Synergistic Effects of Shed-Derived Exosomes, Cu2+, and an Injectable Hyaluronic Acid Hydrogel on Antibacterial, Anti-inflammatory, and Osteogenic Activity for Periodontal Bone Regeneration.

The primary pathology of periodontitis involves the gradual deterioration of periodontal tissues resulting from the inflammatory reaction triggered by bacterial infection. In this study, a novel drug for periodontal pocket injection, known as the Shed-Cu-HA hydrogel, was developed by incorporating copper ions (Cu2+) and Shed-derived exosomes (Shed-exo) inside the hyaluronic acid (HA) hydrogel. Suitable concentrations of Cu2+ and Shed-exo released from Shed-Cu-HA enhanced cell viability and cell proliferation of human periodontal ligament stem cells. Additionally, the Shed-Cu-HA demonstrated remarkable antibacterial effects against the key periodontal pathogen (Aa) owing to the synergistic effect of Cu2+ and HA. Furthermore, the material effectively suppressed macrophage inflammatory response via the IL-6/JAK2/STAT3 pathway. Moreover, the Shed-Cu-HA, combining the inflammation-regulating properties of HA with the synergistic osteogenic activity of Shed-exo and Cu2+, effectively upregulated the expression of genes and proteins associated with osteogenic differentiation. The experimental findings from a mouse periodontitis model demonstrated that the administration of Shed-Cu-HA effectively reduced the extent of inflammatory cell infiltration and bacterial infections in gingival tissues and facilitated the regeneration of periodontal bone tissues and collagen after 2 and 4 weeks of injection. Consequently, it holds significant prospects for future applications in periodontitis treatment.

Mesoporous TiO2 Coatings Regulate ZnO Nanoparticle Loading and Zn2+ Release on Titanium Dental Implants for Sustained Osteogenic and Antibacterial Activity.

Two major issues are currently hindering the clinical practice of titanium dental implants for the lack of biological activities: immediate/early loading risks and peri-implantitis. To solve these issues, it is urgent to develop multifunctional implants modified with effective osteogenic and antibacterial properties. Zinc oxide nanoparticles (ZnO NPs) possess superior antibacterial activity; however, they can rapidly release Zn2+, causing cytotoxicity. In this study, a potential dental implant modification was creatively developed as ZnO nanoparticle-loaded mesoporous TiO2 coatings (nZnO/MTC-Ti) via the evaporation-induced self-assembly method (EISA) and one-step spin coating. The mesoporous TiO2 coatings (MTCs) regulated the synthesis and loading of ZnO NPs inside the nanosized pores. The synergistic effects of MTC and ZnO NPs on nZnO/MTC-Ti not only controlled the long-term steady-state release of Zn2+ but also optimized the charge distribution on the surface. Therefore, the cytotoxicity of ZnO NPs was resolved without triggering excessive reactive oxygen species (ROS). The increased extracellular Zn2+ further promoted a favorable intracellular zinc ion microenvironment through the modulation of zinc transporters (ZIP1 and ZnT1). Owing to that, the adhesion, proliferation, and osteogenic activity of bone mesenchymal stem cells (BMSCs) were improved. Additionally, nZnO/MTC-Ti inhibited the proliferation of oral pathogens (Pg and Aa) by inducing bacterial ROS production. For in vivo experiments, different implants were implanted into the alveolar fossa of Sprague-Dawley rats immediately after tooth extraction. The nZnO/MTC-Ti implants were found to possess a higher capability for enhancing bone regeneration, antibiosis, and osseointegration in vivo. These findings suggested the outstanding performance of nZnO/MTC-Ti implants in accelerating osseointegration and inhibiting bacterial infection, indicating a huge potential for solving immediate/early loading risks and peri-implantitis of dental implants.

Synergistic effect of nanostructure and calcium ions on improving the bioactivity of titanium implants.

Surface structure and composition play essential roles in the osseointegration of titanium implants. In the present study, a nanoscale surface structure incorporated with calcium ions was fabricated on a titanium surface by hydrothermal treatment. The characteristics of the surfaces were analysed, and the bioactivity of the samples was evaluated in vitro and in vivo. nm-Ti and nm/Ca-Ti surfaces were significantly more hydrophilic than control-Ti surfaces. nm/Ca-Ti samples showed much faster bone-like apatite precipitation in simulated body fluid than the other samples. The results of MC3T3-E1 cell tests demonstrated that both nm-Ti and nm/Ca-Ti surfaces accelerated cell adhesion and proliferation. The highest level of osteogenesis-related genes (Runx2, bone morphogenetic protein-2, osteopontin and osteocalcin) were observed in nm/Ca-Ti samples, followed by nm-Ti samples. Alizarin red staining experiment showed that the amount of extracellular matrix mineralized nodules in nm/Ca-Ti group was significantly higher than others. In animal experiments using SD rats, nm/Ca-Ti showed the highest value of new bone formation at two and four weeks. The present study suggested that the nanostructure and calcium ions showed synergetic effects on accelerating bone-like apatite precipitation and osteoblast cell growth and differentiation. Animal experiment further indicated that such surface could promote early osteogenesis.

Predictable digital restorative workflow for minimally invasive esthetic rehabilitation utilizing a virtual patient model with global diagnosis principle.

OBJECTIVE: The conventional anterior esthetic treatment protocol is limited as it's time consuming and unreliable. A predictable digital workflow for minimally invasive anterior esthetic tooth rehabilitation with global diagnosis principle has been introduced in this report. CLINICAL CONSIDERATIONS: A 23-year-old female patient with the chief complaint of unsatisfied shape and color of her anterior teeth visited our hospital for restorative consultation. Three-dimensional Digital Smile Design was used to integrate into a virtual patient model to provide rehabilitative esthetic planning with global diagnostic principle. 3D printer was used for communication and guidance preparation. Digital impression and computer-aided design/computer-aided manufacturing technologies were adopted for making the morphology of designed restorations that can precisely transfer to definitive prostheses. The esthetics, functional occlusion, and gingival tissues remained stable for over a follow-up period of 3 years. No signs of fractures within the restorations were observed. CONCLUSIONS: Minimally invasive anterior esthetic tooth rehabilitation can be readily achieved using a predictable digital workflow with global diagnosis principle. CLINICAL SIGNIFICANCE: This digital approach might promote diagnosis, enhance communication, reduce processing time, and increase the predictability of final outcomes with high comfort and esthetic effect.

Double-edged effects and mechanisms of Zn2+ microenvironments on osteogenic activity of BMSCs: osteogenic differentiation or apoptosis.

Zinc-incorporated biomaterials show promoting effects on osteogenesis; however, excessive zinc ions lead to cytotoxic reactions and also have other adverse effects. Therefore, the double-edged effects of Zn2+ microenvironments on osteogenesis may become critical issues for new material development. This study systematically investigated the bidirectional influences of diverse Zn2+ microenvironments on the cell adhesion, proliferation, osteogenic differentiation and apoptosis of rBMSCs. Furthermore, the mechanisms of zinc-induced osteogenic differentiation of rBMSCs and of cell apoptosis induced by high concentration of Zn2+ were both discussed in detail. The results indicated that the Zn2+ microenvironments of 2 µg mL-1 and 5 µg mL-1 effectively improved the initial adhesion and proliferation of rBMSCs, while that of 15 µg mL-1 had exactly the opposite effect. More importantly, the suitable Zn2+ microenvironments (2 µg mL-1 and 5 µg mL-1) moderately increased the intracellular Zn2+ concentration by regulating zinc transportation, and then activated the MAPK/ERK signaling pathway to induce the osteogenic differentiation of rBMSCs. In contrast, the high Zn2+ concentration (15 µg mL-1) not only inhibited the osteogenic differentiation of rBMSCs by damaging intracellular zinc homeostasis, but also induced rBMSC apoptosis by enhancing intracellular ROS generation. The current study clarified the double-edged effects of Zn2+ microenvironments on the osteogenic properties of rBMSCs and the related mechanisms, and may provide valuable guidance for optimizing the design of zinc-doped biomaterials and zinc-based alloys.

Long-term in vivo evolution of high-purity Mg screw degradation - Local and systemic effects of Mg degradation products.

Magnesium (Mg) based materials are the focus of research for use as degradable materials in orthopedics and cranio-maxillofacial surgery. However, corrosion rate control and biosecurity are still the key issues that need to be solved prior to their clinical applications. In the present study, as-rolled high-purity magnesium (HP Mg, 99.99 wt%) screws were implanted in rabbit tibiae for up to 52 weeks in order to investigate their long-term in vivo degradation and the local and systemic effects of their degradation products. A series of long-term monitoring were performed at various time points (4w, 12w, 26w and 52w) after implantation using numerous investigations such as micro-CT assay, histomorphometric analysis, local micro-environment testing and biochemical analysis of serum and urine. It was revealed that HP Mg screws had a uniform degradation morphology and a slow degradation rate in vivo during the period of 52 weeks. Their degradation products not only increased the local pH values but also changed the local Mg2+ ions concentration and gas cavity area in the peri-implant tissues in a dynamic manner. More importantly, both the new bone formation and bone-implant contact rate were increased at bone-implant interfaces at 26 weeks and 52 weeks post-implantation. Furthermore, neither abnormal elevation of serum magnesium and urine magnesium level, nor liver and kidney dysfunction were detected during the monitoring period of 26 weeks. All these results of long-term investigation suggest that HP Mg screws possess a slow degradation rate, desirable bone repair capacity and long-term local/systemic biosafety, and consequently may have good potential for application as bone fixation devices. STATEMENT OF SIGNIFICANCE: The corrosion resistance control and biosecurity issues of Mg alloys limited their clinical applications in some extent. Mg purification is another effective way to improve corrosion resistance of Mg-based materials. However, the long-term in vivo degradation of high-purity magnesium (HP Mg) and the local and systemic effects of its degradation products have not been fully investigated yet, which are the key factors to determine the clinical application prospect of HP Mg. Especially the changes in peri-implant microenvironment may greatly influence the local physiological response and bone repair. In this study, the long-term evolution tendency of in vivo degradation behavior of HP Mg screws was discovered from the view of space-time. Furthermore, not only the dynamic changes of local microenvironment and the long-term evolution process of bone repair, but also the dynamic systemic responses were systematically revealed. Conclusions of this study may help us to further understand the long-term in vivo evolution of HP Mg degradation and the local/systemic effects of its degradation products and help to guide the design of biodegradable bone fixation material.

Multifunctions of dual Zn/Mg ion co-implanted titanium on osteogenesis, angiogenesis and bacteria inhibition for dental implants.

In order to improve the osseointegration and long-term survival of dental implants, it is urgent to develop a multifunctional titanium surface which would simultaneously have osteogeneic, angiogeneic and antibacterial properties. In this study, a potential dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed via plasma immersion ion implantation (PIII). The Zn/Mg-PIII surfaces were found to promote initial adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) via the upregulation of the gene expression of integrin α1 and integrin ß1. More importantly, it was revealed that Zn/Mg-PIII could increase Zn2+ and Mg2+ concentrations in rBMSCs by promoting the influx of Zn2+ and Mg2+ and inhibiting the outflow of Zn2+, and then could enhance the transcription of Runx2 and the expression of ALP and OCN. Meanwhile, Mg2+ ions from Zn/Mg-PIII increased Mg2+ influx by upregulating the expression of MagT1 transporter in human umbilical vein endothelial cells (HUVECs), and then stimulated the transcription of VEGF and KDR via activation of hypoxia inducing factor (HIF)-1α, thus inducing angiogenesis. In addition to this, it was discovered that zinc in Zn/Mg-PIII had certain inhibitory effects on oral anaerobic bacteria (Pg, Fn and Sm). Finally, the Zn/Mg-PIII implants were implanted in rabbit femurs for 4 and 12weeks with Zn-PIII, Mg-PIII and pure titanium as controls. Micro-CT evaluation, sequential fluorescent labeling, histological analysis and push-out test consistently demonstrated that Zn/Mg-PIII implants exhibit superior capacities for enhancing bone formation, angiogenesis and osseointegration, while consequently increasing the bonding strength at bone-implant interfaces. All these results suggest that due to the multiple functions co-produced by zinc and magnesium, rapid osseointegration and sustained biomechanical stability are enhanced by the novel Zn/Mg-PIII implants, which have the potential application in dental implantation in the future. STATEMENT OF SIGNIFICANCE: In order to enhance the rapid osseointegration and long-term survival of dental implants, various works on titanium surface modification have been carried out. However, only improving osteogenic activity of implants is not enough, because angiogenesis and bacteria inhibition are also very important for dental implants. In the present study, a novel dental implant material-dual Zn/Mg ion co-implanted titanium (Zn/Mg-PIII) was developed, which was found to have superior osteoinductivity, pro-angiogenic effects and inhibitory effects against oral anaerobes. Furthermore, synergistic effects of Zn/Mg ions on osteogenic differentiation of rBMSCs and the possible mechanism were discovered. In addition, rapid osseointegration and sustained biomechanical stability are greatly enhanced by Zn/Mg-PIII implants, which may have the potential application in dental implantation in the future. We believe this paper may be of particular interest to the readers.

Osteoinduction and long-term osseointegration promoted by combined effects of nitrogen and manganese elements in high nitrogen nickel-free stainless steel.

High nitrogen nickel-free stainless steel (HNS) has attracted particular attention in recent years, because of its potential application in orthopedic implants. However, the effects of HNS on osteoblast differentiation of bone marrow mesenchymal stem cells and long-term osseointegration are still unclear. In this study, a newly developed HNS with high manganese (Mn) content (Fe-21Cr-16Mn-2Mo-0.93N) was successfully manufactured. The HNS exhibited the improved bio-corrosion resistance and surface hydrophilicity compared to 316L stainless steel (316L SS) due to its high nitrogen (N) content. The hydrophilic surface of HNS could promote initial adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) via the upregulation of the gene expression of integrin α1 and integrin ß1. The high Mn and nickel-free content of HNS facilitated rBMSC proliferation. More importantly, it was revealed that ionic manganese from HNS could enhance the expression levels of osteoblast-related genes (RUNX-2, ALP, OCN and OPN) of rBMSCs, as well as promote ALP activity and OCN protein expression. Moreover, the activation of extracellular signal-related kinases (ERK) 1/2 pathway, via which HNS might induce osteogenic differentiation, was observed in rBMSCs cultured on HNS. Finally, based on HNS implantation in rabbit tibiae for 4, 12 and 26 weeks with 316L SS as a control, Micro-CT evaluation, sequential fluorescent labeling and histological analysis consistently demonstrated that HNS evidently promoted new bone formation and bone-implant contact around implants. Biomechanical tests also confirmed the increased bonding strength at the bone-HNS implant interface in both early and late stages. These results suggest that HNS can induce osteogenic differentiation of rBMSCs and promote rapid and long-term osseointegration of implants, which may be attributed to the combined effects of N and Mn elements.

[The study of the monomer release from four kinds of temporary crown material by infrared spectrum].

PURPOSE: To study the quantity and characteristic of monomer release from four kinds of temporary crown material. METHODS: The experimental animal model was established by temporary prosthesis on dogs' teeth using four kinds of temporary crown materials.The quantity of residual monomer in temporary crown material was measured by infrared spectra at four different periods before and after wearing crowns. The data were analysed with SAS6.12 software package for one-way ANOVA. RESULTS: During the early period after wearing temporary crowns, the quantity of residual monomer from self-curing resin crowns and heat-curing resin crowns was significantly more than that from DMG-TEMP crown material and Shofu SWIFT-TEMP resin. With the time going on, the difference became less. The residual monomer in DMG-TEMP crown material and Shofu SWIFT-TEMP resin remained steady at a low level all the time, without significant monomer release. CONCLUSIONS: There is significant monomer release from self-curing resin crowns and heat-curing resin crowns early after wearing temporary crowns. DMG-TEMP crowns and Shofu SWIFT-TEMP crowns don't release significant residual monomer.