Periodontal pockets are the major clinical manifestation of Periodontitis, a chronic inflammatory oral disease affecting the teeth-supporting tissues and has high prevalence in the adult population. Periodontal pockets are ideal environments for subgingival bacterial biofilms, that interact with the supragingival oral cavity, mucosal tissues of the pocket and a peripheral circulatory system. Periodontal pockets have been found to harbor viral species such as the Herpes simplex viruses’ family. Recently, the SARS-CoV-2 has gained major interest of the scientific/medical community as it caused a global pandemic (Covid-19) and paralyzed the globe with high figures of infected people worldwide. This virus behavior is still partially understood, and by analyzing some of its features we hypothesized that periodontal pocket could be a favorable anatomical niche for the virus and thus acting as a reservoir for SARS-CoV-2.

Percutaneous and permucosal devices such as catheters, infusion pumps, orthopedic, and dental implants are commonly used in medical treatments. However, these useful devices breach the soft tissue barrier that protects the body from the outer environment, and thus increase bacterial infections resulting in morbidity and mortality. Such associated infections can be prevented if these devices are effectively integrated with the surrounding soft tissue, and thus creating a strong seal from the surrounding environment. However, so far, there are no percutaneous/permucosal medical devices able to prevent infection by achieving strong integration at the soft tissue-device interface. This review gives an insight into the current status of research into soft tissue-implant interface and the challenges associated with these interfaces. Biological soft/hard tissue interfaces may provide insights toward engineering better soft tissue interfaces around percutaneous devices. In this review, focus is put on the history and current findings as well as recent progress of the strategies aiming to develop a strong soft tissue seal around osseointegrated implants, such as orthopedic and dental implants.

The gold standard material for bone regeneration is still autologous bone, a mesenchymal tissue that consists mainly of extracellular matrix (ECM) (90% v/v) and little cellular content (10% v/v). However, the fact that decellularized allogenic bone grafts often present a clinical performance comparable to autologous bone grafts demonstrates the crucial role of ECM in bone regeneration. For long, the mechanism by which bone allografts function was not clear, but recent research has unveiled many unique characteristics of ECM that seem to play a key role in tissue regeneration. This is further confirmed by the fact that synthetic biomaterials with composition and properties resembling bone ECM present excellent bone regeneration properties. In this context, ECM molecules such as glycosaminoglycans (GAGs) and self-assembly peptides (SAPs) can improve the performance of bone regeneration biomaterials. Moreover, decellularized ECM derived either from native tissues such as bone, cartilage, skin, and tooth germs or from cells such as osteoblasts, chondrocytes, and stem cells has shown promising results in bone regeneration applications. Understanding the role of ECM in bone regeneration is crucial for the development of the next generation of biomaterials for bone tissue engineering. In this sense, this review addresses the state-of-the-art on this subject matter.

Background and purpose: Gallium (Ga) has been shown to be effective in the treatment of disorders associated with accelerated bone loss, including cancer-related hypercalcemia and Paget's disease. These clinical applications suggest that Ga could reduce bone resorption. However, few studies have studied the effects of Ga on osteoclastic resorption. Here, we have explored the effects of Ga on bone cells in vitro. Experimental approach:In different osteoclastic models [osteoclasts isolated from long bones of neonatal rabbits (RBC), murine RAW 264.7 cells and human CD14-positive cells], we have performed resorption activity tests, staining for tartrate resistant acid phosphatase (TRAP), real-time polymerase chain reaction analysis, viability and apoptotic assays. We also evaluated the effect of Ga on osteoblasts in terms of proliferation, viability and activity by using an osteoblastic cell line (MC3T3-E1) and primary mouse osteoblasts. Key results: Gallium dose-dependently (0-100 mM) inhibited the in vitro resorption activity of RBC and induced a significant decrease in the expression level of transcripts coding for osteoclastic markers in RAW 264.7 cells. Ga also dramatically reduced the formation of TRAP-positive multinucleated cells. Ga down-regulated in a dose-dependant manner the expression of the transcription factor NFATc1. However, Ga did not affect the viability or activity of primary and MC3T3-E1 osteoblasts. Conclusions and implications:Gallium exhibits a dose-dependent anti-osteoclastic effect by reducing in vitro osteoclastic resorption, differentiation and formation without negatively affecting osteoblasts. We provide evidence that this inhibitory mechanism involves down-regulation of NFATc1 expression, a master regulator of RANK-induced osteoclastic differentiation.

Activated platelet concentrates are autologous blood preparations containing supraphysiological concentration of platelets. Platelet concentrates are commonly used for bone regeneration purposes based on the fact that growth factors released from activated platelets alpha granules have osteoinductive effects on bone cells. Although most preclinical and clinical studies show that platelet concentrates improve the outcomes of bone regeneration procedures, some studies reported conflicting results and even negative effects on bone healing. Several confounding parameters have been suggested as possible reasons for such inconsistencies (i.e. preparation and activation methods). However, heterogeneity in clinical studies makes drawing evidence-based conclusions difficult. On the other hand, recent findings show that the constituents of platelets dense granules (i.e. serotonin, ATP, Ca) have potential inhibitory effects on bone metabolism. Accordingly, we suggest that a partial explanation for the conflicting results could be the potential negative effects that dense granules may have on bone healing.

Platelet concentrates (PCs) are biological autologous products derived from the patient's whole blood and consist mainly of supraphysiologic concentration of platelets and growth factors (GFs). These GFs have anti-inflammatory and healing enhancing properties. Overall, PCs seem to enhance bone and soft tissue healing in alveolar ridge augmentation, periodontal surgery, socket preservation, implant surgery, endodontic regeneration, sinus augmentation, bisphosphonate related osteonecrosis of the jaw (BRONJ), osteoradionecrosis, closure of oroantral communication (OAC), and oral ulcers. On the other hand, no effect was reported for gingival recession and guided tissue regeneration (GTR) procedures. Also, PCs could reduce pain and inflammatory complications in temporomandibular disorders (TMDs), oral ulcers, and extraction sockets. However, these effects have been clinically inconsistent across the literature. Differences in study designs and types of PCs used with variable concentration of platelets, GFs, and leucocytes, as well as different application forms and techniques could explain these contradictory results. This study aims to review the clinical applications of PCs in oral and craniofacial tissue regeneration and the role of their molecular components in tissue healing.

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Periodontal pockets are the major clinical manifestation of Periodontitis, a chronic inflammatory oral disease affecting the teeth-supporting tissues and has high prevalence in the adult population. Periodontal pockets are ideal environments for subgingival bacterial biofilms, that interact with the supragingival oral cavity, mucosal tissues of the pocket and a peripheral circulatory system. Periodontal pockets have been found to harbor viral species such as the Herpes simplex viruses’ family. Recently, the SARS-CoV-2 has gained major interest of the scientific/medical community as it caused a global pandemic (Covid-19) and paralyzed the globe with high figures of infected people worldwide. This virus behavior is still partially understood, and by analyzing some of its features we hypothesized that periodontal pocket could be a favorable anatomical niche for the virus and thus acting as a reservoir for SARS-CoV-2