Degradation, Bone Regeneration and Tissue Response of an Innovative Volume Stable Magnesium-Supported GBR/GTR Barrier Membrane

The potential bone regeneration effects of leptin- and osteolectin-coated 3D-printed PCL scaffolds: anin vivostudy

This study investigated the effectiveness of bone regeneration upon the application of leptin and osteolectin to a three-dimensional (3D) printed poly(ϵ-caprolactone) (PCL) scaffold. A fused deposition modeling 3D bioprinter was used to fabricate scaffolds with a diameter of 4.5 mm, a height of 0.5 mm, and a pore size of 420-520 nm using PCL (molecular weight: 43 000). After amination of the scaffold surface for leptin and osteolectin adhesion, the experimental groups were divided into the PCL scaffold (control), the aminated PCL (PCL/Amine) scaffold, the leptin-coated PCL (PCL/Leptin) scaffold, and the osteolectin-coated PCL (PCL/Osteo) scaffold. Next, the water-soluble tetrazolium salt-1 (WST-1) assay was used to assess cell viability. All groups exhibited cell viability rates of >100%. Female 7-week-old Sprague-Dawley rats were used forin vivoexperiments. Calvarial defects were introduced on the rats' skulls using a 5.5 mm trephine bur. The rats were divided into the PCL (control), PCL/Leptin, and PCL/Osteo scaffold groups. The scaffolds were then inserted into the calvarial defect areas, and the rats were sacrificed after 8-weeks to analyze the defect area. Micro-CT analysis indicated that the leptin- and osteolectin-coated scaffolds exhibited significantly higher bone regeneration. Histological analysis revealed new bone and blood vessels in the calvarial defect area. These findings indicate that the 3D-printed PCL scaffold allows for patient-customized fabrication as well as the easy application of proteins like leptin and osteolectin. Moreover, leptin and osteolectin did not show cytotoxicity and exhibited higher bone regeneration potential than the existing scaffold.

Osteogenic Potential of Magnesium Oxide Nanoparticles in Bone Regeneration: A Systematic Review

Guided bone regeneration (GBR) plays a crucial role in the augmentation of alveolar bone, especially in cases of dental implants. The main principle behind using membranes in guided tissue regeneration (GTR) is to prevent epithelial downgrowth as well as connective tissue on the root surface. However, the membranes lack some major properties, such as osteogenic and antimicrobial properties. Magnesium (Mg) is one of the biodegradable materials that is gaining interest because of its favourable mechanical properties and biocompatibility. It also possesses pro-osteogenic properties and significant inhibition of biofilm formation and maturation. These features have attracted increasing interest in using magnesium oxide nanoparticles in GBR membrane applications. This systematic review assesses the osteogenic potential of magnesium oxide nanoparticles in periodontal bone regeneration. The literature search used PubMed, PubMed Central, Medline, and Cochrane databases to examine systematic reviews published till March 2023. Seven articles were included based on the selection criteria. We included all in vitro and in vivo clinical studies based on the osteogenic potential of magnesium oxide nanoparticles in periodontal bone regeneration. The seven studies provided evidence that magnesium oxide nanoparticles, when incorporated in any substrate, showed higher osteogenic potential in terms of higher alkaline phosphatase levels, bone volume fraction, and bone mineral density. The optimum concentration of magnesium oxide can be an ideal additive to various substrates to promote bone regeneration. Because most of the studies were conducted on calvarial defects, further studies should focus only on bone regeneration related to periodontal regeneration.

Collagen membrane functionalized with magnesium oxide via room-temperature atomic layer deposition promotes osteopromotive and antimicrobial properties

Artificial bone grafting materials such as collagen are gaining interest due to the ease of production and implantation. However, collagen must be supplemented with additional coating materials for improved osteointegration. Here, we report room-temperature atomic layer deposition (ALD) of MgO, a novel method to coat collagen membranes with MgO. Characterization techniques such as X-ray photoelectron spectroscopy, Raman spectroscopy, and electron beam dispersion mapping confirm the chemical nature of the film. Scanning electron and atomic force microscopies show the surface topography and morphology of the collagen fibers were not altered during the ALD of MgO. Slow release of magnesium ions promotes bone growth, and we show the deposited MgO film leaches trace amounts of Mg when incubated in phosphate-buffered saline at 37 °C. The coated collagen membrane had a superhydrophilic surface immediately after the deposition of MgO. The film was not toxic to human cells and demonstrated antibacterial properties against bacterial biofilms. Furthermore, in vivo studies performed on calvaria rats showed MgO-coated membranes (200 and 500 ALD) elicit a higher inflammatory response, leading to an increase in angiogenesis and a greater bone formation, mainly for Col-MgO500, compared to uncoated collagen. Based on the characterization of the MgO film and in vitro and in vivo data, the MgO-coated collagen membranes are excellent candidates for guided bone regeneration.

Resveratrol-loaded co-axial electrospun poly(ε-caprolactone)/chitosan/polyvinyl alcohol membranes for promotion of cells osteogenesis and bone regeneration

The guided bone regeneration (GBR) membranes currently used in clinics are usually compromised by their limited osteogenic induction potential. In this study, we fabricate a core-shell poly(ε-caprolactone)/chitosan/polyvinyl alcohol (PCL/CS/PVA) GBR membrane with different amount of resveratrol (RSV), endowing the PCL/CS/PVA GBR membrane with superior osteogenic induction ability, which was not attained by the regular GBR membrane. The prepared GBR membranes were characterized by scanning electron microscopy, transmission electron microscopy, and CCK-8 and live-dead staining assays, and their osteogenic induction ability was evaluated using Col-I immunofluorescence staining, micro-computed tomography, haematoxylin and eosin staining and immunohistochemical staining. Results of the in vitro release experiment confirmed that the membranes exhibited a continuous RSV release profile for 15 days. Furthermore, the cumulative releasing of RSV was increased from 39.68 ± 2.09 μg to 65.8 ± 2.91 μg with increasing contents of RSV from 0.1 % to 0.5 % (w/v) in the core layer of GBR membranes. In particular, the PCL/CS/PVA GBR membrane loading with 0.5 % RSV most efficiently release RSV in a sustained and controlled manner, which significantly induced osteogenic differentiation of pre-osteoblasts in vitro and bone regeneration in vivo. Based on the in vivo histological findings, newly formed bone tissues with 82.46 ± 9.86 % BV/TV and 0.70 ± 0.07gcm-3 BMD were generated in the defect sites treated by the GBR membrane loaded with 0.5 % RSV, which were the largest values among those for all three groups after 12 weeks of post implantation. Overall, the PCL/CS/PVA GBR membrane loaded with 0.5 % RSV has significant potential for bone regeneration.

Guided Bone Regeneration Using a Novel Magnesium Membrane: A Literature Review and a Report of Two Cases in Humans

Guided bone regeneration (GBR) is a common procedure used to rebuild dimensional changes in the alveolar ridge that occur after extraction. In GBR, membranes are used to separate the bone defect from the underlying soft tissue. To overcome the shortcomings of commonly used membranes in GBR, a new resorbable magnesium membrane has been developed. A literature search was performed via MEDLINE, Scopus, Web of Science and PubMed in February 2023 for research on magnesium barrier membranes. Of the 78 records reviewed, 16 studies met the inclusion criteria and were analyzed. In addition, this paper reports two cases where GBR was performed using a magnesium membrane and magnesium fixation system with immediate and delayed implant placement. No adverse reactions to the biomaterials were detected, and the membrane was completely resorbed after healing. The resorbable fixation screws used in both cases held the membranes in place during bone formation and were completely resorbed. Therefore, the pure magnesium membrane and magnesium fixation screws were found to be excellent biomaterials for GBR, which supports the findings of the literature review.

Republication: In Vitro and Ex Vivo Analysis of Collagen Foams for Soft and Hard Tissue Regeneration

BACKGROUND/AIM

The aim of this study was the conception, production, material analysis and cytocompatibility analysis of a new collagen foam for medical applications.

MATERIALS AND METHODS

After the innovative production of various collagen sponges from bovine sources, the foams were analyzed ex vivo in terms of their structure (including pore size) and in vitro in terms of cytocompatibility according to EN ISO 10993-5/-12. In vitro, the collagen foams were compared with the established biomaterials cerabone and Jason membrane. Materials cerabone and Jason membrane.

RESULTS

Collagen foams with different compositions were successfully produced from bovine sources. Ex vivo, the foams showed a stable and long-lasting primary structure quality with a bubble area of 1,000 to 2,000 μm2 In vitro, all foams showed sufficient cytocompatibility.

CONCLUSION

Collagen sponges represent a promising material for hard and soft tissue regeneration. Future studies could focus on integrating and investigating different additives in the foams.

Bovine hydroxyapatite-based scaffold accelerated the inflammatory phase and bone growth in rats with bone defect

Hydroxyapatite (HA) is a biomaterial widely used to treat bone defect, such as due to traffic accident. The HA scaffold is obtained from synthetic HA or natural sources, such as bovine hydroxyapatite (BHA). This study aims to compare the characteristics and in vivo performance of BHA-based and HA-based scaffolds. For this purpose, the scaffold was formulated with gelatin (GEL) and characterised by SEM-EDX, FTIR and mini autograph. The defect model was carried out on the femur area of Wistar rats classified into three animal groups: defect, HA-GEL and BHA-GEL. Postoperatively (7, 14 and 28 days), the bone was radiologically evaluated, and stained with haematoxylin-eosin, anti-CD80 and anti-CD163. The BHA-GEL scaffold showed a regular surface and spherical particle shape, whereas the HA-GEL scaffold exhibited irregular surface. The BHA-GEL scaffold had higher pore size and compressive strength and lower calcium-to-phosphorus ratio than the HA-GEL scaffold. In vivo study showed that the expression of CD80 in the three experimental groups was not significantly different. However, the expression of CD163 differed significantly between the groups. The BHA-GEL group showed robust expression of CD163 on day 7, which rapidly decreased over time. It also showed increased osteoclasts, osteoblasts and osteocytes cell count that contributed to the integrity of the defect area. In conclusion, the BHA-based scaffold exhibited the desired physical and chemical characteristics that benefit in vivo performance versus the HA-based scaffold. Thus, the BHA-based scaffold may be used as a bone graft.

Degradable Pure Magnesium Used as a Barrier Film for Oral Bone Regeneration

The barrier membrane plays an extremely critical role in guided bone regeneration (GBR), which determines the success or failure of GBR technology. In order to obtain barrier membranes with high mechanical strength and degradability, some researchers have focused on degradable magnesium alloys. However, the degradation rate of pure Mg-based materials in body fluids is rather fast, thus posing an urgent problem to be solved in oral clinics. In this study, a novel micro-arc oxidation (MAO) surface-treated pure Mg membrane was prepared. Electrochemical tests, immersion experiments and in vivo experiments were carried out to investigate its potential use as a barrier membrane. The experimental results showed that the corrosion resistance of a pure Mg membrane treated by MAO is better than that of the uncoated pure Mg. The results of cell experiments showed no obvious cytotoxicity, which suggests the enhanced differentiation of osteoblasts. At the same time, the MAO-Mg membrane showed better biological activity than the pure Ti membrane in the early stage of implantation, exhibiting relatively good bone regeneration ability. Consequently, the MAO membrane has been proven to possess good application prospects for guided bone regeneration.

Recent advances in biofunctional guided bone regeneration materials for repairing defective alveolar and maxillofacial bone: A review

The anatomy of the oral and maxillofacial sites is complex, and bone defects caused by trauma, tumors, and inflammation in these zones are extremely difficult to repair. Among the most effective and reliable methods to attain osteogenesis, the guided bone regeneration (GBR) technique is extensively applied in defective oral and maxillofacial GBR. Furthermore, endowing biofunctions is crucial for GBR materials applied in repairing defective alveolar and maxillofacial bones. In this review, recent advances in designing and fabricating GBR materials applied in oral and maxillofacial sites are classified and discussed according to their biofunctions, including maintaining space for bone growth; facilitating the adhesion, migration, and proliferation of osteoblasts; facilitating the migration and differentiation of progenitor cells; promoting vascularization; providing immunoregulation to induce osteogenesis; suppressing infection; and effectively mimicking natural tissues using graded biomimetic materials. In addition, new processing strategies (e.g., 3D printing) and new design concepts (e.g., developing bone mimetic extracellular matrix niches and preparing scaffolds to suppress connective tissue to actively acquire space for bone regeneration), are particularly worthy of further study. In the future, GBR materials with richer biological functions are expected to be developed based on an in-depth understanding of the mechanism of bone-GBR-material interactions.

Preparation of functional poly-(lactic acid-co-glycolic acid)-based guided bone-regeneration membrane and its application in the reconstruction of mandibular defects in rats

OBJECTIVES

This study aimed to prepare functional composite electrospinning fibrous membranes with the functions of antifibrosis and bacteriostasis, as well as to explore its repair effect on rat jaw defect.

METHODS

Poly-(lactic acid-co-glycolic acid) fibrous membrane loaded with cyclic-arginine-glycine-aspartic acid sequence, ornidazole, and nanohydroxyapatite (n-HA) was prepared by electrospinning as the functional layer (GBRL) for adhering onto defective bone. A barrier layer with the function of supporting and isolating different functional layers was prepared by tape-casting method. Poly(p-dioxanone-co-l-phenylalanine) fiber membrane with the function of inhibiting fibrosis was prepared by electrospinning technology as the antifibrosis layer (AFL). The morphology of the composite membrane was characterized by scanning electron microscopy. The effects of different functional layers on the proliferation of mouse osteoblast precursor cells (MC3T3-E1) and mouse fibroblasts (L929) were studied by cell-proliferation test (CCK-8 method). The inhibitory effect of composite membrane on the proliferation of Porphyromonas gingivalis was studied by bacteriostatic circle test. A rat mandibular-bone defect model was established to study the repair effect of composite fiber membrane on bone-defect tissue. This repair effect was compared with that of collagen oral-repair membrane commonly used in clinics.

RESULTS

The GBRL layer could support the proliferation of MC3T3-E1 cells, and the AFL layer could inhibit the proliferation of L929 cells. Composite membranes loaded with ornidazole could inhibit the proliferation of Porphyromonas gingivalis. Various composite membranes can induce the reconstruction of rat jaw defects, among which the composite membranes loaded with ornidazole and n-HA had the best repair effect, which was better than that of collagen oral-repair membrane.

CONCLUSIONS

The electrospun membrane loaded with ornidazole and n-HA as the composite fiber membrane of GBRL layer had excellent antibacterial and bone-tissue-regeneration activity. The effect was better than that of the commonly used collagen oral-repair membrane. Therefore, this material has great potential to induce bone regeneration for defects caused by periodontal diseases.

Applications of Biodegradable Magnesium-Based Materials in Reconstructive Oral and Maxillofacial Surgery: A Review

Reconstruction of defects in the maxillofacial region following traumatic injuries, craniofacial deformities, defects from tumor removal, or infections in the maxillofacial area represents a major challenge for surgeons. Various materials have been studied for the reconstruction of defects in the maxillofacial area. Biodegradable metals have been widely researched due to their excellent biological properties. Magnesium (Mg) and Mg-based materials have been extensively studied for tissue regeneration procedures due to biodegradability, mechanical characteristics, osteogenic capacity, biocompatibility, and antibacterial properties. The aim of this review was to analyze and discuss the applications of Mg and Mg-based materials in reconstructive oral and maxillofacial surgery in the fields of guided bone regeneration, dental implantology, fixation of facial bone fractures and soft tissue regeneration.

Effect of Different Membranes on Vertical Bone Regeneration: A Systematic Review and Network Meta-Analysis

This study is aimed at performing a systematic review and a network meta-analysis of the effects of several membranes on vertical bone regeneration and clinical complications in guided bone regeneration (GBR) or guided tissue regeneration (GTR). We compared the effects of the following membranes: high-density polytetrafluoroethylene (d-PTFE), expanded polytetrafluoroethylene (e-PTFE), crosslinked collagen membrane (CCM), noncrosslinked collagen membrane (CM), titanium mesh (TM), titanium mesh plus noncrosslinked (TM + CM), titanium mesh plus crosslinked (TM + CCM), titanium-reinforced d-PTFE, titanium-reinforced e-PTFE, polylactic acid (PLA), polyethylene glycol (PEG), and polylactic acid 910 (PLA910). Using the PICOS principles to help determine inclusion criteria, articles are collected using PubMed, Web of Science, and other databases. Assess the risk of deviation and the quality of evidence using the Cochrane Evaluation Manual, and GRADE. 27 articles were finally included. 19 articles were included in a network meta-analysis with vertical bone increment as an outcome measure. The network meta-analysis includes network diagrams, paired-comparison forest diagrams, funnel diagrams, surface under the cumulative ranking curve (SUCRA) diagrams, and sensitivity analysis diagrams. SUCRA indicated that titanium-reinforced d-PTFE exhibited the highest vertical bone increment effect. Meanwhile, we analyzed the complications of 19 studies and found that soft tissue injury and membrane exposure were the most common complications.

Nanotopographical 3D-Printed Poly(ε-caprolactone) Scaffolds Enhance Proliferation and Osteogenic Differentiation of Urine-Derived Stem Cells for Bone Regeneration

3D-printing technology can be used to construct personalized bone substitutes with customized shapes, but it cannot regulate the topological morphology of the scaffold surface, which plays a vital role in regulating the biological behaviors of stem cells. In addition, stem cells are able to sense the topographical and mechanical cues of surface of scaffolds by mechanosensing and mechanotransduction. In our study, we fabricated a 3D-printed poly(ε-caprolactone) (PCL) scaffold with a nanotopographical surface and loaded it with urine-derived stem cells (USCs) for application of bone regeneration. The topological 3D-printed PCL scaffolds (TPS) fabricated by surface epiphytic crystallization, possessed uniformly patterned nanoridges, of which the element composition and functional groups of nanoridges were the same as PCL. Compared with bare 3D-printed PCL scaffolds (BPS), TPS have a higher ability for protein adsorption and mineralization in vitro. The proliferation, cell length, and osteogenic gene expression of USCs on the surface of TPS were significantly higher than that of BPS. In addition, the TPS loaded with USCs exhibited a good ability for bone regeneration in cranial bone defects. Our study demonstrated that nanotopographical 3D-printed scaffolds loaded with USCs are a safe and effective therapeutic strategy for bone regeneration.

Advances in Barrier Membranes for Guided Bone Regeneration Techniques

Guided bone regeneration (GBR) is a widely used technique for alveolar bone augmentation. Among all the principal elements, barrier membrane is recognized as the key to the success of GBR. Ideal barrier membrane should have satisfactory biological and mechanical properties. According to their composition, barrier membranes can be divided into polymer membranes and non-polymer membranes. Polymer barrier membranes have become a research hotspot not only because they can control the physical and chemical characteristics of the membranes by regulating the synthesis conditions but also because their prices are relatively low. Still now the bone augment effect of barrier membrane used in clinical practice is more dependent on the body’s own growth potential and the osteogenic effect is difficult to predict. Therefore, scholars have carried out many researches to explore new barrier membranes in order to improve the success rate of bone enhancement. The aim of this study is to collect and compare recent studies on optimizing barrier membranes. The characteristics and research progress of different types of barrier membranes were also discussed in detail.

Comparative analysis of lateral maxillary sinus augmentation with a xenogeneic bone substitute material in combination with piezosurgical preparation and bony wall repositioning or rotary instrumentation and membrane coverage: a prospective randomized clinical and histological study

OBJECTIVES

The present randomized controlled clinical study aimed to investigate if, in lateral maxillary sinus augmentation, the repositioned bony wall or the application of a collagen membrane results in more preferable new hard tissue formation.

MATERIALS AND METHODS

Forty patients were divided into two study groups. Both groups received a xenogeneic bone substitute material (BSM) during lateral sinus augmentation. In the bony wall group (BW), following piezosurgery, the retrieved bony wall was repositioned. In the collagen membrane group (CM), following rotary instrument preparation, collagen membrane coverage was applied. After 6 months, biopsies were taken to histologically analyze the percentage of BSM, connective tissue (CT), and newly formed bone (NFB) following both approaches.

RESULTS

Forty implants were placed and 29 harvested biopsies could be evaluated. Duration of surgery, membrane perforations, and VAS were detected. Histomorphometrical analysis revealed comparable amounts of all analyzed parameters in both groups in descending order: CT (BW: 39.2 ± 9%, CM: 37,9 ± 8.5%) > BSM (BW: 32.9 ± 6.3%, CM: 31.8 ± 8.8%) > NB (BW: 27.8 ± 11.2%, CM: 30.3 ± 4.5%).

CONCLUSIONS

The results of the present study show that the closure of the access window by means of the retrieved bony wall or a native collagen membrane led to comparable bone augmentation results.

CLINICAL TRIAL

clinicaltrials.gov NCT04811768.

CLINICAL RELEVANCE

Lateral maxillary sinus augmentation with the application of a xenogeneic BSM in combination with a native collagen membrane for bony window coverage represents a reliable method for surgical reconstruction of the posterior maxilla. Piezosurgery with bony window repositioning delivers comparable outcomes without membrane coverage.

Adipose mesenchymal stem cell-based tissue engineering mesh with sustained bFGF release to enhance tissue repair

Pelvic organ prolapse (POP) harms the quality of life of elderly patients. Transvaginal polypropylene mesh repair for POP was a frequently reported complication and was banned by the FDA in 2019. New therapeutic strategies are urgently required, and tissue engineering technology could be a novel therapy. Here, we developed a tissue engineering mesh out of three components: silk fibroin (SF) knitted mesh loaded with basic fibroblast growth factor (bFGF) and adipose-derived stem cells (ADSCs). We used coaxial electrospinning technology to achieve local bFGF release to promote regeneration. Additionally, ADSCs were loaded to demonstrate their paracrine ability of immune regulation and angiogenesis. Meanwhile, knitted silk fibroin mesh provided mechanical support. In vitro, SF/bFGF/ADSC tissue engineering mesh can stably release bFGF and has good biocompatibility, promoting cell proliferation and extracellular matrix synthesis. Six months after the SF/bFGF/ADSC tissue engineering mesh was implanted in a SD rat model, extracellular matrix reorganization, angiogenesis, and immunomodulatory effect, as well as mechanical properties of the implanting position were improved. Hence, SF/bFGF/ADSC tissue engineering mesh could be regarded as a promising option with excellent collagen synthesis, low foreign body response, and early angiogenic ability, providing potential ideas for POP treatment.

Feasibility and Efficacy of a Degradable Magnesium-Alloy GBR Membrane for Bone Augmentation in a Distal Bone-Defect Model in Beagle Dogs

We explored the feasibility and efficacy of a degradable magnesium (Mg) alloy guided bone regeneration (GBR) in the treatment of bone defects after tooth extraction. A GBR membrane (MAR-Gide (MG)) was used to treat a mandibular second molar (M2M)-distal bone defect (DBD). In eight beagle dogs, bilateral mandibular second and fourth premolars were hemi-sected. The distal roots were removed to create a two-wall bony defect of dimension 5 mm × 5 mm × 5 mm to simulate M2M-DBD. Thirty-two bone defects were assigned randomly into four groups according to GBR membranes (MG and Bio-Gide (BG)) applied and the time of killing (3 months and 6 months after surgery). The osteogenesis of bone defects and MG degradation were analyzed using micro-CT, histology (staining, tartrate-resistant acid phosphatase), and inductively coupled plasma mass spectrometry. MG did not increase the prevalence of infection, wound dehiscence, or subcutaneous emphysema compared with those using BG. Trabecular volume/total volume at 3 months (63.71 ± 10.4% vs. 59.97 ± 8.94%) was significantly higher in the group MG than that in the group BG. Implanted MG was degraded completely within 3 months, and "island-shaped" new bone was found near MG degradation products. A significant difference was not found in vertical bone height or percent of new bone formation (45.44 ± 12.28% vs. 43.49 ± 7.12%) between the groups. The concentration of rare-earth elements in mandibular lymph nodes of the group MG was significantly higher than that of the group BG (P ≤ 0.017) but did not lead to histopathological changes. In summary, MG exhibited good biocompatibility and clinical applicability compared with BG in vivo. The osteogenic effect of MG could be enhanced by regulating the degradation rate of Mg-alloy.

A Systematic Review and Network Meta-Analysis of Biomedical Mg Alloy and Surface Coatings in Orthopedic Application

Magnesium alloys have great application prospects as ideal bone implant materials. However, their poor corrosion resistance limits their clinical orthopedic application. Surface modification promotes the corrosion resistance of magnesium. Conversion coatings, such as calcium phosphate (Ca-P) coating, microarc oxidation (MAO) treatment, and fluoride (FLU) treatment, have been extensively investigated in in vivo studies. This systematic review and network meta-analysis compared the influence of different conversion coatings on bone repair, material properties, and systemic host response in orthopedic applications. Using the PICOS model, the inclusion criteria for biodegradable magnesium and its alloys were determined for in vivo studies. Four databases were used. The standard and weight mean differences with 95% confidence intervals were used to analyze new bone formation and degradation rate. Network structure and forest plots were created, and ranking probabilities were estimated. The risk of bias and quality of evidence were assessed using SYRCLE, CERQual, and GRADE tools. In the qualitative analysis, 43 studies were selected, and the evaluation of each outcome indicator was not entirely consistent from article to article. In the quantitative analysis, 21 articles were subjected to network meta-analysis, with 16 articles on implant degradation and 8 articles for new bone formation. Additionally, SUCRA indicated that Ca-P coating exhibited the highest corrosion resistance, followed by FLU treatment. MAO demonstrated the best capability for new bone formation, followed by Ca-P coating. Ca-P coating exhibited the highest overall performance. To conclude, coated Mg can promote better new bone formation than bare Mg and has considerable biocompatibility. Ca-P-coated Mg and MAO-coated Mg have the greatest potential to significantly promote corrosion resistance and bone regeneration, respectively. The findings of this study will provide a theoretical basis for the investigation of composite coatings and guidance for the orthopedic application of Mg bone implants.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

Upregulation of mitochondrial dynamics is responsible for osteogenic differentiation of mesenchymal stem cells cultured on self-mineralized collagen membranes

Collagen membranes crosslinked with high molecular weight polyacrylic acid (HPAA) are capable of self-mineralization via in situ intrafibrillar mineralization. These HPAA-crosslinked collagen membranes (HCM) have been shown to promote osteogenic differentiation of mesenchymal stem cells (MSCs) and enhance bone regeneration in vivo. Nevertheless, the biological triggers involved in those processes and the associated mechanisms are not known. Here, we identified the contribution of mitochondrial dynamics in HCM-mediated osteogenic differentiation of MSCs. Mitochondriogenesis markers were significantly upregulated when MSCs were cultured on HCM, committing the MSCs to osteogenic differentiation. The mitochondria fused to form an interconnected mitochondrial network in response to the high energy requirements. Mitochondrial fission in MSCs was also triggered by HCM; fission slightly declined at 14 days to restore the equilibrium in mitochondrial dynamics. Mitophagy, another event that regulates mitochondrial dynamics, occurred actively to remove dysfunctioned mitochondria and isolate damaged mitochondria from the rest of network. The mitophagy level of MSCs was significantly elevated in the presence of HCM. Taken together, the present findings indicate that upregulation of mitochondrial dynamics via mitochondriogenesis, fusion, fission and mitophagy is responsible for HCM-mediated osteogenic differentiation of MSCs. STATEMENT OF SIGNIFICANCE: High molecular weight polyacrylic acid (HPAA)-crosslinked collagen membrane (HCM) was found to promote in-situ bone regeneration because of it can stimulate osteogenic differentiation of mesenchymal stem cells (MSCs). Nevertheless, the biological triggers involved in those processes and associated mechanisms are not known. This study identifies that activation of mitochondrial dynamics is centrally involved in HCM-mediated osteogenic differentiation of MSCs. The HCM accelerates mitochondriogenesis and regulates homeostasis of the mitochondrial network in response to the increased energy demand for osteogenic differentiation. Concomitantly, mitophagy actively occurs to remove dysfunctioned mitochondria from the rest of the mitochondrial network. Identification of the involvement of mitophagy in HCM-mediated osteogenic differentiation of MSCs opens new vistas in the application of biomimetic mineralization in bone tissue regeneration.

Biocompatibility Analyses of HF-Passivated Magnesium Screws for Guided Bone Regeneration (GBR)

Background: Magnesium (Mg) is one of the most promising materials for human use in surgery due to material characteristics such as its elastic modulus as well as its resorbable and regenerative properties. In this study, HF-coated and uncoated novel bioresorbable magnesium fixation screws for maxillofacial and dental surgical applications were investigated in vitro and in vivo to evaluate the biocompatibility of the HF coating. Methods: Mg alloy screws that had either undergone a surface treatment with hydrofluoric-acid (HF) or left untreated were investigated. In vitro investigation included XTT, BrdU and LDH in accordance with the DIN ISO 10993-5/-12. In vivo, the screws were implanted into the tibia of rabbits. After 3 and 6 weeks, degradation, local tissue reactions and bony integration were analyzed histopathologically and histomorphometrically. Additionally, SEM/EDX analysis and synchrotron phase-contrast microtomography (µCT) measurements were conducted. The in vitro analyses revealed that the Mg screws are cytocompatible, with improved results when the surface had been passivated with HF. In vivo, the HF-treated Mg screws implanted showed a reduction in gas formation, slower biodegradation and a better bony integration in comparison to the untreated Mg screws. Histopathologically, the HF-passivated screws induced a layer of macrophages as part of its biodegradation process, whereas the untreated screws caused a slight fibrous tissue reaction. SEM/EDX analysis showed that both screws formed a similar layer of calcium phosphates on their surfaces and were surrounded by bone. Furthermore, the µCT revealed the presence of a metallic core of the screws, a faster absorbing corrosion front and a slow absorbing region of corroded magnesium. Conclusions: Overall, the HF-passivated Mg fixation screws showed significantly better biocompatibility in vitro and in vivo compared to the untreated screws.

Observation on the Effect of Bone Grafting Alone and Guided Tissue Regeneration Combined with Bone Grafting to Repair Periodontal Intraosseous Defects

Objective

To investigate the curative effect of guided tissue regeneration (GTR) combined with bone grafting and improve the aesthetic appearance of patients' gingiva.

Methods

A total of 86 patients with periodontal intraosseous defects were selected from February 2019 to February 2021. All the patients were divided into a control group and an observation group according to the random number table, with 43 patients in each group. Bone grafting was performed in the control group, while GTR was additionally used in the observation group on the basis of the control group. The surgical data and follow-up data were collected and organized. The alveolar bone mineral density, the change in the height of the bone defect, plaque index (PLI), sulcus hemorrhage index (SBI), PD, gingival recession (GR), clinical attachment loss (CAL), and other relevant data of the two groups in 6 months before and after surgery were compared. Six months after surgery, the cosmetic morphology of the patient's gums in the soft tissues around her teeth was evaluated.

Results

Six months after surgery, the alveolar bone density of patients in two groups increased compared with that before surgery, and the height of the bone defect decreased compared with that before surgery. The alveolar bone density of the observation group was higher than that of the control group, and the height of the bone defect was lower than that of the control group (P < 0.05). Six months after surgery, the PLI, SBI, PD, and CAL of patients in both groups were lower than those before surgery, while the GR was higher than that before surgery. PD and CAL values in the observation group were lower than those in the control group, and GR was higher than that in the control group (P < 0.05). Six months after surgery, there was no significant difference in PLI and SBI scores between the two groups (P < 0.05). Six months after surgery, the gingival cosmetic scores of the two groups of patients were higher than those before surgery. The observation group was higher than the control group (P < 0.05).

Conclusion

GTR combined with bone grafting has a good effect in the repair of periodontal intraosseous defects and can effectively promote the reconstruction and recovery of periodontal intraosseous defects in patients. At the same time, it can significantly improve the aesthetic appearance of patients' gums, with good clinical application value.

Recent progress in materials development and biological properties of GTR membranes for periodontal regeneration

Chronic periodontal is a very common infection that instigates the destruction of oral tissue, and for its treatment, it is necessary to minimize the infection and the defects regeneration. Periodontium consists of four types of tissues: (a) cementum, (b) periodontal ligament, (c) gingiva, and 4) alveolar bone. In separated cavities, regenerative process also allows various cell proliferations. Guided tissue regeneration (GTR) is a potential procedure that favors periodontal regrowth; however, some limitations (such as ineffective hemostatic property, poor mechanical property, and improper biodegradation) are also associated with it. This review mainly emphasizes on the following areas: (a) a summarized overview of the periodontium and its immunological situations, (b) recently utilized treatments for regeneration of distinctive periodontal tissues; (c) an overview of GTR membranes available commercially, and the latest developments on the characterization and processing of GTR membrane material; and 4) the function of the different non-polymeric/polymeric materials, which are acting as drug carriers, antibacterial agents, nanoparticles, and periodontal barrier membranes to prevent periodontal inflammation and to improve the strength of the GTR membrane.

Comparative In Vivo Analysis of the Integration Behavior and Immune Response of Collagen-Based Dental Barrier Membranes for Guided Bone Regeneration (GBR)

Collagen-based resorbable barrier membranes have been increasingly utilized for Guided Bone Regeneration (GBR), as an alternative to non-resorbable synthetic membranes that require a second surgical intervention for removal. One of the most important characteristics of a resorbable barrier membrane is its mechanical integrity that is required for space maintenance and its tissue integration that plays a crucial role in wound healing and bone augmentation. This study compares a commercially available porcine-derived sugar-crosslinked collagen membrane with two non-crosslinked collagen barrier membranes. The material analysis provides an insight into the influence of manufacturing on the microstructure. In vivo subcutaneous implantation model provides further information on the host tissue reaction of the barrier membranes, as well as their tissue integration patterns that involve cellular infiltration, vascularization, and degradation. The obtained histochemical and immunohistochemical results over three time points (10, 30, and 60 days) showed that the tissue response to the sugar crosslinked collagen membrane involves inflammatory macrophages in a comparable manner to the macrophages observed in the surrounding tissue of the control collagen-based membranes, which were proven as biocompatible. The tissue reactions to the barrier membranes were additionally compared to wounds from a sham operation. Results suggest wound healing properties of all the investigated barrier membranes. However, the sugar-crosslinked membrane lacked in cellular infiltration and transmembraneous vascularization, providing an exclusive barrier function in GBR. Moreover, this membrane maintained a similar swelling ratio over examined timepoints, which suggests a very slow degradation pattern and supports its barrier function. Based on the study results, which showed biocompatibility of the sugar crosslinked membrane and its stability up to 60 days post-implantation, it can be concluded that this membrane may be suitable for application in GBR as a biomaterial with exclusive barrier functionality, similar to non-resorbable options.

In Vitro and Ex Vivo Analysis of Collagen Foams for Soft and Hard Tissue Regeneration

BACKGROUND/AIM

The aim of this study was the conception, production, material analysis and cytocompatibility analysis of a new collagen foam for medical applications.

MATERIALS AND METHODS

After the innovative production of various collagen sponges from bovine sources, the foams were analyzed ex vivo in terms of their structure (including pore size) and in vitro in terms of cytocompatibility according to EN ISO 10993-5/-12. In vitro, the collagen foams were compared with the established soft and hard tissue materials cerabone and Jason membrane (both botiss biomaterials GmbH, Zossen, Germany).

RESULTS

Collagen foams with different compositions were successfully produced from bovine sources. Ex vivo, the foams showed a stable and long-lasting primary structure quality with a bubble area of 1,000 to 2,000 μm² In vitro, all foams showed sufficient cytocompatibility.

CONCLUSION

Collagen sponges represent a promising material for hard and soft tissue regeneration. Future studies could focus on integrating and investigating different additives in the foams.

A Comprehensive Review on Surface Modifications of Biodegradable Magnesium-Based Implant Alloy: Polymer Coatings Opportunities and Challenges

The development of biodegradable implants is certainly intriguing, and magnesium and its alloys are considered significant among the various biodegradable materials. Nevertheless, the fast degradation, the generation of a significant amount of hydrogen gas, and the escalation in the pH value of the body solution are significant barriers to their use as an implant material. The appropriate approach is able to solve this issue, resulting in a decrease the rate of Mg degradation, which can be accomplished by alloying, surface adjustment, and mechanical treatment. Surface modification is a practical option because it not only improves corrosion resistance but also prepares a treated surface to improve bone regeneration and cell attachment. Metal coatings, ceramic coatings, and permanent polymers were shown to minimize degradation rates, but inflammation and foreign body responses were also suggested. In contrast to permanent materials, the bioabsorbable polymers normally show the desired biocompatibility. In order to improve the performance of drugs, they are generally encapsulated in biodegradable polymers. This study summarized the most recent advancements in manufacturing polymeric coatings on Mg alloys. The related corrosion resistance enhancement strategies and future potentials are discussed. Ultimately, the major challenges and difficulties are presented with aim of the development of polymer-coated Mg-based implant materials.

The application of Bonelike® Poro as a synthetic bone substitute for the management of critical-sized bone defects - A comparative approach to the autograft technique - A preliminary study

The effective treatment of non-unions and critical-sized defects remains a challenge in the orthopedic field. From a tissue engineering perspective, this issue can be addressed through the application bioactive matrixes to support bone regeneration, such as Bonelike®, as opposed to the widespread autologous grafting technique. An improved formulation of Bonelike® Poro, was assessed as a synthetic bone substitute in an ovine model for critical-sized bone defects. Bone regeneration was assessed after 5 months of recovery through macro and microscopic analysis of the healing features of the defect sites. Both the application of natural bone graft or Bonelike® Poro resulted in bridging of the defects margins. Untreated defect remained as fibrous non-unions at the end of the study period. The characteristics of the newly formed bone and its integration with the host tissue were assessed through histomorphometric and histological analysis, which demonstrated Bonelike® Poro to result in improved healing of the defects. The group treated with synthetic biomaterial presented bone bridges of increased thickness and bone features that more closely resembled the native spongeous and cortical bone. The application of Bonelike® Poro enabled the regeneration of critical-sized lesions and performed comparably to the autograph technique, validating its octeoconductive and osteointegrative potential for clinical application as a therapeutic strategy in human and veterinary orthopedics.

Growth Factors in Oral Tissue Engineering: New Perspectives and Current Therapeutic Options

The present investigation is aimed at systematically analyzing the recent literature about the innovative scaffold involved in the reconstructive surgeries by applying growth factors and tissue engineering. An extensive review of the contemporary literature was conducted according to the PRISMA guidelines by accessing the PubMed, Embase, and Scopus Elsevier databases. Authors performed the English language manuscript research published from 2003 to 2020. A total of 13 relevant studies were included in the present review. The present systematic review included only papers with significant results about correlation between scaffold, molecular features of growth factor, and reconstructive surgeries in oral maxillofacial district. The initial research with filters recorded about 1023 published papers. Beyond reading and considering of suitability, only 42 and then 36 full-text papers were recorded for the revision. All the researches recorded the possibility of using growth factors on rebuilding atrophic jaws. Different growth factors like morphogenetic factors, cytokines, and inflammatory ones and their application over different scaffold materials were recorded. Further investigations should be required in order to state scientific evidence about a clear advantage of applying tissue engineering for therapeutic purpose.

Biocompatibility and Immune Response of a Newly Developed Volume-Stable Magnesium-Based Barrier Membrane in Combination with a PVD Coating for Guided Bone Regeneration (GBR)

To date, there are no bioresorbable alternatives to non-resorbable and volume-stable membranes in the field of dentistry for guided bone or tissue regeneration (GBR/GTR). Even magnesium (Mg) has been shown to constitute a favorable biomaterial for the development of stabilizing structures. However, it has been described that it is necessary to prevent premature degradation to ensure both the functionality and the biocompatibility of such Mg implants. Different coating strategies have already been developed, but most of them did not provide the desired functionality. The present study analyses a new approach based on ion implantation (II) with PVD coating for the passivation of a newly developed Mg membrane for GBR/GTR procedures. To demonstrate comprehensive biocompatibility and successful passivation of the Mg membranes, untreated Mg (MG) and coated Mg (MG-Co) were investigated in vitro and in vivo. Thereby a collagen membrane with an already shown biocompatibility was used as control material. All investigations were performed according to EN ISO 10993 regulations. The in vitro results showed that both the untreated and PVD-coated membranes were not cytocompatible. However, both membrane types fulfilled the requirements for in vivo biocompatibility. Interestingly, the PVD coating did not have an influence on the gas cavity formation compared to the uncoated membrane, but it induced lower numbers of anti-inflammatory macrophages in comparison to the pure Mg membrane and the collagen membrane. In contrast, the pure Mg membrane provoked an immune response that was fully comparable to the collagen membrane. Altogether, this study shows that pure magnesium membranes represent a promising alternative compared to the nonresorbable volume-stable materials for GBR/GTR therapy.

In Vitro and In Vivo Biocompatibility Analysis of a New Transparent Collagen-based Wound Membrane for Tissue Regeneration in Different Clinical Indications

BACKGROUND/AIM

For the treatment of different tissue defects such as jawbone defects, open wound defect, chronic ulcers, dura mater defects and corneal defects, different biomaterials are available. The use of collagen-based materials for these applications has been significantly increased over the past decades due to its excellent biocompatibility and degradability. However, no transparent collagen-based biomaterial is available until now. Thus, a newly developed transparent collagen membrane (TCM) based on natural derived porcine pericardium, which offers numerous application possibilities, was developed. The present study aimed to analyze the in vitro and in vivo biocompatibility using established methods.

MATERIALS AND METHODS

The new TCM membrane and a commercially available collagen membrane (CM, Jason membrane, botiss biomaterials GmbH, Zossen, Germany) were tested for its in vitro cytocompatibility. Furthermore, the in vivo biocompatibility was analyzed using sham operations as control group. In vitro, cytocompatibility was tested in accordance with EN ISO 10993-5/-12 regulations and Live-Dead-stainings. In vivo, a subcutaneous implantation model in BALB/c mice was used and explants were prepared for analyses by established histological, immunohistochemical and histomorphometrical methods.

RESULTS

In vitro, both membranes showed promising cytocompatibility with a slightly better direct cell response in the Live-Dead staining assay for the TCM. In vivo, TCM induced a comparable inflammatory immune response after 10 and 30 days with comparable numbers of M1- and M2-macrophages as also found in the control group without biomaterial insertion.

CONCLUSION

The newly transparent collagen membrane is fully biocompatible and is supporting safe clinical application in tissue repair and surgery.