Bovine pericardium based non-cross linked collagen matrix for successful root coverage, a clinical study in human

Novel Functional Dressing Materials for Intraoral Wound Care

Intraoral wounds represent a particularly challenging category of mucosal and hard tissue injuries, characterized by the unique structures, complex environment, and distinctive healing processes within the oral cavity. They have a common occurrence yet frequently inflict significant inconvenience and pain on patients, causing a serious decline in the quality of life. A variety of novel functional dressings specifically designed for the moist and dynamic oral environment have been developed and realized accelerated and improved wound healing. Thoroughly analyzing and summarizing these materials is of paramount importance in enhancing the understanding and proficiently managing intraoral wounds. In this review, the particular processes and unique characteristics of intraoral wound healing are firstly described. Up-to-date knowledge of various forms, properties, and applications of existing products are then intensively discussed, which are categorized into animal products, plant extracts, natural polymers, and synthetic products. To conclude, this review presents a comprehensive framework of currently available functional intraoral wound dressings, with an aim to provoke inspiration of future studies to design more convenient and versatile materials.

The Long-Term Esthetic and Radiographic Outcome of Implants Placed in the Anterior Maxilla after Ridge Preservation, Combining Bovine Xenograft with Collagen Matrix

The objective of the study was to evaluate the long-term esthetic and radiographic results of implants placed in the anterior maxilla after ridge preservation, combining bovine xenograft with collagen matrix. Fifteen patients who required a single tooth extraction because of fracture, root resorption, or extended caries were included in the study. After extraction, all sites were grafted using Deproteinized Bovine Bone Mineral (DBBM) with collagen and covered by a resorbable collagen matrix (CM). Five months after socket grafting, implants were successfully installed. The implant diameter range was between 3.8 and 4.2 mm. All patients were monitored for over 7 years, both clinically and radiographically. Three independent observers evaluated the long-term esthetic outcome, employing the Pink Esthetic Score (PES) technique. Over a period exceeding seven years, a 100% survival rate was observed for all 15 implants, with minimal marginal bone loss. The mean PES was 11.40 (±1.44) at the first assessment and 11.38 (±1.63) at the second assessment. The difference was not statistically significant (p = 0.978), and the scores of PES measurements indicated excellent esthetic results even after seven years. Based on these preliminary results, it seems that placing collagen bovine bone in a fresh extraction socket, covered with a collagen matrix, can preserve the alveolar ridge and provide long-term stable esthetic results.

The feasibility of injectable PRF (I-PRF) for bone tissue engineering and its application in oral and maxillofacial reconstruction: From bench to chairside

Among all the biomaterials introduced in the field of bone tissue engineering, injectable platelet-rich fibrin (I-PRF) has recently gained considerable attention. I-PRF, as a rich source of biologically active molecules, is a potential candidate which can be easily obtained in bedside and constitutes several biological factors which can result in higher anti-bacterial, anti-inflammatory and regenerative capabilities. According to the studies evaluating the osteogenic efficacy of I-PRF, this biomaterial has exhibited favorable outcomes in terms of adhesion, differentiation, migration, proliferation and mineralization potential of stem cells. In addition, the injectability and ease-of-applicability of this biomaterial has led to its various clinical applications in the oral and maxillofacial bone regeneration such as ridge augmentation, sinus floor elevation, cleft palate reconstruction and so on. Furthermore, to enhance the clinical performance of I-PRF, albumin gel-PRF as a long-lasting material for long-term utilization has been recently introduced with a gradual increase in growth factor release pattern. This review provides a comprehensive approach to better evaluate the applicability of I-PRF by separately appraising its performance in in-vitro, in-vivo and clinical situations. The critical approach of this review toward the different production protocols and different physical and biological aspects of I-PRF can pave the way for future studies to better assess the efficacy of I-PRF in bone regeneration.

Characterization of the Cellular Reaction to a Collagen-Based Matrix: An In Vivo Histological and Histomorphometrical Analysis

The permeability and inflammatory tissue reaction to Mucomaix^® matrix (MM), a non- cross-linked collagen-based matrix was evaluated in both ex vivo and in vivo settings. Liquid platelet rich fibrin (PRF), a blood concentrate system, was used to assess its capacity to absorb human proteins and interact with blood cells ex vivo. In the in vivo aspect, 12 Wister rats had MM implanted subcutaneously, whereas another 12 rats (control) were sham-operated without biomaterial implantation. On days 3, 15 and 30, explantation was completed (four rats per time-point) to evaluate the tissue reactions to the matrix. Data collected were statistically analyzed using analysis of variance (ANOVA) and Tukey multiple comparisons tests (GraphPad Prism 8). The matrix absorbed the liquid PRF in the ex vivo study. Day 3 post-implantation revealed mild tissue inflammatory reaction with presence of mononuclear cells in the implantation site and on the biomaterial surface (mostly CD68-positive macrophages). The control group at this stage had more mononuclear cells than the test group. From day 15, multinucleated giant cells (MNGCs) were seen in the implantation site and the outer third of the matrix with marked increase on day 30 and spread to the matrix core. The presence of these CD68-positive MNGCs was associated with significant matrix vascularization. The matrix degraded significantly over the study period, but its core was still visible as of day 30 post-implantation. The high permeability and fast degradation properties of MM were highlighted.

Mammalian Pericardium-Based Bioprosthetic Materials in Xenotransplantation and Tissue Engineering

Bioprosthetic materials based on mammalian pericardium tissue are the gold standard in reconstructive surgery. Their application range covers repair of rectovaginal septum defects, abdominoplastics, urethroplasty, duraplastics, maxillofacial, ophthalmic, thoracic and cardiovascular reconstruction, etc. However, a number of factors contribute to the success of their integration into the host tissue including structural organization, mechanical strength, biocompatibility, immunogenicity, surface chemistry, and biodegradability. In order to improve the material's properties, various strategies are developed, such as decellularization, crosslinking, and detoxification. In this review, the existing issues and long-term achievements in the development of bioprosthetic materials based on the mammalian pericardium tissue, aimed at a wide-spectrum application in reconstructive surgery are analyzed. The basic technical approaches to preparation of biocompatible forms providing continuous functioning, optimization of biomechanical and functional properties, and clinical applicability are described.

Multiparametric Optical Bioimaging Reveals the Fate of Epoxy Crosslinked Biomeshes in the Mouse Subcutaneous Implantation Model

Biomeshes based on decellularized bovine pericardium (DBP) are widely used in reconstructive surgery due to their wide availability and the attractive biomechanical properties. However, their efficacy in clinical applications is often affected by the uncontrolled immunogenicity and proteolytic degradation. To address this issue, we present here in vivo multiparametric imaging analysis of epoxy crosslinked DBPs to reveal their fate after implantation. We first analyzed the structure of the crosslinked DBP using scanning electron microscopy and evaluated proteolytic stability and cytotoxicity. Next, using combination of fluorescence and hypoxia imaging, X-ray computed microtomography and histology techniques we studied the fate of DBPs after subcutaneous implantation in animals. Our approach revealed high resistance to biodegradation, gradual remodeling of a surrounding tissue forming the connective tissue capsule and calcification of crosslinked DBPs. These changes were concomitant to the development of hypoxia in the samples within 3 weeks after implantation and subsequent induction of angiogenesis and vascularization. Collectively, presented approach provides new insights on the transplantation of the epoxy crosslinked biomeshes, the risks associated with its applications in soft-tissue reconstruction and can be transferred to studies of other types of implants.

Modification of collagen-based sponges can induce an upshift of the early inflammatory response and a chronic inflammatory reaction led by M1 macrophages: an in vivo study

BACKGROUND

The present study evaluated the cellular tissue reaction of two equine-derived collagen hemostatic sponges (E-CHS), which differed in thickness after pressing, over 30 days in vivo. The inflammatory response during physiological wound healing in sham-operated animals was used as control group.

MATERIAL AND METHODS

First, the E-CHS was pressed by applying constant pressure (6.47 ± 0.85 N) for 2 min using a sterile stainless-steel cylinder until the material was uniformly flattened. Consequently, the original (E-CHS), the pressed (P-E-CHS), as well as the control group (CG; sham operation) were studied independently. The 3 groups were evaluated in vivo after subcutaneous implantation in Wistar rats during 3, 15, and 30 days. Histochemical and immunohistochemical methods provided observations of biomaterial degradation rate, cellular inflammatory response, and vascularization pattern. A derivative of human blood known as platelet-rich fibrin (PRF) was used as an ex vivo model to simulate the initial biomaterial-cell interaction. Segments of E-CHS and P-E-CHS were cultivated for 3 and 6 days with PRF, and the release of pro-inflammatory proteins was measured using ELISA. PRF cultivated alone was used as a control group.

RESULTS

At day 3, the CG induced a statistically significant higher presence of monocytes/macrophages (CD68+), pro-inflammatory macrophages (M1; CCR7+), and pro-wound healing macrophages (M2; CD206+) compared to E-CHS and P-E-CHS. At the same time point, P-E-CHS induced a statistically significant higher presence of CD68+ cells compared to E-CHS. After 15 days, E-CHS was invaded by cells and vessels and showed a faster disintegration rate compared to P-E-CHS. On the contrary, cells and vessels were located only in the outer region of P-E-CHS and the biomaterial did not lose its structure and accordingly did not undergo disintegration. The experimental groups induced similar inflammatory reaction primarily with positive pro-inflammatory CD68+/CCR7+ macrophages and a low presence of multinucleated giant cells (MNGCs). At this time point, significantly lower CD68+/CCR7+ macrophages and no MNGCs were detected within the CG when compared to the experimental groups (P < 0.05). After 30 days, E-CHS and P-E-CHS were fully degraded. All groups showed similar inflammatory reaction shifted to a higher presence CD206+ macrophages. A low number of CCR7+ MNGCs were still observable in the implantation bed of both experimental groups. In the ex vivo model, the cells and fibrin from PRF penetrated E-CHS. However, in the case of P-E-CHS, the cells and fibrin stayed on the surface and did not penetrate towards materials central regions. The cultivation of P-E-CHS with PRF induced a statically significant higher release of pro-inflammatory proteins compared to the CG and E-CHS after 3 days.

CONCLUSION

Altering the original presentation of a hemostatic sponge biomaterial by pressing modified the initial biomaterial-cell interaction, delayed the early biomaterial's degradation rate, and altered the vascularization pattern. A pressed biomaterial seems to induce a higher inflammatory reaction at early time points. However, altering the biomaterial did not modify the polarization pattern of macrophages compared to physiologic wound healing. The ex vivo model using PRF was shown to be an effective model to simulate the initial biomaterial-cell interaction in vivo.

CLINICAL RELEVANCE

A pressed hemostatic sponge could be applied for guided tissue regeneration and guided bone regeneration. In that sense, within the limitations of this study, the results show that the same biomaterial may have two specific clinical indications.

Periodontal microsurgery for management of multiple marginal tissue recession using Zucchelli's modification of coronally advanced flap and pericardium membrane in an esthetic zone

Marginal tissue recession (MTR) by definition is an apical shift of gingival margin, which leads to exposure of root surface. Patients affected with MTR often complain of sensitivity to cold on exposed root surfaces apart from esthetic concerns. In this article, a case of multiple Miller's class I MTR who presented with sensitivity to cold in relation to maxillary anterior teeth region was treated using Zucchelli's coronally advanced flap with pericardium membrane under operating microscope. The application of principles of periodontal microsurgery and guided tissue regeneration results in significant root coverage with reduction/elimination of sensitivity. Long-term success of root coverage procedures depends on the removal of etiology and maintenance therapy.

Fifteen Years of Platelet Rich Fibrin in Dentistry and Oromaxillofacial Surgery: How High is the Level of Scientific Evidence?

Platelet-rich fibrin is a blood concentrate system used for soft tissue and bone tissue regeneration. In the last decade, platelet rich fibrin (PRF) has been widely used in different indication fields, particularly in oral and maxillofacial surgery. This review investigates the level of scientific evidence of published articles related to the use of PRF for bone and soft tissue regeneration in dentistry and maxillofacial surgery. An electronic literature research using the biomedical search engine “National Library of Medicine” (PubMed-MEDLINE) was performed in May 2017. A total of 392 articles were found, 72 of which were classified for each indication field. When comparing PRF with biomaterials vs biomaterial alone in sinus lift (5 studies; IIa), no statistically significant differences were detected. Socket preservation and ridge augmentation using PRF significantly enhanced new bone formation compared to healing without PRF (7 studies Ib, IIa, IIb). Reepithelialization and bone regeneration was achieved in 96 of 101 patients diagnosed with medication-related osteonecrosis of the jaw (5 studies, III). In periodontology, PRF alone (6 studies; Ib, IIa, IIb) or its combination with biomaterials (6 studies; Ib, IIa, IIb) significantly improved the pocket depth and attachment loss compared to a treatment without PRF. Over 70% of the patients were part of studies with a high level of scientific evidence (randomized and controlled prospective studies). This published evidence (38 articles), with a high scientific level, showed that PRF is a beneficial tool that significantly improves bone and soft tissue regeneration. However, the clinical community requires a standardization of PRF protocols to further examine the benefit of PRF in bone and soft tissue regeneration in reproducible studies, with a higher scientific level of evidence.

In vivo Implantation of a Bovine-Derived Collagen Membrane Leads to Changes in the Physiological Cellular Pattern of Wound Healing by the Induction of Multinucleated Giant Cells: An Adverse Reaction?

The present study evaluated the tissue response toward a resorbable collagen membrane derived from bovine achilles tendon (test group) in comparison to physiological wound healing (control group). After subcutaneous implantation in Wistar rats over 30 days, histochemical and immunohistochemical methods elucidated the cellular inflammatory response, vascularization pattern, membrane protein and cell absorbance capacity. After 30 days, the test-group induced two different inflammatory patterns. On the membrane surface, multinucleated giant cells (MNGCs) were formed after the accumulation of CD-68-positive cells (macrophages), whereas only mononuclear cells (MNCs) were found within the membrane central region. Peri-implant vascularization was significantly enhanced after the formation of MNGCs. No vessels were found within the central region of the membrane. Physiological wound healing revealed no MNGCs at any time point. These dynamic changes in the cellular reaction and vascularization within the test-group are related typical indications of a foreign body reaction. Due to the membrane-specific porosity, mononuclear cells migrated into the central region, and the membrane maintained its integrity over 30 days by showing no breakdown or disintegration. The ex vivo investigation analyzed the interaction between the membrane and a blood concentrate system, liquid platelet-rich fibrin (liquid PRF), derived from human peripheral blood and consisting of platelets, leukocytes and fibrin. PRF penetrated the membrane after just 15 min. The data question the role of biomaterial-induced MNGCs as a pathological reaction and whether this is acceptable to trigger vascularization or should be considered as an adverse reaction. Therefore, further pre-clinical and clinical studies are needed to identify the types of MNGCs that are induced by clinically approved biomaterials.

Soft Tissue Augmentation Techniques and Materials Used in the Oral Cavity: An Overview

PURPOSE

Oral soft tissue augmentation or grafting procedures are often necessary to achieve proper wound closure after deficits resulting from tumor excision, clefts, trauma, dental implants, and tooth recessions.

MATERIALS AND METHODS

Autologous soft tissue grafts still remain the gold standard to acquire a functionally adequate zone of keratinized attached gingiva. However, soft tissue substitutes are more commonly used because they minimize morbidity and shorten surgical time.

RESULTS

This review aimed to assess soft tissue grafting techniques and materials used in the oral cavity from existing literature. There are a large variety of materials and techniques, including grafts, local flaps, allogenic derived matrices such as acellular dermal allograft, xenogenic tissue matrices from animal origin, and synthetic materials.

CONCLUSIONS

Tissue engineering of oral mucosa represents an interesting alternative to obtain sufficient autologous tissue for reconstructing oral wounds using biodegradable scaffolds, and may improve vascularization and epithelialization, which are critical for successful outcomes.

Reduction of relative centrifugation force within injectable platelet-rich-fibrin (PRF) concentrates advances patients' own inflammatory cells, platelets and growth factors: the first introduction to the low speed centrifugation concept

Purpose

The aim of this study was to analyze systematically the influence of the relative centrifugation force (RCF) on leukocytes, platelets and growth factor release within fluid platelet-rich fibrin matrices (PRF).

Materials and methods

Systematically using peripheral blood from six healthy volunteers, the RCF was reduced four times for each of the three experimental protocols (I–III) within the spectrum (710–44 g), while maintaining a constant centrifugation time. Flow cytometry was applied to determine the platelets and leukocyte number. The growth factor concentration was quantified 1 and 24 h after clotting using ELISA.

Results

Reducing RCF in accordance with protocol-II (177 g) led to a significantly higher platelets and leukocytes numbers compared to protocol-I (710 g). Protocol-III (44 g) showed a highly significant increase of leukocytes and platelets number in comparison to -I and -II. The growth factors’ concentration of VEGF and TGF-β1 was significantly higher in protocol-II compared to -I, whereas protocol-III exhibited significantly higher growth factor concentration compared to protocols-I and -II. These findings were observed among 1 and 24 h after clotting, as well as the accumulated growth factor concentration over 24 h.

Discussion

Based on the results, it has been demonstrated that it is possible to enrich PRF-based fluid matrices with leukocytes, platelets and growth factors by means of a single alteration of the centrifugation settings within the clinical routine.

Conclusions

We postulate that the so-called low speed centrifugation concept (LSCC) selectively enriches leukocytes, platelets and growth factors within fluid PRF-based matrices. Further studies are needed to evaluate the effect of cell and growth factor enrichment on wound healing and tissue regeneration while comparing blood concentrates gained by high and low RCF.

Porcine Dermis-Derived Collagen Membranes Induce Implantation Bed Vascularization Via Multinucleated Giant Cells: A Physiological Reaction?

In this study, the tissue reactions to 2 new porcine dermis-derived collagen membranes of different thickness were analyzed. The thicker material (Mucoderm) contained sporadically preexisting vessel skeletons and fatty islands. The thinner membrane (Collprotect) had a bilayered structure (porous and occlusive side) without any preexisting structures. These materials were implanted subcutaneously in mice to analyze the tissue reactions and potential transmembranous vascularization. Histological and histomorphometrical methodologies were performed at 4 time points (3, 10, 15, and 30 days). Both materials permitted stepwise connective tissue ingrowth into their central regions. In the Mucoderm matrix, newly built microvessels were found within the preexisting vessel and fatty island skeletons after 30 days. This vascularization was independent of the inflammation-related vascularization on both material surfaces. The Collprotect membrane underwent material disintegration by connective tissue strands in combination with vessels and multinucleated giant cells. The histomorphometric analyses revealed that the thickness of Mucoderm did not decrease significantly, while an initial significant decrease of membrane thickness in the case of Collprotect was found at day 15. The present results demonstrate that the 2 analyzed collagen membranes underwent a multinucleated giant cell-associated vascularization. Neither of the materials underwent transmembraneous vascularization. The microvessels were found within the preexisting vessel and fatty island skeletons. Additional long-term studies and clinical studies are necessary to determine how the observed foreign body giant cells affect tissue regeneration.

Porcine Dermis and Pericardium-Based, Non-Cross-Linked Materials Induce Multinucleated Giant Cells After Their In Vivo Implantation: A Physiological Reaction?

The present study analyzed the tissue reaction to 2 novel porcine-derived collagen materials: pericardium versus dermis. By means of the subcutaneous implantation model in mice, the tissue reactions were investigated at 5 time points: 3, 10, 15, 30, and 60 days after implantation. Histologic, histochemical, immunhistologic, and histomorphometric analysis methodologies were applied. The dermis-derived material underwent an early degradation while inducing mononuclear cells together with some multinucleated giant cells and mild vascularization. The pericardium-derived membrane induced 2 different cellular tissue reactions. The compact surface induced mononuclear cells and multinucleated giant cells, and underwent a complete degradation until day 30. The spongy surface of the membrane induced mainly mononuclear cells, and served as a stable barrier membrane for up to 60 days. No transmembranous vascularization was observed within the spongy material surface layer. The present data demonstrate the diversity of the cellular tissue reaction toward collagen-based materials from different tissues. Furthermore, it became obvious that the presence of multinucleated giant cells was associated with the material breakdown/degradation and vascularization. Further clinical data are necessary to assess extent to which the presence of multinucleated giant cells observed here will influence the materials stability, integration, and, correspondingly, tissue regeneration within human tissue.

Porcine dermal matrix in the treatment of dehiscence-type defects--an experimental split-mouth animal trial

OBJECTIVES

To describe histometrical outcomes (tissue thickness, tissue height) of a porcine dermal matrix (PDX) and subepithelial connective tissue (CTG) in the treatment of dehiscence-type defects.

MATERIAL AND METHODS

In five beagle dogs buccal dehiscence defects were created on both upper canines. The defects were covered in a split-mouth design either with a porcine dermal matrix or subepithelial connective tissue. After 4 months histometrical outcomes were evaluated using a nonparametric Brunner-Langer model.

RESULTS

Neither in the test nor in the control specimen signs of inflammation or foreign body reaction was detected. Histometrically, no significant difference was found for tissue thickness and height between both treatment groups.

CONCLUSIONS

Porcine dermal matrix can be used for grafting of dehiscence-type defects. Augmentation of tissue thickness seems to be comparable to subepithelial connective tissue.

Bone Morphometric Evaluation around Immediately Placed Implants Covered with Porcine-Derived Pericardium Membrane: An Experimental Study in Dogs

Objective. To investigate whether porcine-derived bioresorbable pericardium membrane coverage enhances the osseointegration around implants placed in fresh extraction sockets. Study Design. Twenty-four commercially available endosseous implants were placed in the fresh extraction sockets of the mandibular first molar of mature beagles (n = 6). On one side, implants and osteotomy sites were covered with porcine-derived bioresorbable pericardium membranes, whereas on the other side, no membranes were used. After 6 weeks, samples were retrieved and were histologically processed for histomorphometric analysis. Results. The histological observation showed that bone loss and soft tissue migration in the coronal region of the implant were evident for the control group, whereas bone fill was evident up to the neck of the implant for the membrane-covered group. Bone-to-implant contact was significantly higher for the membrane-covered group compared to the control group, 75% and 45% (P < 0.02), respectively. Conclusion. The experimental membranes proved to regenerate bone around implants placed in fresh extraction sockets without soft tissue intrusion.

Non-cross-linked porcine-based collagen I-III membranes do not require high vascularization rates for their integration within the implantation bed: a paradigm shift

There are conflicting reports concerning the tissue reaction of small animals to porcine-based, non-cross-linked collagen I-III membranes/matrices for use in guided tissue/bone regeneration. The fast degradation of these membranes/matrices combined with transmembrane vascularization within 4 weeks has been observed in rats compared with the slow vascularization and continuous integration observed in mice. The aim of the present study was to analyze the tissue reaction to a porcine-based non-cross-linked collagen I-III membrane in mice. Using a subcutaneous implantation model, the membrane was implanted subcutaneously in mice for up to 60 days. The extent of scaffold vascularization, tissue integration and scaffold thickness were assessed using general and specialized histological methods, together with a unique histomorphometrical analysis technique. A dense Bombyx mori-derived silk fibroin membrane was used as a positive control, whilst a polytetrafluoroethylene (PTFE) membrane served as a negative control. Within the observation period, the collagen membrane induced a mononuclear cellular tissue response, including anti-inflammatory macrophages and the absence of multinucleated giant cells within its implantation bed. Transmembrane scaffold vascularization was not observed, whereas a mild scaffold vascularization was generated through microvessels located at both scaffold surfaces. However, the silk fibroin induced a mononuclear and multinucleated cell-based tissue response, in which pro-inflammatory macrophages and multinucleated giant cells were associated with an increasing transmembrane scaffold vascularization and a breakdown of the membrane within the experimental period. The PTFE membrane remained as a stable barrier throughout the study, and visible cellular degradation was not observed. However, multinucleated giant cells were located on both interfaces. The present study demonstrated that the tested non-cross-linked collagen membrane remained as a stable barrier membrane throughout the study period. The membrane integrated into the subcutaneous connective tissue and exhibited only a mild peripheral vascularization without experiencing breakdown. The silk fibroin, in contrast, induced granulation tissue formation, which resulted in its high vascularization and the breakdown of the material over time. The presence of multinucleated giant cells at both interfaces of the PFTE membrane is a sign of its slow cellular biodegradation and might lead to adhesions between the membrane and its surrounding tissue. This hypothesis could explain the observed clinical complications associated with the retrieval of these materials after guided tissue regeneration.