Membranes for the Guided Bone Regeneration

Polycaprolactone/gelatin/ZIF-8 nanofiber membrane for advanced guided tissue regeneration in periodontal therapy

The periodontal tissue regeneration strategy based on guided tissue regeneration (GTR) membranes is an effective therapy for periodontal defects. Traditional GTR membranes, however, primarily serve as physical barriers and lack antimicrobial and osteogenic functions. Herein, we developed a multifunctional nanofiber membrane with zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) loaded in a hydrophilic gelatin layer. The release of Zn2+ from the ZIF-8 NPs effectively promoted bone tissue repair and simultaneously enabled GTR membranes with >99 % antibacterial efficacies against Escherichia coli and Staphylococcus aureus. Additionally, the incorporation of gelatin enhances cellular adhesion and growth. Furthermore, in vivo studies revealed significant bone regeneration, with increased trabecular number and reduced separation. Owing to its multiple functions, excellent biocompatibility and desirable mechanical properties, this membrane has considerable potential in the field of periodontal therapy.

Amino Acid-Based Poly(ester urea) Biodegradable Membrane for Guided Bone Regeneration

Barrier membranes (BM) for guided bone regeneration (GBR) aim to support the osteogenic healing process of a defined bony defect by excluding epithelial (gingival) ingrowth and enabling osteoprogenitor and stem cells to proliferate and differentiate into bone tissue. Currently, the most widely used membranes for these approaches are collagen-derived, and there is a discrepancy in defining the optimal collagen membrane in terms of biocompatibility, strength, and degradation rates. Motivated by these clinical observations, we designed a collagen-free membrane based on l-valine-co-l-phenylalanine-poly(ester urea) (PEU) copolymer via electrospinning. Degradation and mechanical properties of these membranes were performed on as-spun and water-aged samples. Alveolar-bone-derived stem cells (AvBMSCs) were seeded on the PEU BM to assess their cell compatibility and osteogenic characteristics, including cell viability, attachment/spreading, proliferation, and mineralized tissue-associated gene expression. In vivo, PEU BMs were subcutaneously implanted in rats to evaluate their potential to cause inflammatory responses and facilitate angiogenesis. Finally, critical-size calvarial defects and a periodontal model were used to assess the regenerative capacity of the electrospun PEU BM compared to clinically available Cytoflex synthetic membranes. PEU BM demonstrated equal biocompatibility to Cytoflex with superior mechanical performance in strength and elasticity. Additionally, after 14 days, PEU BM exhibited a higher expression of BGLAP/osteocalcin and superior in vivo performance-less inflammation and increased CD31 and VWF expression over time. When placed in critical-sized defects in the calvaria of rats, the PEU BM led to robust bone formation with high expression of osteogenesis and angiogenesis markers. Moreover, our membrane enhanced alveolar bone and cementum regeneration in an established periodontal model after 8 weeks. We demonstrate that the PEU BM exhibits favorable clinical properties, including mechanical stability, cytocompatibility, and facilitated bone formation in vitro and in vivo. This highlights its suitability for GBR in periodontal and craniofacial bone defects.

Systemic ozone therapy as an adjunctive treatment in guided bone regeneration: a histomorphometrical and immunohistochemical study in rats

OBJECTIVES

To assess the effectiveness of ozone therapy in guided bone regeneration (GBR) for critical size calvarial defects in rats.

MATERIALS AND METHODS

96 male Wistar rats were divided into four groups (n = 6 each). An 8 mm critical defect was created in the calvaria of each rat. The groups were: BIO (porcine collagen membrane, BioGide®), BIO + OZ (membrane with systemic ozone therapy every 2 days), COA + OZ (blood clot with ozone therapy), and COA (blood clot only). Evaluations at 7, 15, 30, and 60 days included histological, histomorphometric, inflammatory profile, Micro-CT, and immunohistochemical analyses. Statistical analysis involved two-factor ANOVA with Tukey's post-hoc test for general data, and one-factor ANOVA with Holm-Sidak post-hoc test for Micro-CT data.

RESULTS

The BIO + OZ group demonstrated superior bone regeneration with well-organized, mature bone tissue and significant bone formation at 30 and 60 days. The COA + OZ group showed early angiogenesis and reduced inflammation, resulting in complete defect closure by 30 days. The BIO group had good regeneration, but less mature tissue compared to BIO + OZ. The COA group exhibited limited bone formation and higher porosity.

CONCLUSION

Ozone therapy positively influences bone regeneration by enhancing cell proliferation and the healing response.

CLINICAL RELEVANCE

Improving regenerative processes with auxiliary therapies like ozone therapy can be significant for advancing dental reconstructions.

3D-Printed Silk Proteins for Bone Tissue Regeneration and Associated Immunomodulation

Current bone repair methods have limitations, prompting the exploration of innovative approaches. Tissue engineering emerges as a promising solution, leveraging biomaterials to craft scaffolds replicating the natural bone environment, facilitating cell growth and differentiation. Among fabrication techniques, three-dimensional (3D) printing stands out for its ability to tailor intricate scaffolds. Silk proteins (SPs), known for their mechanical strength and biocompatibility, are an excellent choice for engineering 3D-printed bone tissue engineering (BTE) scaffolds. This article comprehensively reviews bone biology, 3D printing, and the unique attributes of SPs, specifically detailing criteria for scaffold fabrication such as composition, structure, mechanics, and cellular responses. It examines the structural, mechanical, and biological attributes of SPs, emphasizing their suitability for BTE. Recent studies on diverse 3D printing approaches using SPs-based for BTE are highlighted, alongside advancements in their 3D and four-dimensional (4D) printing and their role in osteo-immunomodulation. Future directions in the use of SPs for 3D printing in BTE are outlined.

A comprehensive in vitro characterization of non-crosslinked, diverse tissue-derived collagen-based membranes intended for assisting bone regeneration

Collagen-based membranes are class III-medical devices widely used in dental surgical procedures to favour bone regeneration. Here, we aimed to provide biophysical and biochemical data on this type of devices to support their optimal use and design/manufacturing. To the purpose, four commercial, non-crosslinked collagen-based-membranes, obtained from various sources (equine tendon, pericardium or cortical bone tissues, and porcine skin), were characterized in vitro. The main chemical, biophysical and biochemical properties, that have significant clinical implications, were evaluated. Membranes showed similar chemical features. They greatly differed in morphology as well as in porosity and density and showed a diverse ranking in relation to these latter two parameters. Samples highly hydrated in physiological medium (swelling-ratio values in the 2.5-6.0 range) and, for some membranes, an anisotropic expansion during hydration was, for the first time, highlighted. Rheological analyses revealed great differences in deformability (150-1500kPa G') also alerting about the marked variation in membrane mechanical behaviour upon hydration. Samples proved diverse sensitivity to collagenase, with the cortical-derived membrane showing the highest stability. Biological studies, using human-bone-derived cells, supported sample ability to allow cell proliferation and to prompt bone regeneration, while no relevant differences among membranes were recorded. Prediction of relative performance based on the findings was discussed. Overall, results represent a first wide panel of chemical/biophysical/biochemical data on collagen-based-membranes that 1) enhances our knowledge of these products, 2) aids their optimal use by providing clinicians with scientific basis for selecting products based on the specific clinical situation and 3) represents a valuable reference for optimizing their manufacturing.

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.

Horizontal GBR with anorganic equine bone combined with a customized titanium mesh

This case report describes the fixed rehabilitation of the lower left arch in a patient following an horizontal GBR procedure by means of a customized titanium mesh and a new slow resorption bone substitute of equine origin.

Evaluation of a hydroxyapatite-crosslinked fish gelatin membranes

Background/purpose

Porcine collagen is widely used in regenerative therapies to generate membranes for bone augmentation. However, porcine or bovine gelatin or collagen is often not appropriate for patients with creed and religious beliefs or for allergic reasons. In this study, we evaluated the potential of fish gelatin to generate membranes.

Materials and methods

Fish gelatin and hydroxyapatite (HAp) were used at three different ratios (2:0, 2:1, 2:1.5, and 2:2) to prepare gelatin-hydroxyapatite (G-HAp) membranes via freeze-drying and heat-crosslinking. The surface morphology and cell attachment of G-HAp membranes were observed using scanning electron microscopy and confocal laser microscopy. G-HAp membrane was placed at the bottom of a well plate, and MC3T3-E1 cells were seeded on it. Cell viability and cytotoxicity were tested after 1 and 3 days of culture. Alkaline phosphatase (ALP) and alizarin red staining was performed at 10 and 21 days, respectively.

Results

Viability of cells on G-HAp membrane with the gelatin:HAp ratio of 2:1.5 was significantly higher than that on membranes with other gelatin:HAp ratios. ALP and alizarin red staining showed that ALP-positive areas and calcium deposition were the highest on G-HAp membrane with the gelatin:HAp ratio of 2:1. These membranes showed negligible cytotoxicity.

Conclusion

Fish-derived G-HAp membranes have the potential to promote osteogenic differentiation of MC3T3-E1 cells with negligible cytotoxicity.

Development of Novel Polysaccharide Membranes for Guided Bone Regeneration: In Vitro and In Vivo Evaluations

INTRODUCTION

Guided bone regeneration (GBR) procedures require selecting suitable membranes for oral surgery. Pullulan and/or dextran-based polysaccharide materials have shown encouraging results in bone regeneration as bone substitutes but have not been used to produce barrier membranes. The present study aimed to develop and characterize pullulan/dextran-derived membranes for GBR.

MATERIALS AND METHODS

Two pullulan/dextran-based membranes, containing or not hydroxyapatite (HA) particles, were developed. In vitro, cytotoxicity evaluation was performed using human bone marrow mesenchymal stem cells (hBMSCs). Biocompatibility was assessed on rats in a subcutaneous model for up to 16 weeks. In vivo, rat femoral defects were created on 36 rats to compare the two pullulan/dextran-based membranes with a commercial collagen membrane (Bio-Gide®). Bone repair was assessed radiologically and histologically.

RESULTS

Both polysaccharide membranes demonstrated cytocompatibility and biocompatibility. Micro-computed tomography (micro-CT) analyses at two weeks revealed that the HA-containing membrane promoted a significant increase in bone formation compared to Bio-Gide®. At one month, similar effects were observed among the three membranes in terms of bone regeneration.

CONCLUSION

The developed pullulan/dextran-based membranes evidenced biocompatibility without interfering with bone regeneration and maturation. The HA-containing membrane, which facilitated early bone regeneration and offered adequate mechanical support, showed promising potential for GBR procedures.

Membrane barriers for guided bone regeneration: An overview of available biomaterials

Dental implants revolutionized the treatment options for restoring form, function, and esthetics when one or more teeth are missing. At sites of insufficient bone, guided bone regeneration (GBR) is performed either prior to or in conjunction with implant placement to achieve a three-dimensional prosthetic-driven implant position. To date, GBR is well documented, widely used, and constitutes a predictable and successful approach for lateral and vertical bone augmentation of atrophic ridges. Evidence suggests that the use of barrier membranes maintains the major biological principles of GBR. Since the material used to construct barrier membranes ultimately dictates its characteristics and its ability to maintain the biological principles of GBR, several materials have been used over time. This review, summarizes the evolution of barrier membranes, focusing on the characteristics, advantages, and disadvantages of available occlusive barrier membranes and presents results of updated meta-analyses focusing on the effects of these membranes on the overall outcome.

Antibacterial efficacy of epigallocatechin-3-gallate cross-linked small intestinal submucosa guided bone regeneration membrane

The leading cause of guided bone regeneration (GBR) failure is infection. Herein, we developed a new GBR membrane with good mechanical and osteogenic properties by crosslinking the small intestinal submucosa (SIS) with epigallocatechin-3-gallate (EGCG). Meanwhile, EGCG is also a natural antibacterial agent. This study aimed to investigate the antibacterial efficacy of EGCG-crosslinked SIS (E-SIS) against Staphylococcus aureus and Escherichia coli through EGCG release, bacterial count, live/dead staining, scanning electron microscopy, growth curve, and biofilm formation tests. The results showed that E-SIS effectively inhibited bacteria's growth and adhesion, and its antibacterial activity against Staphylococcus aureus was stronger than that against Escherichia coli. 0.5% E-SIS had the most potent antibacterial activity. The antibacterial mechanism of E-SIS might be related to the release of EGCG and the surface properties of E-SIS. In conclusion, 0.5% E-SIS is a promising GBR membrane with good osteogenic and antibacterial properties.

A Prospective Study of the Assessment of the Efficacy of a Biodegradable Poly(l-lactic acid/ε-caprolactone) Membrane for Guided Bone Regeneration

Biodegradable guided bone regeneration (GBR) membranes consist primarily of collagen and aliphatic polyesters. This study assessed the comparative efficacy of a poly(l-lactic-caprolactone) [P(LA/CL)] membrane versus that of a collagen membrane in GBR. Patients requiring GBR simultaneously or before dental implant placement in edentulous regions were randomly assigned to one of two membranes. Within each membrane, they were subdivided into 3 groups: dental implants were placed simultaneously with GBR in groups A and B, and 180 days post-GBR in group C. The augmented bone width was measured at 1, 3, and 6 mm from the implant's neck (groups A and B) or the reference line (group C), utilizing cone-beam computed tomography images, immediately and 150 days post-surgery. A histological study was performed to evaluate bone formation in group C. No adverse events were observed. In the collagen group, the absorbed ratios of the augmented bone were 40.9 ± 36.7%, 29.4 ± 30.1%, and 11.1 ± 22.0% at 1, 3, and 6 mm, respectively; the ratio at 6 mm was significantly lower than that at 1 mm (p = 0.0442). In the P(LA/CL) group, those were 26.2 ± 27.3%, 17.1 ± 19.7%, and 13.3 ± 16.4% at 1, 3, and 6 mm, respectively, with no significant difference at each point. No significant inter-membrane differences were observed. The bone augmentation potential of the P(LA/CL) membrane matched that of the collagen membrane. P(LA/CL) could be used as a safe and effective membrane in GBR.

Bone grafting techniques and materials for implant dentistry

Bone quality, volume, height and width all play a pivotal role in dental implant stability, success and survival. A lack of adequate bone can be overcome with various bone grafting procedures. Dependent on many factors, including the amount of bone required, the site of implant placement, patient preferences and clinician factors; the type of bone grafting material and procedure undertaken can vary. Supplemental bone can be sourced from a variety of sources, including autogenous, allogenous and xenograft bone. Dependent on the source of the bone, it will have different properties in aiding bone formation, as well as being presented in different formulations, such as bone particles or bone blocks.The aim of this paper is to provide an overview of bone grafting indications, materials and types of bone grafting techniques that can be utilised to aid dental implant provision. It also discusses the properties needed to ensure optimal success of guided bone regeneration techniques.

Platelet rich fibrin is not a barrier membrane! Or is it?

Platelet-rich fibrin (PRF) is widely used in dentistry and other fields of medicine, and its use has become popular in dental implantology. In several published studies, PRF has been used as a barrier membrane. A barrier membrane is a sheet of a certain material that acts as a biological and mechanical barrier against the invasion of cells that are not involved in bone formation, such as epithelial cells. Among the basic requirements of a 'barrier membrane, occlusivity, stiffness, and space maintenance are the criteria that PRF primarily lacks; therefore, it does not fall under the category of barrier membranes. However, there is evidence that PRF membranes are useful in significantly improving wound healing. Does the PRF membrane act as a barrier? Should we think of adding or subtracting some points from the ideal requirements of a barrier membrane, or should we coin a new term or concept for PRF that will incorporate some features of a barrier membrane and be a combination of tissue engineering and biotechnology? This review is aimed at answering the basic question of whether the PRF membrane should be considered a barrier membrane or whether it is something more beyond the boundaries of a barrier membrane.

Optimizing the biodegradability and osteogenesis of biogenic collagen membrane via fluoride-modified polymer-induced liquid precursor process

Biogenic collagen membranes (BCM) have been widely used in guided bone regeneration (GBR) owing to their biodegradability during tissue integration. However, their relatively high degradation rate and lack of pro-osteogenic properties limit their clinical outcomes. It is of great importance to endow BCM with tailored degradation as well as pro-osteogenic properties. In this study, a fluoride-modified polymer-induced liquid precursor (PILP) based biomineralization strategy was used to convert the collagen membrane from an organic phase to an apatite-based inorganic phase, thus achieving enhanced anti-degradation performance as well as osteogenesis. As a result, three phases of collagen membranes were prepared. The original BCM in the organic phase induced the mildest inflammatory response and was mostly degraded after 4 weeks. The organic-inorganic mixture phase of the collagen membrane evoked a prominent inflammatory response owing to the fluoride-containing amorphous calcium phosphate (F-ACP) nanoparticles, resulting in active angiogenesis and fibrous encapsulation, whereas the inorganic phase induced a mild inflammatory response and degraded the least owing to the transition of F-ACP particles into calcium phosphate with high crystallinity. Effective control of ACP is key to building novel apatite-based barrier membranes. The current results may pave the way for the development of advanced apatite-based membranes with enhanced barrier performances.

Evaluation of efficacy of non-resorbable membranes compared to resorbable membranes in patients undergoing guided bone regeneration

Background

Replacement of missing teeth in patients with prolonged edentulism poses a challenge for clinicians. An extended period of edentulism results in severe atrophy of alveolar ridges rendering them unsatisfactory for rehabilitation using an implant-supported prosthesis. To overcome this difficulty, Guided Bone Regeneration (GBR) was introduced and constructed upon the principles of Guided Tissue Regeneration (GTR) procedures. Evidence suggests that GBR has proven to be a predictable treatment modality for treating vertical and horizontal ridge deficiencies.

Objective

The present systematic review aimed to evaluate the efficacy of non-resorbable (N-RES) membranes compared to resorbable (RES) membranes in patients undergoing GBR.

Methods

An electronic search of three databases, including PubMed, Web of Science, and Scopus, was conducted for articles published until March 2022. A supplementary manual search of references from these articles was performed to include any articles that may have been overlooked in the electronic search. Articles that evaluated the efficacy of RES membranes and N-RES membranes in GBR were included. Case reports, case series, commentaries, letters to the editor, narrative or systematic reviews were excluded. Articles in languages other than English were also excluded. The articles were assessed against risk of bias 2 tool for Randomized Control Trials (RCTs) and ROBINS-I tool for Non-Randomized Clinical Trials (N-RCTs). The Grading of Recommendations Assessment, Development and Evaluation (GRADE) assessment was followed based on the Cochrane Handbook for quality assessment. A summary of findings table was used to present the results.

Results

One hundred and fifty one articles were identified in an electronic search. Eight articles met the inclusion criteria and were included in the present systematic review. The studies were conducted on partially or completely edentulous patients with alveolar ridge deficiencies undergoing vertical or horizontal bone for subsequent implant placement. The majority of the studies reported similar results for bone gain in both RES and N-RES membrane groups.

Conclusion

The available evidence suggests that RES and N-RES membranes are equally effective in GBR. However, the evidence must be interpreted with caution due to its 'low quality' GRADE assessment.

Clinical implications

Further research focusing on human clinical trials with well-matched subjects with homogeneity in the type and method of GBR and method of assessment of new bone formation will derive conclusive results on the efficacy of RES and N-RES membranes in achieving new bone formation.

Unique Fiber Morphologies from Emulsion Electrospinning—A Case Study of Poly(ε-caprolactone) and Its Applications

The importance of electrospinning to produce biomimicking micro- and nano-fibrous matrices is realized by many who work in the area of fibers. Based on the solubility of the materials to be spun, organic solvents are typically utilized. The toxicity of the utilized organic solvent could be extremely important for various applications, including tissue engineering, biomedical, agricultural, etc. In addition, the high viscosities of such polymer solutions limit the use of high polymer concentrations and lower down productivity along with the limitations of obtaining desired fiber morphology. This emphasizes the need for a method that would allay worries about safety, toxicity, and environmental issues along with the limitations of using concentrated polymer solutions. To mitigate these issues, the use of emulsions as precursors for electrospinning has recently gained significant attention. Presence of dispersed and continuous phase in emulsion provides an easy route to incorporate sensitive bioactive functional moieties within the core-sheath fibers which otherwise could only be hardly achieved using cumbersome coaxial electrospinning process in solution or melt based approaches. This review presents a detailed understanding of emulsion behavior during electrospinning along with the role of various constituents and process parameters during fiber formation. Though many polymers have been studied for emulsion electrospinning, poly(ε-caprolactone) (PCL) is one of the most studied polymers for this technique. Therefore, electrospinning of PCL based emulsions is highlighted as unique case-study, to provide a detailed theoretical understanding, discussion of experimental results along with their suitable biomedical applications.

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.

Systematic evaluation of three porcine-derived collagen membranes for guided bone regeneration

Guided bone regeneration is one of the most common surgical treatment modalities performed when an additional alveolar bone is required to stabilize dental implants in partially and fully edentulous patients. The addition of a barrier membrane prevents non-osteogenic tissue invasion into the bone cavity, which is key to the success of guided bone regeneration. Barrier membranes can be broadly classified as non-resorbable or resorbable. In contrast to non-resorbable membranes, resorbable barrier membranes do not require a second surgical procedure for membrane removal. Commercially available resorbable barrier membranes are either synthetically manufactured or derived from xenogeneic collagen. Although collagen barrier membranes have become increasingly popular amongst clinicians, largely due to their superior handling qualities compared to other commercially available barrier membranes, there have been no studies to date that have compared commercially available porcine-derived collagen membranes with respect to surface topography, collagen fibril structure, physical barrier property, and immunogenic composition. This study evaluated three commercially available non-crosslinked porcine-derived collagen membranes (Striate+^TM, Bio-Gide^® and Creos^TM Xenoprotect). Scanning electron microscopy revealed similar collagen fibril distribution on both the rough and smooth sides of the membranes as well as the similar diameters of collagen fibrils. However, D-periodicity of the fibrillar collagen is significantly different among the membranes, with Striate+^TM membrane having the closest D-periodicity to native collagen I. This suggests that there is less deformation of collagen during manufacturing process. All collagen membranes showed superior barrier property evidenced by blocking 0.2-16.4 μm beads passing through the membranes. To examine the immunogenic agents in these membranes, we examined the membranes for the presence of DNA and alpha-gal by immunohistochemistry. No alpha-gal or DNA was detected in any membranes. However, using a more sensitive detection method (real-time polymerase chain reaction), a relatively strong DNA signal was detected in Bio-Gide^® membrane, but not Striate+^TM and Creos^TM Xenoprotect membranes. Our study concluded that these membranes are similar but not identical, probably due to the different ages and sources of porcine tissues, as well as different manufacturing processes. We recommend further studies to understand the clinical implications of these findings.

Application of Tissue Engineering in Manufacturing Absorbable Membranes to Improve the Osteopromoting Potential of Collagen

The membranes are an important biomaterial that contribute to osteopromotion. This study aimed to evaluate the osteopromotive potential of collagen membranes associated with Hydroxyapatite (HA) in critical size calvaria rat's defects. Ninety-six Albinus Wistar rats were divided into four groups: (CG) negative control: clot only (CG); positive control: porcine collagen membrane (BG); fish collagen membrane associated with HA (CP); bovine collagen membrane associated with HA (CB), analyzed at 7, 15, 30, and 60 postoperative days. At 30 days, membrane integrity was observed in the CB and fragments in the CP and BG groups were dispersed in the center of the defect. At 60 days, BG demonstrated better results with no statistical difference for the CP group (p = 0.199) and a statistically significant difference for the CB group (p = 0.013). The inflammatory profiles of the BG and CP groups were similar. Immunohistochemistry demonstrated at 60 days moderate osteopontin staining for the BG and CP groups, light staining for the CB, and intense osteocalcin staining for the BG, while the CB and CP groups demonstrated moderate staining. Microtomography revealed the highest mean bone volume (14.247 mm³) in the BG, followed by the CB (11.850 mm³), and CP (9.560 mm³) group. The collagen membranes associated with HA demonstrated an osteopromotive potential.

An Asymmetric Microfluidic/Chitosan Device for Sustained Drug Release in Guided Bone Regeneration Applications

One of the major challenges of guided bone regeneration (GBR) is infections caused by pathogen colonization at wound sites. In this paper, an asymmetric microfluidic/chitosan device was developed to release drugs to inhibit infections and to ensure that guided bone regeneration can be realized. The microfluidic technique was introduced into the GBR membrane for the first time, which demonstrated more controllable drug release, more flexible clinical use and had a lower cost compared with surface treatments and embedded nanoparticles. Based on the theory of diffusion and Fick’s first law, the contact area and concentration gradient were adjusted to realize sustained drug release. The standard deviation of minocycline release over 5 days was only 12.7%, which was lower than the joint effect of porous chitosan discs and nanospheres. The in vitro experiments against E. coli and Streptococcus mutans showed the excellent antibacterial performance of the device (>95%). The in vitro experiments for fibroblasts at the microfluidic side and osteoblasts at the chitosan side showed the satisfactory biocompatibility and the ability of the device to enhance bone regeneration. Therefore, this microfluidic/chitosan device is a promising therapeutic approach to prevent infection and guide bone regeneration.

Guided bone regeneration with extracellular matrix scaffold of small intestinal submucosa membrane

Guided bone regeneration (GBR) is a promising strategy for repairing bone defects using bioactive membranes. In this study, a new type of GBR membrane based on the small intestinal submucosa (SIS) was created, and its surface structure, cytological characteristics, and bone defect repair ability were compared with commonly used membranes. Our results show that compared to the Heal-all and Dentium membranes, the SIS membrane has an asymmetric structure that does not affect the proliferation of bone marrow mesenchymal stem cells (BMSCs). Instead, it increased their formation of calcium nodules and expression of bone morphogenetic protein-2 (BMP-2), alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and osteopontin (OPN). Six weeks after their insertion into a rat calvarial defect model, increased bone growth was observed in the SIS membrane group. Our results indicate that the SIS membrane has good biocompatibility and is more effective in promoting early bone formation than existing membranes. Given the wide range of source materials and simple preparation processes available, SIS membrane is a promising candidate for guided 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.

Chitosan-based biomaterials for the treatment of bone disorders

Bone is an alive and dynamic organ that is well-differentiated and originated from mesenchymal tissues. Bone undergoes continuous remodeling during the lifetime of an individual. Although knowledge regarding bones and their disorders has been constantly growing, much attention has been devoted to effective treatments that can be used, both from materials and medical performance points of view. Polymers derived from natural sources, for example polysaccharides, are generally biocompatible and are therefore considered excellent candidates for various biomedical applications. This review outlines the development of chitosan-based biomaterials for the treatment of bone disorders including bone fracture, osteoporosis, osteoarthritis, arthritis rheumatoid, and osteosarcoma. Different examples of chitosan-based formulations in the form of gels, micro/nanoparticles, and films are discussed herein. The work also reviews recent patents and important developments related to the use of chitosan in the treatment of bone disorders. Although most of the cited research was accomplished before reaching the clinical application level, this manuscript summarizes the latest achievements within chitosan-based biomaterials used for the treatment of bone disorders and provides perspectives for future scientific activities.

Biological Efficacy Comparison of Natural Tussah Silk and Mulberry Silk Nanofiber Membranes for Guided Bone Regeneration

Biopolymer nanofiber membranes are attracting interest as promising biomaterial scaffolds with a remarkable range of structural and functional performances for guided bone regeneration (GBR). In this study, tussah silk nanofiber (TSn) and Bombyx mori silk nanofiber (BSn) membranes were prepared by physical shearing. The diameters of the TSn and BSn membranes were 146.09 ± 63.56 and 120.99 ± 91.32 nm, respectively. TSn showed a Young's modulus of 3.61 ± 0.64 GPa and a tensile strength of 74.27 ± 5.19 MPa, which were superior to those of BSn, with a Young's modulus of 0.16 ± 0.03 GPa and a tensile strength of 4.86 ± 0.61 MPa. The potential of TSn and BSn membranes to guide bone regeneration was explored. In vitro, the TSn membrane exhibited significantly higher cell proliferation for MC3T3-E1 cells than the BSn membrane. In a cranial bone defect in a rat model, the TSn and BSn membranes displayed superior bone regeneration compared to the control because the membrane prevented the ingrowth of soft tissue to the defective area. Compared to the BSn membrane, the TSn membrane improved damaged bone regeneration, presumably due to its superior mechanical properties, high osteoconductivity, and increased cell proliferation. The TSn membrane has a bionic structure, excellent mechanical properties, and greater biocompatibility, making it an ideal candidate for GBR.

Mimicked Periosteum Layer Based on Deposited Particle Silk Fibroin Membrane for Osteogenesis and Guided Bone Regeneration in Alveolar Cleft Surgery: Formation and in Vitro Testing

An alveolar cleft is a critical tissue defect often treated with surgery. In this research, the mimicked periosteum layer based on deposited silk fibroin membrane was fabricated for guided bone regeneration in alveolar cleft surgery. The deposited silk fibroin particle membranes were fabricated by spray-drying with different concentrations of silk fibroin (v/v): 0.5% silk fibroin (0.5% SFM), 1% silk fibroin (1% SFM), 2% silk fibroin (2% SFM), and 1% silk fibroin film (1% SFF) as the control. The membranes were then characterized and the molecular organization, structure, and morphology were observed with FT-IR, DSC, and SEM. Their physical properties, mechanical properties, swelling, and degradation were tested. The membranes were cultured with osteoblast cells and their biological performance, cell viability and proliferation, total protein, ALP activity, and calcium deposition were evaluated. The results demonstrated that the membranes showed molecular transformation of random coils to beta sheets and stable structures. The membranes had a porous layer. Furthermore, they had more stress and strain, swelling, and degradation than the film. They had more unique cell viability and proliferation, total protein, ALP activity, calcium deposition than the film. The results of the study indicated that 1% SFM is promising for guided bone regeneration for alveolar cleft surgery.

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.

ePTFE-based biomedical devices: An overview of surgical efficiency

Polytetrafluoroethylene (PTFE) is a ubiquitous material used for implants and medical devices in general because of its high biocompatibility and inertness: blood vessel, heart, table jawbone, nose, eyes, or abdominal wall can benefit from its properties in case of disease or injury. Its expanded version, ePTFE is an improved version of PTFE with better mechanical properties, which extends its medical applications. A material as frequently used as ePTFE with these exceptional properties deserves a review of its main uses, developments, and possibility of improvements. In this systematic review, we examined clinical trials related to ePTFE-based medical devices from the literature. Then, we excluded all trials using ePTFE as a control to test other devices. ePTFE-coated stents, hemodialysis and bypass grafts, guided bone and tissue regeneration membranes, hernia and heart repair and other devices are reviewed. The rates of success using these devices and their efficiency compared to other materials used for the same purposes are reported. ePTFE appears to be more or just as efficient compared to them. Some success rates remain low, suggesting the need of improvement ePTFE for medical applications.

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.

An Insight into Nano Silver Fluoride-Coated Silk Fibroin Bioinspired Membrane Properties for Guided Tissue Regeneration

The current work focuses on the development of a novel electrospun silk fibroin (SF) nonwoven mat as a GTR membrane with antibacterial, biomineralization and biocompatible properties. The γ-poly glutamic acid (γ-PGA)-capped nano silver fluoride (NSF) and silver diamine fluoride (SDF) were first synthesized, which were dip-coated onto electrospun silk fibroin mats (NSF-SF and SDF-SF). UV-Vis spectroscopy and TEM depicted the formation of silver nanoparticles. NSF-SF and SDF-SF demonstrated antibacterial properties (against Porphyromonas gingivalis) with 3.1 and 6.7 folds higher relative to SF, respectively. Post-mineralization in simulated body fluid, the NSF-SF effectively promoted apatite precipitation (Ca/P ~1.67), while the SDF-SF depicted deposition of silver nanoparticles, assessed by SEM-EDS. According to the FTIR-ATR deconvolution analysis, NSF-SF portrayed ~75% estimated hydroxyapatite crystallinity index (CI), whereas pure SF and SDF-SF demonstrated ~60%. The biocompatibility of NSF-SF was ~82% when compared to the control, while SDF-coated samples revealed in vitro cytotoxicity, further needing in vivo studies for a definite conclusion. Furthermore, the NSF-SF revealed the highest tensile strength of 0.32 N/mm and 1.76% elongation at break. Therefore, it is substantiated that the novel bioactive and antibacterial NSF-SF membranes can serve as a potential candidate, shedding light on further in-depth analysis for GTR applications.

Bacterial adhesion to collagens: implications for biofilm formation and disease progression in the oral cavity

Collagen is the most abundant structural protein in the body and the main component of the extracellular matrix of most tissues, including dentine and periodontal tissues. Despite the well-characterized role of collagen and specifically type-I collagen, as a ligand for host cells, its role as a substrate for bacterial adhesion and biofilm formation is less explored. Therefore, the purpose of this review is to discuss recent findings regarding the adhesion of oral bacteria to collagen surfaces and its role in the progression and severity of oral and systemic diseases. Initial oral colonizers such as streptococci have evolved collagen-binding proteins (cbp) that are important for the colonization of dentine and periodontal tissues. Also, periodontal pathogens such as Porphyromonas gingivalis and Tannerella forsythia utilise cbps for tissue sensing and subsequent invasion. The implications of bacteria-collagen coupling in the context of collagen biomaterials and regenerative dentistry approaches are also addressed. Furthermore, the importance of interdisciplinary techniques such as atomic force microscopy for the nanocharacterization of bacteria-collagen interactions is also considered. Overall, understanding the process of oral bacterial adhesion onto collagen is important for developing future therapeutic approaches against oral and systemic diseases, by modulating the early stages of biofilm formation.

Single stage reconstruction of segmental skeletal defects by bone graft in a synthetic membrane

INTRODUCTION

Segmental skeletal defects are very difficult to treat. The current options are lengthy procedures, require more than one surgery and plagued with many complications. The aim of this study is to assess the results of bone graft in surgicel as a synthetic membrane for reconstruction of segmental skeletal defects in one stage surgery.

METHODS

Fourteen patients with segmental skeletal defects were included in the study. The ages ranged from 20 to 54 years with an average of 32 years. The defects were due to high energy trauma in all cases. The size of the defects ranged from 5 to 12 cm with an average of 7 cm. They were located in the distal femur in 11 cases and middle third of the femur in three cases. All cases were treated by the synthetic membrane technique in one stage surgery. Surgicel was used as a synthetic membrane and both the fibular strut autograft and morselized allograft were used to fill the defects in all patients.

RESULTS

All cases healed without additional procedures after the index surgery except in three cases. The time-to-bone union ranged from six to 13 months with an average of eight months. After physiotherapy all patients regained good range of knee movements except two cases. The complications included deep wound infection in two cases, nonunion of the graft in one case and joint stiffness in two cases.

CONCLUSION

Primary bone graft in surgicel as a synthetic membrane is a good technique for management of post-traumatic bone defects. It reduces the time and number of surgeries required for reconstruction of this difficult problem.

Polymeric membranes for biomedical applications

The rapid development of nanotechnology paved the way for further expansion of polymer chemistry and the fabrication of advanced polymeric membranes. Such modifications allowed enhancing or adding some unique properties, including mechanical strength, excellent biocompatibility, easily controlled degradability, and biological activity. This chapter discusses various applications of polymeric membranes in three significant areas of biomedicine, including tissue engineering, drug delivery systems, and diagnostics. It is intended to highlight here possible ways of improvement the properties of polymeric membranes, by modifying with other polymers, functional groups, compounds, drugs, bioactive components, and nanomaterials.

Development of Zoledronic Acid Containing Biomaterials for Enhanced Guided Bone Regeneration

In recent years, biomaterial-based treatments, also called guided bone regeneration (GBR), which aim to establish a bone regeneration site and prevent the migration of gingival connective tissue and / or peripheral epithelium through the defective area during periodontal surgical procedures have come to the fore. In this report, we have developed a nanoparticle bearing thermosensitive in situ gel formulation of Pluronic F127 and poly(D,L-lactic acid) based membrane to reveal their utilization at GBR by in-vivo applications. In addition, the encouragement of the bone formation in defect area via inhibition of osteoclastic activity is intended by fabrication these biodegradable biomaterials at a lowered Zoledronic Acid (ZA) dose. Both of the developed materials remained stable under specified stability conditions (25 °C, 6 months) and provided the extended release profile of ZA. The in-vivo efficacy of nanoparticle bearing in situ gel formulation, membrane formulation and simultaneous application for guided bone regeneration was investigated in New Zealand female rabbits with a critical size defect of 0.5 × 0.5 cm in the tibia bone for eight weeks. Based on the histopathological findings, lamellar bone and primarily woven bone formations were observed after 8 weeks of post-implantation of both formulations, while fibrosis was detected only in the untreated group. Lamellar bone growth was remarkably achieved just four weeks after the simultaneous application of formulations. Consequently, the simultaneous application of ZA-membrane and ZA-nanoparticles loaded in-situ gel formulations offers enhanced and faster GBR therapy alternatives.

Bioresorbable Magnesium-Based Alloys as Novel Biomaterials in Oral Bone Regeneration: General Review and Clinical Perspectives

Bone preservation and primary regeneration is a daily challenge in the field of dental medicine. In recent years, bioresorbable metals based on magnesium (Mg) have been widely investigated due to their bone-like modulus of elasticity, their high biocompatibility, antimicrobial, and osteoconductive properties. Synthetic Mg-based biomaterials are promising candidates for bone regeneration in comparison with other currently available pure synthetic materials. Different alloys based on Mg were developed to fit clinical requirements. In parallel, advances in additive manufacturing offer the possibility to fabricate experimentally bioresorbable metallic porous scaffolds. This review describes the promising clinical results of resorbable Mg-based biomaterials for bone repair in osteosynthetic application and discusses the perspectives of use in oral bone regeneration.

Biomedical applications of natural rubber latex from the rubber tree Hevea brasiliensis

The past decades have witnessed tremendous progress in biomaterials in terms of functionalities and applications. To realize various functions such as tissue engineering, tissue repair, and controlled release of therapeutics, a biocompatible and biologically active material is often needed. However, it is a difficult task to find either synthetic or natural materials suitable for in vivo applications. Nature has provided us with the natural rubber latex from the rubber tree Hevea brasiliensis, a natural polymer that is biocompatible and has been proved as inducing tissue repair by enhancing the vasculogenesis process, guiding and recruiting cells responsible for osteogenesis, and acting as a solid matrix for controlled drug release. It would be extremely useful if medical devices can be fabricated with materials that have these biological properties. Recently, various types of natural rubber latex-based biomedical devices have been developed to enhance tissue repair by taking advantage of its biological properties. Most of them were used to enhance tissue repair in chronic wounds and critical bone defects. Others were used to design drug release systems to locally release therapeutics in a sustained and controlled manner. Here, we summarize recent progress made in these areas. Specifically, we compare various applications and their performance metrics. We also discuss critical problems with the use of natural rubber latex in biomedical applications and highlight future opportunities for biomedical devices produced either with pre-treated natural rubber latex or with proteins purified from the natural rubber latex.

Simvastatin loaded chitosan guided bone regeneration membranes stimulate bone healing

BACKGROUND AND OBJECTIVE

Electrospun chitosan membranes (ESCM) modified with short-chain fatty acids have the ability to control the release of simvastatin (SMV), an anti-cholesterol drug with osteogenic potential, for guided bone regeneration (GBR) applications. This study evaluated in vivo osteogenic effects of rapid short release of SMV (4 weeks) vs long sustained release (8 weeks) from acetic anhydride (AA)-and hexanoic anhydride (HA)-modified ESCMs, respectively.

METHODS

AA ESCMs loaded with 10 or 50 µg SMV and HA ESCMs loaded with 50 µg SMV were evaluated for biocompatibility and bone formation at 4 and 8 weeks, in 5 mm critical size rat calvarial defects, using histological evaluation and micro-CT analysis.

RESULTS

No severe inflammatory response was noticed around the ESCMs. Less hydrophobic AA membranes showed signs of resorption by week 4 and were almost completely resorbed by week 8 whereas the more hydrophobic HA membranes resorbed slowly, remaining intact over 8 weeks. In micro-CT analysis, 10 µg SMV-loaded AA membranes did not show significant bone formation as compared to non-loaded AA membranes at either evaluation time points. 50 µg SMV-loaded AA membranes stimulated significantly more bone formation than non-loaded AA membranes by week 4 (%bone = 31.0 ± 5.9% (AA50) vs 18.5 ± 13.7% (AA0)) but showed no difference at week 8. HA membranes with 50 µg SMV showed significantly more bone formation as compared to corresponding non-loaded membranes by week 8 (%bone = 61.7 ± 8.9% (HA50) vs 33.9 ± 29.7% (HA0)), though such an effect was not significant at week 4.

CONCLUSION

These results indicate that modified ESCMs may be used to control the release of SMV and promote bone healing in GBR applications.

The Early Fragmentation of a Bovine Dermis-Derived Collagen Barrier Membrane Contributes to Transmembraneous Vascularization-A Possible Paradigm Shift for Guided Bone Regeneration

Collagen-based barrier membranes are an essential component in Guided Bone Regeneration (GBR) procedures. They act as cell-occlusive devices that should maintain a micromilieu where bone tissue can grow, which in turn provides a stable bed for prosthetic implantation. However, the standing time of collagen membranes has been a challenging area, as native membranes are often prematurely resorbed. Therefore, consolidation techniques, such as chemical cross-linking, have been used to enhance the structural integrity of the membranes, and by consequence, their standing time. However, these techniques have cytotoxic tendencies and can cause exaggerated inflammation and in turn, premature resorption, and material failures. However, tissues from different extraction sites and animals are variably cross-linked. For the present in vivo study, a new collagen membrane based on bovine dermis was extracted and compared to a commercially available porcine-sourced collagen membrane extracted from the pericardium. The membranes were implanted in Wistar rats for up to 60 days. The analyses included well-established histopathological and histomorphometrical methods, including histochemical and immunohistochemical staining procedures, to detect M1- and M2-macrophages as well as blood vessels. Initially, the results showed that both membranes remained intact up to day 30, while the bovine membrane was fragmented at day 60 with granulation tissue infiltrating the implantation beds. In contrast, the porcine membrane remained stable without signs of material-dependent inflammatory processes. Therefore, the bovine membrane showed a special integration pattern as the fragments were found to be overlapping, providing secondary porosity in combination with a transmembraneous vascularization. Altogether, the bovine membrane showed comparable results to the porcine control group in terms of biocompatibility and standing time. Moreover, blood vessels were found within the bovine membranes, which can potentially serve as an additional functionality of barrier membranes that conventional barrier membranes do not provide.

Biomechanical properties of the bone during implant placement

Background

In this research the biomechanical properties of a bone model was examined. Porcine ribs are used as experimental model. The objective of this research was to investigate and compare the biomechanical properties of the bone model before and after implant placement.

Methods

The bone samples were divided in three groups, Group 1 where ALL-ON-FOUR protocol was used during pre-drilling and placing the implants, Group 2 where ALL-ON-FOUR protocol was used during pre-drilling, and implants were not placed, and Group 3 consisting of intact bones served as a control group. Static and dynamic loading was applied for examining the model samples. Kruskal–Wallis statistical test and as a post-hoc test Mann–Whitney U test was performed to analyze experimental results.

Results

According to the results of the static loading, there was no significant difference between the implanted and original ribs, however, the toughness values of the bones decreased largely on account of predrilling the bones. The analysis of dynamic fatigue measurements by Kruskal–Wallis test showed significant differences between the intact and predrilled bones.

Conclusion

The pre-drilled bone was much weaker in both static and dynamic tests than the natural or implanted specimens. According to the results of the dynamic tests and after a certain loading cycle the implanted samples behaved the same way as the control samples, which suggests that implantation have stabilized the skeletal bone structure.

Bone-adhesive barrier membranes based on alendronate-functionalized poly(2-oxazoline)s

To create a novel generation of barrier membranes with bone-adhesive properties, three-component membranes were successfully developed using a solvent-free approach by combining an occlusive polyester backing layer with a bone-adhesive fibrous gelatin carrier impregnated with calcium-binding alendronate-functionalized poly(2-oxazoline)s (POx-Ale). The mechanical properties of these novel membranes were similar to other commercially available barrier membranes. In contrast, the adhesion of our membranes towards bone was by far superior (i.e. 62-fold) compared to conventional commercially available Bio-Gide® membranes. Moreover, alendronate-functionalized membranes retained their bone-adhesive properties under wet conditions in phosphate-buffered saline (PBS) solutions with and without collagenase. Finally, the in vitro degradation of the membranes was studied by monitoring their weight loss upon immersion in PBS solutions with and without collagenase. The membranes degraded in a sustained manner, which was accelerated by the presence of collagenase due to enzymatic degradation of the carrier. In conclusion, our results show that surface functionalization of barrier membranes with alendronate moieties renders them adhesive to bone. As such, the biomaterials design strategy presented herein opens up new avenues of research on bone-adhesive membranes for guided bone regeneration.

Titanium mesh for bone augmentation in oral implantology: current application and progress

Guided bone regeneration (GBR) is an effective and simple method for bone augmentation, which is often used to reconstruct the alveolar ridge when the bone defect occurs in the implant area. Titanium mesh has expanded the indications of GBR technology due to its excellent mechanical properties and biocompatibility, so that the GBR technology can be used to repair alveolar ridges with larger bone defects, and can obtain excellent and stable bone augmentation results. Currently, GBR with titanium mesh has various clinical applications, including different clinical procedures. Bone graft materials, titanium mesh covering methods, and titanium mesh fixing methods are also optional. Moreover, the research of GBR with titanium mesh has led to multifarious progresses in digitalization and material modification. This article reviews the properties of titanium mesh and the difference of titanium mesh with other barrier membranes; the current clinical application of titanium mesh in bone augmentation; common complications and management and prevention methods in the application of titanium mesh; and research progress of titanium mesh in digitization and material modification. Hoping to provide a reference for further improvement of titanium mesh in clinical application and related research of titanium mesh.

Silk Protein Paper with In Situ Synthesized Silver Nanoparticles

Silver nanoparticles (AgNPs) are in situ synthesized for the first time on microfibrillated silk (MFS) exfoliated from domesticated Philosamia cynthia ricini (eri) and Bombyx mori (mulberry) silkworm silk fibers. The process is rapid (hours time), does not rely on harmful chemicals, and produces robust and flexible AgNPs coated MFS (MFS-AgNPs) protein papers with excellent handling properties. None of these can be achieved by approaches used in the past to fabricate AgNPs silk systems. MFS bonds the AgNPs strongly, providing good support and stabilization for the NPs, leading to strong wash fastness. The mechanical properties of the MFS-AgNPs papers largely do not change compared to the MFS papers without nanoparticles, except for some higher concentration of AgNPs in the case of mulberry silk. The improved tensile properties of eri silk papers with or without AgNPs compared to mulberry silk papers can be attributed to the higher degree of fibrillation achieved in eri silk and its inherent higher ductility. MFS-AgNPs from eri silk also exhibit strong antibacterial activity. This study provides the basis for the development of smart protein papers based on silk fiber and functional nanomaterials.

Local tissue effects of various barrier membranes in a rat subcutaneous model

Purpose

The purpose of this study was to examine the local tissue reactions associated with 3 different poly(lactic-co-glycolic acid) (PLGA) prototype membranes and to compare them to the reactions associated with commercially available resorbable membranes in rats.

Methods

Seven different membranes—3 synthetic PLGA prototypes (T1, T2, and T3) and 4 commercially available membranes (a PLGA membrane, a poly[lactic acid] membrane, a native collagen membrane, and a cross-linked collagen membrane)—were randomly inserted into 6 unconnected subcutaneous pouches in the backs of 42 rats. The animals were sacrificed at 4, 13, and 26 weeks. Descriptive histologic and histomorphometric assessments were performed to evaluate membrane degradation, visibility, tissue integration, tissue ingrowth, neovascularization, encapsulation, and inflammation. Means and standard deviations were calculated.

Results

The histological analysis revealed complete integration and tissue ingrowth of PLGA prototype T1 at 26 weeks. In contrast, the T2 and T3 prototypes displayed slight to moderate integration and tissue ingrowth regardless of time point. The degradation patterns of the 3 synthetic prototypes were similar at 4 and 13 weeks, but differed at 26 weeks. T1 showed marked degradation at 26 weeks, whereas T2 and T3 displayed moderate degradation. Inflammatory cells were present in all 3 prototype membranes at all time points, and these membranes did not meaningfully differ from commercially available membranes with regard to the extent of inflammatory cell infiltration.

Conclusions

The 3 PLGA prototypes, particularly T1, induced favorable tissue integration, exhibited a similar degradation rate to native collagen membranes, and elicited a similar inflammatory response to commercially available non–cross-linked resorbable membranes. The intensity of inflammation associated with degradable dental membranes appears to relate to their degradation kinetics, irrespective of their material composition.

Effect of Attapulgite-Doped Electrospun Fibrous PLGA Scaffold on Pro-Osteogenesis and Barrier Function in the Application of Guided Bone Regeneration

PURPOSE

Guided bone regeneration (GBR) therapy, which is a widely used technique in clinical practice and is effective in improving the repair of alveolar bone defects or bone mass deficiency regeneration, requires the use of membrane materials with good biocompatibility, barrier function, rigidity matching the space maintenance ability, economic benefits and excellent clinical applicability. The aim of this study was to develop an electrospun attapulgite (ATT)-doped poly (lactic-co-glycolic acid) (PLGA) scaffold (PLGA/ATT scaffold) as a novel material for GBR applications.

METHODS AND RESULTS

Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to determine the morphology and the crystalline structure of the PLGA/ATT scaffolds, respectively. Porosity and contact-angle measurements were also carried out to further characterize the physical properties of the PLGA/ATT scaffolds. The results of in vitro studies showed that bone marrow mesenchymal stem cells (BMSCs) attached more readily to and spread better over the PLGA/ATT scaffolds than the Bio-Gide membrane. Furthermore, in the in vitro osteoinductive experiments with BMSCs, the PLGA/ATT scaffolds were found to enhance the activity of alkaline phosphatase (ALP), promote the formation of mineralized bone nodules, and up-regulate the expression of several osteogenic markers-namely, runt-related transcription factor 2, alkaline phosphatase, osteopontin, and osteocalcin-which are similar to the effects of the Bio-Gide membrane. Further, in in vivo studies, the results of sequential fluorescent labeling, micro-computed tomography, and histological analysis suggest that using the PLGA/ATT scaffolds for repairing V-shaped buccal dehiscence on a dog's tooth root improved bone regeneration, which is not only similar to the result obtained using the Bio-Gide membrane but also much better than that obtained using PLGA scaffolds and the negative control.

CONCLUSION

To achieve satisfactory therapeutic results and to lower the cost of GBR treatment, this study provided a promising alternative material of bio-degradable membrane in clinical treatment.

In vitro evaluation of poly (vinyl alcohol)/collagen blended hydrogels for regulating human periodontal ligament fibroblasts and gingival fibroblasts

Periodontitis is a chronic inflammatory disease that can destroy periodontal tissue. Guided tissue regeneration (GTR) is widely applied to treat periodontitis. However, the challenge is to develop a GTR membrane capable of simultaneously regenerating periodontal tissue and preventing epithelial downgrowth into the defect. Herein, blended hydrogels composed of polyvinyl alcohol (PVA) and fish collagen (Col) were prepared as GTR membranes. The morphology, Col release, and cellular behavior of the blended hydrogels were evaluated. The results showed that the surface porosity and Col release of the PVA/Col blended hydrogels were enhanced by increasing the Col concentration. The adhesion and proliferation of human periodontal ligament fibroblasts (HPDLFs) and human gingival fibroblasts (HGFs) on the PVA/Col blended hydrogels can be regulated by tuning the PVA/Col ratio. The PVA/Col (50:50) blended hydrogel exhibited the highest cell proliferation rate for HPDLFs with spread cell morphology; the lowest viability for HGFs was found on the PVA/Col (100:0) hydrogel. Thus, by controlling the ratio of PVA to Col, multifunctional PVA/Col blended hydrogels able to regulate the cellular behavior of HPDLFs and HGFs can be developed, demonstrating their potential as GTR membrances for guiding periodontal tissue regeneration.

Which substances loaded onto collagen scaffolds influence oral tissue regeneration?-an overview of the last 15 years

BACKGROUND

Collagen scaffolds are widely used for guided bone or tissue regeneration. Aiming to enhance their regenerative properties, studies have loaded various substances onto these scaffolds. This review aims to provide an overview of existing literature which conducted in vitro, in vivo, and clinical testing of drug-loaded collagen scaffolds and analyze their outcome of promoting oral regeneration.

MATERIALS AND METHODS

PubMed, Scopus, and Ovid Medline® were systematically searched for publications from 2005 to 2019. Journal articles assessing the effect of substances on oral hard or soft tissue regeneration, while using collagen carriers, were screened and qualitatively analyzed. Studies were grouped according to their used substance type-biological medical products, pharmaceuticals, and tissue-, cell-, and matrix-derived products.

RESULTS

A total of 77 publications, applying 36 different substances, were included. Collagen scaffolds were demonstrating favorable adsorption behavior and release kinetics which could even be modified. BMP-2 was investigated most frequently, showing positive effects on oral tissue regeneration. BMP-9 showed comparable results at lower concentrations. Also, FGF2 enhanced bone and periodontal healing. Antibiotics improved the scaffold's anti-microbial activity and reduced the penetrability for bacteria.

CONCLUSION

Growth factors showed promising results for oral tissue regeneration, while other substances were investigated less frequently. Found effects of investigated substances as well as adsorption and release properties of collagen scaffolds should be considered for further investigation.

CLINICAL RELEVANCE

Collagen scaffolds are reliable carriers for any of the applied substances. BMP-2, BMP-9, and FGF2 showed enhanced bone and periodontal healing. Antibiotics improved anti-microbial properties of the scaffolds.