Mooring Stone-Like Arg114 Pulls Diverse Bulged Peptides: First Insight into African Swine Fever Virus-Derived T Cell Epitopes Presented by Swine Major Histocompatibility Complex Class I.

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF), which is a devastating pig disease threatening the global pork industry. However, currently, no commercial vaccines are available. During the pig immune response, major histocompatibility complex class I (MHC-I) molecules select viral peptide epitopes and present them to host cytotoxic T lymphocytes, thereby playing critical roles in eliminating viral infections. Here, we screened peptides derived from ASFV and determined the molecular basis of ASFV-derived peptides presented by the swine leukocyte antigen 1*0101 (SLA-1*0101). We found that peptide binding in SLA-1*0101 differs from the traditional mammalian binding patterns. Unlike the typical B and F pockets used by the common MHC-I molecule, SLA-1*0101 uses the D and F pockets as major peptide anchor pockets. Furthermore, the conformationally stable Arg114 residue located in the peptide-binding groove (PBG) was highly selective for the peptides. Arg114 draws negatively charged residues at positions P5 to P7 of the peptides, which led to multiple bulged conformations of different peptides binding to SLA-1*0101 and creating diversity for T cell receptor (TCR) docking. Thus, the solid Arg114 residue acts as a "mooring stone" and pulls the peptides into the PBG of SLA-1*0101. Notably, the T cell recognition and activation of p72-derived peptides were verified by SLA-1*0101 tetramer-based flow cytometry in peripheral blood mononuclear cells (PBMCs) of the donor pigs. These results refresh our understanding of MHC-I molecular anchor peptides and provide new insights into vaccine development for the prevention and control of ASF. IMPORTANCE The spread of African swine fever virus (ASFV) has caused enormous losses to the pork industry worldwide. Here, a series of ASFV-derived peptides were identified, which could bind to swine leukocyte antigen 1*0101 (SLA-1*0101), a prevalent SLA allele among Yorkshire pigs. The crystal structure of four ASFV-derived peptides and one foot-and-mouth disease virus (FMDV)-derived peptide complexed with SLA-1*0101 revealed an unusual peptide anchoring mode of SLA-1*0101 with D and F pockets as anchoring pockets. Negatively charged residues are preferred within the middle portion of SLA-1*0101-binding peptides. Notably, we determined an unexpected role of Arg114 of SLA-1*0101 as a "mooring stone" which pulls the peptide anchoring into the PBG in diverse "M"- or "n"-shaped conformation. Furthermore, T cells from donor pigs could activate through the recognition of ASFV-derived peptides. Our study sheds light on the uncommon presentation of ASFV peptides by swine MHC-I and benefits the development of ASF vaccines.

Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics.

Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.

Colloidal Phenol-Amine Coating on Implants for Improved Anti-Inflammation and Osteogenesis.

Phenol-amine coatings have attracted significant attention in recent years owing to their adjustable composition and multifaceted biological functionalities. The current preparation of phenol-amine coatings, however, involves a chemical reaction within the solution or interface, resulting in lengthy preparation times and necessitating specific reaction conditions, such as alkaline environments and oxygen presence. The facile, rapid, and eco-friendly preparation of phenol-amine coatings under mild conditions continues to pose a challenge. In this study, we use a macromolecular phenol-amine, Tanfloc, to form a stable colloid under neutral conditions, which was then rapidly adsorbed on the titanium surface by electrostatic action and then spread and fused to form a continuous coating within several minutes. This nonchemical preparation process was rapid, mild, and free of chemical additives. The in vitro and in vivo results showed that the Tanfloc colloid fusion coating inhibited destructive inflammation, promoted osteogenesis, and enhanced osteointegration. These remarkable advantages of the colloidal phenol-amine fusion coating highlight the suitability of its future application in clinical practice.

Cellulose nanofibers-based composite film with broadening MXene layer spacing and rapid moisture separation for humidity sensing and humidity actuators.

Based on the basic idea of expanding the interlayer spacing of MXene, utilizing the effect of gallic acid-modified cellulose nanofibers for rapid moisture separation, the flexible sensing and driving composite film with a perfect balance among humidity signal response and mechanical properties was prepared. Inspired by the stacking of autumn fallen leaves, the cellulose nanofibers-based composite films were formed by self-assembly under vacuum filtration of blending gallic acid-modified cellulose nanofibers with MXene. The enhanced mechanical properties (tensile strength 131.1 MPa, puncture load 0.88 N, tearing strength 165.55 N/mm, and elongation at break 16.14 %), humidity sensing (the stable induced voltage 63.7 mV and response/recovery time 3.2/5.1 s), and humidity driving (154.7° bending angle) properties were observed. The synergistic effect of hydrogen bonds, the "pinning effect" arising from the side chains, and the hierarchical layered microstructure contributed to the enhanced performance. This work exemplifies the application of green natural product for preparing intelligent sensing, wearable devices, and biomimetic robots.

Built-up sodium alginate/chlorhexidine multilayer coating on dental implants with initiating anti-infection and cyto-compatibility sequentially for soft-tissue sealing.

Soft-tissue sealing at transmucosal sites is very important for preventing the invasion of pathogens and maintaining the long-term stability and function of dental implants. However, the colonization of oral pathogens on the implant surface and surrounding soft tissues can disturb the early establishment of soft-tissue sealing and even induce peri-implant infection. The purpose of this study was to construct two antibacterial coatings with 5 or 10 sodium alginate/chlorhexidine bilayers on titanium surfaces using layer-by-layer self-assembly technology to promote soft-tissue sealing. The corresponding chemical composition, surface topography, wettability and release behaviour were investigated to prove that the resultant coating of sodium alginate and chlorhexidine was coated on the porous titanium surface. In-vitro and in-vivo antibacterial results showed that both prepared coatings inhibited or killed the bacteria on their surfaces and the surrounding areas to prevent plaque biofilm formation, especially the coating with 10 bilayers. Although both coatings inhibited the initial adhesion of fibroblasts, the cytocompatibility gradually improved with coating degradation. More importantly, both coatings achieved cell adhesion and proliferation in an in-vitro bacterial environment and effectively alleviated bacteria-induced subcutaneous inflammation in-vivo. Therefore, this study demonstrated that the multilayered coating could prevent implant-related infections in the initial stage of implant surgery and then improve soft-tissue integration with implant devices.

A programmed surface on dental implants sequentially initiates bacteriostasis and osseointegration.

Osteogenesis surrounding dental implants is initiated by a series of early physiological events, including the inflammatory response. However, the persistence of an anti-infection surface often results in compromised histocompatibility and osseointegration. Here, we presented a programmed surface containing both silver nanoparticles (AgNPs) and silver ions (Ag+) with a heterogeneous structure and time-dependent functionalities. The AgNPs were located at the surface of the heparin-chitosan polyelectrolyte coating (PEM), whereas Ag+ was distributed at both the surface and inside of the coating under optimized conditions (pH=4). The optimized coating (Ag-4) exhibited potent bactericidal activity at the early stage (12 and 24 h after inoculation) and a sustained antibacterial efficacy in the subsequent stage (one or two weeks), as it gradually depleted. Furthermore, compared to coatings with sustained high silver concentrations in bacteria-cell coculture experiments, the degradable Ag-4 coating demonstrated improved cytocompatibility, better cell viability, and morphology over time. At a later stage (within one month), the in vivo test revealed that Ag-4-coated titanium had superior histocompatibility and osteogenesis outcomes compared to bare titanium in a bacteria-exposed environment. The programmed surface of dental implants presented in this study offers innovative ideas for sequential antibacterial effects and osseointegration.

A homogeneous dopamine-silver nanocomposite coating: striking a balance between the antibacterial ability and cytocompatibility of dental implants.

Silver has been widely used for surface modification to prevent implant-associated infections. However, the inherent cytotoxicity of silver greatly limited the scope of its clinical applications. The construction of surfaces with both good antibacterial properties and favorable cytocompatibility still remains a challenge. In this study, a structurally homogeneous dopamine-silver (DA/Ag) nanocomposite was fabricated on the implant surface to balance the antibacterial activity and cytocompatibility of the implant. The results show that the DA/Ag nanocomposites prepared under the acidic conditions (pH = 4) on the titanium surface are homogeneous with higher Ag+ content, while an obvious core (AgNPs)-shell (PDA) structure is formed under neutral (pH = 7) and alkaline conditions (pH = 10), and the subsequent heat treatment enhanced the stability of PDA-AgNPs nanocomposite coatings on porous titanium. The antibacterial test, cytotoxicity test, hypodermic implantation and osteogenesis test revealed that the homogeneous PDA-AgNPs nanocomposite coating achieved the balance between the antibacterial ability and cytocompatibility, and had the best outcomes for soft tissue healing and bone formation around the implants. This study provides a facile strategy for preparing silver-loaded surfaces with both good antibacterial effect and favorable cytocompatibility, which is expected to further improve the therapeutic efficacy of silver composite-coated dental implants.

Real-world study of antiresorptive-related osteonecrosis of jaw based on the US food and drug administration adverse event reporting system database.

Objective: This study aims to explore the risk signals of osteonecrosis of the jaw induced by antiresorptive drugs and provide references for the clinical safety application. Method: According to the FDA's Adverse Event Reporting System (FAERS), from January 2004 to September 2021, we chose "Osteonecrosis of the jaw (10064658)" and "Exposed bone in jaw (10071014)" as preferred terms, "antiresorptive drugs" as the target drugs, and primary suspect drug as the drug role code in the dataset. We evaluated the association between drugs and adverse events by using reporting odds ratio (ROR) based on disproportionality analysis. We took the High-Level Terms (HLT) of MedDRA® as the classification level of indications to calculate ROR to compare the signal difference of ONJ in different indications. In addition, patients with antiresorptive-induced osteonecrosis of the jaw and the time of onset of the condition following different antiresorptive medications were collected for the study. Results: The FAERS contained 18,421 reports relating to jaw osteonecrosis from January 2004 to September 2021. A total of eight antiresorptive agents were included in the analysis. From high to low, the ROR of ONJ induced by antiresorptive agents (regardless of indication) is pamidronate (ROR = 494.8), zoledronic acid (ROR = 431.9), denosumab (ROR = 194.8), alendronate (ROR = 151.2), risedronate (ROR = 140.2), etidronic acid (ROR = 64.5), ibandronate (ROR = 40.8), and romosozumab (ROR = 6.4). HLT ROR values for "metabolic bone disorders" were the lowest for each drug, while HLT ROR values were high for "tumor-related indications," including breast and nipple neoplasms malignant, plasma cell myelomas, and prostatic neoplasms malignant. The onset time for osteonecrosis of the jaw as median (Q1, Q3), osteoporosis-related indications, and the onset time for ONJ were 730 (368, 1268), 489.5 (236.3, 909.8), 722.5 (314, 1055), 761 (368, 1720), and 153 (50, 346) for zoledronic acid, denosumab, ibandronate, risedronate, and romosozumab, respectively. Cancer-related indications: the onset time for ONJ were 680.5 (255.3, 1283), 488 (245, 851), and 696.5 (347, 1087) for zoledronic acid, denosumab, and pamidronate, respectively. Conclusion: When antiresorptive drugs are used for metastasis, they have the largest risk signal, followed by malignancy, and the smallest is osteoporosis. The onset time of ONJ may not be related to the indications. The onset time of ONJ for BPs was about 2 years, denosumab about 1.3 years, and romosozumab less than 1 year, which may be related to sequential treatment. When used according to the instructions, the risk of ONJ caused by denosumab was higher than that of zoledronic acid, regardless of the indication. Based on these findings, researchers will continue to monitor and identify risk factors.

Comparison of in Vascular Bioreactors and In Vivo Models of Degradation and Cellular Response of Mg-Zn-Mn Stents.

Traditional in vitro evaluation criteria of magnesium (Mg)-based stents cannot reflect the degradation process in vivo, due to the interdependence and interference between biodegradable properties and bioenvironment. The current direct and indirect evaluation approaches of in vitro biocompatibility do not have a hydrodynamic environment and vascular biological structure existing in vivo. Herein, we designed a vascular bioreactor to provide an ex vivo culture environment for vessels, which reveals the degradation behavior of Mg-Zn-Mn stent and the effect of its degradation on cells. We reported that rabbit carotid arteries could maintain native morphology and viability in the bioreactor under the best condition within a flow rate of 5.4 mL min-1 and a culture time of one week. With this culture condition, Mg-Zn-Mn stents were implanted into the arteries in the bioreactors and compared with in vivo rabbit models. The arteries maintained cell survival in the bioreactor, but the cell attachment was absent on the stent struts, associated with a fast degradation. Conversely, the stents achieved a rapid and complete endothelialization in vivo for two weeks. This study could provide a correlation and difference of the degradation behavior and cellular response to the degradation of Mg-based stent between ex vivo and in vivo approaches.

Multifunctional Coatings of Titanium Implants Toward Promoting Osseointegration and Preventing Infection: Recent Developments.

Titanium and its alloys are dominant material for orthopedic/dental implants due to their stable chemical properties and good biocompatibility. However, aseptic loosening and peri-implant infection remain problems that may lead to implant removal eventually. The ideal orthopedic implant should possess both osteogenic and antibacterial properties and do proper assistance to in situ inflammatory cells for anti-microbe and tissue repair. Recent advances in surface modification have provided various strategies to procure the harmonious relationship between implant and its microenvironment. In this review, we provide an overview of the latest strategies to endow titanium implants with bio-function and anti-infection properties. We state the methods they use to preparing these efficient surfaces and offer further insight into the interaction between these devices and the local biological environment. Finally, we discuss the unmet needs and current challenges in the development of ideal materials for bone implantation.

Efficient inactivation of African swine fever virus by a highly complexed iodine.

African swine fever (ASF) is a highly lethal contagious disease of swine caused by African swine fever virus (ASFV). Cleaning and disinfection remain one of the most effective tools to prevent the ASFV spread in pig holdings. This study evaluated the inactivation effect of a highly complexed iodine (HPCI) disinfectant against ASFV. A commercially available povidone-iodine (PVP-I) was used as reference for comparison. The results showed that 5% HPCI and 5% PVP-I did not exhibit cytotoxicity in primary porcine alveolar macrophages, and 107.0 and 105.0 TCID50/mL ASFV were completely inactivated by 5% and 0.25% HPCI, respectively, in 5 min via either immersion or spray disinfection. However, 5% PVP-I required at least 15 min to completely inactivate 107.0 TCID50/mL ASFV, whereas 0.25% PVP-I failed to completely inactivate 105.0 TCID50/mL ASFV. This study demonstrated that HPCI could rapidly and efficiently inactivate ASFV, representing an effective disinfectant for ASF control.

A tough nitric oxide-eluting hydrogel coating suppresses neointimal hyperplasia on vascular stent.

Vascular stent is viewed as one of the greatest advancements in interventional cardiology. However, current approved stents suffer from in-stent restenosis associated with neointimal hyperplasia or stent thrombosis. Herein, we develop a nitric oxide-eluting (NOE) hydrogel coating for vascular stents inspired by the biological functions of nitric oxide for cardiovascular system. Our NOE hydrogel is mechanically tough and could selectively facilitate the adhesion of endothelial cells. Besides, it is non-thrombotic and capable of inhibiting smooth muscle cells. Transcriptome analysis unravels the NOE hydrogel could modulate the inflammatory response and induce the relaxation of smooth muscle cells. In vivo study further demonstrates vascular stents coated with it promote rapid restoration of native endothelium, and persistently suppress inflammation and neointimal hyperplasia in both leporine and swine models. We expect such NOE hydrogel will open an avenue to the surface engineering of vascular implants for better clinical outcomes.

Electrically Activated Soft Robots: Speed Up by Rolling.

Soft robots show excellent body compliance, adaptability, and mobility when coping with unstructured environments and human-robot interactions. However, the moving speed for soft locomotion robots is far from that of their rigid partners. Rolling locomotion can provide a promising solution for developing high-speed robots. Based on different rolling mechanisms, three rolling soft robot (RSR) prototypes with advantages of simplicity, lightweight, fast rolling speed, good compliance, and shock resistance are fabricated by using dielectric elastomer actuators. The experimental results demonstrate that the impulse-based and gravity-based RSRs can move both stably and continuously on the ground with a maximum speed higher than 1 blps (body length per second). The ballistic RSR exhibits a high rolling speed of ∼4.59 blps. And during its accelerating rolling process, the instantaneous rolling speed of the robot prototype reaches about 0.65 m/s (13.21 blps), which is much faster than most of the previously reported locomotion robots driven by soft responsive materials. The structure design and implementation methods based on different rolling mechanisms presented can provide guidance and inspiration for creating new, fast-moving, and hybrid mobility soft robots.

Mussel-inspired "built-up" surface chemistry for combining nitric oxide catalytic and vascular cell selective properties.

Specific selectivity of vascular cells and antithrombogenicity are crucial factors for the long-term success of vascular implants. In this work, a novel concept of mussel-inspired "built-up" surface chemistry realized by sequential stacking of a copper-dopamine network basement, followed by a polydopamine layer is introduced to facilitate the combination of nitric oxide (NO) catalysis and vascular cell selectivity. The resultant "built-up" film allowed easy manipulation of the content of copper ions and the density of catechol/quinone groups, facilitating the multifunctional surface engineering of vascular devices. For example, the chelated copper ions in the copper-dopamine network endow a functionalized vascular stent with a durable release of NO via catalytic decomposition of endogenous S-nitrosothiol. Meanwhile, the catechol/quinone groups on the film surface allow the facile, secondary grafting of the REDV peptide to develop a selectivity for vascular cells, as a supplement to the functions of NO. As a result, the functionalized vascular stent perfectly combines the functions of NO and REDV, showing excellent antithrombotic properties and competitive selectivity toward the endothelial cells over the smooth muscle cells, hence impressively promotes re-endothelialization and improves anti-restenosis in vivo. Therefore, the first mussel-inspired "built-up" surface chemistry can be a promising candidate for the engineering of multifunctional surfaces.

Metal-catechol-(amine) networks for surface synergistic catalytic modification: Therapeutic gas generation and biomolecule grafting.

Regarding the high requirement of cardiac and vascular implants in tissue engineering, a novel concept of surface chemistry strategy featuring multiple functions is proposed in this study, which provides glutathione peroxidase (GPx)-like catalytic activity and allows secondary reactions for grafting functional biomolecules. The suggested strategy is the fabrication of a metal-catechol-(amine) network (MCAN) containing copper ions with GPx-like activity, amine-bearing hexamethylenediamine (HD) and wet adhesive catechol dopamine (DA). With a simple one-step molecular/ion co-assembly, the developed copper-DA-HD (CuII-DA/HD) network can be used to catalyze the generation of therapeutic nitric oxide (NO) gas in a durable and dose-controllable manner. The primary amine groups in the CuII-DA/HD network facilitate the secondary immobilization of bivalirudin (BVLD) to further provide an antithrombotic activity as supplement to the functions of NO. The CuII-DA/HD + BVLD coating functionalized on cardiovascular stents successfully improved thromboresistance, anti-restenosis, and promotes re-endothelialization in vivo. With regard to the ease of operation and low cost, the synergetic modification using MCAN strategy is of great potential for developing multifunctional blood-contacting materials/devices.

Biomimetic engineering endothelium-like coating on cardiovascular stent through heparin and nitric oxide-generating compound synergistic modification strategy.

Co-immobilization of two or more molecules with different and complementary functions to prevent thrombosis, suppress smooth muscle cell (SMC) proliferation, and support endothelial cell (EC) growth is generally considered to be promising for the re-endothelialization on cardiovascular stents. However, integration of molecules with distinct therapeutic effects does not necessarily result in synergistic physiological functions due to the lack of interactions among them, limiting their practical efficacy. Herein, we apply heparin and nitric oxide (NO), two key molecules of the physiological functions of endothelium, to develop an endothelium-mimetic coating. Such coating is achieved by sequential conjugation of heparin and the NO-generating compound selenocystamine (SeCA) on an amine-bearing film of plasma polymerized allylamine. The resulting surface combines the anti-coagulant (anti-FXa) function provided by the heparin and the anti-platelet activity of the catalytically produced NO. It also endows the stents with the ability to simultaneously up-regulate α-smooth muscle actin (α-SMA) expression and to increase cyclic guanylate monophosphate (cGMP) synthesis of SMC, thereby significantly promoting their contractile phenotype and suppressing their proliferation. Importantly, this endothelium-biomimetic coating creates a favorable microenvironment for EC over SMC. These features impressively improve the antithrombogenicity, re-endothelialization and anti-restenosis of vascular stents in vivo.

Plant-inspired gallolamine catalytic surface chemistry for engineering an efficient nitric oxide generating coating.

A novel concept of generating therapeutic gas, nitric oxide (NO) via catalytic phenolic-amine "gallolamine" surface chemistry is developed. The concept is realized using plant polyphenol, gallic acid, and a glutathione peroxidase-like organoselenium compound cystamine or selenocystamine through one-step phenol-amine molecular assembling process. The resulting NO-generating coating with phenolic-cystamine or -selenocystamine framework showed the ability for long-term, steady and controllable range of NO release rates being unparalleled with any existing NO-releasing or NO-generating surface engineering toolkits. STATEMENT OF SIGNIFICANCE: Developing a facile and versatile strategy for a NO-generating coating with long-term, stable and adjustable NO release is of great interest for the application of blood-contacting materials and devices. Covalent immobilization of glutathione peroxidase (GPx)-like compound to generate NO from a material surface by exposure of endogenously existed S-nitrothiol (RSNO) is a popular strategy. However, it is generally involved in multi-step and complicated processes. Moreover, the amount of immobilized GPx-like compounds is limited by the density of introduced reactive functional groups on a surface. Herein, we propose a novel concept of catalytic plant-inspired gallolamine surface chemistry for material-independent NO-generating coatings. The concept is realized using plant polyphenol, gallic acid, and a GPx-like organoselenium compound cystamine or selenocystamine through one-step phenol-amine molecular assembling process. Without tedious multi-step synthesis, complicated surface treatments, and leakage of toxic chemicals, our unprecedentedly simple, histocompatible and biocompatible phenolic-cystamine or -selenocystamine framework demonstrated long-term, on-demand and facile dose controls of NO generated from the engineering surfaces. These unique features of such a NO-generating coating imparted a material with ability to impressively improve anti-thrombogenicity in vivo. This work constitutes the first report of an interfacial catalytic coating based on material-independent surface chemistry by plant polyphenols. This concept not only expands the application of material-independent surface chemistry in an interfacial catalytic area, but also can be a new platform for antithrombotic materials.

Polydopamine Modified TiO2 Nanotube Arrays for Long-Term Controlled Elution of Bivalirudin and Improved Hemocompatibility.

Sustained and controllable release characteristics are pivotal factors for novel drug delivery technologies. TiO2 nanotube arrays prepared by self-ordering electrochemical anodization are attractive for the development of biomedical devices for local drug delivery applications. In this work, several layers of polydopamine (PDA) were deposited to functionalize TiO2 nanotube arrays. The anticoagulant drug bivalirudin (BVLD) was used as a model drug. PDA extended the release period of BVLD and maintained a sustained release kinetic. Depending on the number of PDA layers, the release characteristics of BVLD improved, as there was a reduced burst release (from 45% to 11%) and extended overall release period from 40 days to more than 300 days in the case of 5 layers. Besides, the BVLD loaded 5-layer PDA coating maintained the high bioactivity of BVLD and effectively reduced the thrombosis formation by inhibition of the adhesion and denaturation of fibrinogen, platelets, and other blood components. Both in vitro and ex vivo blood evaluation results demonstrated that this coating significantly improved the hemocompatibility. These results confirmed the capability of PDA fitted TiO2 nanotube systems to be applied for local drug delivery over an extended period with well retained bioactivity and predictable release kinetics.

[Effect of hemostatic agent on bonding strength of deciduous tooth dentin].

PUPPOSE: To investigate the effect of hemostatic agent on bonding strength of deciduous tooth dentin. METHODS: Forty deciduous molars were used to make dentin grinding model and randomly divided into observation group and control group, 20 teeth in each group. Teeth in the observation group were covered with hemostatic agent for 30s, and then washed, followed by processing; while teeth in the control group were subjected to bonding directly. Micro tensile bond strength and micro leakage were measured and compared in the two groups. SPSS19.0 software package was used to analyze the data. RESULTS: Micro tensile bond strength of the observation group was (12.84±2.10) MPa, significantly lower than that of the control group (P<0.05); most resin protrusion in the observation group was > 35 µm and long and dense, extending into the open dentinal tubules; while resin protrusion in the control group was about 7 to 35 µm, with obvious collateral communication. There was no significant difference in the degree of micro leakage between the two groups (P>0.05). CONCIUSIONS: Hemostatic agent has certain impact on the dentin bonding strength of deciduous tooth, special attention should be paid during clinical application.

Effects of ethanol-wet bonding technique on root dentine adhesion.

OBJECTIVE: To investigate the effects of ethanol-wet bonding on the adhesion of experimental hydrophobic and commercial hydrophilic adhesives to root dentine. METHODS: A total of 43 single-rooted integrated human premolars were selected and sectioned. Of the 86 initially obtained specimens, 66 were randomly and equally divided into water-wet bonding and ethanol-wet bonding groups (n = 33). The specimens of each group were subdivided into three subgroups (n = 11) based on different adhesives: two experimental hydrophobic adhesives (Bis-GMA/TEGDMA, BT; and UDMA/TEGDMA, UT) and one commercial hydrophilic adhesive (Adper™ Single Bond 2, SB). The root surfaces were ground, acid-etched and rinsed and resin composite applied. After storing in distilled water for 24 h at 37°C, the shear bond strength (SBS) of each specimen was measured. A sample from each subgroup was randomly selected and prepared for scanning electron microscopy (SEM) analysis. The remaining 20 specimens were used in the contact angle (CA) experiment, and the values of CA were measured. SBS was analysed with two-way ANOVA/Tukey's multiple comparison test and CA with independent sample t test. RESULTS: A significant increase in SBS to root dentine was observed in the ethanol-wet bonding group compared with the traditional water-wet bonding group. The experimental hydrophobic adhesives (UT group) with ethanol-wet bonding presented the highest SBS (22.44 ± 3.32 MPa). CA increased significantly after the dentine surfaces were dried, especially for the water-saturated group. CONCLUSION: The adhesion to root dentine surfaces with ethanol-wet bonding may be superior to water-wet bonding.