibrin hydrogel, bone marrow stromal cells (BMSCs) and transforming growth factor-β1 (TGF-β1) for cartilage tissue, a bilayer poly(L-lactide-co-caprolactone) (PLCL)-fibrous membrane loaded with chondroitin sulfate and bioactive glass, respectively, for calcified cartilage, and a 3D-printed calcium silicate ceramic scaffold for subchondral bone. The triphasic scaffold was press-fitted into the osteochondral defects in rabbit (cylindrical defects with a diameter of 4 mm and a depth of 4 mm) and minipig knee joints (cylindrical defects with a diameter of 10 mm and a depth of 6 mm). The μ-CT and histological analysis showed that the triphasic scaffold was partly degraded, and significantly promoted the regeneration of hyaline cartilage after they were implanted in vivo. The superficial cartilage showed good recovery and uniformity. The calcified cartilage layer (CCL) fibrous membrane was in favor of a better cartilage regeneration morphology, a continuous cartilage structure and less fibrocartilage tissue formation. The bone tissue grew into the material, while the CCL membrane limited bone overgrowth. The newly generated osteochondral tissues were well integrated with the surrounding tissues too.

Bioceramic scaffolds with triply periodic minimal surface architectures guide early-stage bone regeneration

The pore architecture of porous scaffolds is a critical factor in osteogenesis, but it is a challenge to precisely configure strut-based scaffolds because of the inevitable filament corner and pore geometry deformation. This study provides a pore architecture tailoring strategy in which a series of Mg-doped wollastonite scaffolds with fully interconnected pore networks and curved pore architectures called triply periodic minimal surfaces (TPMS), which are similar to cancellous bone, are fabricated by a digital light processing technique. The sheet-TPMS pore geometries (s-Diamond, s-Gyroid) contribute to a 3‒4-fold higher initial compressive strength and 20%-40% faster Mg-ion-release rate compared to the other-TPMS scaffolds, including Diamond, Gyroid, and the Schoen's I-graph-Wrapped Package (IWP) in vitro. However, we found that Gyroid and Diamond pore scaffolds can significantly induce osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Analyses of rabbit experiments in vivo show that the regeneration of bone tissue in the sheet-TPMS pore geometry is delayed; on the other hand, Diamond and Gyroid pore scaffolds show notable neo-bone tissue in the center pore regions during the early stages (3-5 weeks) and the bone tissue uniformly fills the whole porous network after 7 weeks. Collectively, the design methods in this study provide an important perspective for optimizing the pore architecture design of bioceramic scaffolds to accelerate the rate of osteogenesis and promote the clinical translation of bioceramic scaffolds in the repair of bone defects.

Modularized bioceramic scaffold/hydrogel membrane hierarchical architecture beneficial for periodontal tissue regeneration in dogs

BACKGROUND

Destruction of alveolar bone and periodontal ligament due to periodontal disease often requires surgical treatment to reconstruct the biological construction and functions of periodontium. Despite significant advances in dental implants in the past two decades, it remains a major challenge to adapt bone grafts and barrier membrane in surgery due to the complicated anatomy of tooth and defect contours. Herein, we developed a novel biphasic hierarchical architecture with modularized functions and shape based on alveolar bone anatomy to achieve the ideal outcomes.

METHODS

The integrated hierarchical architecture comprising of nonstoichiometric wollastonite (nCSi) scaffolds and gelatin methacrylate/silanized hydroxypropyl methylcellulose (GelMA/Si-HPMC) hydrogel membrane was fabricated by digital light processing (DLP) and photo-crosslinked hydrogel injection technique respectively. The rheological parameters, mechanical properties and degradation rates of composite hydrogels were investigated. L-929 cells were cultured on the hydrogel samples to evaluate biocompatibility and cell barrier effect. Cell scratch assay, alkaline phosphatase (ALP) staining, and alizarin red (AR) staining were used to reveal the migration and osteogenic ability of hydrogel membrane based on mouse mandible-derived osteoblasts (MOBs). Subsequently, a critical-size one-wall periodontal defect model in dogs was prepared to evaluate the periodontal tissue reconstruction potential of the biphasic hierarchical architecture.

RESULTS

The personalized hydrogel membrane integrating tightly with the nCSi scaffolds exhibited favorable cell viability and osteogenic ability in vitro, while the scratch assay showed that osteoblast migration was drastically correlated with Si-HPMC content in the composite hydrogel. The equivalent composite hydrogel has proven good physiochemical properties, and its membrane exhibited potent occlusive effect in vivo; meanwhile, the hierarchical architectures exerted a strong periodontal regeneration capability in the periodontal intrabony defect models of dogs. Histological examination showed effective bone and periodontal ligament regeneration in the biomimetic architecture system; however, soft tissue invasion was observed in the control group.

CONCLUSIONS

Our results suggested that such modularized hierarchical architectures have excellent potential as a next-generation oral implants, and this precisely tuned guided tissue regeneration route offer an opportunity for improving periodontal damage reconstruction and reducing operation sensitivity.

Precisely Tuning the Pore-Wall Surface Composition of Bioceramic Scaffolds Facilitates Angiogenesis and Orbital Bone Defect Repair

Orbital bone damage (OBD) may result in severe post-traumatic enophthalmos, craniomaxillofacial deformities, vision loss, and intracranial infections. However, it is still a challenge to fabricate advanced biomaterials that can match the individual anatomical structure and enhance OBD repair in situ. Herein, we aimed to develop a selective surface modification strategy on bioceramic scaffolds and evaluated the effects of inorganic or organic functional coating on angiogenesis and osteogenesis, ectopically and orthotopically in OBD models. It was shown that the low thermal bioactive glass (BG) modification or layer-by-layer assembly of a biomimetic hydrogel (Biogel) could readily integrate into the pore wall of the bioceramic scaffolds. The BG and Biogel modification showed appreciable enhancement in the initial compressive strength (∼30-75%) or structural stability in vivo, respectively. BG modification could enhance by nearly 2-fold the vessel ingrowth, and the osteogenic capacity was also accelerated, accompanied with a mild scaffold biodegradation after 3 months. Meanwhile, the Biogel-modified scaffolds showed enhanced osteogenic differentiation and mineralization through calcium and phosphorus retention. The potential mechanism of the enhanced bone repair was elucidated via vascular and osteogenic cell responses in vitro, and the cell tests indicated that the Biogel and BG functional layers were both beneficial for in vitro osteoblastic differentiation and mineralization on bioceramics. Totally, these findings demonstrated that the bioactive ions or biomolecules could significantly improve the angiogenic and osteogenic capabilities of conventional bioceramics, and the integration of inorganic or organic functional coating in the pore wall is a highly flexible material toolbox that can be tailored directly to improve orbital bone defect repair.

Magnesium-Containing Silicate Bioceramic Degradable Intramedullary Nail for Bone Fractures

Intramedullary nails (INs) have significant advantages in rigid fracture fixation. Due to the stress shielding effect and lack of biological activity, traditional metal INs often lead to delay union or nonunion fracture healing. Undegradable metals also need to be removed by a second surgery, which will impose a potential risk to the patient. Current degradable biomaterials with low strength cannot be used in INs. Manufacturing high-strength biodegradable INs (BINs) is still a challenge. Here, we reported a novel high strength bioactive magnesium-containing silicate (CSi-Mg) BIN. This BIN is manufactured by using casting, freeze drying, and sintering techniques and has extremely high bending strength and stable internal and external structures. The manufacturing parameters were systematically studied, such as the paste component, freeze-drying process, and sintering process. This manufacturing method can be applied to various sizes of BINs. The CSi-Mg BIN also has good bioactivity and biodegradation properties. This novel bioactive BIN is expected to replace the traditional metal INs and become a more effective way of treating fractures.

Integrating pore architectures to evaluate vascularization efficacy in silicate-based bioceramic scaffolds

Pore architecture in bioceramic scaffolds plays an important role in facilitating vascularization efficiency during bone repair or orbital reconstruction. Many investigations have explored this relationship but lack integrating pore architectural features in a scaffold, hindering optimization of architectural parameters (geometry, size and curvature) to improve vascularization and consequently clinical outcomes. To address this challenge, we have developed an integrating design strategy to fabricate different pore architectures (cube, gyroid and hexagon) with different pore dimensions (∼350, 500 and 650 μm) in the silicate-based bioceramic scaffolds via digital light processing technique. The sintered scaffolds maintained high-fidelity pore architectures similar to the printing model. The hexagon- and gyroid-pore scaffolds exhibited the highest and lowest compressive strength (from 15 to 55 MPa), respectively, but the cube-pore scaffolds showed appreciable elastic modulus. Moreover, the gyroid-pore architecture contributed on a faster ion dissolution and mass decay in vitro. It is interesting that both μCT and histological analyses indicate vascularization efficiency was challenged even in the 650-μm pore region of hexagon-pore scaffolds within 2 weeks in rabbit models, but the gyroid-pore constructs indicated appreciable blood vessel networks even in the 350-μm pore region at 2 weeks and high-density blood vessels were uniformly invaded in the 500- and 650-μm pore at 4 weeks. Angiogenesis was facilitated in the cube-pore scaffolds in comparison with the hexagon-pore ones within 4 weeks. These studies demonstrate that the continuous pore wall curvature feature in gyroid-pore architecture is an important implication for biodegradation, vascular cell migration and vessel ingrowth in porous bioceramic scaffolds.

Bone tissue regeneration: The role of finely tuned pore architecture of bioactive scaffolds before clinical translation

Spatial dimension of pores and interconnection in macroporous scaffolds is of particular importance in facilitating endogenous cell migration and bone tissue ingrowth. However, it is still a challenge to widely tune structure parameters of scaffolds by conventional methods because of inevitable pore geometrical deformation and poor pore interconnectivity. Here, the long-term in vivo biological performances of nonstoichiometric bioceramic scaffolds with different pore dimensions were assessed in critical-size femoral bone defect model. The 6% Mg-substituted wollastonite (CSi-Mg6) powders were prepared via wet-chemical precipitation and the scaffolds elaborately printed by ceramic stereolithography, displaying designed constant pore strut and tailorable pore height (200, 320, 450, 600 μm), were investigated thoroughly in the bone regeneration process. Together with detailed structural stability and mechanical properties were collaboratively outlined. Both μCT and histological analyses indicated that bone tissue ingrowth was retarded in 200 μm scaffolds in the whole stage (2-16 weeks) but the 320 μm scaffolds showed appreciable bone tissue in the center of porous constructs at 6-10 weeks and matured bone tissue were uniformly invaded in the whole pore networks at 16 weeks. Interestingly, the neo-tissue ingrowth was facilitated in the 450 μm and 600 μm scaffolds after 2 weeks and higher extent of bone regeneration and remodeling at the later stage. These new findings provide critical information on how engineered porous architecture impact bone regeneration in vivo. Simultaneously, this study shows important implications for optimizing the porous scaffolds design by advanced additive manufacture technique to match the clinical translation with high performance.

Research status of biodegradable metals designed for oral and maxillofacial applications: A review

The oral and maxillofacial regions have complex anatomical structures and different tissue types, which have vital health and aesthetic functions. Biodegradable metals (BMs) is a promising bioactive materials to treat oral and maxillofacial diseases. This review summarizes the research status and future research directions of BMs for oral and maxillofacial applications. Mg-based BMs and Zn-based BMs for bone fracture fixation systems, and guided bone regeneration (GBR) membranes, are discussed in detail. Zn-based BMs with a moderate degradation rate and superior mechanical properties for GBR membranes show great potential for clinical translation. Fe-based BMs have a relatively low degradation rate and insoluble degradation products, which greatly limit their application and clinical translation. Furthermore, we proposed potential future research directions for BMs in the oral and maxillofacial regions, including 3D printed BM bone scaffolds, surface modification for BMs GBR membranes, and BMs containing hydrogels for cartilage regeneration, soft tissue regeneration, and nerve regeneration. Taken together, the progress made in the development of BMs in oral and maxillofacial regions has laid a foundation for further clinical translation.

Tuning filament composition and microstructure of 3D-printed bioceramic scaffolds facilitate bone defect regeneration and repair

It is still a challenge to optimize the component distribution and microporous structures in scaffolds for tailoring biodegradation (ion releasing) and enhancing bone defect repair within an expected time stage. Herein, the core–shell-typed nonstoichiometric wollastonite (4% and 10% Mg-doping calcium silicate; CSiMg4, CSiMg10) macroporous scaffolds with microporous shells (adding ∼10 μm PS microspheres into shell-layer slurry) were fabricated via 3D printing. The initial mechanical properties and bio-dissolution (ion releasing) in vitro, and osteogenic capacity in vivo of the bioceramic scaffolds were evaluated systematically. It was shown that endowing high-density micropores in the sparingly dissolvable CSiMg10 or dissolvable CSiMg4 shell layer inevitably led to nearly 30% reduction of compressive strength, but such micropores could readily tune the ion release behaviour of the scaffolds (CSiMg4@CSiMg10 vs. CSiMg4@CSiMg10-p; CSiMg10@CSiMg4 vs. CSiMg10@CSiMg4-p). Based on the in rabbit femoral bone defect repair model, the 3D μCT reconstruction and histological observation demonstrated that the CSiMg4@CSiMg10-p scaffolds displayed markedly higher osteogenic capability than the other scaffolds after 12 weeks of implantation. It demonstrated that core–shell bioceramic 3D printing technique can be developed to fabricate single-phase or biphasic bioactive ceramic scaffolds with accurately tailored filament biodegradation for promoting bone defect regeneration and repair in some specific pathological conditions.

Prospect of Metal Ceramic (Titanium-Wollastonite) Composite as Permanent Bone Implants: A Narrative Review

This literature review discusses the influence of titanium ceramic composites as a biomaterial towards the fabrication of implants for orthopedic applications. The concept of applying metal-ceramic composites enable many novel combinations in the design and fabrication of complex materials which enhances functionality to improve cell and tissue matrix interactions particularly in the formation of bone. Specific focus is placed on its plethora of materials selected from the metals and ceramic group and identifying the optimal combination that matches them. The prospect of wollastonite as the ceramic counterpart is also highlighted. In this review, we have highlighted the different fabrication methods for such metal-ceramic materials as well as the role that these hybrids play in an in vitro and in vivo environment. Its economic potential as a bone implant material is also discussed.

Rational design of nonstoichiometric bioceramic scaffolds via digital light processing: tuning chemical composition and pore geometry evaluation

Bioactive ceramics are promising candidates as 3D porous substrates for bone repair in bone regenerative medicine. However, they are often inefficient in clinical applications due to mismatching mechanical properties and compromised biological performances. Herein, the additional Sr dopant is hypothesized to readily adjust the mechanical and biodegradable properties of the dilute Mg-doped wollastonite bioceramic scaffolds with different pore geometries (cylindrical-, cubic-, gyroid-) by ceramic stereolithography. The results indicate that the compressive strength of Mg/Sr co-doped bioceramic scaffolds could be tuned simultaneously by the Sr dopant and pore geometry. The cylindrical-pore scaffolds exhibit strength decay with increasing Sr content, whereas the gyroid-pore scaffolds show increasing strength and Young's modulus as the Sr concentration is increased from 0 to 5%. The ion release could also be adjusted by pore geometry in Tris buffer, and the high Sr content may trigger a faster scaffold bio-dissolution. These results demonstrate that the mechanical strengths of the bioceramic scaffolds can be controlled from the point at which their porous structures are designed. Moreover, scaffold bio-dissolution can be tuned by pore geometry and doping foreign ions. It is reasonable to consider the nonstoichiometric bioceramic scaffolds are promising for bone regeneration, especially when dealing with pathological bone defects.

Biodegradable intramedullary nail (BIN) with high-strength bioceramics for bone fracture

About 10 million fractures occur worldwide each year, of which more than 60% are long bone fractures. It is generally agreed that intramedullary nails have significant advantages in rigid fracture fixation. Metal intramedullary nails (INs) can provide strong support but a stress shielding effect can occur that results in nonunion healing in clinic. Nondegradable metals also need to be removed by a second operation. Could INs be biodegradable and used to overcome this issue? As current degradable biomaterials always suffer from low strength and cannot be used in Ins, herein, we report a novel device consisting of biodegradable IN (BIN) made for the first time with bioceramics. These BINs have an extremely high bending strength and stable internal and external structure. Experiments show that the BINs could not only fix and support the tibial fracture model, but also promote osteogenesis and affect the microenvironment of the bone marrow cavity. Therefore, they could be expected to replace traditional metal IN and become a more effective treatment option for tibial fractures.

Radiological evaluations of low cost wollastonite nano-ceramics graft doped with iron oxide in the treatment of induced defects in canine mandible

Wollastonite with/without maghemite [(Fe2O3), 0, 3 and 10 wt%] was prepared by facile wet precipitation method. Effect of Fe2O3 presence in the obtained nano-ceramics on physical structure, morphology, size and the mechanical features was evaluated using X-ray diffraction, transmission electron microscope, and universal testing machine. Moreover, the in vitro biomineralization was examined using simulated body fluid (SBF) by means of scanning electron microscope/energy dispersive X-ray, Fourier transform infrared, and inductively coupled plasma. An in vivo study was conducted on 24 adult male mongrel dogs to test the biosafety of fabricated samples in the reconstruction of experimentally induced mandibular bone defects. Bone density was measured through cone beam computed tomography analysis conducted at 1 and 3 months following surgery. Wollastonite was the main phase in all the prepared samples however little maghemite was developed in Fe-containing samples. No remarkable changes were recognized for physical structure of obtained microcrystalline structures, however, a decrease in particle size was noted in the existence of Fe2O3 (10-15 nm) when compared to the pure wollastonite (30-50 nm). Mechanical features were dependent on the included Fe2O3 concentration within the wollastonite ceramic matrix. The degree of biomineralization of the samples immersed in SBF was elevated with the increase in Fe2O3 percentage. Clinically, the reconstruction of bone defects was uneventful without any adverse toxic effect. Bone density was significantly increased at 1 and 3 months (p < .001) in grafted defects compared to control ones. Increasing the doping concentrations of iron oxide was associated with significant increase (p < .001) of bone density in all induced defects. Due to the impressive healing effect of current fabricated nano-ceramics, they are recommended to be utilized as low cost bone graft alternatives.

Development of 3D Bioactive Scaffolds through 3D Printing Using Wollastonite-Gelatin Inks

The bioactivity of scaffolds represents a key property to facilitate the bone repair after orthopedic trauma. This study reports the development of biomimetic paste-type inks based on wollastonite (CS) and fish gelatin (FG) in a mass ratio similar to natural bone, as an appealing strategy to promote the mineralization during scaffold incubation in simulated body fluid (SBF). High-resolution 3D scaffolds were fabricated through 3D printing, and the homogeneous distribution of CS in the protein matrix was revealed by scanning electron microscopy/energy-dispersive X-ray diffraction analysis (SEM/EDX) micrographs. The bioactivity of the scaffold was suggested by an outstanding mineralization capacity revealed by the apatite layers deposited on the scaffold surface after immersion in SBF. The biocompatibility was demonstrated by cell proliferation established by MTT assay and fluorescence microscopy images and confirmed by SEM micrographs illustrating cell spreading. This work highlights the potential of the bicomponent inks to fabricate 3D bioactive scaffolds and predicts the osteogenic properties for bone regeneration applications.

Modification of pore-wall in direct ink writing wollastonite scaffolds favorable for tuning biodegradation and mechanical stability and enhancing osteogenic capability

Surface chemistry and mechanical stability determine the osteogenic capability of bone implants. The development of high-strength bioactive scaffolds for in-situ repair of large bone defects is challenging because of the lack of satisfying biomaterials. In this study, highly bioactive Ca-silicate (CSi) bioceramic scaffolds were fabricated by additive manufacturing and then modified for pore-wall reinforcement. Pure CSi scaffolds were fabricated using a direct ink writing technique, and the pore-wall was modified with 0%, 6%, or 10% Mg-doped CSi slurry (CSi, CSi-Mg6, or CSi-Mg10) through electrostatic interaction. Modified CSi@CSi-Mg6 and CSi@CSi-Mg10 scaffolds with over 60% porosity demonstrated an appreciable compressive strength beyond 20 MPa, which was ~2-fold higher than that of pure CSi scaffolds. CSi-Mg6 and CSi-Mg10 coating layers were specifically favorable for retarding bio-dissolution and mechanical decay of scaffolds in vitro. In-vivo investigation of critical-size femoral bone defects repair revealed that CSi@CSi-Mg6 and CSi@CSi-Mg10 scaffolds displayed limited biodegradation, accelerated new bone ingrowth (4-12 weeks), and elicited a suitable mechanical response. In contrast, CSi scaffolds exhibited fast biodegradation and retarded new bone regeneration after 8 weeks. Thus, tailoring of the chemical composition of pore-wall struts of CSi scaffolds is beneficial for enhancing the biomechanical properties and bone repair efficacy.

Effect of Foreign Ion Substitution and Micropore Tuning in Robocasting Single-Phase Bioceramic Scaffolds on the Physicochemical Property and Vascularization

The inorganic powder slurry extrusion printing technique known as robocasting is an interesting method to fabricate complex porous architectures whereby feedstocks containing organic binders and powders are printed and the resulting scaffolds are subjected to sintering. A major limiting factor of this technique is the simultaneous tailoring of vascularization efficacy and osteogenic activity, usually done by adding the secondary phase in the organic slurry before the writing step. Mechanical mixing of biphasic powders is required to avoid compromising the biological performance and physical defects caused by significantly different physicochemical properties. This study addresses this issue by developing a selective ion doping and microstructure tuning for the production of bioceramic scaffolds with a binozzle robocasting process. Different metal ions (Sr²⁺, Mg²⁺) were doped into wollastonite (CaSiO₃; CSi) powders considering the mechanical stability and bioactive enhancement of the bioceramic scaffolds. Subsequently, the Mg-doped CSi slurries were used as shell-nozzle feedstocks added with 5, 10, and 15 μm diameter polystyrene microbeads that allowed shell-layer micropore production in pore struts during sintering. Finally, the most promising pore-strut microstructures and mechanical evolution of scaffolds were evaluated, and especially the enhanced fibrovascularization potential was confirmed in dorsal muscle embedding model in rabbits. This study may open an avenue to designing multiproperty-tuned macro- and microporous bioceramics for bone regenerative medicine, especially in challenging bone defect conditions.

Effect of strontium-containing on the properties of Mg-doped wollastonite bioceramic scaffolds

BACKGROUND

Bone scaffold is one of the most effective methods to treat bone defect. The ideal scaffold of bone tissue should not only provide space for bone tissue growth, but also have sufficient mechanical strength to support the bone defect area. Moreover, the scaffold should provide a customized size or shape for the patient's bone defect.

METHODS

In this study, strontium-containing Mg-doped wollastonite (Sr-CSM) bioceramic scaffolds with controllable pore size and pore structure were manufactured by direct ink writing 3D printing. Biological properties of Sr-CSM scaffolds were evaluated by apatite formation ability, in vitro proliferation ability of rabbit bone-marrow stem cells (rBMSCs), and alkaline phosphatase (ALP) activity using β-TCP and Mg-doped wollastonite (CSM) scaffolds as control. The compression strength of three scaffold specimens was probed after completely drying them while been submerged in Tris-HCl solution for 0, 2,4 and 6 weeks.

RESULTS

The mechanical test results showed that strontium-containing Mg-doped wollastonite (Sr-CSM) scaffolds had acceptable initial compression strength (56 MPa) and maintained good mechanical stability during degradation in vitro. Biological experiments showed that Sr-CSM scaffolds had a better apatite formation ability. Cell experiments showed that Sr-CSM scaffold had a higher cell proliferation ability compared with β-TCP and CSM scaffold. The higher ALP activity of Sr-CSM scaffold indicates that it can better stimulate osteoblastic differentiation and bone mineralization.

CONCLUSIONS

Therefore, Sr-CSM scaffolds not only have acceptable compression strength, but also have higher osteogenesis bioactivity, which can be used in bone tissue engineering scaffolds.

Advanced biomaterials for repairing and reconstruction of mandibular defects

Mandibles are the largest and strongest bone in the human face and are often severely compromised by mandibular defects, compromising the quality of life of patients. Mandibular defects may result from trauma, inflammatory disease and benign or malignant tumours. The reconstruction of mandibular defect has been a research hotspot in oral and maxillofacial surgery. Although the principles and techniques of mandibular reconstruction have made great progress in recent years, the development of biomedical materials is still facing technical bottleneck, and new materials directly affect technological breakthroughs in this field. This paper reviews the current status of research and application of various biomaterials in mandibular defects and systematically elaborates different allogeneic biomaterial-based approaches. It is expected that various biomaterials, in combination with new technologies such as digital navigation and 3D printing, could be tuned to build new types of scaffold with more precise structure and components, addressing needs of surgery and post-reconstruction. With the illustration and systematization of different solutions, aims to inspire the development of reconstruction biomaterials.

In vitro Chondrocyte Responses in Mg-doped Wollastonite/Hydrogel Composite Scaffolds for Osteochondral Interface Regeneration

The zone of calcified cartilage (ZCC) is the mineralized region between the hyaline cartilage and subchondral bone and is critical in cartilage repair. A new non-stoichiometric calcium silicate (10% Ca substituted by Mg; CSi-Mg10) has been demonstrated to be highly bioactive in an osteogenic environment in vivo. This study is aimed to systematically evaluate the potential to regenerate osteochondral interface with different amount of Ca-Mg silicate in hydrogel-based scaffolds, and to compare with the scaffolds containing conventional Ca-phosphate biomaterials. Hydrogel-based porous scaffolds combined with 0-6% CSi-Mg10, 6% β-tricalcium phosphate (β-TCP) or 6% nanohydroxyapatite (nHAp) were made with three-dimensional (3D) printing. An increase in CSi-Mg10 content is desirable for promoting the hypertrophy and mineralization of chondrocytes, as well as cell proliferation and matrix deposition. Osteogenic and chondrogenic induction were both up-regulated in a dose-dependent manner. In comparison with the scaffolds containing 6% β-TCP or nHAp, human deep zone chondrocytes (hDZCs) seeded on CSi-Mg10 scaffold of equivalent concentration exhibited higher mineralization. It is noteworthy that the hDZCs in the 6% CSi-Mg10 scaffolds maintained a higher expression of the calcified cartilage zone specific extracellular matrix marker and hypertrophic marker, collagen type X. Immunohistochemical and Alizarin Red staining reconfirmed these findings. The study demonstrated that hydrogel-based hybrid scaffolds containing 6% CSi-Mg10 are particularly desirable for inducing the formation of calcified cartilage.

Nonstoichiometric wollastonite bioceramic scaffolds with core-shell pore struts and adjustable mechanical and biodegradable properties

Controllable mechanical strength and biodegradation of bioceramic scaffolds is a great challenge to treat the load-bearing bone defects. Herein a new strategy has been developed to fabricate porous bioceramic scaffolds with adjustable component distributions based on varying the core-shell-structured nozzles in three-dimensional (3D) direct ink writing platform. The porous bioceramic scaffolds composed of different nonstoichiometic calcium silicate (nCSi) with 0%, 4% or 10% of magnesium-substituting-calcium ratio (CSi, CSi-Mg4, CSi-Mg10) was fabricated. Beyond the mechanically mixed composite scaffolds, varying the different nCSi slurries through the coaxially aligned bilayer nozzle makes it easy to create core-shell bilayer bioceramic filaments and better control of the different nCSi distribution in pore strut after sintering. It was evident that the magnesium substitution in CSi contributed to the increase of compressive strength for the single-phasic scaffolds from 11.2 MPa (CSi), to 39.4 MPa (CSi-Mg4) and 80 MPa (CSi-Mg10). The nCSi distribution in pore struts in the series of core-shell-strut scaffolds could significantly adjust the strength [e.g. CSi@CSi-Mg10 (58.9 MPa) vs CSi-Mg10@CSi (30.4 MPa)] and biodegradation ratio in Tris buffer for a long time stage (6 weeks). These findings demonstrate that the nCSi components with different distributions in core or shell layer of pore struts lead to tunable strength and biodegradation inside their interconnected macropore architectures of the scaffolds. It is possibly helpful to develop new bioactive scaffolds for time-dependent tailoring mechanical and biological performances to significantly enhance bone regeneration and repair applications, especially in some load-bearing bone defects.

3D printed porous ceramic scaffolds for bone tissue engineering: a review

This study summarizes the recent research status and development of three-dimensional (3D)-printed porous ceramic scaffolds in bone tissue engineering. Recent literature on 3D-printed porous ceramic scaffolds was reviewed. Compared with traditional processing and manufacturing technologies, 3D-printed porous ceramic scaffolds have obvious advantages, such as enhancement of the controllability of the structure or improvement of the production efficiency. More sophisticated scaffolds were fabricated by 3D printing technology. 3D printed bioceramics have broad application prospects in bone tissue engineering. Through understanding the advantages and limitations of different 3D-printing approaches, new classes of bone graft substitutes can be developed.

Custom Repair of Mandibular Bone Defects with 3D Printed Bioceramic Scaffolds

Implanting artificial biomaterial implants into alveolar bone defects with individual shape and appropriate mechanical strength is still a challenge. In this study, bioceramic scaffolds, which can precisely match the mandibular defects in macro and micro, were manufactured by the 3-dimensional (3D) printing technique according to the computed tomography (CT) image. To evaluate the stimulatory effect of the material substrate on bone tissue regeneration in situ in a rabbit mandibular alveolar bone defect model, implants made with the newly developed, mechanically strong ~10% Mg-substituted wollastonite (Ca_90%Mg_10%SiO₃; CSi-Mg10) were fabricated, implanted into the bone defects, and compared with implants made with the typical Ca-phosphate and Ca-silicate porous bioceramics, such as β-tricalcium phosphate (TCP), wollastonite (CaSiO₃; CSi), and bredigite (Bred). The initial physicochemical tests indicated that although the CSi-Mg10 scaffolds had the largest pore dimension, they had the lowest porosity mainly due to the significant linear shrinkage of the scaffolds during sintering. Compared with the sparingly dissolvable TCP scaffolds (~2% weight loss) and superfast dissolvable (in Tris buffer within 6 wk) pure CSi and Bred scaffolds (~12% and ~14% weight loss, respectively), the CSi-Mg10 exhibited a mild in vitro biodissolution and moderate weight loss of ~7%. In addition, the CSi-Mg10 scaffolds showed a considerable initial flexural strength (31 MPa) and maintained very high flexural resistance during soaking in Tris buffer. The in vivo results revealed that the CSi-Mg10 scaffolds have markedly higher osteogenic capability than those on the TCP, CSi, and Bred scaffolds after 16 wk. These results suggest a promising potential application of customized CSi-Mg10 3D robocast scaffolds in the clinic, especially for repair of alveolar bone defects.

3D robocasting magnesium-doped wollastonite/TCP bioceramic scaffolds with improved bone regeneration capacity in critical sized calvarial defects

Using artificial biomaterials in bone regenerative medicine for highly efficient osteoconduction into the bone defect to decrease the bone healing time is still a challenge. In this research, magnesium (Mg)-doped wollastonite (∼10% Mg was substituted for calcium (Ca) in β-CaSiO₃) (CSi-Mg10) bioceramic scaffolds with ultrahigh mechanical strength were fabricated using ceramic ink writing three dimensional (3D) printing. To evaluate the potential of other additives on the new bone regeneration efficiency, β-tricalcium phosphate (β-TCP) was introduced to the CSi-Mg10 ceramic ink at a concentration of 15% and the biphasic bioceramic scaffolds (CSi-Mg10/TCP15) were also fabricated using 3D printing. The mechanical characterization indicated that introduction of β-TCP led to nearly 50% mechanical decay, although the effect of the two heating schedules (one- and two-step sintering) on the compressive and flexural strengths of the scaffolds was significantly different. The bone regeneration results in critical sized calvarial defect of rabbits showed that the CSi-Mg10/TCP15 scaffolds displayed a markedly higher osteogenic capability than those on the CSi-Mg10 and β-TCP scaffolds after eight weeks, and reached ∼35% new bone tissue regeneration at 12 weeks postoperatively. These findings demonstrate that the CSi-Mg10/TCP15 bioceramic scaffolds can be well suited for stimulating in situ bone regeneration and for use in tissue engineering applications.

Core–shell-structured nonstoichiometric bioceramic spheres for improving osteogenic capability

Precisely controlling the composition distribution and pore-network evolution in the foreign ion doped, core–shell Ca-silicate bioceramic microspheres is favorable for tailoring osteogenicity in critical size bone defects.

3D printing of Mg-substituted wollastonite reinforcing diopside porous bioceramics with enhanced mechanical and biological performances

Mechanical strength and its long-term stability of bioceramic scaffolds is still a problem to treat the osteonecrosis of the femoral head. Considering the long-term stability of diopside (DIO) ceramic but poor mechanical strength, we developed the DIO-based porous bioceramic composites via dilute magnesium substituted wollastonite reinforcing and three-dimensional (3D) printing. The experimental results showed that the secondary phase (i.e. 10% magnesium substituting calcium silicate; CSM10) could readily improve the sintering property of the bioceramic composites (DIO/CSM10-x, x = 0-30) with increasing the CSM10 content from 0% to 30%, and the presence of the CSM10 also improved the biomimetic apatite mineralization ability in the pore struts of the scaffolds. Furthermore, the flexible strength (12.5-30 MPa) and compressive strength (14-37 MPa) of the 3D printed porous bioceramics remarkably increased with increasing CSM10 content, and the compressive strength of DIO/CSM10-30 showed a limited decay (from 37 MPa to 29 MPa) in the Tris buffer solution for a long time stage (8 weeks). These findings suggest that the new CSM10-reinforced diopside porous constructs possess excellent mechanical properties and can potentially be used to the clinic, especially for the treatment of osteonecrosis of the femoral head work as a bioceramic rod.

Systematical Evaluation of Mechanically Strong 3D Printed Diluted magnesium Doping Wollastonite Scaffolds on Osteogenic Capacity in Rabbit Calvarial Defects

Wollastonite (CaSiO3; CSi) ceramic is a promising bioactive material for bone defect repair due to slightly fast degradation of its porous constructs in vivo. In our previous strategy some key features of CSi ceramic have been significantly improved by dilute magnesium doping for regulating mechanical properties and biodegradation. Here we demonstrate that 6 ~ 14% of Ca substituted by Mg in CSi (CSi-Mgx, x = 6, 10, 14) can enhance the mechanical strength (>40 MPa) but not compromise biological performances of the 3D printed porous scaffolds with open porosity of 60‒63%. The in vitro cell culture tests in vitro indicated that the dilute Mg doping into CSi was beneficial for ALP activity and high expression of osteogenic marker genes of MC3T3-E1 cells in the scaffolds. A good bone tissue regeneration response and elastoplastic response in mechanical strength in vivo were determined after implantation in rabbit calvarial defects for 6‒12 weeks. Particularly, the CSi-Mg10 and CSi-Mg14 scaffolds could enhance new bone regeneration with a significant increase of newly formed bone tissue (18 ~ 22%) compared to the pure CSi (~14%) at 12 weeks post-implantation. It is reasonable to consider that, therefore, such CSi-Mgx scaffolds possessing excellent strength and reasonable degradability are promising for bone reconstruction in thin-wall bone defects.

The outstanding mechanical response and bone regeneration capacity of robocast dilute magnesium-doped wollastonite scaffolds in critical size bone defects

Mechanically strong, highly osteogenic dilute magnesium-doped wollastonite robocast scaffolds.