Immature permanent incisors with complicated crown fractures treated with partial pulpotomy using white mineral trioxide aggregate and IRoot BP plus-a retrospective long-term study.

BACKGROUND/AIMS: Calcium silicate cements have been widely used for pulpotomies in immature permanent teeth with complicated crown fractures due to their superior properties. However, few studies have evaluated the long-term outcomes of white mineral trioxide aggregate (WMTA) and iRoot BP Plus for partial pulpotomies. The aim of this study was to investigate the long-term clinical and radiographic outcomes of WMTA and iRoot BP Plus for partial pulpotomies in immature permanent incisors with complicated crown fractures. MATERIALS AND METHODS: Children who had partial pulpotomies of immature permanent incisors with complicated crown fractures using WMTA or iRoot BP Plus as capping agents were enrolled. Eighty immature permanent incisors in 68 children (aged 8-13 years) were included. They were divided into two groups (WMTA and iRoot BP Plus) according to the capping agents. Clinical and radiographic information was collected during a 5-year follow-up period. Study data were analyzed using Chi-square tests or Fisher exact tests. RESULTS: The clinical and radiographic success rates in the WMTA (n = 36) and iRoot BP Plus groups (n = 44) were 94.4% versus 97.7% and 88.9% versus 97.7%, respectively (both p < .05). The average observation period was 74.5 ± 13.2 months and 61.9 ± 1.6 months in the WMTA and iRoot BP Plus groups, respectively (p < .01). Five cases presented with periapical radiolucencies. The WMTA group had four cases of pulp canal calcification (11.1%), while the iRoot BP Plus group had two cases (4.6%). There was crown discolouration in all cases in the WMTA group, but none in the iRoot BP Plus group. CONCLUSION: Both WMTA and iRoot BP Plus had favorable outcomes in promoting physiological development and maintaining the basic functions of immature permanent incisors with complicated crown fractures. As a partial pulpotomy material, iRoot BP Plus may be more suitable for the esthetic zone than WMTA.

Efficacy of the dual-action GA-KR12 peptide for remineralising initial enamel caries: an in vitro study.

OBJECTIVE: To investigate the antibiofilm and remineralising effects of the dual-action peptide GA-KR12 on artificial enamel caries. MATERIALS AND METHODS: Enamel blocks with artificial caries were treated with sterilised deionised water as control or GA-KR12. The blocks underwent biochemical cycling with Streptococcus mutans for 3 weeks. The architecture, viability, and growth kinetics of the biofilm were determined, respectively, by scanning electron microscopy (SEM), confocal laser scanning microscopy, and quantitative (culture colony-forming units, CFUs). The mineral loss, calcium-to-phosphorus ratio, surface morphology, and crystal characteristics of the enamel surface were determined, respectively, using micro-computed tomography, energy dispersive spectroscopy, SEM, and X-ray diffraction (XRD). RESULTS: SEM showed confluent growth of S. mutans in the control group but not in the GA-KR12-treated group. The dead-to-live ratios of the control and GA-KR12-treated groups were 0.42 ± 0.05 and 0.81 ± 0.08, respectively (p < 0.001). The log CFUs of the control and GA-KR12-treated groups were 8.15 ± 0.32 and 6.70 ± 0.49, respectively (p < 0.001). The mineral losses of the control and GA-KR12-treated groups were 1.39 ± 0.09 gcm-3 and 1.19 ± 0.05 gcm-3, respectively (p < 0.001). The calcium-to-phosphorus molar ratios of the control and GA-KR12-treated groups were 1.47 ± 0.03 and 1.57 ± 0.02, respectively (p < 0.001). A uniformly remineralised prismatic pattern on enamel blocks was observed in the GA-KR12-treated but not in the control group. The hydroxyapatite in the GA-KR12-treated group was better crystallised than that in the control group. CONCLUSION: The dual-action peptide GA-KR12 inhibited the growth of S. mutans biofilm and promoted the remineralisation of enamel caries. CLINICAL RELEVANCE: GA-KR12 potentially is applicable for managing enamel caries.

A tooth-binding antimicrobial peptide to prevent the formation of dental biofilm.

Dental caries is primarily caused by pathogenic bacteria infection, and Streptococcus mutans is considered a major cariogenic pathogen. Moreover, antimicrobial peptides have been considered an alternative to traditional antibiotics in treating caries. This study aimed to design a tooth-binding antimicrobial peptide and evaluate its antimicrobial efficacy against S. mutans. An antimicrobial peptide of polyphemusin I (PI) was modified by grafting a tooth-binding domain of diphosphoserine (Ser(p)-Ser(p)-) to create the peptide of Ser(p)-Ser(p)-polyphemusin I (DPS-PI). PI and DPS-PI were synthesized by Fmoc solid-phase peptide synthesis. The minimum inhibitory concentration of PI and DPS-PI against S. mutans were tested. Scanning electron microscopy (SEM) were used to observe the growth of S. mutans on PI and DPS-PI treated enamel surfaces. The growth of S. mutans was evaluated by optical density (OD) at 590 nm. Inhibition of dental plaque biofilm development in vivo were investigated. The cytocompatibility to bone mesenchymal stem cells (BMSCs) was tested. The MIC of PI and DPS-PI were 40 and 80 µg/ml, respectively. SEM images showed that S. mutans were sparsely distributed on the DPS-PI treated enamel surface. OD findings indicated that DPS-PI maintained its inhibition effect on S. mutans growth after 24 h. The incisor surfaces of rabbits treated with DPS-PI developed significantly less dental plaque biofilm than that on PI treated surfaces. The DPS-PI had good biocompatibility with the cells. We successfully constructed a novel tooth-binding antimicrobial peptide against S. mutans in vitro and inhibited dental plaque biofilm development in vivo. DPS-PI may provide a feasible alternative to conventional antibiotics for the prevention and treatment of dental caries. Dental caries is primarily caused by pathogenic bacteria infection, and Streptococcus mutans is considered a major cariogenic pathogen. A tooth-binding antimicrobial peptide was designed by grafted diphosphoserine (-Ser(p)-Ser(p)-) to the structure of polyphemusin I. This novel tooth-binding antimicrobial peptide can inhibit dental plaque biofilm development and thus provide a feasible alternative to conventional antibiotics for the prevention and treatment of dental caries.

A sub-milligram-synthesis protocol for in vitro screening of HDAC11 inhibitors.

This work demonstrated the high efficiency of a sub-milligram-synthesis based medicinal chemistry method. Totally 72 compounds, consisting a tri-substituted pyrrolidine core, were prepared. Around 0.1mg of each compound was solid-phase synthesized. Based on the additive property of UV absorptions of unconjugated chromophores of a molecule, these compounds were quantified by UV measurement. A hit, whose IC50 value was 1.2µM in HDAC11 inhibition assays, highlights the applicability of the approach reported here in future optimization works.

Methods for biomimetic remineralization of human dentine: a systematic review.

This study aimed to review the laboratory methods on biomimetic remineralization of demineralized human dentine. A systematic search of the publications in the PubMed, TRIP, and Web of Science databases was performed. Titles and abstracts of initially identified publications were screened. Clinical trials, reviews, non-English articles, resin-dentine interface studies, hybrid layer studies, hybrid scaffolds studies, and irrelevant studies were excluded. The remaining papers were retrieved with full texts. Manual screening was conducted on the bibliographies of remaining papers to identify relevant articles. A total of 716 studies were found, and 690 were excluded after initial screening. Two articles were identified from the bibliographies of the remaining papers. After retrieving the full text, 23 were included in this systematic review. Sixteen studies used analogues to mimic the functions of non-collagenous proteins in biomineralization of dentine, and four studies used bioactive materials to induce apatite formation on demineralized dentine surface. One study used zinc as a bioactive element, one study used polydopamine, and another study constructed an agarose hydrogel system for biomimetic mineralization of dentine. Many studies reported success in biomimetic mineralization of dentine, including the use of non-collagenous protein analogues, bioactive materials, or elements and agarose hydrogel system.

A novel self-assembled oligopeptide amphiphile for biomimetic mineralization of enamel.

BACKGROUND: Researchers are looking for biomimetic mineralization of ena/mel to manage dental erosion. This study evaluated biomimetic mineralization of demineralized enamel induced by a synthetic and self-assembled oligopeptide amphiphile (OPA). RESULTS: The results showed that the OPA self-assembled into nano-fibres in the presence of calcium ions and in neutral acidity. The OPA was alternately immersed in calcium chloride and sodium hypophosphate solutions to evaluate its property of mineralization. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed nucleation and growth of amorphous calcium phosphate along the self-assembled OPA nano-fibres when it was repetitively exposed to solutions with calcium and phosphate ions. Energy dispersive spectrometry (EDS) confirmed that these nano-particles contained calcium and phosphate. Furthermore, electron diffraction pattern suggested that the nano-particles precipitated on OPA nano-fibres were comparable to amorphous calcium phosphate. Acid-etched human enamel slices were incubated at 37°C in metastable calcium phosphate solution with the OPA for biomimetic mineralization. SEM and X-ray diffraction indicated that the OPA induced the formation of hydroxyapatite crystals in organized bundles on etched enamel. TEM micrographs revealed there were 20-30 nm nano-amorphous calcium phosphate precipitates in the biomimetic mineralizing solution. The particles were found separately bound to the oligopeptide fibres. Biomimetic mineralization with or without the oligopeptide increased demineralized enamel microhardness. CONCLUSIONS: A novel OPA was successfully fabricated, which fostered the biomimetic mineralization of demineralized enamel. It is one of the primary steps towards the design and construction of novel biomaterial for future clinical therapy of dental erosion.

A novel oligopeptide simulating dentine matrix protein 1 for biomimetic mineralization of dentine.

OBJECTIVE: The objectives were to design and fabricate an oligopeptide that simulates dentine matrix protein 1 (DMP1) to study its ability to bind to dentine collagen fibrils and induce biomimetic mineralization for the management of dentine hypersensitivity. MATERIALS AND METHODS: A novel oligopeptide was developed by connecting the collagen-binding domain of DMP1 to the hydrophilic C-terminal of amelogenin. Fluorescein isothiocyanate-coupled oligopeptide was applied to the completely demineralized dentine collagen and examined using fluorescent microscopy. The nucleation and growth of hydroxyapatite were initiated by immersing oligopeptide into calcium chloride and sodium hydrogen phosphate solutions. Scanning electron microscopy (SEM), transmission electron microscopy, and selected area electron diffraction (SAED) were used to examine the formation. Dentine slices were acid-etched, coated with oligopeptide, and immersed into a metastable calcium phosphate solution. Dentine mineralization was evaluated by SEM, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). RESULTS: Fluorescent dentine collagen was identified in the specimens. The nucleation and growth of crystals were detected after immersing the oligopeptide into calcium chloride and sodium hydrogen phosphate solutions. Under SEM, crystals were observed covering the oligopeptide-coated dentine surface, within the demineralized dentine collagen matrix and occluding dentinal tubules. SAED, XRD, and FTIR confirmed that the crystals were hydroxyapatite. CONCLUSION: A novel oligopeptide-simulating DMP1 was developed, that can bind to collagen fibrils, initiate mineralization, and induce biomimetic mineralization of dentine. CLINICAL RELEVANCE: Biomimetic mineralization of dentine facilitated by this oligopeptide is a potential therapeutic technique for the management of dentine hypersensitivity.

Clinical influencing factors of vital pulp therapy on pulpitis permanent teeth with 2 calcium silicate-based materials: A randomized clinical trial.

BACKGROUND: Compared with traditional root canal therapy (RCT), vital pulp therapy (VPT) is a personalized and minimally invasive method for the treatment of pulpitis caused by dental caries. However, there are still no clear guidelines for VPT because high-quality randomized clinical trials are scarce. This prospective cohort study evaluated the clinical efficacy of VPT with the light-curable calcium silicate-based material TheraCal LC (TH) and bioceramic material iRoot BP Plus (BP) in reversible and irreversible pulpitis permanent teeth with carious exposures. METHODS: 115 teeth with reversible or irreversible pulpitis caused by deep care were randomly divided into 2 groups. TheraCal LC and iRoot BP Plus were used for the pulp capping. Direct pulp capping (DPC), partial pulpotomy (PP) and full pulpotomy (FP) were performed based on observation of the exposed pulp. Postoperative discomforts were enquired and recorded via follow-up phone calls. Clinical and radiographic evaluations were performed 3, 6, and 12 months postoperatively. RESULTS: The overall clinical success rate in the first year was 90.4% (47/52) in both groups. The TH group required less operating time, showed lower levels of pain, and had shorter pain duration post-operative (P < .001). According to the binary logistic regression model, preoperative pain duration was significantly correlated with the prognosis of VPT (P = .011). CONCLUSION: VPT with TheraCal LC and iRoot BP Plus in pulpitis permanent carious teeth both achieved good clinical outcomes, and TheraCal LC can be easily operated for clinical use. Preoperative pain duration of the affected tooth might have a significant correlation with the prognosis of VPT.

Extrafibrillar demineralization: Yes or no?

OBJECTIVE: Extrafibrillar demineralization is considered to be an ideal solution for addressing the durability of resin-dentin bonding interfaces. However, its theoretical basis is contradictory to ionization equilibrium of hydroxyapatite dissolution. In this study, various calcium chelators were selected as dentin conditioners to explore the essence of dentin demineralization with chelators and its effect on resin-dentin adhesion. METHODS: Polyethyleneimine grafted with EDTA and polyacrylic acid sodium (PAAN450k) larger than 40 kDa, as well as PAAN (PAAN3k) and EDTA smaller than 6 kDa, were prepared as dentin conditioners. The dentin powder was designed to characterize whether it would demineralize without contact with PAAN450k. Dentin demineralization effect with four conditioners was evaluated with field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy and quantification of hydroxyproline concentration after enzymatic degradation. Micro-tensile bond strength (µTBS) test and failure mode analysis were employed to assess the bonding effect of the four chelators in both wet and dry bonding, with H3PO4 wet bonding serving as the control group. RESULTS: Demineralization occurs when PAAN450k was not in direct contact with the dentin powder. The extrafibrillar demineralization cannot be induced by any chelator regardless of its molecular weight. Complete demineralization including extrafibrillar and intrafibrillar demineralization would occur with sufficient interaction time. Moreover, chelators could not provide a reliable dentin bonding effect under a short interaction time. SIGNIFICANCE: From the perspective of theory and application, extrafibrillar demineralization is not a reliable strategy, which provides a reminder for exploring new strategies in the future.

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.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

Antibacterial effects of silver diamine fluoride on multi-species cariogenic biofilm on caries.

BACKGROUNDS: Silver diamine fluoride (SDF) has clinical success in arresting dentin caries, this study aimed to investigate its mechanism of action. METHODS: Using a computer-controlled artificial mouth, we studied the effect of 38% SDF on cariogenic biofilms and dentin carious lesions. We used five common cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus and Actinomyces naeslundii) to form a cariogenic biofilm that generated carious lesions with a depth of approximately 70 um on human dentin blocks. We applied 38% SDF to the lesions in the test group and water to those in the control group. The blocks were incubated in the artificial mouth for 21 days before evaluation. Microbial kinetics, architecture, viability and distribution were evaluated every 7 days using colony forming unit (CFU), scanning electron microscopy and confocal laser scanning microscopy. The physical properties of the carious lesions were evaluated with microhardness testing, energy dispersive spectroscopy (EDS) and Fourier transform infra-red spectroscopy (FTIR). RESULTS: The CFU results revealed fewer colony forming units in the test group compared with the control group (p < 0.01). Scanning electron microscopy and confocal microscopy showed less bacterial growth in the test group, and confluent cariogenic biofilm in the control group (p < 0.01). The microhardness and weight percentages of calcium and phosphorus in the test group from the outermost 50mum were higher than in the control group (p < 0.05). EDS showed that calcium and phosphous were higher in outer 50 mum in test groups than in the control FTIR revealed less exposed collagen I in the test lesions compared with the control group (p < 0.01). CONCLUSIONS: 38% SDF inhibits multi-species cariogenic biofilm formation on dentin carious lesions and reduces the demineralization process.

Is Etiology a Key Factor for Regenerative Endodontic Treatment Outcomes?

INTRODUCTION: This study aimed to evaluate treatment outcomes of regenerative endodontic treatment (RET) in nonvital immature permanent teeth due to developmental malformation and trauma, and to analyze the influence of etiology on the prognosis. METHODS: Fifty-five cases were included and divided into a malformation group (n = 33) and a trauma group (n = 22). Treatment outcomes were classified as healed, healing, and failure. Root development was evaluated in terms of root morphology and the percentage changes in root length, root width, and apical diameter during a follow-up period of 12-85 months (mean 30.8 months). RESULTS: The mean age and the mean degree of root development in the trauma group were significantly younger than that in the malformation group. The success rate of RET was 93.9% (81.8% healed, 12.1% healing) in the malformation group and 90.9% (68.2% healed, 22.7% healing) in the trauma group, showing no statistically significant difference. The proportion of type I-III root morphology in the malformation group (97%, 32/33) was significantly higher than that in the trauma group (77.3%, 17/22) (P < .05), whereas there was no significant difference in the percentage changes of root length, root width, and apical diameter between the 2 groups. Six cases (6/55, 10.9%) showed no significant root development (type IV-V) (1 in the malformation group and 5 in the trauma group). Six cases (6/55, 10.9%) revealed intracanal calcification. CONCLUSIONS: RET achieved reliable outcomes regarding the healing of apical periodontitis and continued root development. The etiology seems to influence the outcome of RET. Malformation cases presented with a better prognosis than trauma cases after RET.

Er:YAG Laser Physical Etching and Ultra-High-Molecular-Weight Cross-Linked Sodium Polyacrylate Chemical Etching for a Reliable Dentin Dry Bonding.

Dentin bond interface stability is the key issue of dental adhesion in present clinical dentistry. The concept of selective extrafibrillar demineralization has opened a new way to maintain intrafibrillar minerals to prevent interface degradation. Here, using ultra-high-molecular-weight sodium polyacrylate [Carbopol (Carbo) > 40 kDa] as a calcium chelator, we challenge this concept and propose a protocol for reliable dentin dry bonding. The results of high-resolution transmission electron microscopy revealed periodic bands of 67 nm dentin collagen fibrils after Carbo etching, and the hydroxyproline concentration increasing with prolonged chelating time denied the concept of extrafibrillar demineralization. The results that wet and dry bonding with Carbo-based demineralization produced a weaker bond strength than the traditional phosphoric acid wet adhesion suggested that the Carbo-based demineralization is an unreliable adhesion strategy. A novel protocol of Er:YAG laser physical etching followed by Carbo chemical etching for dentin adhesion revealed that a micro-/nano-level rough, rigid, and non-collagen exposed dentin surface was produced, the micro-tensile bond strength was maintained after aging under dry and wet bonding modes, and in situ zymography and nanoleakage within the hybrid layers presented lower signals after aging. Cell culture in vitro and a rabbit deep dentin adhesion model in vivo proved that this protocol is safe and biocompatible. Taken together, the concept of extrafibrillar demineralization is limited and insufficient to use in the clinic. The strategy of Er:YAG laser physical etching followed by Carbo chemical etching for dentin adhesion produces a bonding effect with reliability, durability, and safety.

A dual functional polypeptide with antibacterial and anti-inflammatory properties for the treatment of periodontitis.

Periodontitis has been reported as the sixth most prevalent disease in human beings. This destructive disease is closely related to systemic diseases. Existing local drug delivery systems for periodontitis suffer from poor antibacterial effect and drug resistance. Inspired by the pathogenesis of periodontitis, we implemented a strategy to construct a dual functional polypeptide LL37-C15, which exhibited remarkable antibacterial effect against P. gingivalis and A. actinomycetemcomitans. In addition, LL37-C15 inhibits the release of pro-inflammatory cytokines by controlling the inflammatory pathway and reversing macrophage M1. Furthermore, the anti-inflammatory effect of LL37-C15 was also verified in vivo in a periodontitis rat model through the morphometry and histological observations of alveolar bone, hematoxylin-eosin, and Trap staining in gingival tissue. The results of molecular dynamics simulations showed that LL37-C15 could selectively destroy the bacterial cell membrane and protect the animal cell membrane in a self-destructive manner. The results showed that the polypeptide LL37-C15, as a novel promising therapeutic agent, exhibited a great potential for the periodontitis management. What's more, this dual functional polypeptide provides a promising strategy for building a multifunctional therapeutic platform against the inflammation and other diseases.

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.

EDTA-functionalized silica nanoparticles as a conditioning agent for dentin bonding using etch-and-rinse technique.

OBJECTIVE: This study investigated the possibility of using ethylenediaminetetraacetic acid functionalized silica nanoparticles (EDTA-SiO2) as a dentin-conditioning agent using etch-and-rinse technique to promote the durability of dentin bonding. METHODS: The SiO2-EDTA were synthesized by N- [(3- trimethoxysilyl) propyl] ethylenediamine triacetic acid (EDTA-TMS) and SiO2 (50 nm), then characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The capacity of SiO2-EDTA to chelate calcium ions from dentin was examined by inductively coupled plasma-optic emission spectrometry (ICP-OES). The dentin surfaces conditioned with SiO2-EDTA were detected by field emission scanning electron microscopy (SEM), TEM and microhardness testing. For dentin bonding, dentin surfaces were adopted wet- or dry-bonding technique and bonded with adhesive (AdperTM Single Bond2) and applied composite resin (Filtek Z350) on them. The durability of dentin bonding was evaluated by mircotensile bond strength test, in-situ zymography and nanoleakage testing. RESULTS: FTIR, TGA and XPS results showed that SiO2-EDTA contained N element and carboxyl groups. SEM, TEM and microhardness results indicated that SiO2-EDTA group created extrafibrillar demineralization and retained more intrafibrillar minerals within dentin surface. In the dentin bonding experiment, SiO2-EDTA group achieved acceptable bond strength, and reduced the activity of matrix metalloproteinase and nanoleakage along bonding interface. CONCLUSION: It was possible to generate a feasible dentin conditioning agent (SiO2-EDTA), which could create dentin extrafibrillar demineralization and improve dentin bond durability. CLINICAL SIGNIFICANCE: This study introduces a new dentin conditioning scheme based on SiO2-EDTA to create extrafibrillar demineralization for dentin bonding. This strategy has the potential to be used in clinic to promote the life of restoration bonding.

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.

Oxidized Dopamine Acrylamide Primer to Achieve Durable Resin-Dentin Bonding.

The durability of the resin-dentin bonding interface is a key issue in clinical esthetic dentistry. Inspired by the extraordinary bioadhesive properties of marine mussels in a wet environment, we designed and synthetized N-2-(3,4-dihydroxylphenyl) acrylamide (DAA) according to the functional domain of mussel adhesive proteins. DAA's properties of collagen cross-linking, collagenase inhibition, inducing collagen mineralization in vitro, and as a novel prime monomer for clinical dentin adhesion use, its optimal parameters, and effect on the adhesive longevity and the bonding interface's integrity and mineralization, were evaluated in vitro and in vivo. The results showed that oxide DAA can inhibit the activity of collagenase and cross collagen fibers to improve the anti-enzymatic hydrolysis of collagen fibers and induce intrafibrillar and interfibrillar collagen mineralization. As a primer used in the etch-rinse tooth adhesive system, oxide DAA can improve the durability and integrity of the bonding interface by anti-degradation and mineralization of the exposed collagen matrix. Oxidized DAA (OX-DAA) is a promising primer for improving dentin durability; using 5% OX-DAA ethanol solution and treating the etched dentin surface for 30 s is the optimal choice when used as a primer in the etch-rinse tooth adhesive system.

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.