Collagen based barrier membranes for periodontal guided bone regeneration applications

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.

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.

Healing outcomes of open versus closed flap procedures for collagen membrane coverage following immediate dental implant placements with simultaneous guided tissue regeneration

OBJECTIVE

To compare the outcomes of open healing to complete closure for collagen membrane coverage for immediate implant placements with simultaneous guided bone regeneration (GBR) in two retrospective cohorts.

METHODS

The subjects included 118 patients who received Bio-Gide® collagen membrane coverage for immediate implant placements and GBR in 20 anterior and 98 posterior teeth. For 58 patients, gingival flaps were released to achieve full coverage of collagen membrane (CC group). For 60 patients, no efforts were made to release the gingival flaps and collagen membrane was left exposed for open healing (OH group). Antibiotics and analgesics were prescribed for 7 days after surgery. The width of crestal open wounds were measured after surgery (W0), and at 1, 2 and 16 weeks (W16). Changes in bone mass were assessed by cone-beam computed tomography after implant placement and again at W16. Gingival and bone tissues over the implant cover screws were harvested and assessed for 16 patients in the OH group at W16.

RESULTS

No wound dehiscence occurred in the CC group from W0 to W16. Both the vertical and horizontal bone dimension changes were not significantly different between the OH and CC group. For the OH group, soft tissue was completely healed at W16 when the initial wound widths were ≤6 mm. For those with initial wound widths ≥ 7 mm, the cover screws were exposed in 5/16 patients at W16 but did not affect the final restorations. Tissue staining showed keratinized mucosa and new bone formation above the dental implant in the OH group.

CONCLUSION

Open healing achieved healing outcomes similar to those of complete closure for collagen membrane coverage following immediate implant placements.

CLINICAL SIGNIFICANCE

For immediate implant placement requiring bone grafting and collagen membrane coverage, it is unnecessary to release the gingival flaps or use tissue grafts to achieve full coverage of the crestal wounds. Open healing with exposed membrane could achieve similar outcomes with less pain and swelling.

Exosomes and exosome composite scaffolds in periodontal tissue engineering

Promoting complete periodontal regeneration of damaged periodontal tissues, including dental cementum, periodontal ligament, and alveolar bone, is one of the challenges in the treatment of periodontitis. Therefore, it is urgent to explore new treatment strategies for periodontitis. Exosomes generated from stem cells are now a promising alternative to stem cell therapy, with therapeutic results comparable to those of their blast cells. It has great potential in regulating immune function, inflammation, microbiota, and tissue regeneration and has shown good effects in periodontal tissue regeneration. In addition, periodontal tissue engineering combines exosomes with biomaterial scaffolds to maximize the therapeutic advantages of exosomes. Therefore, this article reviews the progress, challenges, and prospects of exosome and exosome-loaded composite scaffolds in periodontal regeneration.

Synthesis, Characterization, and Induced Osteogenic Differentiation Effect of Collagen Membranes Functionalized by Polydopamine/Graphene Oxide for Bone Tissue Engineering

Collagen is one of the most common natural absorbable polymers, which is widely used as a barrier membrane in biomedical fields due to its many desirable biological properties. However, absorbable membranes such as collagen have their own disadvantages such as unpredictable degradation rates, poor rigidity leading to tissue collapse, and limited osteogenic properties and cell adhesion. In this study, a modified collagen membrane with a polydopamine-graphene oxide (PDA/GO) complex was synthesized to improve the characteristics of collagen for bone tissue engineering. The successful synthesis of PDA/GO on collagen membranes was verified using X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The wettability of PDA/GO-modified collagen membranes was considerably improved based on the characterization by water contact angle compared to the uncoated membranes and surface coatings solely by either PDA or GO. The modified PDA/GO coating also enhanced the mechanical properties such as tensile strength and biodegradation rate of collagen membranes. In addition, the PDA/GO coating effectively enhanced the biocompatibility of collagen membranes as verified by the enhanced proliferation and adhesion of human bone marrow stem cells (hBMSCs). Additionally, the effects of PDA/GO coating on the osteogenic differentiation of hBMSCs on collagen membranes were investigated through alkaline phosphatase (ALP) activity and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The PDA/GO coating on collagen membranes resulted in a significant increase in osteogenic properties compared with the uncoated collagen membranes. According to the results of the current study, the combination of PDA and GO-modified collagen membranes could be used for bone tissue engineering and biomedical applications.

Osteogenic differentiation and reconstruction of mandible defects using a novel resorbable membrane: An in vitro and in vivo experimental study

To evaluate the cellular response of both an intact fish skin membrane and a porcine-derived collagen membrane and investigate the bone healing response of these membranes using a translational, preclinical, guided-bone regeneration (GBR) canine model. Two different naturally sourced membranes were evaluated in this study: (i) an intact fish skin membrane (Kerecis Oral®, Kerecis) and (ii) a porcine derived collagen (Mucograft®, Geistlich) membrane, positive control. For the in vitro experiments, human osteoprogenitor (hOP) cells were used to assess the cellular viability and proliferation at 24, 48, 72, and 168 h. ALPL, COL1A1, BMP2, and RUNX2 expression levels were analyzed by real-time PCR at 7 and 14 days. The preclinical component was designed to mimic a GBR model in canines (n = 12). The first step was the extraction of premolars (P1-P4) and the 1st molars bilaterally, thereby creating four three-wall box type defects per mandible (two per side). Each defect site was filled with bone grafting material, which was then covered with one of the two membranes (Kerecis Oral® or Mucograft®). The groups were nested within the mandibles of each subject and membranes randomly allocated among the defects to minimize potential site bias. Samples were harvested at 30-, 60-, and 90-days and subjected to computerized microtomography (μCT) for three-dimensional reconstruction to quantify bone formation and graft degradation, in addition to histological processing to qualitatively analyze bone regeneration. Neither the intact fish skin membrane nor porcine-based collagen membrane presented cytotoxic effects. An increase in cell proliferation rate was observed for both membranes, with the Kerecis Oral® outperforming the Mucograft® at the 48- and 168-hour time points. Kerecis Oral® yielded higher ALPL expression relative to Mucograft® at both 7- and 14-day points. Additionally, higher COL1A1 expression was observed for the Kerecis Oral® membrane after 7 days but no differences were detected at 14 days. The membranes yielded similar BMP2 and RUNX2 expression at 7 and 14 days. Volumetric reconstructions and histologic micrographs indicated gradual bone ingrowth along with the presence of particulate bone grafts bridging the defect walls for both Kerecis Oral® and Mucograft® membranes, which allowed for the reestablishment of the mandible shape after 90 days. New bone formation significantly increased from 30 to 60 days, and from 60 to 90 days in vivo, without significant differences between membranes. The amount of bovine grafting material (%) within the defects significantly decreased from 30 to 90 days. Collagen membranes led to an upregulation of cellular proliferation and adhesion along with increased expression of genes associated with bone healing, particularly the intact fish skin membrane. Despite an increase in the bone formation rate in the defect over time, there was no significant difference between the membranes.

Efficacy of concentrated growth factor (CGF) in the surgical treatment of oral diseases: a systematic review and meta-analysis

BACKGROUND

Concentrated growth factor (CGF), a new autologous platelet concentrate, has been widely investigated to the adjunctive treatment of oral diseases. This study aims to evaluate the efficacy of CGF in the surgical treatment of oral diseases.

METHODS

MEDLINE, Web of Science, Scopus, Cochrane, and EMBASE databases were searched up to July 2023. Only randomized clinical trials were included. The methodologic quality was evaluated by the Cochrane Risk of Bias Tool. RevMan 5.4 software was used for data analysis.

RESULTS

In the treatment of periodontal intrabony defects, bone graft combined with CGF was significantly superior to bone graft (P < 0.01), with mean intrabony defect depth reduction of 1.41 mm and mean clinical attachment level gain of 0.55 mm. In the regenerative surgery of furcation defects, the effect of CGF group was significantly better than control group (P < 0.0001), with mean probing depth reduction of 0.99 mm, vertical bone gain of 0.25 mm, and horizontal bone gain of 0.34 mm. CGF combined with coronally advanced flap (CAF) was more effective than CAF alone (mean keratinized tissue width increase of 0.41 mm, mean gingival thickness increase of 0.26 mm, P < 0.00001), but less effective than connective tissue graft (CTG) combined with CAF (mean root coverage difference of -15.1%, mean gingival thickness difference of -0.5 mm, P < 0.0001). In the alveolar ridge preservation, additional use of CGF reduced horizontal bone resorption by 1.41 mm and buccal vertical bone resorption by 1.01 mm compared to control group (P < 0.0001). The VAS score of CGF group was significantly lower than that of the control group at the 1st and 7th day after oral surgery (P < 0.0001).

CONCLUSIONS

CGF can exert a positive adjunctive effect for the regenerative surgery of periodontal intrabony defects, furcation defects, and alveolar ridge preservation procedure. CGF combined with CAF has a better therapeutic effect on gingival recession compared to CAF alone, although it is not as effective as CTG combined with CAF. CGF could promote postoperative healing and pain relief in oral surgery within a week. There is currently not enough evidence to support the clinical benefits of CGF in other oral surgeries.

In vivo evaluation of bone regeneration using ZIF8-modified polypropylene membrane in rat calvarium defects

AIM

The profound potential of zeolitic imidazolate framework 8 (ZIF8) thin film for inducing osteogenesis has been previously established under in vitro conditions. As the next step towards the clinical application of ZIF8-modified substrates in periodontology, this in vivo study aimed to evaluate the ability of the ZIF8 crystalline layer to induce bone regeneration in an animal model defect.

MATERIALS AND METHODS

Following the mechanical characterization of the membranes and analysing the in vitro degradation of the ZIF8 layer, in vivo bone regeneration was evaluated in a critical-sized (5-mm) rat calvarial bone defect model. For each animal, one defect was randomly covered with either a polypropylene (PP) or a ZIF8-modified membrane (n = 7 per group), while the other defect was left untreated as a control. Eight weeks post surgery, bone formation was assessed by microcomputed tomography scanning, haematoxylin and eosin staining and immunohistochemical analysis.

RESULTS

The ZIF8-modified membrane outperformed the PP membrane in terms of mechanical properties and revealed a trace Zn+2 release. Results of in vivo evaluation verified the superior barrier function of the ZIF8-coated membrane compared with pristine PP membrane. Compared with the limited marginal bone formation in the control and PP groups, the defect area was almost filled with mature bone in the ZIF8-coated membrane group.

CONCLUSIONS

Our results support the effectiveness of the ZIF8-coated membrane as a promising material for improving clinical outcomes of guided bone regeneration procedures, without using biological components.

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.

Periodontal Guided Tissue Regeneration Membranes: Limitations and Possible Solutions for the Bottleneck Analysis

Guided tissue regeneration (GTR) is an important surgical method for periodontal regeneration. By placing barrier membrane on the root surface of the tooth to guide the adhesion and proliferation of periodontal ligament cells, periodontal tissue regeneration can be achieved. This review intends to analyze the current limitations of GTR membranes and to propose possible solutions for developing new ones. Limitations of current GTR membranes include nonabsorbable membranes and absorbable synthetic polymer membranes exhibit weak biocompatibility; when applying to a large defect wound, the natural collagen membrane with fast degradation rate have limited mechanical strength, and the barrier function may not be maintained well. Although the degradation time can be prolonged after cross-linking, it may cause foreign body reaction and affect tissue integration; The clinical operation of current barrier membranes is inconvenient. In addition, most of the barrier membranes lack bioactivity and will not actively promote periodontal tissue regeneration. Possible solutions include using electrospinning (ELS) techniques, nanofiber scaffolds, or developing functional gradient membranes to improve their biocompatibility; adding Mg, Zn, and/or other metal alloys, or using 3D printing technology to improve their mechanical strength; increasing the concentration of nanoparticles or using directional arrangement of membrane fibers to control the fiber diameter and porosity of the membrane, which can improve their barrier function; mixing natural and synthetic polymers as well as other biomaterials with different degradation rates in proportion to change the degradation rate and maintain barrier function; to improve the convenience of clinical operation, barrier membranes that meets personalized adhesion to the wound defect can be manufactured; developing local controlled release drug delivery systems to improve their bioactivity. Impact statement This review provides an up-to-date summary of commonly commercial periodontal guided tissue regeneration membranes, and analyze their limitations in clinical use. Using studies published recently to explore possible solutions from several perspectives and to raise possible strategies in the future. Several strategies have tested in vivo/in vitro, which will guide the way to propel clinical translation, meeting clinical needs.

Biphasic scaffolds of polyvinyl alcohol/gelatin reinforced with polycaprolactone as biomedical materials supporting for bone augmentation based on anatomical mimicking; fabrication, characterization, physical and mechanical properties, and in vitro testing

Reinforced biphasic scaffolds were fabricated with based materials design of anatomical mimicking and evaluated to identify the certain application for maxillofacial surgery. The scaffolds created the polyvinyl alcohol (PVA) with a percentage of gelatin of 5% and were coated with polycaprolactone (PCL) that a different number of cycles 0, 1, 5, 10, and 15 cycles (PCL0, PCL1, PCL5, PCL10, and PCL15 were used to fabricate biphasic scaffolds via bubbling and freeze-thawing before reinforce with immersion coating techniques. The structure and morphology of the scaffolds were characterized and observed by a scanning electron microscope, a differential scanning calorimeter, and a thermogravimetric analyzer, respectively. The performance of the scaffolds was tested in terms of their swelling behavior, degradation, and mechanical properties. They were cultured with MC3T3E1 osteoblast cells and L929 fibroblast cells. The main biological performance of cell proliferation was analyzed, and protein synthesis, calcium synthesis, and alkaline phosphatase activity of the scaffolds were studied. Their morphology demonstrated fewer pores when coated with PCL. Mechanical strength of the modified scaffolds increased followed by the cycles of coating with PCL. The scaffolds with more cycle of PCL coating lower swelling and degradability than without PCL coating. They had more thermal stability than the scaffold without PCL coating. The scaffolds with PCL coating demonstrated better bio-functionality to activate cell response than without coating. Finally, the result exhibited that PCL10 provide a suitably reinforced biphasic scaffold with high promise for maxillofacial surgery.

Addition of Resolvins D1 or E1 to Collagen Membranes Mitigates Their Resorption in Diabetic Rats

Uncontrolled diabetes is characterized by aberrant inflammatory reactions and increased collagenolysis. We have reported that it accelerates the degradation of implanted collagen membranes (CM), thus compromising their function in regenerative procedures. In recent years, a group of physiological anti-inflammatory agents called specialized pro-resolving lipid mediators (SPMs) have been tested as a treatment for various inflammatory conditions, either systemically or locally, via medical devices. Yet, no study has tested their effect on the fate of the biodegradable material itself. Here, we measured the in vitro release over time of 100 or 800 ng resolvin D1 (RvD1) incorporated into CM discs. In vivo, diabetes was induced in rats with streptozotocin, while buffer-injected (normoglycemic) rats served as controls. Resolvins (100 or 800 ng of RvD1 or RvE1) were added to biotin-labeled CM discs, which were implanted sub-periosteally over the calvaria of rats. Membrane thickness, density, and uniformity were determined by quantitative histology after 3 weeks. In vitro, significant amounts of RvD1 were released over 1-8 days, depending on the amount loaded. In vivo, CMs from diabetic animals were thinner, more porous, and more variable in thickness and density. The addition of RvD1 or RvE1 improved their regularity, increased their density, and reduced their invasion by the host tissue significantly. We conclude that addition of resolvins to biodegradable medical devices can protect them from excessive degradation in systemic conditions characterized by high degree of collagenolysis.

Local Delivery and Controlled Release Drugs Systems: A New Approach for the Clinical Treatment of Periodontitis Therapy

Periodontitis is an inflammatory disease of the gums characterized by the degeneration of periodontal ligaments, the formation of periodontal pockets, and the resorption of the alveolar bone, which results in the destruction of the teeth's supporting structure. Periodontitis is caused by the growth of diverse microflora (particularly anaerobes) in the pockets, releasing toxins and enzymes and stimulating the immune system. Various approaches, both local and systemic, have been used to treat periodontitis effectively. Successful treatment depends on reducing bacterial biofilm, bleeding on probing (BOP), and reducing or eliminating pockets. Currently, the use of local drug delivery systems (LDDSs) as an adjunctive therapy to scaling and root planing (SRP) in periodontitis is a promising strategy, resulting in greater efficacy and fewer adverse effects by controlling drug release. Selecting an appropriate bioactive agent and route of administration is the cornerstone of a successful periodontitis treatment plan. In this context, this review focuses on applications of LDDSs with varying properties in treating periodontitis with or without systemic diseases to identify current challenges and future research directions.

Antimicrobial and Osteogenic Effects of Collagen Membrane Decorated with Chitosan-Nano-Hydroxyapatite

Collagen membranes are routinely used in oral surgery for bone regeneration. Despite their numerous advantages, such as stimulating bone growth, bacterial contamination still remains one of the disadvantages of membrane use. Thus, we assessed the biocompatibility and osteogenic and antibacterial properties of a collagen membrane (OsteoBiol) modified with chitosan (CHI) and hydroxyapatite nanoparticles (HApNPs). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR FT-IR), X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) were performed for membrane characterization. Biocompatibility was assessed on dental pulp stem cells (DPSCs) by an MTT assay, while the osteogenic effect was assessed by an ALP activity assay and qPCR analysis of osteogenic markers (BMP4, ALP, RUNX2, and OCN). Antimicrobial properties were investigated by counting colony-forming units (CFUs) of Streptococcus mitis, Porphyromonas gingivalis, and Fusobaterium nucleatum on membranes and in the surrounding medium. Membranes showed no cytotoxicity. ALP activity was higher and ALP, BMP4, and OCN genes were up-regulated in DPSCs on modified membranes compared to unmodified membranes. The CFUs were reduced on modified membranes and in the medium. Modified membranes showed great biocompatibility and a high osteoinductive effect. Additionally, they showed antimicrobial and antibiofilm effects against periopathogens. It can be concluded that the incorporation of CHI and hydroxyapatite nanoparticles in collagen membranes may be advantageous to promote osteogenesis and reduce bacterial adhesion.

Improving Bone Formation by Guided Bone Regeneration Using a Collagen Membrane with rhBMP-2: A Novel Concept

We examined whether recombinant human bone morphogenetic protein-2 (rhBMP-2) when applied to collagen membranes, would reinforce them during guided bone regeneration. Four critical cranial bone defects were created and treated in 30 New Zealand white rabbits, including a control group, critical defect only; group 1, collagen membrane only; group 2, biphasic calcium phosphate (BCP) only; group 3, collagen membrane + BCP; group 4, collagen membrane with rhBMP-2 (1.0 mg/mL); group 5, collagen membrane with rhBMP-2 (0.5 mg/mL); group 6, collagen membrane with rhBMP-2 (1.0 mg/mL) + BCP; and group 7, collagen membrane with rhBMP-2 (0.5 mg/mL) + BCP. After a 2-, 4-, or 8-week healing period, the animals were sacrificed. The combination of collagen membranes with rhBMP-2 and BCP yielded significantly higher bone formation rates compared to the other groups (control group and groups 1-5 < groups 6 and 7; p < 0.05). A 2-week healing period yielded significantly lower bone formation than that at 4 and 8 weeks (2 < 4 = 8 weeks; p < 0.05). This study proposes a novel GBR concept in which rhBMP-2 is applied to collagen membranes outside instead of inside the grafted area, thereby inducing quantitatively and qualitatively enhanced bone regeneration in critical bone defects.

Periodontal tissue regeneration by recombinant human collagen peptide granules applied with β-tricalcium phosphate fine particles

OBJECTIVES

Recombinant human collagen peptide (RCP) is a recombinantly created xeno-free biomaterial enriched in arginine-glycine-aspartic acid sequences with good processability whose use for regenerative medicine applications is under investigation. The biocompatibility and osteogenic ability of RCP granules combined with β-tricalcium phosphate (TCP) submicron particles (β-TCP/RCP) were recently demonstrated. In the present study, β-TCP/RCP was implanted into experimental periodontal tissue defects created in beagles to investigate its regenerative effects.

METHODS

An RCP solution was lyophilized, granulated, and thermally cross-linked into particles approximately 1 mm in diameter. β-TCP dispersion (1 wt%; 500 μL) was added to 100 mg of RCP granules to form β-TCP/RCP. A three-walled intrabony defect (5 mm × 3 mm × 4 mm) was created on the mesial side of the mandibular first molar and filled with β-TCP/RCP.

RESULTS

A micro-computed tomography image analysis performed at 8 weeks postoperative showed a significantly greater amount of new bone after β-TCP/RCP grafting (2.2-fold, P < 0.05) than after no grafting. Histological findings showed that the transplanted β-TCP/RCP induced active bone-like tissue formation including tartaric acid-resistant acid phosphatase- and OCN-positive cells as well as bioabsorbability. Ankylosis did not occur, and periostin-positive periodontal ligament-like tissue formation was observed. Histological measurements performed at 8 weeks postoperative revealed that β-TCP/RCP implantation formed 1.7-fold more bone-like tissue and 2.1-fold more periodontal ligament-like tissue than the control condition and significantly suppressed gingival recession and epithelial downgrowth (P < 0.05).

CONCLUSIONS

β-TCP/RCP implantation promoted bone-like and periodontal ligament-like tissue formation, suggesting its efficacy as a periodontal tissue regenerative material.

Role of periosteum in alveolar bone regeneration comparing with collagen membrane in a buccal dehiscence model of dogs

To investigate the role of periosteum on the treatment of buccal dehiscence defects comparing with collagen membrane in canine model. Bilateral dehiscence-type defects at the buccal side on the distal root of the lower 3rd/4th premolars were created in six beagle dogs with a total of 24 defects and assigned into three groups: Group A: blood clot in an untreated defect; Group B: deproteinized bovine bone material (DBBM) covered with an absorbable membrane; Group C: DBBM covered with the periosteum. The structural parameters for trabecular architecture and vertical bone regeneration were evaluated. Histological and histomorphometric evaluation were carried out to observe new bone formation and mineralization in the graft site. Immunohistochemical analysis was performed to identify the expression of osteopontin (OPN) and osteocalcin (OCN) at postoperative 3 months. Group C achieved greater vertical alveolar bone gain than that of group A and group B. The periosteum-covered group showed significantly greater new bone formation and accelerated mineralization. The greater immunolabeling for OPN and OCN was observed in group C than in group A. Periosteal coverage has explicit advantages over collagen membranes for the quality and quantity of new bone regeneration in dehiscence defects repairing.

Effect of ozone therapy on the modulation of inflammation and on new bone formation in critical defects of rat calvaria filled with autogenous graft

OBJECTIVE

The aim of this study was to evaluate the effect of ozone therapy on new bone formation and inflammation modulation in defects of rat calvaria filled with autogenous bone.

MATERIAL AND METHODS

Critical size defects were created in the calvaria of 24 male Wistar rats. The animals were randomly divided into four groups according to the treatment: G1: clot; G2: clot and covered with xenogenic membrane; G3: particulate autogenous bone graft; G4: autogenous bone graft and application of 3 mL O₂/O₃ gas mixture (10 µg/ml). The defects were filled immediately after surgery with a bilateral retroauricular application, in the region immediately above the incision. After 21 days, the animals were euthanized, and the samples were processed for morphometric evaluations designed to measure both the intensity of the inflammatory infiltrate, and the presence of new bone formation in the defect.

RESULTS

The results showed a lower inflammation score and higher mean of newly formed bone in the region of the defect for the group associated with ozone therapy (G4). The bone formed in the region of the defect could be observed as being more lamellar and mineralized in the case of associated ozone therapy.

CONCLUSION

Ozone therapy represents a promising adjuvant therapy to accelerate tissue regeneration.

In vivo evaluation of a collagen membrane in bone neoformation: A morphological and histomorphometric study

OBJECTIVE

Guided bone regeneration (GBR) is a technique that involves the placement of mechanical barriers to protect the blood clot, and create an isolated space to prevent competition from epithelial and connective tissues in bone augmentation treatments. Collagen membranes stand out from other materials available for performing regenerative surgeries, and are widely used because of their ability to promote cell adhesion and homeostasis, and their biocompatibility, ease of handling, and low immunogenicity. In this context, researchers have investigated xenogenic membranes/barriers that cost less and have slower resorption rates. The current study aimed to assess the osteogenic potential induced by a crosslinked, synthesized xenogenic membrane 100 µm thick when applied in vivo to critical defects in rat calvaria.

MATERIAL AND METHODS

Critical size defects were created in the calvaria of thirty male Wistar rats, and randomly divided into the following two groups: G1 - clot covered with a commercial xenogenic membrane (Lumina-Coat®, Criteria, Brazil), and G2 - clot covered with a synthesized xenogenic membrane. The animals were euthanized after 7, 15 and 30 days, and samples of calvaria were processed to perform morphometric evaluations to measure bone neoformation in the defect region. In addition, ultrastructural characterization of the collagen membranes was performed by scanning electron microscope. The quantitative analyses were carried out by adopting a significance level of 5%.

RESULTS

The ultrastructural characterization revealed that the synthesized membrane had thicker collagen fibers and a more cohesive surface, compared with the Lumina-Coat® collagen membrane (G1). There was no significant difference in bone neoformation between the membranes (p>0.05), at any of the time periods analyzed. The bone quantification area increased significantly over time for both membranes (p<0.05).

CONCLUSION

The synthesized membrane exhibited morphological characteristics similar to those of the commercial membrane evaluated, allowed potentially active participation in the bone neoformation process, and served as a low-cost alternative for GBR procedures.

Bone Regenerative Potential of Cross-Linked Collagen Membrane in Peri-Implant Osseous Defect: Case Series with Histologic/Micro-Computed Tomographic Findings

The role of a barrier membrane is crucial in guided bone regeneration (GBR) for space creation and cell occlusiveness. Those properties of the membrane should be sustained for a sufficient period. For such purpose, several cross-linked collagen membranes were introduced and demonstrated favorable clinical outcomes. However, histologic data were not sufficient to support the effect of cross-linked collagen membranes. In the present case series, healing after GBR using a cross-linked collagen membrane was investigated in-depth via histologic and micro-computed tomographic (micro-CT) analyses. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide cross-linked collagen membrane was used in GBR for treating various peri-implant bone defects in seven patients. After 4-7 months of healing, newly formed tissue of hard consistency was observed over the implant platform. This tissue was carefully harvested and assessed. In micro-CT and histological analyses, evident new bone formation was revealed, especially in the vicinity of the collagen membrane. Moreover, it was histologically found that some newly formed bone was in intimate contact with the membrane. Although the exact mechanism of bone regeneration in the present cases was not clearly elucidated, the cross-linked collagen membrane appeared to contribute to ossification in GBR. Further studies are needed to confirm the findings of the present case series.

Injectable Hydrogel Membrane for Guided Bone Regeneration

In recent years, multicomponent hydrogels such as interpenetrating polymer networks (IPNs) have emerged as innovative biomaterials due to the synergistic combination of the properties of each network. We hypothesized that an innovative non-animal IPN hydrogel combining self-setting silanized hydroxypropyl methylcellulose (Si-HPMC) with photochemically cross-linkable dextran methacrylate (DexMA) could be a valid alternative to porcine collagen membranes in guided bone regeneration. Calvaria critical-size defects in rabbits were filled with synthetic biphasic calcium phosphate granules in conjunction with Si-HPMC; DexMA; or Si-HPMC/DexMA experimental membranes; and in a control group with a porcine collagen membrane. The synergistic effect obtained by interpenetration of the two polymer networks improved the physicochemical properties, and the gel point under visible light was reached instantaneously. Neutral red staining of murine L929 fibroblasts confirmed the cytocompatibility of the IPN. At 8 weeks, the photo-crosslinked membranes induced a similar degree of mineral deposition in the calvaria defects compared to the positive control, with 30.5 ± 5.2% for the IPN and 34.3 ± 8.2% for the collagen membrane. The barrier effect appeared to be similar in the IPN test group compared with the collagen membrane. In conclusion, this novel, easy-to-handle and apply, photochemically cross-linkable IPN hydrogel is an excellent non-animal alternative to porcine collagen membrane in guided bone regeneration procedures.

Modulation of the biophysical and biochemical properties of collagen by glycation for tissue engineering applications

The structural and functional properties of collagen are modulated by the presence of intramolecular and intermolecular crosslinks. Advanced Glycation End-products (AGEs) can produce intermolecular crosslinks by bonding the free amino groups of neighbouring proteins. In this research, the following hypothesis is explored: The accumulation of AGEs in collagen decreases its proteolytic degradation rates while increasing its stiffness. Fluorescence Lifetime Imaging (FLIM) and Fourier-transform infrared spectroscopy (FTIR) detect biochemical changes in collagen scaffolds during the glycation process. The accumulation of AGEs increases exponentially in the collagen scaffolds as a function of Methylglyoxal (MGO) concentration by performing autofluorescence measurement and competitive ELISA. Glycated scaffolds absorb water at a much higher rate confirming the direct affinity between AGEs and interstitial water within collagen fibrils. In addition, the topology of collagen fibrils as observed by Atomic Force Microscopy (AFM) is a lot more defined following glycation. The elastic modulus of collagen fibrils decreases as a function of glycation, whereas the elastic modulus of collagen scaffolds increases. Finally, the enzymatic degradation of collagen by bacterial collagenase shows a sigmoidal pattern with a much slower degradation rate in the glycated scaffolds. This study identifies unique variations in the properties of collagen following the accumulation of AGEs. STATEMENT OF SIGNIFICANCE: In humans, Advanced Glycation End-products (AGEs) are naturally produced as a result of aging process. There is an evident lack of knowledge in the basic science literature explaining the biomechanical impact of AGE-mediated crosslinks on the functional and structural properties of collagen at both the nanoscale (single fibrils) and mesoscale (bundles of fibrils). This research, demonstrates how it is possible to harness this natural phenomenon in vitro to enhance the properties of engineered collagen fibrils and scaffolds. This study identifies unique variations in the properties of collagen at nanoscale and mesoscale following accumulation of AGEs. In their approach, they investigate the unique properties conferred to collagen, namely enhanced water sorption, differential elastic modulus, and finally sigmoidal proteolytic degradation behavior.

Elastin Barrier Membranes for Guided Tissue Regeneration Technologies

This article discusses the prospects for the use of new elastin barrier membranes manufactured using adapted technologies for the selective isolation of the elastin component from the extracellular xenogenic matrix of the pericardium ligamentous apparatus: (1) by high-temperature extraction under pressure; (2) cyanogen bromide method. A commercial material, Geistlich Bio–Gide® membrane (BG), was used as a control comparison group. It is shown that the materials of group (1) have a high degree of biocompatibility, exceeding the indicators of the control group BG. Based on the results of an study in a model of subcutaneous heterotopic implantation in rats, it was shown that elastin BM has a chemoattractant effect on the mesenchymal recipient cells and, unlike the control, is able to integrate to a high degree into the surrounding recipient tissues. At the same time, the materials of group (1) had a pronounced proangiogenic effect. Thus, it has been shown that elastin BM groups (1) have a medium-term barrier function and are able to induce full-fledged cellular repopulation and local neoangiogenesis, which can be useful in clinical practice, primarily in GTR technologies (with gingival flap augmentation) or when used together with other BM as an angiogenesis inducer to ensure formation of the vascular bed in GBR technologies of bone tissue.

Introducing Nanozymes: New Horizons in Periodontal and Dental Implant Care

The prevalence of periodontal and peri-implant diseases has been increasing worldwide and has gained a lot of attention. As multifunctional nanomaterials with enzyme-like activity, nanozymes have earned a place in the biomedical field. In periodontics and implantology, nanozymes have contributed greatly to research on maintaining periodontal health and improving implant success rates. To highlight this progress, we review nanozymes for antimicrobial therapy, anti-inflammatory therapy, tissue regeneration promotion, and synergistic effects in periodontal and peri-implant diseases. The future prospects of nanozymes in periodontology and implantology are also discussed along with challenges.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The use of periodontal membranes in the field of periodontology: spotlight on collagen membranes

Periodontal regenerative techniques are performed to accomplish the restitution of soft and hard teeth-supporting tissues that have been lost due to trauma or inflammatory disease. Periodontal membranes are used for these techniques to provide support and a framework for cell growth and tissue regeneration. They act as a temporary and selective barrier to cell proliferation. Easy clinical handling, biomechanical specifications, high biocompatibility, cell-occlusivity, and satisfactory bioresorption rate are essential properties a membrane needs to be effective. The creation and maintenance of a secluded space is also a fundamental rule in periodontal regenerative techniques. The use of barrier membranes in the field of restorative dentistry has progressed toward the use of minimally invasive approaches optimizing wound closure and limiting patient morbidity. This review intends to provide an overview of the major cellular events in the surgical wound and membrane surface. It was also performed to assess, from literature data, the pertinence of using non-resorbable and resorbable membranes for this regenerative purpose. Special attention will be given to collagen membranes.

Polydopamine-mediated graphene oxide and nanohydroxyapatite-incorporated conductive scaffold with an immunomodulatory ability accelerates periodontal bone regeneration in diabetes

Regenerating periodontal bone tissues in the aggravated inflammatory periodontal microenvironment under diabetic conditions is a great challenge. Here, a polydopamine-mediated graphene oxide (PGO) and hydroxyapatite nanoparticle (PHA)-incorporated conductive alginate/gelatin (AG) scaffold is developed to accelerate periodontal bone regeneration by modulating the diabetic inflammatory microenvironment. PHA confers the scaffold with osteoinductivity and PGO provides a conductive pathway for the scaffold. The conductive scaffold promotes bone regeneration by transferring endogenous electrical signals to cells and activating Ca²⁺ channels. Moreover, the scaffold with polydopamine-mediated nanomaterials has a reactive oxygen species (ROS)-scavenging ability and anti-inflammatory activity. It also exhibits an immunomodulatory ability that suppresses M1 macrophage polarization and activates M2 macrophages to secrete osteogenesis-related cytokines by mediating glycolytic and RhoA/ROCK pathways in macrophages. The scaffold induces excellent bone regeneration in periodontal bone defects of diabetic rats because of the synergistic effects of good conductive, ROS-scavenging, anti-inflammatory, and immunomodulatory abilities. This study provides fundamental insights into the synergistical effects of conductivity, osteoinductivity, and immunomodulatory abilities on bone regeneration and offers a novel strategy to design immunomodulatory biomaterials for treatment of immune-related diseases and tissue regeneration.

•

The conductive PGO-PHA-AG scaffold can activate Ca²⁺ channels.

•The PGO-PHA-AG scaffold had ROS-scavenging and anti-inflammatory activities.

•The scaffold exhibited an immunomodulatory ability.

•The scaffold induced excellent periodontal bone regeneration in diabetes.

Chitosan/Xanthan membrane containing hydroxyapatite/Graphene oxide nanocomposite for guided bone regeneration

OBJECTIVE

To develop a chitosan-xanthan (CX) membrane associated with Hydroxyapatite (HA) and different concentrations of graphene oxide (GO).

METHODOLOGY

The CX complex was associated with the hydroxyapatite-graphene oxide (HAGO) nanocomposite in different concentrations. The experimental groups were:1) CX; 2) Chitosan-Xanthan/Hydroxyapatite (CXHA); 3) Chitosan-Xanthan/Hydroxyapatite-Graphene Oxide 0.5% (CXHAGO 0.5%); 4) CXHAGO 1.0%; 5) CXHAGO 1.5%. The membranes characterizations were performed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Contact angle, Tensile Strength, in vitro Bioactivity and the in vitro Cell viability (MTT test). The data was submitted to the Normality and Homogeneity tests. In vitro Indirect Cytotoxicity assay data was statistically analyzed by two-way ANOVA and Tukey's test (α = 0.05). Tensile Strength and Contact Angle data were statistically analyzed by one-way ANOVA followed by Tukey's test (α = 0.05).

RESULTS

XRD, FTIR and Raman spectroscopy confirmed the characteristic bands of the CX polymeric complex, the phosphate bands related to HA, and the presence of GO. SEM images demonstrated the non-porous and homogeneous surface of membranes. The contact angle test showed the hydrophilic characteristic of all membranes (p > 0.05). CX showed tensile strength significantly higher than other membranes. The apatite deposition was observed in all membranes after performing the bioactivity test. The cell viability of CXHAGO 1.0% and CXHAGO 1.5% was significantly higher than CX.

CONCLUSION

The addition of HAGO reduced the mechanical strength of membranes, but improved its cell viability. It demonstrated the potential of CXHAGO membranes to be used in guided bone regeneration therapies.

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.

Proliferation and Morphological Assessment of Human Periodontal Ligament Fibroblast towards Bovine Pericardium Membranes: An In Vitro Study

Over the past decade regenerative branches of dentistry have taken on more and more importance, resulting in the development of performing scaffold materials. These should induce cell adhesion, support, and guide the tissues’ growth. Among the developed materials, we can include resorbable or non-membranes. The purpose of this study was to investigate the proliferation abilities and the attachment of human periodontal ligament fibroblasts (HPLIFs) over two bovine pericardium membranes with different thicknesses, 0.2 mm and 0.4 mm, respectively. These membranes have been decellularized by the manufacturer, preserving the three-dimensional collagen’s structure. The HPLFs were cultured in standard conditions and exposed to the tested materials. XTT was performed to assess cell proliferation, while light microscopy (LM) and scanning electron microscopy (SEM) observations assessed fibroblast morphology at different times (T1, T2, and T3). Proliferation assays have shown a statistically significant difference in growth at T1 (p < 0.05) in the cells cultured with a thicker membrane compared to the thinner one. LM analysis showed healthy fibroblasts in contact with the membranes, appearing larger and with a polygonal shape. SEM observation demonstrated thickening of the fibroblasts which continued to adhere to the membrane’s surface, with enlarged polygonal shape and developed filipodia and lamellipodia. These results showed a similar cell behavior over the two bovine pericardium membranes, demonstrating a cellular migration along and within the layers of the membrane, binding with membrane fibers by means of filopodial extensions. Knowledge of the effects of the collagen membranes derived from bovine pericardium on cellular behavior will help clinicians choose the type of scaffolds according to the required clinical situation.

The Use of Biocompatible Membranes in Oral Surgery: The Past, Present & Future Directions. A Narrative Review

The use of biocompatible membranes in periodontal and oral surgery is an important part of regeneration. Over the years, several different membranes have been developed, ranging from non-resorbable membranes that have to be removed in a separate procedure, to collagen membranes that completely resorb on their own, thus avoiding the need for a second surgery. Autogenous membranes are becoming increasingly popular in more recent years. These membranes can be used with a great variety of techniques in the four main hard tissue regenerative procedures: guided tissue regeneration, alveolar ridge preservation, guided bone regeneration and sinus floor augmentation. A review of the literature was conducted in order to identify the most commonly used membranes in clinical practice, as well as the most promising ones for regeneration procedures in the future. The information provided in this review may serve as a guide to clinicians, in order to select the most applicable membrane for the clinical case treated as the correct choice of materials may be critical in the procedure's success.

Analysis of the biocompatibility of a biocelulose and a poly L- lactic acid membrane

The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim: The purpose of the present study was to evaluate the biocompatibility of poly (L- lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods: Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) – Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results: The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion: The PLLA and COL membranes present better biocompatibility than the BC membranes.

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.

Challenges and tissue engineering strategies of periodontal guided tissue regeneration

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

Synthesis of Antibacterial Hybrid Hydroxyapatite/Collagen/Polysaccharide Bioactive Membranes and Their Effect on Osteoblast Culture

Inspired by the composition and confined environment provided by collagen fibrils during bone formation, this study aimed to compare two different strategies to synthesize bioactive hybrid membranes and to assess the role the organic matrix plays as physical confinement during mineral phase deposition. The hybrid membranes were prepared by (1) incorporating calcium phosphate in a biopolymeric membrane for in situ hydroxyapatite (HAp) precipitation in the interstices of the biopolymeric membrane as a confined environment (Methodology 1) or (2) adding synthetic HAp nanoparticles (SHAp) to the freshly prepared biopolymeric membrane (Methodology 2). The biopolymeric membranes were based on hydrolyzed collagen (HC) and chitosan (Cht) or κ-carrageenan (κ-carr). The hybrid membranes presented homogeneous and continuous dispersion of the mineral particles embedded in the biopolymeric membrane interstices and enhanced mechanical properties. The importance of the confined spaces in biomineralization was confirmed by controlled biomimetic HAp precipitation via Methodology 1. HAp precipitation after immersion in simulated body fluid attested that the hybrid membranes were bioactive. Hybrid membranes containing Cht were not toxic to the osteoblasts. Hybrid membranes added with silver nanoparticles (AgNPs) displayed antibacterial action against different clinically important pathogenic microorganisms. Overall, these results open simple and promising pathways to develop a new generation of bioactive hybrid membranes with controllable degradation rates and antimicrobial properties.

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.

Efficacy of concentrated growth factor versus collagen membrane in reconstructive surgical therapy of peri-implantitis: 3-year results of a randomized clinical trial

Objectives

To compare the 3-year clinical and radiographic outcomes of two different reconstructive surgical management of peri-implantitis using a bone substitute in combination with either concentrated growth factor (CGF) or collagen membrane (CM).

Material and methods

Fifty-one patients who had at least one implant presenting peri-implantitis with an intrabony defect were filled with a xenogenic bone grafting material and covered either CGF or CM. Clinical and radiographic assessments were carried out at baseline and postoperative years 1 and 3. Three different composite outcomes were defined to evaluate treatment success at a 3-year follow-up. The effects of possible prognostic indicators on treatment success were identified by using multilevel regression analysis.

Results

The changes in probing depth (PD) and radiographic vertical defect depth (VDD) between baseline and year 1 and baseline and year 3 presented significantly greater decreases for the CM group in comparison with the CGF group (p < 0.05). No significant differences between the two treatment modalities were demonstrated regarding treatment success outcomes. History of periodontitis, VDD at baseline, and the number of intrabony defect walls revealed significant impacts on treatment success (p = 0.033; OR = 3.50, p = 0.039; OR = 0.975, and p = 0.024; OR = 7.0 and p = 0.019;OR = 6.0, respectively).

Conclusions

CM in combination with a bone substitute seems to have slightly better outcomes compared to the CGF membranes in reconstructive surgical therapy of peri-implantitis. The history of periodontitis, baseline VDD, and peri-implant bone defect configuration could be possible predictors influencing treatment success.

Trial registration

ClinicalTrials.gov NCT04769609.

Clinical relevance

For the reconstruction of peri-implant bone defects, using a bone substitute in combination with a collagen membrane may show more favorable outcomes.

Analysis of a Pure Magnesium Membrane Degradation Process and Its Functionality When Used in a Guided Bone Regeneration Model in Beagle Dogs

For the surgical technique of guided bone regeneration (GBR), the choice of available barrier membranes has until recently not included an option that is mechanically strong, durable, synthetic and resorbable. The most commonly used resorbable membranes are made from collagen, which are restricted in their mechanical strength. The purpose of this study is to evaluate the degradation and regeneration potential of a magnesium membrane compared to a collagen membrane. In eighteen beagle dogs, experimental bone defects were filled with bovine xenograft and covered with either a magnesium membrane or collagen membrane. The health status of the animals was regularly monitored and recorded. Following sacrifice, the hemimandibles were prepared for micro-CT (μ-CT) analysis. Complications during healing were observed in both groups, but ultimately, the regenerative outcome was similar between groups. The μ-CT parameters showed comparable results in both groups in terms of new bone formation at all four time points. In addition, the μ-CT analysis showed that the greatest degradation of the magnesium membranes occurred between 1 and 8 weeks and continued until week 16. The proportion of new bone within the defect site was similar for both treatment groups, indicating the potential for the magnesium membrane to be used as a viable alternative to collagen membranes. Overall, the new magnesium membrane is a functional and safe membrane for the treatment of defects according to the principles of GBR.

Fabrication of oxidized sodium alginate-collagen heterogeneous bilayer barrier membrane with osteogenesis-promoting ability

Guided bone regeneration technique is an effective approach to repair bone defects, in which a barrier membrane is essential. However, the collagen barrier membranes commonly used lose stability quickly, leading to connective tissue invasion and failure of osteogenesis. Herein, we presented an oxidized sodium alginate (OSA)-collagen heterogeneous bilayer barrier membrane with well-controlled pore size and osteogenesis-promoting ability. The OSA crosslinking significantly improved the structural stability, compressive strength, swelling behavior, and slowed down the biodegradation rate of collagen membranes. Meanwhile, the collagen-based membranes exhibited superior cytocompatibility, osteogenesis-promotion, and barrier function against fibroblasts. Especially, the osteogenic differentiation was most promoted on the membrane with a large pore size (240-310 μm), while the barrier function was most improved on the membrane with a small pore size (30-60 μm). Then the above two membranes were combined together to obtain a heterogeneous bilayer membrane. This bilayer barrier membrane showed excellent osteogenesis-promoting ability in rats.

Permeability of P. gingivalis or its metabolic products through collagen and dPTFE membranes and their effects on the viability of osteoblast-like cells: an in vitro study

Membrane exposure is a widely reported and relatively common complication in Guided Bone Regeneration (GBR) procedures. The introduction of micro-porous dPTFE barriers, which are impervious to bacterial cells, could reduce the technique sensitivity to membrane exposure, even if there are no studies investigating the potential passage of bacterial metabolites through the barrier. Aim of this study was the in vitro evaluation of the permeability of three different GBR membranes (dPTFE, native and cross-linked collagen membranes) to Porphyromonas gingivalis; in those cases, where bacterial penetration could not be observed, another purpose was the analysis of the viability and differentiation capability of an osteosarcoma (U2OS) cell line in presence of bacteria eluate obtained through membrane percolation. A system leading to the percolation of P. gingivalis broth culture through the experimental membranes was arranged to assess the permeability to bacteria after 24 and 72 h of incubation. The obtained solution was then added to U2OS cell cultures which underwent, after 10 days of incubation, MTT and red alizarin essays. The dPTFE membrane showed resistance to bacterial penetration, while both types of collagen membranes were crossed by P. gingivalis after 24 h. The bacteria eluate filtered through dPTFE membrane didn't show any toxicity on U2OS cells. Results of this study demonstrate that dPTFE membranes can contrast the penetration of both P. gingivalis and its metabolites toxic for osteoblast-like cells. The toxicity analysis was not possible for the collagen membranes, since permeability to bacterial cells was observed within the first period of incubation.

Amelotin Promotes Mineralization and Adhesion in Collagen-Based Systems

Introduction

Periodontitis is characterized by the destruction of tooth-supporting tissues including the alveolar bone. Barrier membranes are used in dentistry for tissue regenerative therapy. Nevertheless, conventional membranes have issues related to membrane stability and direct induction of bone mineralization. Amelotin (AMTN), an enamel matrix protein, regulates hydroxyapatite crystal nucleation and growth. To apply an AMTN membrane in clinical practice, we investigated the mineralizing and adhesive effects of recombinant human (rh) AMTN in vitro using a collagen-based system.

Methods

Collagen hydrogel incorporated with rhAMTN (AMTN gel) and rhAMTN-coated dentin slices were prepared. AMTN gel was then applied on a commercial membrane (AMTN membrane). Samples were incubated for up to 24 h in mineralization buffer, and the structures were observed. The peak adhesive tensile strength between the dentin and AMTN membrane was measured. Using an enzyme-linked immunosorbent assay, the release kinetics of rhAMTN from the membrane were investigated.

Results

The AMTN gel resulted in the formation of hydroxyapatite deposits both onto and within the collagen matrix. Furthermore, coating the dentin surface with rhAMTN promoted the precipitation of mineral deposits on the surface. Interestingly, site-specific mineralization was observed in the AMTN membrane. Only 1% of rhAMTN was released from the membrane. Hence, the AMTN membrane adhered to the dentin surface with more than twofold greater tensile strength than that detected for a rhAMTN-free barrier membrane.

Conclusions

RhAMTN can accelerate mineralization and adhesion in collagen-based systems. Furthermore, the AMTN membrane could inform the optimal design of calcified tissue regenerative materials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00722-2.

Asymmetric resorbable-based dental barrier membrane for periodontal guided tissue regeneration and guided bone regeneration: A review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are two common dental regenerative treatments targeted at reconstructing damaged periodontal tissue and bone caused by periodontitis. During GTR/GBR treatment, a barrier membrane is placed in the interface between the soft tissue and the periodontal defect to inhibit soft tissue ingrowth and creating a space for the infiltration of slow-growing bone cells into the defect site. Recently, asymmetric resorbable-based barrier membrane has received a considerable attention as a new generation of GTR/GBR membrane. Despite numerous literatures about asymmetric-based membrane that had been published, there is lacks comprehensive review on asymmetric barrier membrane that particularly highlight the importance of membrane structure for periodontal regeneration. In this review, we systematically cover the latest development and advancement of various kinds of asymmetric barrier membranes used in periodontal GTR/GBR application. Herein, the ideal requirements for constructing a barrier membrane as well as the rationale behind the asymmetric design, are firstly presented. Various innovative methods used in fabricating asymmetric barrier membrane are being further discussed. Subsequently, the application and evaluation of various types of asymmetric barrier membrane used for GTR/GBR are compiled and extensively reviewed based on the recent literatures reported. Based on the existing gap in this field, the future research directions of asymmetric resorbable-based barrier membrane such as its combination potential with bone grafts, are also presented.

Periodontal Wound Healing and Regeneration: Insights for Engineering New Therapeutic Approaches

Periodontitis is a widespread inflammatory disease that leads to loss of the tooth supporting periodontal tissues. The few therapies available to regenerate periodontal tissues have high costs and inherent limitations, inspiring the development of new approaches. Studies have shown that periodontal tissues have an inherent capacity for regeneration, driven by multipotent cells residing in the periodontal ligament (PDL). The purpose of this review is to describe the current understanding of the mechanisms driving periodontal wound healing and regeneration that can inform the development of new treatment approaches. The biologic basis underlying established therapies such as guided tissue regeneration (GTR) and growth factor delivery are reviewed, along with examples of biomaterials that have been engineered to improve the effectiveness of these approaches. Emerging therapies such as those targeting Wnt signaling, periodontal cell delivery or recruitment, and tissue engineered scaffolds are described in the context of periodontal wound healing, using key in vivo studies to illustrate the impact these approaches can have on the formation of new cementum, alveolar bone, and PDL. Finally, design principles for engineering new therapies are suggested which build on current knowledge of periodontal wound healing and regeneration.

Characterization of Five Collagenous Biomaterials by SEM Observations, TG-DTA, Collagenase Dissolution Tests and Subcutaneous Implantation Tests

Collagenous biomaterials that are clinically applied in dentistry have dermis-type and membrane-type, both of which are materials for promoting bone and soft tissue formation. The properties of materials supplied with different types could affect their biodegradation periods. The purpose of this study was to characterize five of these products by four different methods: scanning electron microscopy (SEM) observation, thermogravimetry-differential thermal analysis (TG-DTA), 0.01 wt% collagenase dissolution test, and subcutaneous implantation test in vivo. SEM micrographs revealed that both dermis and membranous materials were fibrous and porous. The membranous materials had higher specific derivative thermal gravimetry (DTG) peak temperatures in TG-DTA at around 320 °C, longer collagenase dissolution time ranging from about 300 to 500 min, and more longevity in mice exceeding 9 weeks than the dermis materials. There existed a correlation between the peak temperature in TG-DTA and the collagenase dissolution time. It was considered that higher cross-link degree among collagen fibrils of the membrane-type collagenous materials might account for these phenomena. The experimental protocol and numerical results obtained could be helpful for selection and future development of fibrous collagenous biomaterials in clinical use.

Endogenous Mechanisms of Craniomaxillofacial Repair: Toward Novel Regenerative Therapies

In the fields of oral and craniomaxillofacial surgery, regeneration of multiple tissue types-including bone, skin, teeth, and mucosal soft tissue-is often a desired outcome. However, limited endogenous capacity for regeneration, as well as predisposition of many tissues to fibrotic healing, may prevent recovery of normal form and function for patients. Recent basic science research has advanced our understanding of molecular and cellular pathways of repair in the oral/craniofacial region and how these are influenced by local microenvironment and embryonic origin. Here, we review the current state of knowledge in oral and craniomaxillofacial tissue repair/regeneration in four key areas: bone (in the context of calvarial defects and mandibular regeneration during distraction osteogenesis); skin (in the context of cleft lip/palate surgery); oral mucosa (in the context of minimally scarring repair of mucosal injuries); and teeth (in the context of dental disease/decay). These represent four distinct healing processes and outcomes. We will discuss both divergent and conserved pathways of repair in these contexts, with an eye toward fundamental mechanisms of regeneration vs. fibrosis as well as translational research directions. Ultimately, this knowledge can be leveraged to develop new cell-based and molecular treatment strategies to encourage bone and soft tissue regeneration in oral and craniomaxillofacial surgery.

A bioinspired Janus polyurethane membrane for potential periodontal tissue regeneration

Guided tissue regeneration (GTR) is the main therapeutic method for periodontal tissue regeneration. The key to the GTR strategy is the membrane which can assist the reconstruction of bone tissue in the periodontal defect and prevent the migration of epithelium and fibroblasts to the defect. However, the existing periodontal membrane cannot effectively promote periodontal tissue regeneration due to the limited bioactivity and physicochemical function. Here, we developed a bioinspired degradable polyurethane membrane with Janus surface morphology by integrating bioactive dopamine (DA) and an antibacterial Gemini quaternary ammonium salt (QAS). The Janus surface of the membrane is fabricated through spontaneous microphase separation, resulting from the different migration of functional segments between the air-contact upper surface with enriched antibacterial QAS and the substrate-contact bottom with enriched bioactive DA. The smooth surface of the upper membrane used to face the soft tissues can reduce cell adhesion to suppress the migration of fibroblasts, while the rough surface with a topological micro-pit structure of the bottom side facing the bone has excellent function of autonomic mineralization and cell adhesion to promote bone tissue reconstruction. In addition, the membrane containing the antibacterial QAS shows excellent antibacterial effect on common oral pathogens, such as S. aureus and S. mutans. Moreover, the specific dopamine group also endows the membrane with excellent antioxidant efficiency. In vivo research shows that this Janus polyurethane membrane can effectively promote periodontal tissue regeneration in a rat periodontal defect model. Combined with its excellent mechanical properties and biocompatibility, the polyurethane membrane is a promising material for potential periodontal tissue regeneration.

A Review of the Effects of Collagen Treatment in Clinical Studies

Collagen, an abundant extracellular matrix protein, has been found to have a lot of pharmaceuticals, medicine, food, and cosmetics applications. Increased knowledge of collagen sources, extraction techniques, structure, and properties in the last decades has helped develop more collagen-based products and tissue engineering biomaterials. Collagen products have been playing an important role in benefiting the health of the human body, especially for aging people. In this paper, the effects of collagen treatment in different clinical studies including skin regeneration, bone defects, sarcopenia, wound healing, dental therapy, gastroesophageal reflux, osteoarthritis, and rheumatoid arthritis have been reviewed. The collagen treatments were significant in these clinical studies. In addition, the associations between these diseases were discussed. The comorbidity of these diseases might be closely related to collagen deficiency, and collagen treatment might be a good choice when a patient has more than one of these diseases, including the coronavirus disease 2019 (COVID-19). It concludes that collagen-based medication is useful in treating comorbid diseases and preventing complications.

Craniofacial Bone Tissue Engineering: Current Approaches and Potential Therapy

Craniofacial bone defects can result from various disorders, including congenital malformations, tumor resection, infection, severe trauma, and accidents. Successfully regenerating cranial defects is an integral step to restore craniofacial function. However, challenges managing and controlling new bone tissue formation remain. Current advances in tissue engineering and regenerative medicine use innovative techniques to address these challenges. The use of biomaterials, stromal cells, and growth factors have demonstrated promising outcomes in vitro and in vivo. Natural and synthetic bone grafts combined with Mesenchymal Stromal Cells (MSCs) and growth factors have shown encouraging results in regenerating critical-size cranial defects. One of prevalent growth factors is Bone Morphogenetic Protein-2 (BMP-2). BMP-2 is defined as a gold standard growth factor that enhances new bone formation in vitro and in vivo. Recently, emerging evidence suggested that Megakaryocytes (MKs), induced by Thrombopoietin (TPO), show an increase in osteoblast proliferation in vitro and bone mass in vivo. Furthermore, a co-culture study shows mature MKs enhance MSC survival rate while maintaining their phenotype. Therefore, MKs can provide an insight as a potential therapy offering a safe and effective approach to regenerating critical-size cranial defects.

Microtomographic reconstruction of mandibular defects treated with xenografts and collagen-based membranes: A pre-clinical minipig model

BACKGROUND

The goal of this study was to evaluate hard tissue response following guided bone regeneration using commercially available bovine bone grafts and collagen membranes; bilayer collagen membrane and porcine pericardium-based membrane, by means of a non-destructive three-dimensional (3D) computerized volumetric analysis following microtomography reconstruction.

MATERIAL AND METHODS

Bone regenerative properties of various bovine bone graft materials were evaluated in the Göttingen minipig model. Two standardized intraosseous defects (15mm x 8mm x 8mm) were created bilaterally of the mandible of eighteen animals (n=72 defects). Groups were nested within the same subject and randomly distributed among the sites: (i) negative control (no graft and membrane), (ii) bovine bone graft/bilayer collagen membrane (BOB) (iii) Bio-Oss® bone graft/porcine pericardium-based membrane (BOJ) and (iv) cerabone® bone graft/porcine pericardium-based membrane (CJ). Samples were harvested at 4, 8, and 12-week time points (n=6 animal/time point). Segments were scanned using computerized microtomography (μCT) and three dimensionally reconstructed utilizing volumetric reconstruction software. Statistical analyses were performed using IBM SPSS with a significance level of 5%.

RESULTS

From a temporal perspective, tridimensional evaluation revealed gradual bone ingrowth with the presence of particulate bone grafts bridging the defect walls, and mandibular architecture preservation over time. Volumetric analysis demonstrated no significant difference between all groups at 4 weeks (p>0.127). At 8 and 12 weeks there was a higher percentage of new bone formation for control and CJ groups when compared to BOB and BOJ groups (p<0.039). The natural bovine bone graft group showed more potential for graft resorption over time relative to bovine bone graft, significantly different between 4 and 8 weeks (p<0.003).

CONCLUSIONS

Volumetric analysis yielded a favorable mandible shape with respect to time through the beneficial balance between graft resorption/bone regenerative capacity for the natural bovine bone graft.

Natural Polymers for the Maintenance of Oral Health: Review of Recent Advances and Perspectives

The success of modern dental treatment is strongly dependent on the materials used both temporarily and permanently. Among all dental materials, polymers are a very important class with a wide spectrum of applications. This review aims to provide a state-of-the-art overview of the recent advances in the field of natural polymers used to maintain or restore oral health. It focuses on the properties of the most common proteins and polysaccharides of natural origin in terms of meeting the specific biological requirements in the increasingly demanding field of modern dentistry. The use of naturally derived polymers in different dental specialties for preventive and therapeutic purposes has been discussed. The major fields of application cover caries and the management of periodontal diseases, the fabrication of membranes and scaffolds for the regeneration of dental structures, the manufacturing of oral appliances and dentures as well as providing systems for oral drug delivery. This paper also includes a comparative characteristic of natural and synthetic dental polymers. Finally, the current review highlights new perspectives, possible future advancements, as well as challenges that may be encountered by researchers in the field of dental applications of polymers of natural origin.