Cross-linked Collagen Membrane Research Articles

Extraction and Socket Preservation before Implant Placement Using Freeze-Dried Allograft (FDBA) and Platelet-Rich Fibrin in Smokers: Radiographic and Histological Evaluation

Background: Dental extraction can initiate a sequence of biological events that may lead to an insufficient bone volume, which can compromise implant placement. To minimize bone loss, alveolar ridge preservation procedures were developed. However, smoking has been shown to adversely affect the outcomes of the procedures. Hence, this clinical study aimed to assess the ability of platelet-rich fibrin to maintain ridge volume and its ability to generate vital bone in smokers. Methods: Eighteen current heavy smokers with a total of forty upper molars indicated for extraction and implant placement were randomly allocated to four different groups: an advanced platelet-rich fibrin group (A-PRF) (n = 10), a factor-enriched bone graft matrix covered by A-PRF group (A/S-PRF) (n = 10); a freeze-dried bone allograft covered by a crosslinked collagen membrane group (FDBA/CM) (n = 10), which served as a positive control; and a negative-control resorbable collagen plug group (RCP) (n = 10). Two consecutive high-resolution CBCT images were taken for each augmented socket to evaluate the bone volume, one at baseline and the other after six months, and four different measurements (vertical height, horizontal 1 mm H1, horizontal 3 mm, and horizontal 5 mm) were taken for each image. To evaluate the bone vitality, three bone samples were harvested for each group and were analyzed histologically using H and E staining. The results were analyzed using SPSS version 26.0 through the Wilcoxon sign rank test and Kruskal–Wallis test. Results: In terms of preserving bone volume, A/S-PRF showed no significant reduction in bone after six months, while A-PRF showed a significant loss according to two measurements (vertical and horizontal 5 mm), and the last two groups showed a significant loss in all four measurements. For vital bone formation, three groups (A-PRF, A/S-PRF, and RCP) showed the generation of only vital bone, while the fourth group (FDBA/CM) showed the generation of a mixture of vital and non-vital bone. Conclusions: Based on the outcomes of this study, PRF was able to minimize bone loss following dental extraction and generate vital bone in smokers.

Collagen Membrane as Water-Based Gel Electrolyte for Electrochromic Devices.

Bio-based polymers are attracting great interest due to their potential for several applications in place of conventional polymers. In the field of electrochemical devices, the electrolyte is a fundamental element that determines their performance, and polymers represent good candidates for developing solid-state and gel-based electrolytes toward the development of full-solid-state devices. In this context, the fabrication and characterization of uncrosslinked and physically cross-linked collagen membranes are reported to test their potential as a polymeric matrix for the development of a gel electrolyte. The evaluation of the membrane's stability in water and aqueous electrolyte and the mechanical characterization demonstrated that cross-linked samples showed a good compromise in terms of water absorption capability and resistance. The optical characteristics and the ionic conductivity of the cross-linked membrane, after overnight dipping in sulfuric acid solution, demonstrated the potential of the reported membrane as an electrolyte for electrochromic devices. As proof of concept, an electrochromic device was fabricated by sandwiching the membrane (after sulfuric acid dipping) between a glass/ITO/PEDOT:PSS substrate and a glass/ITO/SnO2 substrate. The results in terms of optical modulation and kinetic performance of such a device demonstrated that the reported cross-linked collagen membrane could represent a valid candidate as a water-based gel and bio-based electrolyte for full-solid-state electrochromic devices.

Occlusive and Proliferative Properties of Different Collagen Membranes—An In Vitro Study

Different collagen barrier membranes come in various sources and crosslinking that may affect barrier function and tissue integration. This study investigated barrier function and tissue integration of the three different collagen membranes (Jason®: porcine pericardium, GENOSS: bovine tendon, and BioMend® Extend: cross-linked bovine tendon) with human gingival fibroblasts. The barrier function and tissue integration properties were determined under confocal microscopy. Morphological characteristics were observed using scanning electron microscopy. Our results showed that all collagen membranes allowed a small number of cells to migrate, and the difference in barrier function ability was not significant. The cross-linked characteristics did not improve barrier ability. The native collagen membrane surfaces allowed evenly scattered proliferation of HGF, while the cross-linked collagen membrane induced patchy proliferation. Statistically significant differences in cell proliferation were found between Jason and BioMend Extend membranes (p = 0.04). Scanning electron microscope showed a compact membrane surface at the top, while the bottom surfaces displayed interwoven collagen fibers, which were denser in the crosslinked collagen membranes. Within the limitations of this study, collagen membranes of different origins and physical properties can adequately prevent the invasion of unwanted cells. Native collagen membranes may provide a better surface for gingival cell attachment and proliferation.

Tissue integration patterns of non-crosslinked and crosslinked collagen membranes: an experimental in vivo study.

Non-crosslinked and crosslinked collagen membranes are known to exhibit distinct degradation characteristics, resulting in contrasting orientations of the adjacent tissues and different biological processes. The aim of this study was to conduct a histomorphometric assessment of non-crosslinked and crosslinked collagen membranes regarding neovascularization, tissue integration, tissue encapsulation, and biodegradation. Guided bone regeneration was performed using either a non-crosslinked (BG) or a crosslinked collagen membrane (CM) in 15 beagle dogs, which were euthanized at 4, 8, and 16 weeks (n=5 each) for histomorphometric analysis. The samples were assessed regarding neovascularization, tissue integration, encapsulation, the remaining membrane area, and pseudoperiosteum formation. The BG and CM groups were compared at different time periods using nonparametric statistical methods. The remaining membrane area of CM was significantly greater than that of BG at 16 weeks; however, there were no significant differences at 4 and 8 weeks. Conversely, the neovascularization score for CM was significantly less than that for BG at 16 weeks. BG exhibited significantly greater tissue integration and encapsulation scores than CM at all time periods, apart from encapsulation at 16 weeks. Pseudoperiosteum formation was observed in the BG group at 16 weeks. Although BG membranes were more rapidly biodegraded than CM membranes, they were gradually replaced by connective tissue with complete integration and maturation of the surrounding tissues to form dense periosteum-like connective tissue. Further studies need to be performed to validate the barrier effect of the pseudoperiosteum.

Soft-Tissue Healing Assessment after Extraction and Socket Preservation Using Platelet-Rich Fibrin (PRF) in Smokers: A Single-Blinded, Randomized, Controlled Clinical Trial.

Background: Wound healing is essential in any surgical procedure, and multiple factors, such as smoking, can impair it. The aim of this clinical trial was to evaluate the ability of platelet-rich fibrin to enhance socket wound healing in smokers. Methods: A total of 18 smoker participants with forty non-restorable upper molars indicated for extraction were recruited to the study and were randomly allocated to four different groups for the assessment of four techniques: advanced platelet-rich fibrin (A-PRF), factor-enriched bone graft matrix with advanced platelet-rich fibrin (A/S-PRF), freeze-dried bone allograft and crosslinked collagen membrane (FDBA/CM), and resorbable collagen plug (RCP). One examiner clinically measured soft-tissue closure and the healing pattern using a periodontal probe and a healing index. Each subject was given a questionnaire after each follow-up visit to record several patient-reported experience measures (PREMs). This was conducted at baseline and 10, 21, and 28 days after the extraction procedure. Results: Both A-PRF and A/S-PRF showed significant results in terms of mesio-distally (p = 0.012), and healing pattern parameters (p < 0.0001), while RCP showed the least favorable outcome. Conclusions: Different forms of PRF exhibited enhanced wound closure and healing patterns, as well as reduced post-operative complications among smokers.

Impact of Cross-Linked Hyaluronic Acid on Osteogenic Differentiation of SAOS-2 Cells in an Air-Lift Model.

The aim of this study was to investigate the impact of cross-linked hyaluronic acid on osteoblast-like cells seeded on top of two collagen substrates, native porcine pericardium membrane (substrate A) and ribose cross-linked collagen membranes (substrate B), in an air-lift model. Substrates A or B, saturated with three hyaluronic acid concentrations, served as membranes for SAOS-2 cells seeded on top. Cultivation followed for 7 and 14 days in the air-lift model. Controls used the same substrates without hyaluronic pre-treatment. Cells were harvested, and four (Runx2, BGLAP, IBSP, Cx43) different osteogenic differentiation markers were assessed by qPCR. Triplicated experiment outcomes were statistically analyzed (ANOVA, t-test; SPSS). Supplementary histologic analysis confirmed the cells’ vitality. After seven days, only few markers were overexpressed on both substrates. After 14 days, targeted genes were highly expressed on substrate A. The same substrate treated with 1:100 diluted xHyA disclosed statistically significant different expression level vs. substrate B (p = 0.032). Time (p = 0.0001), experimental condition as a function of time (p = 0.022), and substrate (p = 0.028) were statistically significant factors. Histological imaging demonstrated vitality and visualized nuclei. We conclude that the impact of hyaluronic acid resulted in a higher expression profile of SAOS-2 cells on substrate A compared to substrate B in an air-lift culture after two weeks.

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

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

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 72h of incubation. The obtained solution was then added to U2OS cell cultures which underwent, after 10days 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 24h. 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.

Outcomes of reconstructive periodontal surgery with different types of barrier membranes

Relevance. Reconstructive periodontal surgery is one of the most effective methods of restoring tooth-supporting apparatus damaged by microbial inflammation and destruction. For this purpose, they use non-resorbable and resorbable biomaterials, which act as a temporary barrier between the tissues with different mitotic potential during early healing. Since the properties of barrier membranes determine the degree of invasiveness and postoperative morbidity, and, finally, the success of the surgery, it is relevant to study the outcomes of periodontal reconstruction with one of the modern collagen membranes cross-linked by ribose.Purpose. To comparatively assess the outcomes of periodontal reconstructions with a resorbable and non-resorbable barrier material.Material and methods. The study is a prospective randomized blind controlled clinical trial. The study included 37 patients (14 men, 23 women) aged 45-65 years, who, after the initial therapy, underwent 62 guided tissue regenerations using e-PTFE and resorbable collagen membrane cross-linked by ribose. The study compared the clinical and radiographic results before and 18 months after the surgery. We evaluated the probing depth (periodontal pocket), gingival recession level, loss of clinical attachment level, width and height of periodontal infrabony defects, gain in clinical attachment level. The material was statistically processed using StatSoft STATISTICA 10.0.1011 for Windows. The statistical unit is a periodontal defect.Results. In the postoperative period, the main (31%) and control (42%) groups exhibited the areas of membrane exposure; 16 periodontal defects, only in the control group, demonstrated the extensive membrane exposure, of which 11 membranes were prematurely removed due to infection of the reconstruction site. In the main group, fibrin allowed exposed area healing in the usual time without medical assistance. After 18 months, the gain in the clinical attachment level was 3.5 mm in the main group versus 2.8 mm in the control group (at p=0.03) with a significant decrease in the probing depth compared to that before treatment; the level of recession also changed positively, although not significantly. The type of periodontal defect (the parameter is higher in three-wall and two-wall defects) appeared to remarkably influence the gain in clinical attachment level.Conclusion. The study evidenced that the resorbable cross-linked collagen membrane demonstrated clinically acceptable outcome of the damaged periodontium reconstruction due to, first of all, increased predictability of the course of the early postoperative period, a significant reduction in morbidity and invasiveness of intervention.

Optimizing the bio-degradability and biocompatibility of a biogenic collagen membrane through cross-linking and zinc-doped hydroxyapatite

Biogenic collagen membranes have been widely used as soft tissue barriers in guided bone regeneration (GBR) and guided tissue regeneration (GTR). Nevertheless, their clinical performance remains unsatisfactory because of their low mechanical strength and fast degradation rate in vivo. Although cross-linking with chemical agents is effective and reliable for prolonging the degradation time of collagen membranes, some adverse effects including potential cytotoxicity and undesirable tissue integration have been observed during this process. As a fundamental nutritional trace element, zinc plays an active role in promoting the growth of cells and regulating the degradation of the collagen matrix. Herein, a biogenic collagen membrane was cross-linked with glutaraldehyde-alendronate to prolong its degradation time. The physiochemical and biological properties were enhanced by the incorporation of zinc-doped nanohydroxyapatite (nZnHA), with the native structure of collagen preserved. Specifically, the cross-linking combined with the incorporation of 1% and 2% nZnHA seemed to endow the membrane with the most appropriate biocompatibility and tissue integration capability among the cross-linked membranes, as well as offering a degradation period of six weeks in a rat subcutaneous model. Thus, improving the clinical performance of biogenic collagen membranes by cross-linking together with the incorporation of nZnHA is a promising strategy for the improvement of biogenic collagen membranes. Statement of significanceThe significance of this research includes:•We fabricated a cross-linked collagen membrane with enhanced mechanical properties, prolonged degradation time and uncompromised biocompatibility by GA-alendronate cross-linking and nZnHA doping.•Tuning the incorporation concentration of zinc ions can effectively manipulate the biocompatibility and degradation process of the membrane fabricated.•We proposed a promising strategy to improve the clinical performance of biogenic collagen membranes by cross-linking together with the incorporation of nZnHA.

Lateral Ridge Augmentation Using Cross-Linked or Non-Cross-Linked Collagen Membrane: A Pilot Randomized Clinical Trial

Purpose: The aim of this investigation is to test, in a lateral ridge augmentation model without simultaneous implant placement, the effect of using a cross-linked collagen membrane and a non-cross-linked collagen membrane on guided bone regeneration. Material and Methods: Edentulous alveolar ridges of less than 5 mm width were treated with guided bone regeneration using a glutaraldehyde cross-linked collagen membrane (CL) or a non-cross-linked collagen membrane (NonCL). In all treated cases the bone graft used was a combination of autogenous bone scrapings and deproteinized bovine bone mixed in a 1:3 ratio. Ridge measurements were recorded clinically (during augmentation surgery and during implant placement surgery) and radiographically on the CBCT scans (pre-op, 1 week post-op and at implant placement). All ridge measurements were recorded at 1, 3 and 5 mm from the ridge crest. Soft tissue healing was assessed during the follow-up visits at 1, 2, 4, 8, 12, 16, 20 and 24 weeks post-op. A histological analysis was performed on core biopsies retrieved axially from implant or pontic sites. Results: Four patients were recruited and randomly allocated to treatment groups. Ridge width gain (RWgain) was significantly better for the CL group as assessed clinically. At 1, 3 and 5 mm from ridge crest, the clinically assessed gain was respectively 5.50 mm ± 2.121, 5.40 mm ± 2.074, 5.60 mm ± 1.140 for the CL group and -1.33 mm ± 0.577, 1.33 mm ± 2.517 and 2.00 mm ± 1.000 for the NonCL group. Graft volume resorption was significantly higher in the NonCL group (62%) in comparison to the CL group (10.9%). No soft tissue complications occurred during follow-ups in neither group. Histologically, both groups showed signs of bone remodeling and vital bone formation. New bone formation in the NonCL group was 23.64 % ± 0.64 and in the CL group was 15.75% ± 8.73. Conclusion: Despite the limitations of this pilot study, The CL membrane showed better performance than the NonCL membrane in terms of ridge width gain and in terms of graft volume consolidation as assessed clinically and radiographically. Although no statistical comparison was possible, the NonCL group presented a higher percentage of new bone formation than the CL group.

Combined Sinus Grafting and Lateral Augmentation by a Hyaluronic Acid-Facilitated Guided Bone Regeneration Protocol – Case Series Supported by Human Histologic Analysis

Guided Bone Regeneration (GBR) is a well-established procedure for the regeneration of alveolar bone defects. In the case of highly complex defect situations, however, inconsistent treatment results are often achieved. Hyaluronic Acid (HA) fulfills several relevant preliminary success criteria for improved regenerative treatment outcomes in complex defects: HA supports the creation of a toxin-free wound area, HA improves wound space stabilization, accelerates wound healing and supports regenerative processes crucial for bone regeneration. The novelty in the reported cases is the use of porcine derived bone substitute particulate hydrated with a cross-linked hyaluronic acid for simultaneous sinus grafting and lateral/vertical ridge augmentation in combination with a ribose cross-linked collagen membrane. The approval of the feasibility is provided with the clinical and histological observations. Three consecutive cases received the abovementioned material combination for staged sinus floor elevation and additional augmentation procedure by one operator according to a standardized protocol. All three sites constantly demonstrate superior clinical outcomes in terms of radiographically impressive tissue enhancement and implant function. The clinical outcomes are supported by qualitative histological analysis reflecting great similarity between samples regarding the observed process of new bone formation and bone substitute behavior. The specific staining allows for detection of osteoclastic activity and indicates the tendency of the particulate bone substitute to degrade over time once integrated.

Horizontal Augmentation of Chronic Mandibular Defects by the Guided Bone Regeneration Approach: A Randomized Study in Dogs.

Various biomaterial combinations have been studied focusing on their ability to stabilize blood clots and maintain space under soft tissue to support new bone formation. A popular combination is Deproteinized Bovine Bone Mineral (DBBM) placed with a native collagen membrane (NCM) tacked to native bone. In this study, we compared the outcome of this treatment option to those achieved with three different graft/membrane combinations with respect to total newly occupied area and the mineralized compound inside. After bi-lateral extraction of two mandibular premolars in five adult beagles L-shaped alveolar defects were created. A total of 20 defects healed for 6 weeks resulting in chronic type bone defects. At baseline, four options were randomly allocated to five defects each: a. DBBM + NCM with a four-pin fixation across the ridge; b. DBBM + RCLC (ribose cross-linked collagen membrane); c. DBBM + NPPM (native porcine pericardium membrane); and d. Ca-sulfate (CS) + RCLC membrane. Membranes in b/c/d were not fixed; complete tensionless wound closure was achieved by CAF. Termination after 3 months and sampling followed, and non-decalcified processing and toluidine blue staining were applied. Microscopic images obtained at standardized magnification were histomorphometrically assessed by ImageJ software (NIH). An ANOVA post hoc test was applied; histomorphometric data are presented in this paper as medians and interquartile ranges (IRs). All sites healed uneventfully, all sites were sampled and block separation followed before Technovit embedding. Two central sections per block for each group were included. Two of five specimen were lost due to processing error and were excluded from group b. New bone area was significantly greater for option b. compared to a. (p = 0.001), c. (p = 0.002), and d. (p = 0.046). Residual non-bone graft area was significantly less for option d. compared to a. (p = 0.026) or c. (p = 0.021). We conclude that collagen membranes with a prolonged resorption/barrier profile combined with bone substitutes featuring different degradation profiles sufficiently support new bone formation. Tacking strategy/membrane fixation appears redundant when using these biomaterials.

Vertical and horizontal ridge augmentation using customized CAD/CAM titanium mesh with versus without resorbable membranes. A randomized clinical trial

ObjectivesThe aim was to evaluate the role of resorbable membranes applied over customized titanium meshes related to soft tissue healing and bone regeneration after vertical/horizontal bone augmentation.Materials and MethodsThirty patients with partial edentulism of the maxilla/mandible, with vertical/horizontal reabsorption of the alveolar bone, and needing implant‐supported restorations, were randomly divided into two groups: Group A was treated using only custom‐made meshes (Mesh‐) and Group B using custom‐made meshes with cross‐linked collagen membranes (Mesh+). Data collection included surgical/technical and healing complications, “pseudo‐periosteum” thickness, bone density, planned bone volume (PBV), regenerated bone volume (RBV), regeneration rate (RR), vertical bone gain (VBG), and implant survival in regenerated areas. Statistical analysis was performed between the two study groups using a significance level of α = .05.ResultsRegarding the healing complications, the noninferiority analysis proved to be inconclusive, despite the better results of group Mesh+ (13%) compared to group Mesh‐ (33%): estimated value −1.13 CI‐95% from −0.44 to 0.17. Superiority approach confirmed the absence of significant differences (p = .39). RBV was 803.27 mm3 and 843.13 mm3, respectively, and higher RR was observed in group Mesh+ (82.3%) compared to Mesh‐ (74.3%), although this value did not reach a statistical significance (p = .44). All 30 patients completed the study, receiving 71 implants; 68 out of them were clinically stable and in function.ConclusionThe results showed that customized meshes alone do not appear to be inferior to customized meshes covered by cross‐linked collagen membranes in terms of healing complication rates and regeneration rates, although superior results were observed in group Mesh+compared to group Mesh‐ for all variables.

Hard Tissue Volume Stability Effect beyond the Bony Envelope of a Three-Dimensional Preformed Titanium Mesh with Two Different Collagen Barrier Membranes on Peri-Implant Dehiscence Defects in the Anterior Maxilla: A Randomized Clinical Trial.

This single-blinded, randomized, controlled study aimed to clinically and radiographically evaluate hard tissue volume stability beyond the bony envelope using three-dimensional preformed titanium mesh (3D-PFTM) for peri-implant dehiscence defects in the anterior maxilla. A total of 28 patients who wished to undergo implant surgery combined with guided bone regeneration (GBR) after extraction of a single maxillary anterior tooth were randomly assigned to two groups depending on the type of collagen membrane used, additionally with the 3D-PFTM—test (n = 14, cross-linked collagen membrane; CCM) and control (n = 14, non-cross-linked collagen membrane; NCCM) groups. Each implant was evaluated radiographically using CBCT at baseline, immediately after surgery, and at 6 months postoperatively. The relative position and distances from the bony envelope to the outlines of the augmented ridge were further determined immediately after GBR and 6 months after healing. At the platform level, the mean horizontal hard tissue gain (HG) at all the sites was 2.35 ± 0.68 mm at 6 months postoperatively. The mean HG rate was 84.25% ± 14.19% in the CCM group and 82.56% ± 13.04% in the NCCM group, but the difference was not significant between the groups. In all cases, HG was maintained beyond the bony envelope even after 6 months of GBR. This study suggests that 3D-PFTM should be considered a valuable option for GBR for peri-implant dehiscence defects in the anterior maxilla. In addition, 3D-PFTM may confer predictable hard tissue volume stability even after the healing period of hard tissue augmented outside the bony envelope by GBR.

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

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

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

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

Application of Epigallocatechin-3-gallate (EGCG) Modified 1-Ethyl-3-(3-dimethylaminopropylcarbodiimide hydrochloride/N-hydroxy-succinimide (EDC/NHS) Cross-Linked Collagen Membrane to Promote Macrophage Adhesion

The chemically cross-linking 1-ethyl-3-(3-dimethylaminopropylcarbodiimide hydrochloride/N-hydroxy-succinimide (EDC/NHS) collagen membrane endows such natural polymers with promising mechanical properties. Nevertheless, it is inadequate to advance the modulation of foreign body response (FBR) after implantation or guidance of tissue regeneration. In previous research, macrophages have a strong regulatory effect on regeneration, and such enhanced membranes underwent the modification with Epigallocatechin-3-gallate (EGCG) could adjust the recruitment and phenotypes of macrophages. Accordingly, we develop EGCG-EDC/NHS membranes, prepared with physical immersion, while focusing on the surface morphology through SEM, the biological activity of collagen was determined by FTIR, the activity and adhesion of cell culture in vitro, angiogenesis and monocyte/macrophage recruitment after subcutaneous implantation in vivo, are characterized. It could be concluded that it is hopeful EGCG-EDC/NHS collagen membrane can be used in implant dentistry for it not only retains the advantages of the collagen membrane itself, but also improves cell viability, adhesion, vascularization, and immunoregulation tendency.

Immunohistochemical characteristics of lateral bone augmentation using different biomaterials around chronic peri-implant dehiscence defects: An experimental in vivo study.

To investigate the immunohistochemical characteristics of a highly porous synthetic bone substitute and a cross-linked collagen membrane for guided bone regeneration. Three experimental groups were randomly allocated at chronic peri-implant dehiscence defect in 8 beagle dogs: (i) biphasic calcium phosphate covered by a cross-linked collagen membrane (test group), (ii) deproteinized bovine bone mineral covered by a natural collagen membrane (positive control) and (iii) no treatment (negative control). After 8 and 16weeks of submerged healing, dissected tissue blocks were processed for immunohistochemical analysis. Seven antibodies were used to detect the remaining osteogenic and angiogenic potential, and quantitative immunohistochemical analysis was done by software. The antigen reactivity of alkaline phosphatase was significantly higher in the test group compared to the positive and negative controls, and it maintained till 16weeks. The intensity of osteocalcin was significantly higher in the positive control at 8weeks than the other groups, but significantly decreased at 16weeks and no difference was found between the groups. A significant large number of TRAP-positive cells were observed in the test group mainly around the remaining particles at 16weeks. The angiogenic potential was comparable between the groups showing no difference in the expression of transglutaminase II and vascular endothelial growth factor. Guided bone regeneration combining a highly porous biphasic calcium phosphate synthetic biomaterial with a crosslinked collagen membrane, resulted in extended osteogenic potential when compared to the combination of deproteinized bovine bone mineral and a native collagen membrane.

Retrospective Analysis of the Effect of Three-Dimensional Preformed Titanium Mesh on Peri-Implant Non-Contained Horizontal Defects in 100 Consecutive Cases

This study aimed to clinically and radiographically evaluate the results of guided bone regeneration (GBR) using three-dimensional preformed titanium mesh (3-D-PFTM) for non-contained horizontal defects in 100 consecutive cases. This study involved 100 patients (129 implants) with peri-implant non-contained horizontal defects. The patients were divided into three groups: 3-D-PFTM alone (Group 1), 3-D-PFTM plus cross-linked collagen membrane (Group 2), and 3-D-PFTM plus non-cross-linked collagen membrane (Group 3). Each implant was evaluated radiographically using CBCT at baseline and 6 months postoperatively. At the platform level, the mean horizontal hard tissue gain of all the sites was 3.1 ± 1.3 mm at 6 months postoperatively. The mean rate of mesh exposure was 11.8% in Group 1, 4.2% in Group 2, and 5.0% in Group 3. The mean hard tissue gain rate was 71.0 ± 23.0% in group 1, 84.2 ± 21.5% in group 2, and 84.0 ± 22.9% in group 3. Groups 2 and 3 showed significantly higher hard tissue gain rates than group 1. However, there was no significant difference between the rates in groups 2 and 3. Within the limitations of this study, 3-D-PFTM should be considered as a valuable option for GBR for peri-implant non-contained horizontal defects. The use of an additional resorbable collagen membrane provides additional advantages.