Xenogeneic bone substitute materials are widely used in oral implantology. Prior to their clinical use, purification of the former bone tissue has to be conducted to ensure the removal of immunogenic components and pathogens. Different physicochemical methods are applied for purification of the donor tissue, and temperature treatment is one of these methods. Differences in these methods and especially the application of different temperatures for purification may lead to different material characteristics, which may influence the tissue reactions to these materials and the related (bone) healing process. However, little is known about the different material characteristics and their influences on the healing process. Thus, the aim of this mini-review is to summarize the preparation processes and the related material characteristics, safety aspects, tissue reactions, resorbability and preclinical and clinical data of two widely used xenogeneic bone substitutes that mainly differ in the temperature treatment: sintered (cerabone) and non-sintered (Bio-Oss) bovine-bone materials. Based on the summarized data from the literature, a connection between the material-induced tissue reactions and the consequences for the healing processes are presented with the aim of translation into their clinical application.

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.

Worldwide population aging and associated with it epidemics of osteoporosis, widespread of bone and joint reconstructive surgery and first of all joint replacement lead to explosive growth of interest in bone grafting.Although autografts are still the golden standard in bone regeneration, allogeneic bone substitutes have reached a state that allows for their application with satisfying clinical results. However, it has repeatedly been supposed that the different allogeneic materials underwent different purification processes, which modifies bone regeneration properties of these materials and also for different safety conditions. In the present publication, the treatment of the precursor tissue, the safety conditions, and the regenerative possibilities of C+TBA bone blocks based in preclinical and clinical data are described. Thus, it is described how the risks of infections and also immunological reactions becomes completely eliminated, while the special purification process allows for preservation of the native structure of the bone block. Both the in vitro studies and the clinical trials including histological follow-ups showed the optimal regeneration properties of these bone blocks. It has been shown that the allogeneic bone grafts have been integrated without causing inflammatory anomalies at the implantation site. Altogether, the allogeneic bone substitute material serves as an excellent basis for the formation of new bone. Finally, the combination of the allogeneic C+TBA bone blocks with different antibiotics is described. Interestingly, it is possible to combine the allogeneic bone substitute ether with antibiotics in the sense of prophylaxis and/or with bone marrow aspirate in order to accelerate bone remodeling.

Although various studies have investigated differences in the tissue reaction pattern to synthetic and xenogeneic bone substitute materials (BSMs), a lack of knowledge exists regarding the classification of both materials based on the DIN ISO 10993-6 scoring system, as well as the histomorphometrical measurement of macrophage subtypes within their implantation beds. Thus, the present study was conducted to analyze in vivo responses to both xenogeneic and synthetic bone substitute granules. A standardized calvaria implantation model in Wistar rats, in combination with established scoring, histological, histopathological, and histomorphometrical methods, was conducted to analyze the influence of both biomaterials on bone regeneration and the immune response. The results showed that the application of the synthetic BSM maxresorb® induced a higher pro-inflammatory tissue response, while the xenogeneic BSM cerabone® induced a higher anti-inflammatory reaction. Additionally, comparable bone regeneration amounts were found in both study groups. Histopathological scoring revealed that the synthetic BSM exhibited non-irritant scores at all timepoints using the xenogeneic BSM as control. Overall, the results demonstrated the biocompatibility of synthetic BSM maxresorb® and support the conclusion that this material class is a suitable alternative to natural BSM, such as the analyzed xenogeneic material cerabone®, for a broad range of indications.

In general, it has been revealed that interaction of bone substitute material with the host immune system is dependent upon their physico-chemical properties. In the case of xeno-grafts, different purification methods are applied to process the precursor tissue. One purification method that differs the most is the applied temperature. Materials treated with low and high temperatures are available. In this context, the question remains as to the influence of the different temperature treatments on the physical and chemical material properties and, thus, on the tissue reactions during the healing processes. It has been hypothesized that materials that induce mononuclear cells induce physiological healing processes, while a pathological reaction is accompanied with the induction of multinucleated giant cells (MNGCs). In this mini-review, the focus is on the comparison of preclinical research into tissue reactions to sintered and non-sintered bovinederived xenograft. Interpretation of this data showed that an induction of higher numbers of MNGCs by sintered xenograft also induced a higher implant bed vascu-larization. Finally, the higher number of MNGCs and increased vascularization presumably resulted in a higher expression of anti-inflammatory molecules that may support the process of bone remodeling.

Background: Bioglass is a highly adoptable bone substitute material which can be combined with so-called therapeutic ions. However, knowledge is poor regarding the influence of therapeutic ions on immune reactions and associated bone healing. Thus, the aim of this work was to investigate the influence of strontium-and copper-doped bioglass on the induction of M1 and M2 macrophages, as well as vascularization. Materials and Methods: Two types of alkali glass were produced based on ICIE16 bioglass via the melt-quench method with the addition of 5 wt% copper or strontium . Pure ICIE16 and 45S5 bioglass were used as control materials. The ion release and chemical composition of the bioglass were investigated, and an in vivo experiment was subcutaneously performed on Sprague-Dawley rats. Results: Scanning electron microscopy revealed significant differences in the surface morphology of the bioglass materials. Energy dispersive X-ray spectroscopy confirmed the efficiency of the doping process by showing the ion-release kinetics. ICIE16-Cu exhibited a higher ion release than ICIE16-Sr. ICIE16-Cu induced low immune cell migration and triggered not only a low number of M1 and M2 macrophages but also of blood vessels. ICIE16-Sr induced higher numbers of M1 macrophages after 30 days. Both bioglass types induced numbers of M2 macrophages comparable with those found in the control groups. Conclusion: Bioglass doping with copper and strontium did not significantly influence the foreign body response nor vascularization of the implantation bed in vivo. However, all the studied bioglass materials seemed to be biocompatible.Bone substitute materials (BSMs) are a small group including biomaterials mainly based on natural or synthetic calcium phosphates and similar compounds (1). Bioactive glass is a specific subgroup which has been shown to be a good BSM due to its optimal bonding to newly formed bone tissue and due to the formation of a hydroxycarbonate apatite layer which supports bone regeneration (2). Since the invention of bioactive glass materials in the 1970s by Professor Larry L. Hench, with 45S5 ® bioglass being one of the first developed materials, much research has been conducted on bioactive glass (3). Silicate-based bioactive glass and glass ceramics, such as Perioglas ® (4) and Ceravital ® (5, 6), have been clinically used as BSMs for several decades. Nevertheless, 2149

The current environmental problems require the use of low-energy, environmentally friendly methods and nature-like technologies for the creation of materials. In this work, we aim to study the possibility of the direct biotransformation of fibrillar cellulose by fungi through obtaining a cellulose/mycelium-based biocomposite. The cellulose micro- and nanofibrils were used as the main carbon sources in the solid-phase cultivation of basidiomycete Trametes hirsuta. The cellulose fibrils in this process act as a template for growing mycelium with the formation of well-developed net structure. The biotransformation dynamics of cellulose fibrils were studied with the help of scanning electron microscopy. The appearance of nitrogen in the structure of formed fibers was revealed by elemental analysis and FTIR-spectroscopy. The fibers diameters were estimated based on micrograph analysis and the laser diffraction method. It was shown that the diameter of cellulose fibrils can be tuned by fungi through obtaining cellulose-based mycelium fibers with a narrower diameter-size distribution as compared to the pristine cellulose fibrils. The morphology of the resulting mycelium differed when the micro or nanofibrils were used as a substrate.

Background. There are few cases of entire femur modular replacement with hip and knee joints in patients with periprosthetic joint infection (PJI) in literature. They report encouraging results in patients of elderly and senile age. We present case of a copper-coated femoral spacer implantation to 50-year-old patient with multiple PJI episodes and osteomyelitis of the entire femur.Clinical presentation. A 40-year-old male patient after resection of the proximal part of the right femur for fibrotic osteodysplasia underwent total hip arthroplasty with replacement of 15 cm of the femur. In December 2010 (20 months after implantation), instability of the femoral component developed, revision arthroplasty was performed with stem recementation. After 4 months, sinus tract formed in the area of the postoperative scar. After another 4 months, the head of the prosthesis was dislocated. In September 2011, the endoprosthesis components were removed and a unipolar cement spacer was implanted. The limb immobilized in a hip spica cast. Methicillin-sensitive S. epidermidis (MSSE) was detected in the preoperative joint aspiration puncture and periprosthetic tissues. After 3 months (December 2011), patient underwent revision total hip arthroplasty (25 cm defect was replaced). 5 years of PJI remission followed. In November 2016 after PJI recurrence the endoprosthesis was removed, and an articulating spacer was implanted. P. aeruginosa was detected in periprosthetic tissues. For the past 2.5 years there were periodically sinus tracts formations. In August of 2019 spacer’s migration resulted in an intercondylar fracture of the right femur. In September 2019, spacer was removed, and MSSE was detected in the surrounding tissues. An articulating cement spacer based on an oncological modular total femur coppercoated endoprosthesis was implanted. At each control examination during the year copper concentration in blood serum was determined, it did not exceed 900–1200 mcg/l. No local or systemic side effects were detected. The patient started working 3 months after surgery. After 6 months poor functioning sinus tract formed in the postoperative scar area in the lower third of the thigh. 1.5 years after the operation, the functional condition is satisfactory.Conclusion. The use of the copper-coated spacer based on modular total femur endoprosthesis with hip and knee joints in a patient with multiple PJI allowed to improve the function of the limb and reduce the severity of the infectious process. No local or systemic toxic effects of copper were detected.