Clinical applications of bone graft substitutes

Assessment of bone regeneration after maxillary radicular cyst enucleation with or without bone grafting materials: a retrospective cohort study

OBJECTIVE

The limitations of spontaneous bone healing underscore the necessity for exploring alternative strategies to enhance bone regeneration in maxillary radicular cyst cases. This retrospective study aimed to assess the impact of a bone substitute material (i.e., Bio-Oss) on bone volume regeneration following maxillary radicular cyst enucleation using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Seventy-three patients with maxillary radicular cysts were divided into two groups: one undergoing guided bone regeneration (GBR) with Bio-Oss and absorbable collagen membrane (n = 35), and the other receiving cyst excision alone (n = 38). Volumetric measurements using Amira software on CBCT scans evaluated bone regeneration, with cystic lesion shrinkage rates calculated. Intergroup comparisons utilized independent sample t-tests (P < 0.05), and linear regression analysis assessed the influence of preoperative cyst volume and group on bone healing.

RESULTS

Both groups showed similar success rates in bone formation at the 12-month follow-up, with no significant differences between them (mean (SD), control: 75.16 (19.17) vs. GBR: 82 (20.22), P > 0.05). Linear regression analysis revealed a negative correlation between preoperative cyst volume and bone regeneration in both groups (P < 0.05).

CONCLUSION

Bio-Oss may not significantly enhance bone augmentation in maxillary radicular cysts. In addition, preoperative cyst volume negatively affected the shrinkage rate of cystic lesions.

CLINICAL RELEVANCE

Clinicians should consider patient-specific factors such as anatomy and lesion size when determining the need for bone substitute materials. Future research could focus on optimizing treatment protocols and alternative regenerative strategies to improve patient outcomes in maxillary cyst cases.

Clindamycin phosphate and bone morphogenetic protein-7 loaded combined nanoparticle-graft and nanoparticle-film formulations for alveolar bone regeneration - An in vitro and in vivo evaluation

Commonly utilized techniques for healing alveolar bone destruction such as the use of growth factors, suffering from short half-life, application difficulties, and the ability to achieve bioactivity only in the presence of high doses of growth factor. The sustained release of growth factors through a scaffold-based delivery system offers a promising and innovative tool in dentistry. Furthermore, it is suggested to guide the host response by using antimicrobials together with growth factors to prevent recovery and achieve ideal regeneration. Herein, the aim was to prepare and an in vitro - in vivo evaluation of bone morphogenetic protein 7 (BMP-7) and clindamycin phosphate (CDP) loaded polymeric nanoparticles, and their loading into the alginate-chitosan polyelectrolyte complex film or alloplastic graft to accelerate hard tissue regeneration. PLGA nanoparticles containing CDP and BMP-7, separately or together, were prepared using the double emulsion solvent evaporation technique. Through in vitro assays, it was revealed that spherical particles were homogeneously distributed in the combination formulations, and sustained release could be achieved for >12 weeks with all formulations. Also, results from the micro-CT and histopathological analyses indicated that CDP and BMP-7 loaded nanoparticle-film formulations were more effective in treatment than the nanoparticle loaded grafts.

Functional Approaches in Promoting Vascularization and Angiogenesis in Bone Critical-Sized Defects via Delivery of Cells, Growth Factors, Drugs, and Particles

Critical-sized bone defects, or CSDs, are defined as bone defects that cannot be regenerated by themselves and require surgical intervention via employing specific biomaterials and a certain regenerative strategy. Although a variety of approaches can be used to treat CSDs, poor angiogenesis and vascularization remain an obstacle in these methods. The complex biological healing of bone defects depends directly on the function of blood flow to provide sufficient oxygen and nutrients and the removal of waste products from the defect site. The absence of vascularization can lead to non-union and delayed-union defect development. To overcome this challenge, angiogenic agents can be delivered to the site of injury to stimulate vessel formation. This review begins by introducing the treatment methods for CSDs. The importance of vascularization in CSDs is subsequently highlighted. Delivering angiogenesis agents, including relevant growth factors, cells, drugs, particles, cell secretion substances, their combination, and co-delivery to CSDs are fully explored. Moreover, the effects of such agents on new bone formation, followed by vessel formation in defect areas, are evaluated.

Biomimicking design of artificial periosteum for promoting bone healing

Background

Periosteum is a vascularized tissue membrane covering the bone surface and plays a decisive role in bone reconstruction process after fracture. Various artificial periosteum has been developed to assist the allografts or bionic bone scaffolds in accelerating bone healing. Recently, the biomimicking design of artificial periosteum has attracted increasing attention due to the recapitulation of the natural extracellular microenvironment of the periosteum and has presented unique capacity to modulate the cell fates and ultimately enhance the bone formation and improve neovascularization.

Methods

A systematic literature search is performed and relevant findings in biomimicking design of artificial periosteum have been reviewed and cited.

Results

We give a systematical overview of current development of biomimicking design of artificial periosteum. We first summarize the universal strategies for designing biomimicking artificial periosteum including biochemical biomimicry and biophysical biomimicry aspects. We then discuss three types of novel versatile biomimicking artificial periosteum including physical-chemical combined artificial periosteum, heterogeneous structured biomimicking periosteum, and healing phase-targeting biomimicking periosteum. Finally, we comment on the potential implications and prospects in the future design of biomimicking artificial periosteum.

Conclusion

This review summarizes the preparation strategies of biomimicking artificial periosteum in recent years with a discussion of material selection, animal model adoption, biophysical and biochemical cues to regulate the cell fates as well as three types of latest developed versatile biomimicking artificial periosteum. In future, integration of innervation, osteochondral regeneration, and osteoimmunomodulation, should be taken into consideration when fabricating multifunctional artificial periosteum.

The Translational Potential of this Article: This study provides a holistic view on the design strategy and the therapeutic potential of biomimicking artificial periosteum to promote bone healing. It is hoped to open a new avenue of artificial periosteum design with biomimicking considerations and reposition of the current strategy for accelerated bone healing.

Challenges and tissue engineering strategies of periodontal guided tissue regeneration

Periodontitis is a chronic infectious oral disease with a high prevalence rate in the world, and is a major cause of tooth loss. Nowadays, people have realized that the local microenvironment that includes proteins, cytokines, and extracellular matrix has a key influence on the functions of host immune cells and periodontal ligament stem cells during a chronic infectious disease such as periodontitis. The above pathological process of periodontitis will lead to a defect of periodontal tissues. Through the application of biomaterials, biological agents, and stem cells therapy, guided tissue regeneration (GTR) makes it possible to reconstruct healthy periodontal ligament tissue after local inflammation control. To date, substantial advances have been made in periodontal guided tissue regeneration. However, the process of periodontal remodeling experiences complex microenvironment changes, and currently periodontium regeneration still remains to be a challenging feat. In this review, we summarized the main challenges in each stage of periodontal regeneration, and try to put forward appropriate biomaterial treatment mechanisms or potential tissue engineering strategies that provide a theoretical basis for periodontal tissue engineering regeneration research.

State-of-Art of Standard and Innovative Materials Used in Cranioplasty

Cranioplasty is the surgical technology employed to repair a traumatic head injury, cerebrovascular disease, oncology resection and congenital anomalies. Actually, different bone substitutes are used, either derived from biological products such as hydroxyapatite and demineralized bone matrix or synthetic ones such as sulfate or phosphate ceramics and polymer-based substitutes. Considering that the choice of the best material for cranioplasty is controversial, linked to the best operation procedure, the intent of this review was to report the outcome of research conducted on materials used for such applications, comparing the most used materials. The most interesting challenge is to preserve the mechanical properties while improving the bioactivity, porosity, biocompatibility, antibacterial properties, lowering thickness and costs. Among polymer materials, polymethylmethacrylate and polyetheretherketone are the most motivating, due to their biocompatibility, rigidity and toughness. Other biomaterials, with ecofriendly attributes, such as polycaprolactone and polylactic acid have been investigated, due to their microstructure that mimic the trabecular bone, encouraging vascularization and cell-cell communications. Taking into consideration that each material must be selected for specific clinical use, the main limitation remains the defects and the lack of vascularization, consequently porous synthetic substitutes could be an interesting way to support a faster and wider vascularization, with the aim to improve patient prognosis.

The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.

Efficacy of Nano Composite Porous 3D Scaffold of Crab Shell and Al-Kharit Histological and Radiological for Bone Repair in Vivo

The present study was conducted to evaluate the effect of scaffold fabricated from Nano crab shell and Al-kharit (Papyrus Vaccine) for enhancing the healing of the experimentally induced bone defect in dogs. For this purpose, twenty healthy adult mongrel dogs were used in this study which divided randomly into two equal groups, under general anesthesia, 1 cm bone gap was created in the distal part of the tibia, that fixed by bone plate and screws. Nano crab shell scaffold was implanted. All experimental animals showed normal situation without any infection at the site of operation, while the radiography showed a periosteal and endosteal reaction. Moreover, the gaps were bridged faster in the treated group as compared with the control group. Treated animals showed new bone formation which represented by obvious lamellar bone, haversian canal and osteocyte cells in 90 days. In conclusion, the Nano crab shell scaffold gave better acceleration in the bone healing process, also this scaffolds may provide insight into the clinical repair of large bone defects

Characteristics, Treatments, and Outcomes of Tibial Plateau Nonunions: A Systematic Review

BACKGROUND

Due to the rare incidence of tibial plateau nonunions, current studies are limited to small sample sizes and patient demographics. The aim of this systematic review is to quantify and report patient and fracture traits, possible risk factors, and treatment outcomes of tibial plateau nonunions.

METHODS

PubMed, Clinical Key, and MEDLINE were searched for articles published prior to August 2020 in accordance to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The authors used varying combinations of the following terms to identify relevant articles: "tibial," "plateau," "nonunion," "non-union." Studies were assessed for patient demographics, pre-revision nonunion characteristics, treatment, and post-revision outcomes.

RESULTS

Eight studies were included, yielding 31 tibial plateau nonunions (21 males, 10 females). The majority of nonunions were associated with high energy trauma (52.2%) and were Schatzker class VI (54.8%). Schatzker class I and II nonunions were not attributed to neglect, contradicting previous suggestions. Time to union was 4.0 months, the most common treatments being autologous bone grafting (76.7%) and revision plating (63.3%).

CONCLUSION

This study demonstrates the effectiveness of autologous bone grafts and revision plating for tibial plateau nonunions. Physicians may use these findings to guide decision making in the event of high energy plateau nonunions. Lastly, various limitations exist within the current literature, emphasizing the need for standardized reporting measures.

Human Teeth-Derived Bioceramics for Improved Bone Regeneration

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is one of the most promising candidates of the calcium phosphate family, suitable for bone tissue regeneration due to its structural similarities with human hard tissues. However, the requirements of high purity and the non-availability of adequate synthetic techniques limit the application of synthetic HAp in bone tissue engineering. Herein, we developed and evaluated the bone regeneration potential of human teeth-derived bioceramics in mice's defective skulls. The developed bioceramics were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (FE-SEM). The developed bioceramics exhibited the characteristic peaks of HAp in FTIR and XRD patterns. The inductively coupled plasma mass spectrometry (ICP-MS) technique was applied to determine the Ca/P molar ratio in the developed bioceramics, and it was 1.67. Cytotoxicity of the simulated body fluid (SBF)-soaked bioceramics was evaluated by WST-1 assay in the presence of human alveolar bone marrow stem cells (hABMSCs). No adverse effects were observed in the presence of the developed bioceramics, indicating their biocompatibility. The cells adequately adhered to the bioceramics-treated media. Enhanced bone regeneration occurred in the presence of the developed bioceramics in the defected skulls of mice, and this potential was profoundly affected by the size of the developed bioceramics. The bioceramics-treated mice groups exhibited greater vascularization compared to control. Therefore, the developed bioceramics have the potential to be used as biomaterials for bone regeneration application.

New Strategies in Enhancing Spinal Fusion

The biologic steps involved in creating a bony fusion between adjacent segments of the spine are a complex and highly coordinated series of events. There have been significant advancements in bone grafts and bone graft substitutes in order to augment spinal fusion. While autologous bone grafting remains the gold standard, allograft bone grafting, synthetic bone graft substitutes, and bone graft enhancers are appropriate in certain clinical situations. This article provides an overview of the basic biology of spinal fusion and strategies for enhancing fusion through innovations in bone graft material.

Nanocrystalline hydroxyapatite-poly(thioketal urethane) nanocomposites stimulate a combined intramembranous and endochondral ossification response in rabbits

Resorbable bone cements are replaced by bone osteoclastic resorption and osteoblastic new bone formation near the periphery. However, the ideal bone cement would be replaced by new bone through processes similar to fracture repair, which occurs through a variable combination of endochondral and intramembranous ossification. In this study, nanocrystalline hydroxyapatite (nHA)-poly(thioketal urethane) (PTKUR) cements were implanted in femoral defects in New Zealand White rabbits to evaluate ossification at 4, 12, and 18 months. Four formulations were tested: an injectable, flowable cement and three moldable putties with varying ratios of calcium phosphate to sucrose granules. New bone formation and resorption of the cement by osteoclasts occurred near the periphery. Stevenel's Blue and Safranin O staining revealed infiltration of chondrocytes into the cements and ossification of the cartilaginous intermediate. These findings suggest that nHA-PTKUR cements support combined intramembranous and endochondral ossification, resulting in enhanced osseointegration of the cement that could potentially improve patient outcomes.

Design, Optimization, and Evaluation of Additively Manufactured Vintiles Cellular Structure for Acetabular Cup Implant

Cellular materials with very highly regulated micro-architectures are promising applicant materials for orthopedic medical uses while requiring implants or substituting for bone due to their ability to promote increased cell proliferation and osseointegration. This study focuses on the design of an acetabular cup (AC) cellular implant which was built using a vintiles cellular structure with an internal porosity of 56–87.9% and internal pore dimensions in the range of 600–1200 μm. The AC implant was then optimized for improving mechanical performance to reduce stress shielding by adjusting the porosity to produce stiffness (elastic modulus) to match with the bone, and allowing for bone cell ingrowth. The optimized and non-optimized AC cellular implant was fabricated using the SLM additive manufacturing process. Simulation (finite element analysis, FEA) was carried out and all cellular implants are finally tested under static loading conditions. The result showed that on the finite element model of an optimized implant, cellular has shown 69% higher stiffness than non-optimized. It has been confirmed by experimental work shown that the optimized cellular implant has a 71% higher ultimate compressive strength than the non-optimized counterpart. Finally, we developed an AC implant with mechanical performance adequately close to that of human bone.

Verifying measurements of residual calcium content in demineralised cortical bone

Calcium contents of demineralised human cortical bone determined by titrimetric assay and atomic absorption spectrophotometry technique were verified by comparing to neutron activation analysis which has high recovery of more than 90%. Conversion factors determined from the comparison is necessary to correct the calcium content for each technique. Femurs from cadaveric donors were cut into cortical rings and demineralised in 0.5 M hydrochloric acid for varying immersion times. Initial calcium content in the cortical bone measured by titration was 4.57%, only 21% of the measurement by neutron activation analysis; while measured by atomic absorption spectrophotometer was 13.4%, only 61% of neutron activation analysis. By comparing more readings with the measurements by neutron activation analysis with 93% recovery, a conversion factor of 4.83 was verified and applied for the readings by titration and 1.45 for atomic absorption spectrophotometer in calculating the correct calcium contents. The residual calcium content started to reduce after the cortical bone was demineralised in hydrochloric acid for 8 h and reduced to 13% after 24 h. Using the linear relationship, the residual calcium content could be reduced to less than 8% after immersion in hydrochloric acid for 40 h. Atomic absorption spectrophotometry technique is the method of choice for calcium content determination as it is more reliable compared to titrimetric assay.

Polydopamine coating promotes early osteogenesis in 3D printing porous Ti6Al4V scaffolds

BACKGROUND

Titanium implants are widely used in orthopedic and dental for more than 30 years. Its stable physicochemical properties and mechanical strength are indeed appropriate for implantation. However, the Bioinertia oxidized layer and higher elastic modulus often lead to the early implantation failure.

METHODS

In this study, we proposed a simple design of porous structure to minimize the disparity between scaffold and natural bone tissue, and introduced a one-step reaction to form a polydopamine (PDA) layer on the surface of titanium for the purpose of improving osteogenesis as well. The porous scaffolds with pore size of 400 µm and porosity of 44.66% were made by additive manufacturing. The cell behavior was tested by seeding MC3T3-E1 cells on Ti6Al4V films for 15 days. The biomechanical properties were then analyzed by finite element (FE) method and the in vivo osteogenesis effect was accordingly evaluated by implanting the scaffolds for 5 weeks in rabbits.

RESULTS

According to the achieved results, it was revealed that the immersion for 40 min with dopamine could significantly improve the cell adhesion. The proposed method for design of porous structure can avoid the stress shielding effect and bone growth inside the PDA coating scaffolds, which were observed at the early stage of bone healing process.

CONCLUSIONS

It can be concluded that the proposed PDA coating method is effective in promoting early osteogenesis, as well as being easy to operate, and can be helpful in the future clinical application of titanium implants.

Biomimetic Tissue-Engineered Bone Substitutes for Maxillofacial and Craniofacial Repair: The Potential of Cell Sheet Technologies

Maxillofacial defects are complex lesions stemming from various etiologies: accidental, congenital, pathological, or surgical. A bone graft may be required when the normal regenerative capacity of the bone is exceeded or insufficient. Surgeons have many options available for bone grafting including the "gold standard" autologous bone graft. However, this approach is not without drawbacks such as the morbidity associated with harvesting bone from a donor site, pain, infection, or a poor quantity and quality of bone in some patient populations. This review discusses the various bone graft substitutes used for maxillofacial and craniofacial repair: allografts, xenografts, synthetic biomaterials, and tissue-engineered substitutes. A brief overview of bone tissue engineering evolution including the use of mesenchymal stem cells is exposed, highlighting the first clinical applications of adipose-derived stem/stromal cells in craniofacial reconstruction. The importance of prevascularization strategies for bone tissue engineering is also discussed, with an emphasis on recent work describing substitutes produced using cell sheet-based technologies, including the use of thermo-responsive plates and the self-assembly approach of tissue engineering. Indeed, considering their entirely cell-based design, these natural bone-like substitutes have the potential to closely mimic the osteogenicity, osteoconductivity, osteoinduction, and osseointegration properties of autogenous bone for maxillofacial and craniofacial reconstruction.

Bone substitutes: a review of their characteristics, clinical use, and perspectives for large bone defects management

Bone replacement might have been practiced for centuries with various materials of natural origin, but had rarely met success until the late 19th century. Nowadays, many different bone substitutes can be used. They can be either derived from biological products such as demineralized bone matrix, platelet-rich plasma, hydroxyapatite, adjunction of growth factors (like bone morphogenetic protein) or synthetic such as calcium sulfate, tri-calcium phosphate ceramics, bioactive glasses, or polymer-based substitutes. All these substitutes are not suitable for every clinical use, and they have to be chosen selectively depending on their purpose. Thus, this review aims to highlight the principal characteristics of the most commonly used bone substitutes and to give some directions concerning their clinical use, as spine fusion, open-wedge tibial osteotomy, long bone fracture, oral and maxillofacial surgery, or periodontal treatments. However, the main limitations to bone substitutes use remain the management of large defects and the lack of vascularization in their central part, which is likely to appear following their utilization. In the field of bone tissue engineering, developing porous synthetic substitutes able to support a faster and a wider vascularization within their structure seems to be a promising way of research.

Monitoring the osseointegration process in porous Ti6Al4V implants produced by additive manufacturing: an experimental study in sheep

BACKGROUND

This study investigated the design and osseointegration process of transitive porous implants that can be used in humans and all trabecular and compact bone structure animals. The aim was to find a way of forming a strong and durable tissue bond on the bone-implant interface.

METHODS

Massive and transitive porous implants were produced on a direct metal laser sintering machine, surgically implanted into the skulls of sheep and kept in place for 12 weeks. At the end of the 12-week period, the Massive and porous implants removed from the sheep were investigated by scanning electron microscopy (SEM) to monitor the osseointegration process.

RESULTS

In the literature, each study has selected standard sizes for pore diameter in the structures they use. However, none of these involved transitional porous structures. In this study, as opposed to standard pores, there were spherical or elliptical pores at the micro level, development channels and an inner region. Bone cells developed in the inner region. Transitive pores grown gradually in accordance with the natural structure of the bone were modeled in the inner region for cells to develop. Due to this structure, a strong and durable tissue bond could be formed at the bone-implant interface.

CONCLUSIONS

Osseointegration processes of Massive vs. porous implants were compared. It was observed that cells were concentrated on the surface of Massive implants. Therefore, osseointegration between implant and bone was less than that of porous implants. In transitive porous implants, as opposed to Massive implants, an outer region was formed in the bone-implant interface that allowed tissue development.

Three-dimensional printed bone scaffolds: The role of nano/micro-hydroxyapatite particles on the adhesion and differentiation of human mesenchymal stem cells

Bone tissue engineering is strongly dependent on the use of three-dimensional scaffolds that can act as templates to accommodate cells and support tissue ingrowth. Despite its wide application in tissue engineering research, polycaprolactone presents a very limited ability to induce adhesion, proliferation and osteogenic cell differentiation. To overcome some of these limitations, different calcium phosphates, such as hydroxyapatite and tricalcium phosphate, have been employed with relative success. This work investigates the influence of nano-hydroxyapatite and micro-hydroxyapatite (nHA and mHA, respectively) particles on the in vitro biomechanical performance of polycaprolactone/hydroxyapatite scaffolds. Morphological analysis performed with scanning electron microscopy allowed us to confirm the production of polycaprolactone/hydroxyapatite constructs with square interconnected pores of approximately 350 µm and to assess the distribution of hydroxyapatite particles within the polymer matrix. Compression mechanical tests showed an increase in polycaprolactone compressive modulus ( E) from 105.5 ± 11.2 to 138.8 ± 12.9 MPa (PCL_nHA) and 217.2 ± 21.8 MPa (PCL_mHA). In comparison to PCL_mHA scaffolds, the addition of nano-hydroxyapatite enhanced the adhesion and viability of human mesenchymal stem cells as confirmed by Alamar Blue assay. In addition, after 14 days of incubation, PCL_nHA scaffolds showed higher levels of alkaline phosphatase activity compared to polycaprolactone or PCL_mHA structures.

Ceramic Biocomposites as Biodegradable Antibiotic Carriers in the Treatment of Bone Infections

Local release of antibiotic has advantages in the treatment of chronic osteomyelitis and infected fractures. The adequacy of surgical debridement is still key to successful clearance of infection but local antibiotic carriers seem to afford greater success rates by targeting the residual organisms present after debridement and delivering much higher local antibiotic concentrations compared with systemic antibiotics alone. Biodegradable ceramic carriers can be used to fill osseous defects, which reduces the dead space and provides the potential for subsequent repair of the osseous defect as they dissolve away. A dissolving ceramic antibiotic carrier also raises the possibility of single stage surgery with definitive closure and avoids the need for subsequent surgery for spacer removal.

In this article we provide an overview of the properties of various biodegradable ceramics, including calcium sulphate, the calcium orthophosphate ceramics, calcium phosphate cement and polyphasic carriers. We summarise the antibiotic elution properties as investigated in previous animal studies as well as the clinical outcomes from clinical research investigating their use in the surgical management of chronic osteomyelitis.

Calcium sulphate pellets have been shown to be effective in treating local infection, although newer polyphasic carriers may support greater osseous repair and reduce the risk of further fracture or the need for secondary reconstructive surgery. The use of ceramic biocomposites to deliver antibiotics together with BMPs, bisphosphonates, growth factors or living cells is under investigation and merits further study.

We propose a treatment protocol, based on the Cierny-Mader classification, to help guide the appropriate selection of a suitable ceramic antibiotic carrier in the surgical treatment of chronic osteomyelitis.

In vitro and in vivo study of additive manufactured porous Ti6Al4V scaffolds for repairing bone defects

Metallic implants with a low effective modulus can provide early load-bearing and reduce stress shielding, which is favorable for increasing in vivo life-span. In this research, porous Ti6Al4V scaffolds with three pore sizes (300~400, 400~500, and 500~700 μm) were manufactured by Electron Beam Melting, with an elastic modulus range of 3.7 to 1.7 GPa. Cytocompatibility in vitro and osseointegration ability in vivo of scaffolds were assessed. hBMSCs numbers increased on all porous scaffolds over time. The group with intended pore sizes of 300 to 400 μm was significantly higher than that of the other two porous scaffolds at days 5 and 7. This group also had higher ALP activity at day 7 in osteogenic differentiation experiment. The scaffold with pore size of 300 to 400 μm was implanted into a 30-mm segmental defect of goat metatarsus. In vivo evaluations indicated that the depth of bone ingrowth increased over time and no implant dislocation occurred during the experiment. Based on its better cytocompatibility and favorable bone ingrowth, the present data showed the capability of the additive manufactured porous Ti6Al4V scaffold with an intended pore size of 300 to 400 μm for large segmental bone defects.

A Comparison of Biocompatibility of a Titanium Alloy Fabricated by Electron Beam Melting and Selective Laser Melting

Electron beam melting (EBM) and selective laser melting (SLM) are two advanced rapid prototyping manufacturing technologies capable of fabricating complex structures and geometric shapes from metallic materials using computer tomography (CT) and Computer-aided Design (CAD) data. Compared to traditional technologies used for metallic products, EBM and SLM alter the mechanical, physical and chemical properties, which are closely related to the biocompatibility of metallic products. In this study, we evaluate and compare the biocompatibility, including cytocompatibility, haemocompatibility, skin irritation and skin sensitivity of Ti6Al4V fabricated by EBM and SLM. The results were analysed using one-way ANOVA and Tukey’s multiple comparison test. Both the EBM and SLM Ti6Al4V exhibited good cytobiocompatibility. The haemolytic ratios of the SLM and EBM were 2.24% and 2.46%, respectively, which demonstrated good haemocompatibility. The EBM and SLM Ti6Al4V samples showed no dermal irritation when exposed to rabbits. In a delayed hypersensitivity test, no skin allergic reaction from the EBM or the SLM Ti6Al4V was observed in guinea pigs. Based on these results, Ti6Al4V fabricated by EBM and SLM were good cytobiocompatible, haemocompatible, non-irritant and non-sensitizing materials. Although the data for cell adhesion, proliferation, ALP activity and the haemolytic ratio was higher for the SLM group, there were no significant differences between the different manufacturing methods.

"Three-in-One minimally invasive approach to surgical treatment of pediatric pathological fractures with wide bone loss through bone cysts: ESIN, curettage and packing with injectable HA bone substitute. A retrospective series of 116 cases."

INTRODUCTION

The outcome of pathological fracture due to large aggressive benign stage 3 Dormans and Flynn lesions [6] is often unsatisfactory and the rate of recurrence is high. No single technique has been considered safe and successful. Many Authors suggested curettage and bone grafting as the unique effective treatment in cases of large defect but, because of the invasive and complex nature of the operation (it needs a double-step procedure), it is not preferred. The purpose of this study is to examine the effectiveness of a minimally invasive treatment in one step through ESIN, curettage and packing with self-setting calcium phosphate cement.

PATIENTS AND METHODS

This is a retrospective study of 116 children admitted at the Division of Pediatric Orthopaedics Surgery of Santobono Children Hospital between 2006 and 2014 with a diagnosis of pathological fracture due to large aggressive ostheolytic benign lesions (stage 3 Dormans and Flynn). The size of bone loss was measured on the AP and ML radiographs and all the cysts with a caudo cranial extension from 5 to 8cm and with a medio lateral extension from 3 to 5cm were included. Mean time follow up 24 months was performed.

RESULTS

The three-in-one procedure was applied in all 116 patients. After two years of follow up, 113 patients were classified as healed and just 3 required 3 years to complete heal. No severe life threatening adverse effects or complications associated with the use of ESIN and injectable HA were recorded during the follow up period of 24-36 months. Fracture healing occurred in all cases within 4-6 weeks with adequate periosteal and endosteal callus formation. No second pathological fractures occurred in our series as well as no cysts reoccurred. Patients with humeral localizations showed a more rapid regain of muscular function and reestablishment of a complete range of motion.

CONCLUSIONS

The proposed three-in-one procedure has shown to be efficient, cost-effective, associated to high rates of definitive bone healing and low incidence of adverse effects.

A Novel HA/β-TCP-Collagen Composite Enhanced New Bone Formation for Dental Extraction Socket Preservation in Beagle Dogs

Past studies in humans have demonstrated horizontal and vertical bone loss after six months following tooth extraction. Many biomaterials have been developed to preserve bone volume after tooth extraction. Type I collagen serves as an excellent delivery system for growth factors and promotes angiogenesis. Calcium phosphate ceramics have also been investigated because their mineral chemistry resembles human bone. The aim of this study was to compare the performance of a novel bioresorbable purified fibrillar collagen and hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) ceramic composite versus collagen alone and a bovine xenograft-collagen composite in beagles. Collagen plugs, bovine graft-collagen composite and HA/β-TCP-collagen composite were implanted into the left and right first, second and third mandibular premolars, and the fourth molar was left empty for natural healing. In total, 20 male beagle dogs were used, and quantitative and histological analyses of the extraction ridge was done. The smallest width reduction was 19.09% ± 8.81% with the HA/β-TCP-collagen composite at Week 8, accompanied by new bone formation at Weeks 4 and 8. The HA/β-TCP-collagen composite performed well, as a new osteoconductive and biomimetic composite biomaterial, for socket bone preservation after tooth extraction.

Complete twelve month bone remodeling with a bi-phasic injectable bone substitute in benign bone tumors: a prospective pilot study

Background

Benign primary bone tumors are commonly treated by surgery involving bone grafts or synthetic bone void fillers. Although synthetic bone grafts may provide early mechanical support while minimizing the risk of donor-site morbidity and disease transmission, difficult handling properties and less than optimal transformation to bone have limited their use.

Methods

In a prospective series, patients with benign bone tumors were treated by minimal invasive intervention with a bi-phasic and injectable ceramic bone substitute (CERAMENT™ BONE VOID FILLER, BoneSupport, Sweden) with the hypothesis that open surgery with bone grafting might be avoided. The defects were treated by either mini-invasive surgery (solid tumors) or percutaneous injection (cysts) and followed clinically and radiologically for 12 months. CT scan was performed after 12 months to confirm bone remodeling of the bone substitute. All patients were allowed full weight bearing immediately after surgery.

Results

Fourteen patients with a median age of 13 years (range 7–75) were consecutively recruited during 11 months. Eleven lesions were bone cysts (eight unicameral and three post-traumatic) and three were solid benign tumors. The median size of the lesions was 40 mL (range 1–152). The most common location was humerus (n = 10). After 12 months the defects completely or partially filled with median 18 mL (range 5–28) of bone substitute demonstrated full resolution (Neer Classification grade I) in 11 patients, partial resolution (Neer II) in 2 patients and in 1 patient the cyst persisted (Neer III).

No lesions required recurrent surgery during the observation period. No post-operative fracture or infection was recorded.

Conclusions

Minimal invasive treatment with a bi-phasic and injectable ceramic bone substitute might offer an alternative to regular bone grafting due to convenient handling properties and rapid bone remodeling.

Trial Registration

ClinicalTrials NCT02567084 Release Date 10/01/2015

Effect exerted by Teriparatide upon Repair Function of β-tricalcium phosphate to ovariectomised rat's femoral metaphysis defect caused by osteoporosis

In this study, we tested the effect of Teriparatide (PTH) in combination with β-tricalcium phosphate (β-TCP) as a bone void filler in an ovariectomised rat distal femoral metaphysis model.β-TCP is a completely resorbable synthetic calcium phosphate and the Teriparatide is a drug that can promote bone formation in the condition of osteoporosis. A critical size defect of 3mm in diameter, a through-hole bone defect, was drilled into each distal femur of the ovariectomised rats. The hole was filled with β-TCP and the rat was injected PTH Teriparatide (30μg/kg) in peritoneum 5 times per week. After 4and 8 weeks the animals were killed and the degree of bone healing analysed. In total, 60 animals were investigated. When the β-TCP and PTH were used, histological, biochemistry and histomor-phometric evaluations revealed significantly better bone healing in terms of quantity and quality of the newly formed bone. The Ovariectomised rats which suffer from femur metaphysis defect are cured by embedding β-tricalcuim phosphate and intermittently cured by parathyroid hormone (PTH).

Treatment study of distal femur for parathyroid hormone (1-34) and β-tricalcium phosphate on bone formation in critical-sized defects in osteopenic rats

The objective of this study was to evaluate the effect of following combined treatment with parathyroid hormone (1-34) (PTH) and β-tricalcium phosphate (β-TCP) on local bone formation in a rat 3-mm critical-sized defect at the distal femur. Fourteen weeks were allowed to pass before defect surgery for the establishment of osteopenic animal models chronically fed a low-protein diet. All animals were randomly divided into four groups: group PTH; group β-TCP, group PTH + β-TCP, and a control group. All rats then underwent a surgical procedure to create bone defects in the bilateral distal femurs, and β-TCP was implanted into critical-sized defects for the groups designated as β-TCP and group PTH + β-TCP. After the defect operation, all animals from group PTH and group PTH + β-TCP received following subcutaneous injections with PTH (60 μg/kg, three times per week) until euthanasia at 4 and 8 weeks. The distal femurs and blood were collected for evaluation. The results of study showed the strongest effect on accelerating the local bone formation with treatment β-TCP and PTH at 4 weeks and 8 weeks. The results from our study demonstrate that a combination of PTH and β-TCP had an additive effect on local bone formation in osteopenic rats chronically fed a low-protein diet.

Treatment study of distal femur for parathyroid hormone (1-34) and β-tricalcium phosphate on bone formation in critical size defects in rats

The objective of this study was to evaluate local bone formation following systemic administration of parathyroid hormone (1-34), a surgically implanted synthetic β-tricalcium phosphate bone biomaterial serving as a matrix to support new bone formation. Twelve weeks after bilateral ovariectomy, all rats underwent bone defect in the distal femurs, and β-tricalcium phosphate was implanted into critical sized defects. After defect operation, all animals were randomly divided into four groups and received following subcutaneous injections until death at four and eight weeks: sham rats (group ST); sham rats + parathyroid hormone, 30 µg/kg, three times a week (group SPT); OVX rats (group OT); and OVX rats + parathyroid hormone (group OPT). The distal femurs of rats were harvested for evaluation. The treatment group demonstrating the highest levels of new bone formation was the defects treated with parathyroid hormone as assessed by micro-computed tomography, biomechanical strength, and histological analysis for sham rats. Furthermore, parathyroid hormone showed a stronger effect on accelerating the degradation of β-tricalcium phosphate. Osteoporosis can limit the function of parathyroid hormone and/or β-tricalcium phosphate. The results from our study demonstrate that combination of parathyroid hormone and β-tricalcium phosphate brings better effect to bone tissue repair in non-osteoporosis and/or osteoporosis status.

Use of demineralized bone matrix in the extremities

Autologous bone graft is considered as the gold standard for all indications for bone grafting procedures but the limited availability and complications in donor site resulted in seeking other options like allografts and bone graft substitutes. Demineralized bone matrix (DBM) is an allograft product with no quantity limitation. It is an osteoconductive material with osteoinductive capabilities, which vary among different products, depending on donor characteristics and differences in processing of the bone. The purpose of the present review is to provide a critical review of the existing literature concerning the use of DBM products in various procedures in the extremities. Clinical studies describing the use of DBM alone or in combination with other grafting material are available for only a few commercial products. The Level of Evidence of these studies and the resulting Grades of Recommendation are very low. In conclusion, further clinical studies of higher quality are required in order to improve the Recommendation Grades for or against the use of DBM products in bone grafting procedures.

Biomimetic scaffolds based on hydroxyapatite nanorod/poly(D,L) lactic acid with their corresponding apatite-forming capability and biocompatibility for bone-tissue engineering

This study presents a facile synthesis of biomimetic hydroxyapatite nanorod/poly(D,L) lactic acid (HAp/PDLLA) scaffolds with the use of solvent casting combined with a salt-leaching technique for bone-tissue engineering. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy were used to observe the morphologies, pore structures of synthesized scaffolds, interactions between hydroxyapatite nanorods and poly(D,L) lactic acid, as well as the compositions of the scaffolds, respectively. Porosity of the scaffolds was determined using the liquid substitution method. Moreover, the apatite-forming capability of the scaffolds was evaluated through simulated body fluid (SBF) incubation tests, whereas the viability, attachment, and distribution of human osteoblast cells (MG 63 cell line) on the scaffolds were determined through alamarBlue assay and confocal laser microscopy after nuclear staining with 4',6-diamidino-2-phenylindole and actin filaments of a cytoskeleton with Oregon Green 488 phalloidin. Results showed that hydroxyapatite nanorod/poly(D,L) lactic acid scaffolds that mimic the structure of natural bone were successfully produced. These scaffolds possessed macropore networks with high porosity (80-84%) and mean pore sizes ranging 117-183 μm. These scaffolds demonstrated excellent apatite-forming capabilities. The rapid formation of bone-like apatites with flower-like morphology was observed after 7 days of incubation in SBFs. The scaffolds that had a high percentage (30 wt.%) of hydroxyapatite demonstrated better cell adhesion, proliferation, and distribution than those with low percentages of hydroxyapatite as the days of culture increased. This work presented an efficient route for developing biomimetic composite scaffolds, which have potential applications in bone-tissue engineering.

Tomographic imaging of fragmented cortical bone heteroimplant and methylmethacrylate in segmental bone defect of rabbit tibia

PURPOSE

To evaluate the performance of composites consisting of fragmented cortical bone heteroimplant in association with methylmethacrylate preserved in 98% glycerin, in segmental bone defect of rabbit tibia medial metaphysis.

METHODS

In this study were used twelve adult New Zealand rabbits, divided into three groups of four animals each: G30 (30 days), G60 (60 days) and G90 (90 days). The bone defects previously created in the tibia were filled with composites and both were evaluated by cone-beam computed tomography, immediately after surgery and after 30, 60, and 90 days.

RESULTS

The composites fulfilled and remained in the sites of bone defects in all cases and were not registered signals of infection, migration or rejection.

CONCLUSIONS

The implanted composites promoted the bone defects repair without signals of infection and/or rejection. The composites are one more option for bone defects repair.

Pore Geometry Optimization of Titanium (Ti6Al4V) Alloy, for Its Application in the Fabrication of Customized Hip Implants

The present study investigates the mechanical response of representative volume elements of porous Ti-6Al-4V alloy, to arrive at a desired range of pore geometries that would optimize the reduction in stiffness necessary for biocompatibility with the stress concentration arising around the pore periphery, under physiological loading conditions with respect to orthopedic hip implants. A comparative study of the two is performed with the aid of a newly defined optimizing parameter called pore efficiency that takes into consideration both the stiffness quantity and the stress localization around pores. To perform a detailed analysis of the response of the porous structure over the entire spectrum of loading conditions that a hip implant is subjected to in vivo, the mechanical responses of 3D finite element models of cubic and rectangular parallelepiped geometries, with porosities varying over a range of 10% to 60%, are simulated under representative compressive, flexural as well as combined loading conditions. The results that are obtained are used to suggest a range of pore diameters that lower the effective stiffness and modulus of the implant to around 60% of the stiffness and modulus of dense solid implants while keeping the stress levels within permissible limits.

Setting time and formability of calcium phosphate cements prepared using modified dicalcium phosphate anhydrous powders

Calcium phosphate cements (CPCs) were prepared using Ca4(PO4)2O (TeCP) and modified CaHPO4 (DCPA) to evaluate the effects of the powder properties for DCPA particles on the setting time and formability of the resulting CPCs. Two types of modified DCPA were prepared by milling commercially available DCPA with ethanol (to produce E-DCPA) or distilled water (to produce W-DCPA). The E-DCPA samples consisted of well-dispersed, fine primary particles, while the W-DCPA samples contained agglomerated particles, and had a smaller specific surface area. The mean particle size decreased with increased milling time in both cases. The raw CPC powders prepared using W-DCPA had a higher packing density than those prepared using E-DCPA, regardless of the mean particle size. The setting time of the CPC paste after mixing with distilled water decreased with decreases in the mean particle size and specific surface area, for both types of DCPA. The CPCs prepared using W-DCPA showed larger plasticity values compared with those prepared using E-DCPA, which contributed to the superior formability of the W-DCPA samples. The CPCs prepared using W-DCPA showed a short setting time and large plasticity values, despite the fact that only a small amount of liquid was used for the mixing of the raw CPC powders (a liquid-to-powder ratio of 0.25 g g(-1) was used). It is likely that the higher packing density of the raw CPC powders prepared using W-DCPA was responsible for the higher performance of the resulting CPCs.

The composite of hydroxyapatite and calcium sulphate: a review of preclinical evaluation and clinical applications

Recent publications have shown that the combination of α-calcium sulfate hemihydrate, the densest form of hydrates and hydroxyapatite (HA) particles gives good clinical outcome in various applications. It has large potential as bone substitute since the material transforms to bone throughout the entire volume and not only by creeping substitution, from the surface toward the inside. Release of important proteins for osteogenesis has been observed around implanted material and is speculated to be due to fast dissolution of the calcium sulfate phase in combination with the osteoconductive and bioactive nature of HA. In diabetic foot infection, the osteoconductive HA/calcium sulfate material has been successfully used loaded with antibiotics and since it is injectable, the application is minimally invasive, easy and precise. It is a bone substitute for the future.

Aspecto radiológico e macroscópico de matriz óssea mineralizada heteróloga fragmentada e polimetilmetacrilato autoclavados em falha óssea de tíbia de coelho

Foi realizada falha segmentar com 6mm de diâmetro na região metafisária medial de tíbias de 12 coelhos, onde foi implantado uma associação de micro e macrofragmentos de matriz óssea cortical heteróloga fragmentada conservada em glicerina (98%) e polimetilmetacrilato autoclavados, para a sua reconstrução, e avaliados radiológica e macroscopicamente aos 30, 60, 90 e 120 dias. Houve adesão, em relação ao tempo, dos micro e macrocompósitos ao leito receptor, em 100% dos casos, mostrando ser biologicamente biocompatível, pois promoveram a reparação de falhas ósseas, sem sinais de infecção, migração e/ou rejeição, podendo, dessa forma, ser mais uma opção como substituto para preencher grandes defeitos ósseos.

In vitro evaluation of three different biomaterials as scaffolds for canine mesenchymal stem cells

PURPOSE

To evaluate in vitro ability the of three different biomaterials - purified hydroxyapatite, demineralized bone matrix and castor oil-based polyurethane - as biocompatible 3D scaffolds for canine bone marrow mesenchymal stem cell (MSC) intending bone tissue engineering.

METHODS

MSCs were isolated from canine bone marrow, characterized and cultivated for seven days with the biomaterials. Cell proliferation and adhesion to the biomaterial surface were evaluated by scanning electron microscopy while differentiation into osteogenic lineage was evaluated by Alizarin Red staining and Sp7/Osterix surface antibody marker.

RESULTS

The biomaterials allowed cellular growth, attachment and proliferation. Osteogenic differentiation occurred in the presence of hydroxyapatite, and matrix deposition commenced in the presence of the castor oil-based polyurethane.

CONCLUSION

All the tested biomaterials may be used as mesenchymal stem cell scaffolds in cell-based orthopedic reconstructive therapy.

Consideration of bone regeneration effect of stem cells: comparison between adipose-derived stem cells and demineralized bone matrix

BACKGROUND

Currently, many studies have sought to address the regeneration of extensive bone defects using stem cells. Here, the authors injected adipose-derived stem cells and demineralized bone matrix (DBM) into areas of bone defect in rabbits and compared their effect on bone regeneration to study the clinical usefulness of stem cells.

METHODS

This study used 20 male New Zealand white rabbits. Four craniectomies were made in 20 male New Zealand white rabbits' calvaria, and 4 different groups of experimental conditions were applied to each of the 4 cranial defects. To the first group, 0.2 mL of DBX, a commercially available clinical preparation ofDBM, was applied with fibrin glue. To the second group, 0.2 mL of adipose-derived stem cells, with confirmed bone differentiation ability, was applied with fibrin glue. To the third group, 0.1 mL of DBX, 0.1 mL of adipose-derived stem cells, and fibrin glue were applied. The fourth group of defects acted as the control and was left unaltered. After 6 weeks, regenerated bone from each defect site in each rabbit was collected and measured for volume change. Bone regeneration was assessed with three-dimensional skull bone computed tomography and histological analysis.

RESULTS

Osteoblasts were confirmed in all defect groups after 6 weeks. Overall, bone regeneration was weakest in the control group, whereas other groups of defects showed distinct bone regeneration. In particular, group 3, to which adipose-derived stem cells and DBM were applied, demonstrated the most active regeneration.

CONCLUSIONS

Both adipose-derived stem cells and DBM demonstrated regeneration effect on cranial defects in rabbits, but it is difficult to conclude which was better, because in each case the amount of regenerated bone was within the margin of error. However, as the most active bone regeneration was observed when both adipose-derived stem cells and DBM were applied together, this combination could be helpful in the correction of extensive bone defects.

Avaliação morfológica e por imagem radiográfica da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina para reparação de falhas ósseas em tíbias de coelhos

Os traumas que resultam em fraturas ósseas, principalmente as cominutivas, têm uma importância muito grande na rotina clínico-cirúrgica veterinária e humana. Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia esquerda de 12 coelhos, a qual foi preenchida com implante constituído de matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina (98%) para a sua reconstrução. Foi realizada avaliação morfológica e radiológica aos 30, 60, 90 e 120 dias e observou-se a incorporação do implante ao leito receptor, em 100% dos casos, mostrando ser biologicamente compatível, pois promoveu a reparação das falhas ósseas, sem sinais de infecção, migração e/ou rejeição, sendo uma opção de substituto para preencher defeitos ósseos.

Repairing a critical-sized bone defect with highly porous modified and unmodified baghdadite scaffolds

This is the first reported study to prepare highly porous baghdadite (Ca₃ZrSi₂O₉) scaffolds with and without surface modification and investigate their ability to repair critical-sized bone defects in a rabbit radius under normal load. The modification was carried out to improve the mechanical properties of the baghdadite scaffolds (particularly to address their brittleness) by coating their surfaces with a thin layer (∼400 nm) of polycaprolactone (PCL)/bioactive glass nanoparticles (nBGs). The β-tricalcium phosphate/hydroxyapatite (TCP/HA) scaffolds with and without modification were used as the control groups. All of the tested scaffolds had an open and interconnected porous structure with a porosity of ∼85% and average pore size of 500 μm. The scaffolds (six per scaffold type and size of 4 mm × 4 mm × 15 mm) were implanted (press-fit) into the rabbit radial segmental defects for 12 weeks. Micro-computed tomography and histological evaluations were used to determine bone ingrowth, bone quality, and implant integration after 12 weeks of healing. Extensive new bone formation with complete bridging of the radial defect was evident with the baghdadite scaffolds (modified/unmodified) at the periphery and in close proximity to the ceramics within the pores, in contrast to TCP/HA scaffolds (modified/unmodified), where bone tended to grow between the ulna adjacent to the implant edge. Although the modification of the baghdadite scaffolds significantly improved their mechanical properties, it did not show any significant effect on in vivo bone formation. Our findings suggest that baghdadite scaffolds with and without modification can serve as a potential material to repair critical sized bone defects.

Mandibular reconstruction using fresh frozen bone allograft after conservative enucleation of a mandibular odontogenic myxoma

The purpose of this article was to report the clinical, radiographic, and histological findings about a case of a young woman affected by a mandibular odontogenic myxoma. Conservative tumor resection was followed by immediate reconstructive treatment using fresh-frozen human bone graft, instead of autologous bone graft, as material for bone regeneration. Odontogenic myxoma, according to the World Health Organization, is classified as a benign tumor of mesenchymal origin whether or not containing odontogenic epithelium. Radiological and histological examination of the lesion confirmed the presence of an odontogenic myxoma, which was 21.2 mm high and 47.6 mm long; the lesion underwent biopsy evaluation before enucleation. According to literature and with the aim of a patient free of disease, conservative enucleation of the lesion was performed. The residual bone defect was filled with fresh-frozen bone allograft. At 6 months after surgery, no evidence of major complications was observed; the computed tomography scan revealed effective bone regeneration through the grafted area. The use of fresh-frozen bone allograft, thanks to its osteoinductive and osteoconductive properties, may represent an optional choice for reconstruction of bone defects after jaw tumor removal.

Effect of self-assembled nanofibrous silk/polycaprolactone layer on the osteoconductivity and mechanical properties of biphasic calcium phosphate scaffolds

We here present the first successful report on combining nanostructured silk and poly(ε-caprolactone) (PCL) with a ceramic scaffold to produce a composite scaffold that is highly porous (porosity ∼85%, pore size ∼500 μm, ∼100% interconnectivity), strong and non-brittle with a surface that resembles extracellular matrix (ECM). The ECM-like surface was developed by self-assembly of nanofibrous structured silk (20-80 nm diameter, similar to native collagen found in ECM) over a thin PCL layer which is coated on biphasic calcium phosphate (BCP) scaffolds. The effects of different concentrations of silk solution on the mechanical and physical properties of the scaffolds were also comprehensively examined. Our results showed that using silk only (irrespective of concentration) for the modification of ceramic scaffolds could drastically reduce the compressive strength of the modified scaffolds in aqueous media, and the modification made a limited contribution to improving scaffold toughness. Using PCL/nanostructured silk the compressive strength and modulus of the modified scaffolds reached 0.42 MPa (compared with 0.07 MPa for BCP) and ∼25 MPa (compared with 5 MPa for BCP), respectively. The failure strain of the modified scaffold increased more than 6% compared with a BCP scaffold (failure strain of less than 1%), indicating a transformation from brittle to elastic behavior. The cytocompatibility of ECM-like composite scaffolds was investigated by studying the attachment, morphology, proliferation and bone-related gene expression of primary human bone-derived cells. Cells cultured on the developed scaffolds for 7 days had significant up-regulation of cell proliferation (∼1.6-fold higher, P<0.001) and osteogenic gene expression levels (collagen type I, osteocalcin and bone sialoprotein) compared with the other groups tested.

Unitary bioresorbable cage/core bone graft substitutes for spinal arthrodesis coextruded from polycaprolactone biocomposites

A unitary bioresorbable cage/core bone graft substitute consisting of a stiff cage and a softer core with interconnected porosity is offered for spinal arthrodesis. Polycaprolactone, PCL, was used as the matrix and hydroxyapatite, HA, and β-tricalcium phosphate, TCP, were used in the formulation of the cage layer to impart modulus increase and osteoconductivity while the core consisted solely of PCL. The crystallinity, biodegradation rate (under accelerated conditions) and mechanical properties, i.e., the uniaxial compression, relaxation modulus upon step compression and cyclic compressive fatigue properties, of the co-extruded cage/core bone graft substitutes could be manipulated by changes in the concentration of HA/TCP in the cage layer. The cyclic fatigue behavior of the cage/core bone graft substitutes were also compared to the behavior of bovine vertebral cancellous bone characterized under similar testing conditions. The biocompatibility of the cage/core bone graft substitutes were assessed via in vitro culturing of human bone marrow derived stromal cells, BMSCs. The cell proliferation rates, time dependencies of the alkaline phosphates (ALP) activity and the expressions of bone markers, i.e., Runx2, ALP, collagen type I, osteopontin and osteocalcin, and the collected μ-CT images demonstrated the differentiation of BMSCs via osteogenic lineage and formation of mineralized bone tissue to indicate the biocompatibility of the cage/core bone graft substitutes.

Evaluation of the ability of collagen-glycosaminoglycan scaffolds with or without mesenchymal stem cells to heal bone defects in Wistar rats

PURPOSE

The aim of this experiment was to examine the capacity of collagen-glycosaminoglycan scaffolds, with or without mesenchymal stem cells, to satisfactorily repair a 5-mm rat calvarial defect.

METHODS

Fifty-five Wistar rats were used in the study. The defects were either left empty to serve as controls (n = 7) or filled with cell-free scaffolds (n = 11), cell-seeded scaffolds that were pre-cultured in standard culture medium (n = 13), cell-seeded scaffolds that were pre-cultured in osteoinductive factor-supplemented medium (n = 12) or particulate autogenous bone (n = 12). The animals were sacrificed at 12 weeks after surgery, and specimens were prepared for histomorphometric analysis. The linear bone healing and the bone area within the defect were measured.

RESULTS

Comparable results were obtained using cell-free collagen-glycosaminoglycan scaffolds and autogenous bone both in terms of linear bone healing (P < 0.986) and area of new bone (P < 0.846). While the test groups showed significantly more bone formation compared to the empty defect control group, the linear bone healing and area of new bone within the defect were significantly lower in the cell-seeded scaffolds than in the cell-free scaffolds. The results have demonstrated that a cell-free collagen-glycosaminoglycan scaffold is capable of repairing a 5-mm rat calvarial defect as effectively as autogenous bone and that seeding the scaffold with pre-cultured mesenchymal stem cells prior to implantation offered no beneficial effect and resulted in incomplete healing of the defect.

CONCLUSIONS

The results thus suggest that the scaffold has immense potential for tissue repair showing favorable osteoconductive properties, biocompatibility and degradability.

In vivo alveolar bone regeneration by bone marrow stem cells/fibrin glue composition

The repair of alveolar bone defects caused by trauma, periodontal diseases and inflammation is still a challenge for both researchers and clinicians. Although there are many attempts to regenerate bone based on different seed cells and scaffolds, the results are still unsatisfactory. This study aims to clarify whether it could be efficient to reconstruct the alveolar bone by the combination of bone marrow stem cells (BMSCs) without pre-osteoinduction in vitro with fibrin glue (FG). The BMSCs were obtained from 2-week-old Sprague-Dawley (SD) rats and expanded in vitro with non-introduction. Afterwards, they were composited with FG for in vivo implantation. The animal models of traumatic alveolar bone defects were established bilaterally in the maxilla of 15 rats which were randomly divided into 3 groups. The BMSCs/FG composition was transplanted into 5 rats of the treated group. Another 5 rats in the negative control group were transplanted by pure FG without BMSCs. The rest 5 rats served as the blank control. Gross observation and histological analysis were made to evaluate the new bone formation 6 weeks after transplantation. Micro-CT was also used to estimate the bone healing through three-dimensional reconstruction and the bone density analysis. The amount of new bone formed in the treated group was significantly greater than the negative and blank control. Our results suggest that the strategy of combing BMSCs with FG is effective in the repair of alveolar bone defects. Its clinical application is promising.