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

Preparation, Physicochemical Characterization, and In Vitro and In Vivo Osteogenic Evaluation of Reinforced PLLA-PLCL/HA Resorbable Membranes

This study aimed to develop reinforced poly(L-lactide)-poly(L-lactide-co-ε-caprolactone)/hydroxyapatite (PLLA-PLCL/HA) resorbable membranes for guided bone regeneration (GBR), focusing on optimizing the degradation rate by adjusting PLLA molecular weight. We aimed to achieve a balance between mechanical strength and bioactivity to enhance the efficacy of bone regeneration. PLLA-PLCL/HA membranes with varying degradation rates were fabricated by modifying the molecular weight of PLLA. The membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), andx-ray diffraction (XRD). Mechanical properties were evaluated using three-point bending tests, and in vitro cytocompatibility was assessed through MC3T3-E1 cell adhesion and proliferation. For in vivo experiments, a cranial defect mouse model was used to investigate degradation and osteogenic potential, and bone regeneration was evaluated using micro-CT, histological staining, and immunohistochemistry. The reinforced membranes exhibited superior bending strength compared to collagen membranes. The in vitro studies confirmed excellent cytocompatibility, and in vivo results showed that membranes with slower early stage degradation promoted bone regeneration, emphasizing the importance of degradation control in GBR membranes. The optimized PLLA-PLCL/HA membranes, which combine enhanced mechanical properties and controlled biodegradability, are promising candidates for clinical GBR applications.

Advances in Synthetic Polymer Membranes for Guided Bone Regeneration in Dental Implants: A Scoping Review

BACKGROUND

Different approaches are proposed for bone volume gain in the case of atrophic alveolar ridges, with guided bone regeneration (GBR) and guided tissue regeneration (GTR) being the most used techniques. These techniques require the placement of barrier membranes, which is the main element of the bone growth strategy, among which there is a wide range depending on their origin or degradation. This literature review aims to provide an update on the latest advances in polymeric membranes of synthetic origin currently used in bone regeneration.

MATERIALS AND METHODS

Two bibliographic searches were carried out in the PubMed (MEDLINE) and Scopus databases using a search strategy in which inclusion and exclusion criteria were applied.

RESULTS

For the selection of articles, the PRISMA guide flow chart was followed, and after a selection process, 11 articles were analyzed based on the characteristics of the marketed membranes and the results obtained after their use.

CONCLUSIONS

It can be concluded that polymeric membranes play a fundamental role in guided bone regeneration, providing an effective barrier that facilitates bone growth and improves the success of dental implantology treatments.

Comparative evaluation of allograft particulate bone and cortical bone blocks combined with xenograft bone for labial bone defects in the aesthetic zone: a prospective cohort study

PURPOSE

This study aimed to evaluate the osteogenic performance of allograft particulate bone and cortical bone blocks combined with xenograft under bovine pericardium membranes, for treating different degrees of labial bone defects in the aesthetic zone.

MATERIALS AND METHODS

Twenty-four patients with bone defects were divided into two groups based on defect severity (Terheyden 1/4 and 2/4 groups). The Terheyden 1/4 group received granular bone grafts alone, while the Terheyden 2/4 group received cortical bone blocks combined with granular bone grafts. Cone beam computed tomography scans were taken preoperatively, immediately postoperatively, and six months postoperatively. Primary outcomes included labial bone formation, alveolar bone formation, bone resorption rate, osteogenic efficiency, and complications.

RESULTS

Labial bone thickness in both groups exceeded 2 mm after six months. Labial bone formation at the implant shoulder in the Terheyden 1/4 group was 2.35 ± 2.68 mm, and 2.26 ± 1.66 mm in the Terheyden 2/4 group (p > 0.05). Labila and alveolar bone formation at 2-5 mm below the implant shoulder was significantly greater in the Terheyden 2/4 group (p < 0.05). Alveolar bone resorption and the bone resorption rate at 2-5 mm below the implant shoulder was lower in the Terheyden 2/4 group (p < 0.05). Osteogenic efficiency was 64.43 ± 2.76%, with no significant difference between groups (p > 0.05). No complications were observed.

CONCLUSION

Both treatment approaches achieved satisfactory bone regeneration, but combining cortical bone blocks with granular grafts provided better outcomes for larger defects, with greater bone formation and less resorption. Further research with longer follow-up is required to confirm long-term stability.

TRIAL REGISTRATION

The study was retrospectively registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ) with the registration number ChiCTR2300070538 on April 14, 2023.

The Microbial Diversity and Biofilm Characteristics of d-PTFE Membranes Used for Socket Preservation: A Randomized Controlled Clinical Trial

BACKGROUND

Understanding microbial colonization on different membranes is critical for guided bone regeneration procedures such as socket preservation, as biofilm formation may affect healing and clinical outcomes. This randomized controlled clinical trial (RCT) investigates, for the first time, the microbiome of two different high-density polytetrafluoroethylene (d-PTFE) membranes that are used in socket preservation on a highly molecular level and in vivo.

METHODS

This RCT enrolled 39 participants, with a total of 48 extraction sites, requiring subsequent implant placement. Sites were assigned to two groups, each receiving socket grafting with a composite bone graft (50% autogenous bone, 50% bovine xenograft) and covered by either a permamem® (group P) or a Cytoplast™ (group C). The membranes were removed after four weeks and analyzed using scanning electron microscopy (SEM) for bacterial adherence, qPCR for bacterial species quantification, and next-generation sequencing (NGS) for microbial diversity and composition assessment.

RESULTS

The four-week healing period was uneventful in both groups. The SEM analysis revealed multispecies biofilms on both membranes, with membranes from group C showing a denser extracellular matrix compared with membranes from group P. The qPCR analysis indicated a higher overall bacterial load on group C membranes. The NGS demonstrated significantly higher alpha diversity on group C membranes, while beta diversity indicated comparable microbiota compositions between the groups.

CONCLUSION

This study highlights the distinct microbial profiles of two d-PTFE membranes during the four-week socket preservation period. Therefore, the membrane type and design do, indeed, influence the biofilm composition and microbial diversity. These findings may have implications for healing outcomes and the risk of infection in the dental implant bed and should therefore be further explored.

From Waste to Innovation: A Circular Economy Approach for Tissue Engineering by Transforming Human Bone Waste into Novel Collagen Membranes

The aim of the circular economy is to treat waste as a valuable raw material, reintegrating it into the industrial economy and extending the lifecycle of subsequent products. Efforts to reduce the production of hard-to-recycle waste are becoming increasingly important to manufacturers, not only of consumer goods but also of specialized items that are difficult to manufacture, such as medical supplies, which have now become a priority for the European Union. The purpose of the study is to manufacture a novel human-purified type I collagen membrane from bone remnants typically discarded during the processing of cortico-cancellous bones in tissue banks and to evaluate its mechanical properties and effectiveness in regenerating bone-critical mandibular defects in rabbits. To prepare the novel membrane, cortico-cancellous bone chip samples from a local tissue bank were processed to isolate collagen by demineralization under agitation in HCl, cast into a silicone mold, and air-dried at room temperature and UV irradiation. The average thickness of the four batches analyzed by SEM was 37.3 μm. The average value of Young's modulus and tensile strength obtained from the specimens was 2.56 GPa and 65.43 Mpa, respectively. The membrane's efficacy was tested by creating a critical bicortical and bilateral osteoperiosteal defect in rabbit mandibles. The right-side defects were covered with the collagen membrane, while the left-side defects were left untreated as a control. Nine weeks post-surgery, clinical, radiological, and histological analyses demonstrated new bone formation in the treated areas, whereas the control sites showed no bone regeneration. This innovative approach not only contributes to sustainability in healthcare by optimizing biological waste but also exemplifies efficient resource use in line with the circular economy, offering a cost-effective, biocompatible option that could benefit national health systems.

Comparative Analysis of Gelatin/Polylactic Acid and Commercial PLA Membranes for Guided Bone Regeneration: A Randomized Clinical Trial

BACKGROUND This study included 32 patients with single missing teeth and alveolar bone defects and aimed to compare outcomes from guided bone regeneration with a gelatin/polylactic acid (GT/PLA) barrier membrane and a Guidor® bioresorbable matrix barrier dental membrane. MATERIAL AND METHODS A total of 32 participants were recruited in the clinical study, with single missing teeth and alveolar bone defects, requiring guided bone regeneration (32 missing teeth in total). They were randomly divided into the GT/PLA membrane group (experimental) and Guidor® membrane group (control) by the envelope method (n=16). Both membranes were used intraoperatively to cover the bone substitute material. Cone beam computed tomography (CBCT) was performed immediately and at 6 months after surgery to assess the amount of bone resorption. In addition, the osteogenic efficacy was calculated. The soft tissue index (STI), wound healing, membrane exposure, and incidence of infection in the operative area were evaluated. RESULTS The implant survival rate was 100% in both groups. The average bone resorption was 148.54±107.42 mm³ in the experimental group and 185.25±85.31 mm³ in the control group (P=0.163); the osteogenic efficacy was 75% in the experimental group and 56% in the control group (P=0.458). Moreover, the parameters of STI, wound healing, membrane exposure, and incidence of infection in the operative area showed no statistically significant difference between the 2 groups (P>0.05). CONCLUSIONS The GT/PLA barrier membrane yielded non-inferior clinical and imaging results to the GUIDOR® membrane, exhibiting good efficacy and biocompatibility in GBR.

Impact of regenerative procedure on the healing process following surgical root canal treatment: A systematic review and meta-analysis

INTRODUCTION

Different Guided Tissue Regeneration (GTR) procedures, such as membranes, bone substitute materials, and Autologous Platelet Concentrates (APCs), have been applied after surgical root canal treatment (SRCT), which produce different outcomes. This study aimed to evaluate the impact of regenerative procedures on the healing process following SRCT.

METHODS

A comprehensive search of PubMed, Embase, Scopus, Cochrane, and the Web of Science found Randomized Controlled Trials (RCTs) published until February 25, 2024. Manual searches were also conducted. Our main outcome was SRCT success or failure after GTR procedures. The Risk Ratio (RR) and failure rate meta-analysis used a fixed effects model with a 95% confidence interval (CI). Subgroup analyses were conducted based on the use of different GTR procedures for varying lesion types in SRCT.

RESULTS

Out of 1,605 records, 16 studies with 690 lesions were included. Overall, GTR procedures significantly improved healing after SRCT in both 2D (RR: 0.50; 95% CI, 0.34-0.73; P < 0.001) and 3D evaluation methods (RR: 0.36; 95% CI, 0.15-0.90; P < 0.001) with no significant difference between the two methods.

CONCLUSION

GTR significantly improved SRCT healing regardless of the evaluation method used. Combining collagen membranes with bovine bone-derived hydroxyapatite significantly enhanced the healing process. Additionally, GTR procedures significantly improve healing in through-and-through lesions.

Challenges and Innovations in Alveolar Bone Regeneration: A Narrative Review on Materials, Techniques, Clinical Outcomes, and Future Directions

This review explores the recent advancements and ongoing challenges in regenerating alveolar bone, which is essential for dental implants and periodontal health. It examines traditional techniques like guided bone regeneration and bone grafting, alongside newer methods such as stem cell therapy, gene therapy, and 3D bioprinting. Each approach is considered for its strengths in supporting bone growth and integration, especially in cases where complex bone defects make regeneration difficult. This review also looks at different biomaterials, from bioactive scaffolds to nanomaterials, assessing how well they encourage cell growth and healing. Personalized treatments, like customized 3D-printed scaffolds, show promise in enhancing bone formation and tissue compatibility. Additionally, signaling molecules, like bone morphogenetic proteins, play a crucial role in guiding the process of bone formation and remodeling. Despite these advances, challenges remain-particularly with severe bone loss and with refining biomaterials for more reliable, long-term outcomes. This review proposes combining advanced materials, regenerative technologies, and personalized approaches to achieve more effective and consistent outcomes in oral and maxillofacial surgery.

Zinc nanoparticles induced eggshell collagen membrane used for guided bone regeneration: A novel approach in rabbit models

Conventional methods of guided bone regeneration (GBR) in bone tissue engineering frequently encounter challenges in attaining adequate antibacterial and osteogenic qualities owing to intrinsic limits. The purpose of this preclinical study was to assess the effectiveness of two distinct membranes, Healiguide® and a unique GBR membrane produced from eggshell membranes (ESM), in combination with bone graft replacement in animal models. The objective of this study was to evaluate the efficacy of a new guided bone regeneration membrane developed from eggshell membrane that incorporates zinc nanoparticles for the regeneration of bone tissue in rabbit models. Groups A (no membrane), B (new ESM GBR membrane), and C (Healiguide® membrane) were assigned to three groups, with eight male New Zealand rabbits weighing two-three kilograms each. Standardized surgical procedures were implemented, and histological analysis along with radiographic examination was used for follow-up assessments six and 12 weeks after surgery. Radiographic examination and histological sectioning revealed differences in bone density and quality between the groups. Group B showed the highest level of bone regeneration, followed by Groups C and A. Statistical analysis confirmed a significant difference between the groups (p < 0.05). The eggshell membrane showed encouraging results in the enhancement of bone regeneration and integration in rabbit models. These results suggest its potential as a viable alternative to GBR in bone tissue engineering, with promising prospects for improving clinical outcomes. However, additional studies and clinical trials are required to confirm its safety and effectiveness for medical use.

Cortical Laminar Bone Membrane: Transforming Regenerative Approaches in Dentistry

Cortical laminar bone membrane (CLBM) is well known for its extraordinary mechanical properties, biocompatibility, and osteoconductive potential, and thus, it has been revealed as a revolutionary biomaterial in periodontal and alveolar bone regeneration. CLBM offers a superior alternative to traditional barrier membranes used in guided bone regeneration (GBR) and guided tissue regeneration (GTR). CLBM represents a significant advancement in managing complex defects by overcoming common limitations such as premature degradation and inadequate soft tissue support. The review combines insights from current research to evaluate the properties, biological mechanisms, and clinical applications of CLBM, alongside its comparative advantages and limitations.

Resorbable engineered barrier membranes for oral surgery applications

Population aging, reduced economic capacity, and neglecting the treatments for oral pathologies, are the main causal factors for about 3 billion individuals who are suffering from partial/total edentulism or alveolar bone resorption: thus, the demand for dental implants is increasingly growing. To achieve a good prognosis for implant-supported restorations, adequate peri-implant bone volume is mandatory. The Guided Bone Regeneration (GBR) technique is one of the most applied methods for alveolar bone reconstruction and treatment of peri-implant bone deficiencies. This technique involves the use of different types of membranes in association with some bone substitutes (autologous, homologous, or heterologous). However, time for bone regeneration is often too long and the bone quality is not simply predictable. This study aims at engineering and evaluating the efficacy of modified barrier membranes, enhancing their bioactivity for improved alveolar bone tissue regeneration. We investigated membranes functionalized with chitosan (CS) and chitosan combined with the peptide GBMP1α (CS + GBMP1α), to improve bone growth. OsseoGuard® membranes, derived from bovine Achilles tendon type I collagen crosslinked with formaldehyde, were modified using CS and CS + GBMP1α. The functionalization, carried out with 1-ethyl-3-(3 dimethylaminopropyl)carbodiimide and sulfo-N-Hydroxysuccinimide (EDC/sulfo-NHS), was assessed through FT-IR and XPS analyses. Biological assays were performed by directly seeding human osteoblasts onto the materials to assess cell proliferation, mineralization, gene expression of Secreted Phosphoprotein 1 (SPP1) and Runt-Related Transcription Factor 2 (Runx2), and antibacterial properties. Both CS and CS + GBMP1α functionalizations significantly enhanced human osteoblast proliferation, mineralization, gene expression, and antibacterial activity compared to commercial membranes. The CS + GBMP1α functionalization exhibited superior outcomes in all biological assays. Mechanical tests showed no significant alterations of membrane biomechanical properties post-functionalization. The engineered membranes, especially those functionalized with CS + GBMP1α, are suitable for GBR applications thanks to their ability to enhance osteoblast activity and promote bone tissue regeneration. These findings suggest a potential advancement in the treatment of oral cavity problems requiring bone regeneration.

Complication rates of guided bone regeneration using titanium-reinforced PTFE membranes: a retrospective analysis

INTRODUCTION

This study analyzed complication rates of guided bone regeneration (GBR) using titanium-reinforced polytetrafluoroethylene (PTFE) membranes for alveolar ridge augmentation.

MATERIAL AND METHODS

84 patients treated with GBR using titanium-reinforced PTFE membranes (91 sites) were retrospectively analyzed. Complications such as membrane exposure and early removal were analyzed concerning patient age, defect site position, size, simultaneous vs. two-stage implant placement, smoking, and the use of bone grafts (BG) and substitutes (BS).

RESULTS

Early removal due to membrane exposure was necessary in 14/91 sites (15.4%). No correlation was found between early removal and patient age (p = 0.917). Analyzing early removal between the upper and lower jaw and between both jaws' anterior and posterior tooth regions revealed no correlations (p = 0.381 and 0.477, respectively). Defect sites sizes of 5-6 mm exhibited the highest rate of membrane exposure, requiring early removal, accounting for 57.1% of these sites (8/14). No correlation was observed between the defect sites size and early removal (p = 0.660). Comparison of simultaneous (74 sites) vs. two-stage implant placement (16 sites) showed no correlation with early removal (p = 0.706). Membrane exposure incidence was 42.9% among smokers (27 patients, 32.1%) and 57.1% among non-smokers (57 patients, 67.9%), without correlation. No correlation was found between the type of BG and BS and early removal (p = 0.500).

CONCLUSION

GBR using titanium-reinforced PTFE membranes is effective for alveolar ridge augmentation and has favorable long-term outcomes.

CLINICAL RELEVANCE

Careful surgical technique and postoperative care can minimize the notable risk of PTFE membrane exposure.

Enhancing Guided Bone Regeneration with a Novel Carp Collagen Scaffold: Principles and Applications

Bone defects resulting from trauma, surgery, and congenital, infectious, or oncological diseases are a functional and aesthetic burden for patients. Bone regeneration is a demanding procedure, involving a spectrum of molecular processes and requiring the use of various scaffolds and substances, often yielding an unsatisfactory result. Recently, the new collagen sponge and its structural derivatives manufactured from European carp (Cyprinus carpio) were introduced and patented. Due to its fish origin, the novel scaffold poses no risk of allergic reactions or transfer of zoonoses and additionally shows superior biocompatibility, mechanical stability, adjustable degradation rate, and porosity. In this review, we focus on the basic principles of bone regeneration and describe the characteristics of an "ideal" bone scaffold focusing on guided bone regeneration. Moreover, we suggest several possible applications of this novel material in bone regeneration processes, thus opening new horizons for further research.

Long-Term Volumetric Stability of Maxillary Sinus Floor Augmentation Using a Xenograft Bone Substitute and Its Combination with Autologous Bone: A 6+ Year Retrospective Follow-Up Study Using Cone Beam Computed Tomography

Deproteinised bovine bone (DBB) is widely used as bone substitute in maxillary sinus floor augmentation (MSFA) surgery. No previous studies have shown the long-term volumetric changes in the augmented bone when using DBB. The selected patients had MFSA performed using a lateral window technique and a xenograft, alone or in combination with the patient's autologous bone from the mandible. Cone beam computed tomography (CBCT) images were used to compare the volumetric changes in the augmented bone for patients over a period of 6 or more years. No significant bone reduction was seen in the augmented bone region when comparing MSFA after 7 months and 6 or more years after dental implantation.

Resorbable bilayer membrane made of L-lactide-ε-caprolactone in guided bone regeneration: an in vivo experimental study

PURPOSE

Guided bone regeneration (GBR) is an accepted method in dental practice that can successfully increase the bone volume of the host at sites chosen for implant placement; however, existing GBR membranes exhibit rapid absorption and lack of adequate space maintenance capabilities. We aimed to compare the effectiveness of a newly developed resorbable bilayer membrane composed of poly (L-lactic acid) and poly (-caprolactone) (PLACL) with that of a collagen membrane in a rat GBR model.

METHODS

The rat calvaria was used as an experimental model, in which a plastic cylinder was placed. We operated on 40 male Fisher rats and subsequently performed micro-computed tomography and histomorphometric analyses to assess bone regeneration.

RESULTS

Significant bone regeneration was observed, which was and similar across all the experimental groups. However, after 24 weeks, the PLACL membrane demonstrated significant resilience, and sporadic partial degradation. This extended preservation of the barrier effect has great potential to facilitate optimal bone regeneration.

CONCLUSIONS

The PLACL membrane is a promising alternative to GBR. By providing a durable barrier and supporting bone regeneration over an extended period, this resorbable bilayer membrane could address the limitations of the current membranes. Nevertheless, further studies and clinical trials are warranted to validate the efficacy and safety of The PLACL membrane in humans.

Horizontal and Vertical Defect Management with a Novel Degradable Pure Magnesium Guided Bone Regeneration (GBR) Membrane-A Clinical Case

Background and objectives: In guided bone regeneration (GBR), large defects comprising both horizontal and vertical components usually require additional mechanical support to stabilize the augmentation and preserve the bone volume. This additional support is usually attained by using non-resorbable materials. A recently developed magnesium membrane presents the possibility of providing mechanical support whilst being completely resorbable. The aim of this case report was to describe the application and outcome of the magnesium membrane in combination with a collagen pericardium membrane for GBR. Materials and methods: A 74 year old, in an otherwise good general health condition, was presented with stage 2 grade A periodontitis and an impacted canine. After extraction of the impacted canine, a defect was created with both vertical and horizontal components. The defect was augmented using the magnesium membrane to create a supportive arch to the underlying bone graft and a collagen pericardium membrane was placed on top to aid with the soft tissue closure. Results: Upon reentry at 8 months, complete resorption of the magnesium devices was confirmed as there were no visible remnants remaining. A successful augmentation outcome had been achieved as the magnesium membrane in combination with the collagen membrane had maintained the augmented bone well. Two dental implants could be successfully placed in the healed augmentation. Conclusions: In this case, the magnesium membrane in combination with a collagen pericardium membrane presented a potentially viable alternative treatment to titanium meshes or titanium-reinforced membranes for the augmentation of a defect with both horizontal and vertical components that is completely resorbable. It was demonstrated that it is possible to attain a good quality and quantity of bone using a resorbable system that has been completely resorbed by the time of reentry.

Comparative evidence of different surgical techniques for the management of vertical alveolar ridge defects in terms of complications and efficacy: A systematic review and network meta-analysis

AIM

To systematically appraise the available evidence on vertical ridge augmentation (VRA) techniques and estimate a treatment-based ranking on the incidence of complications as well as their clinical effectiveness.

MATERIALS AND METHODS

Searches were conducted in six databases to identify randomized clinical trials comparing VRA techniques up to November 2022. The incidence of complications (primary) and of early, major, surgical and intra-operative complications, vertical bone gain (VBG), marginal bone loss, need for additional grafting, implant success/survival, and patient-reported outcome measures (secondary) were chosen as outcomes. Direct and indirect effects and treatment ranking were estimated using Bayesian pair-wise and network meta-analysis (NMA) models.

RESULTS

Thirty-two trials (761 participants and 943 defects) were included. Five NMA models involving nine treatment groups were created: onlay, inlay, dense-polytetrafluoroethylene, expanded-polytetrafluoroethylene, titanium, resorbable membranes, distraction osteogenesis, tissue expansion and short implants. Compared with short implants, statistically significant higher odds ratios of healing complications were confirmed for all groups except those with resorbable membranes (odds ratio 5.4, 95% credible interval 0.92-29.14). The latter group, however, ranked last in clinical VBG.

CONCLUSIONS

VRA techniques achieving greater VBG are also associated with higher incidence of healing complications. Guided bone regeneration techniques using non-resorbable membranes yield the most favourable results in relation to VBG and complications.

Resorbable Membranes for Guided Bone Regeneration: Critical Features, Potentials, and Limitations

Lack of horizontal and vertical bone at the site of an implant can lead to significant clinical problems that need to be addressed before implant treatment can take place. Guided bone regeneration (GBR) is a commonly used surgical procedure that employs a barrier membrane to encourage the growth of new bone tissue in areas where bone has been lost due to injury or disease. It is a promising approach to achieve desired repair in bone tissue and is widely accepted and used in approximately 40% of patients with bone defects. In this Review, we provide a comprehensive examination of recent advances in resorbable membranes for GBR including natural materials such as chitosan, collagen, silk fibroin, along with synthetic materials such as polyglycolic acid (PGA), polycaprolactone (PCL), polyethylene glycol (PEG), and their copolymers. In addition, the properties of these materials including foreign body reaction, mechanical stability, antibacterial property, and growth factor delivery performance will be compared and discussed. Finally, future directions for resorbable membrane development and potential clinical applications will be highlighted.

Physical, mechanical, and biological properties of collagen membranes for guided bone regeneration: a comparative in vitro study

BACKGROUND

To provide a reference for clinical selection of collagen membranes by analyzing the properties of three kinds of collagen membranes widely used in clinics: Bio-Gide membrane from porcine dermis (PD), Heal-All membrane from bovine dermis (BD), and Lyoplant membrane from bovine pericardium (BP).

METHODS

The barrier function of three kinds of collagen membranes were evaluated by testing the surface morphology, mechanical properties, hydrophilicity, and degradation rate of collagen membranes in collagenase and artificial saliva. In addition, the bioactivity of each collagen membrane as well as the proliferation and osteogenesis of MC3T3-E1 cells were evaluated. Mass spectrometry was also used to analyze the degradation products.

RESULTS

The BP membrane had the highest tensile strength and Young's modulus as well as the largest water contact angle. The PD membrane exhibited the highest elongation at break, the smallest water contact angle, and the lowest degradation weight loss. The BD membrane had the highest degradation weight loss, the highest number of proteins in its degradation product, the strongest effect on the proliferation of MC3T3-E1 cells, and the highest expression level of osteogenic genes.

CONCLUSIONS

The PD membrane is the best choice for shaping and maintenance time, while the BD membrane is good for osteogenesis, and the BP membrane is suitable for spatial maintenance. To meet the clinical requirements of guided bone regeneration, using two different kinds of collagen membranes concurrently to exert their respective advantages is an option worth considering.

Finite element analysis of stress in oral mucosa and titanium mesh interface

BACKGROUND

The stiffness of titanium mesh is a double-blade sword to repair larger alveolar ridges defect with excellent space maintenance ability, while invade the surrounding soft tissue and lead to higher mesh exposure rates. Understanding the mechanical of oral mucosa/titanium mesh/bone interface is clinically meaningful. In this study, the above relationship was analyzed by finite elements and verified by setting different keratinized tissue width in oral mucosa.

METHODS

Two three-dimensional finite element models were constructed with 5 mm keratinized tissue in labial mucosa (KM cases) and 0 mm keratinized tissue in labial mucosa (LM cases). Each model was composed of titanium mesh, titanium screws, graft materials, bone, teeth and oral mucosa. After that, a vertical (30 N) loadings were applied from both alveolar ridges direction and labial mucosa direction to stimulate the force from masticatory system. The displacements and von Mises stress of each element at the interfaces were analyzed.

RESULTS

Little displacements were found for titanium mesh, titanium screws, graft materials, bone and teeth in both LM and KM cases under different loading conditions. The maximum von Mises stress was found around the lingual titanium screw insertion place for those elements in all cases. The keratinized tissue decreased the displacement of oral mucosa, decreased the maximum von Mises stress generated by an alveolar ridges direction load, while increased those stress from labial mucosa direction load. Only the von Mises stress of the KM cases was all lower than the tensile strength of the oral mucosa.

CONCLUSION

The mucosa was vulnerable under the increasing stress generated by the force from masticatory system. The adequate buccal keratinized mucosa width are critical factors in reducing the stress beyond the titanium mesh, which might reduce the titanium exposure rate.

Barrier Membranes for Guided Bone Regeneration (GBR): A Focus on Recent Advances in Collagen Membranes

Guided bone regeneration (GBR) has become a clinically standard modality for the treatment of localized jawbone defects. Barrier membranes play an important role in this process by preventing soft tissue invasion outgoing from the mucosa and creating an underlying space to support bone growth. Different membrane types provide different biological mechanisms due to their different origins, preparation methods and structures. Among them, collagen membranes have attracted great interest due to their excellent biological properties and desired bone regeneration results to non-absorbable membranes even without a second surgery for removal. This work provides a comparative summary of common barrier membranes used in GBR, focusing on recent advances in collagen membranes and their biological mechanisms. In conclusion, the review article highlights the biological and regenerative properties of currently available barrier membranes with a particular focus on bioresorbable collagen-based materials. In addition, the advantages and disadvantages of these biomaterials are highlighted, and possible improvements for future material developments are summarized.