Search Results (266)

Fluoride remains the keystone of evidence-based caries prevention by stabilizing the mineral balance at the tooth–biofilm–saliva interface. Contemporary understanding emphasizes a predominantly post-eruptive, topical mode of action where fluoride inhibits demineralization and accelerates remineralization. This interfacial catalysis is reinforced by pH-responsive calcium-fluoride-like reservoirs that release fluoride during acid challenges. While community water fluoridation confers population-level reductions, the most effective approach is sustaining low-level fluoride in the biofilm environment. Evidence confirms that toothpastes with 1000–1500 ppm fluoride provide a dose–response benefit in children, while 5000 ppm concentrations are indicated for high-risk scenarios such as root caries and xerostomia. Beyond physicochemical effects, fluoride modulates the oral microbiome by inhibiting bacterial enzymes and proton pumps, shifting community function toward a health-associated state without reducing overall diversity. In restorative dentistry, glass ionomer cements offer superior preventive effects against secondary caries compared to amalgam; however, marginal integrity, adhesive performance, and clinical technique, rather than fluoride release alone, remain the primary determinants of success. Despite well-known risks associated with high systemic intake, such as fluorosis, current evidence does not indicate genotoxic or adverse microbiome effects in humans from routine topical use of standard fluoride products at recommended preventive concentrations. Overall, fluoride’s cariostatic value rests on frequent, low-level exposures that maintain tissues in a repair-favoring state. Full article

Bio-silica particles derived from rice husks were coated with MgAl layered double hydroxides (LDHs) and thermally converted into layered double oxides (LDOs) to evaluate fluoride capture and release capability. The deposition of an MgAl LDH layer on the silica particle makes the LDH more accessible for interaction. Fluoride loading was tested in aqueous and ethanol–water media, with mixed solvents consistently enhancing uptake. Release studies in demineralized water showed relatively rapid desorption (~1500 min), whereas embedding particles in an acrylic matrix reduced the release rate by nearly two orders of magnitude, enabling sustained release levels suitable for dental applications. Ethanol promoted both ion exchange and memory effect mechanisms, providing tunable control over fluoride incorporation and release. These functional composites demonstrate potential for controlled delivery in dental restorative materials, highlighting their potential as adaptive fillers that can enhance the mechanical properties while also serving a functional base for low fluoride release. Full article

Dual-layer membranes can offer significant advantages in desalination via membrane distillation (MD) compared to conventional single-layer designs. In this study, we report the development of a novel dual-layer nylon/polyvinylidene fluoride (PVDF) membrane with a Janus architecture, specifically engineered for application in sweeping gas membrane distillation (SGMD). The non-solvent induced phase separation (NIPS) method was used to cast PVDF solution on the top of a commercial nylon membrane. Water contact angle (WCA) measurements showed asymmetrical wettability. Scanning electron microscopy (SEM) confirmed that the PVDF layer was firmly anchored to the nylon support without signs of delamination. Desalination experiments were conducted using SGMD, where a significant flux enhancement as high as 81.2% was observed when the feed solution contacted the hydrophilic nylon surface while the hydrophobic PVDF surface faced the permeate side with gas flow. This enhancement was attributed to the high partitioning coefficient of the liquid–vapor mixture on the hydrophilic feed surface and the rapid vapor release across the hydrophobic permeate surface. Overall, these results demonstrate that hydrophilic membranes with small pore sizes (i.e., 0.22 µm) can serve effectively as supports when fabricated using the NIPS process, enabling new configurations for high-performance SGMD. Full article

Per- and polyfluoroalkyl substances (PFASs) are persistent aquatic contaminants whose strong C–F bonds make conventional water treatment ineffective. This review critically synthesizes recent progress in aqueous PFAS degradation through four mechanistic routes: oxidation-driven, biodegradation, reduction-driven, and nonradical processes. Rather than evaluating technologies by parent-compound disappearance alone, we compare their defluorination and mineralization capacities, matrix tolerance, byproduct risks, energy demand, operational stability, and technology readiness. Oxidative and reductive systems can promote rapid degradation or defluorination, but their performance is often constrained by radical/electron quenching, incomplete mineralization, and sensitivity to PFAS structure and water chemistry. Biodegradation and enzymatic approaches offer mild transformation pathways but remain limited by slow kinetics, narrow substrate specificity, and uncertain toxicity evolution. Nonradical and thermochemical processes show stronger potential for deep destruction, particularly in concentrated PFAS streams. Overall, electrochemical oxidation, plasma treatment, and thermal/supercritical oxidation appear closer to practical implementation for spent adsorbents, regenerants, industrial concentrates, and other high-strength wastes, whereas many photocatalytic, biological, and microdroplet systems remain laboratory-stage. Future research should prioritize integrated separation–destruction treatment trains and standardized metrics including total organic fluorine removal, fluoride release, final residual PFAS concentrations relative to regulatory thresholds, transformation-product toxicity, energy consumption, and life-cycle impacts. Full article

Lithium-ion batteries (LIBs) release significant amounts of toxic, corrosive, and flammable gases when they enter thermal runaway (TR). These emissions can be hazardous to human health, damage nearby equipment, pose fire and explosion risks, and degrade air quality. This study measured concentrations for a range of hazardous gases released from TR-driven combustion of cylindrical lithium iron phosphate (LFP) and pouch-style lithium cobalt oxide (LCO) LIB cells. Gas emissions were measured by dedicated analyzers and Fourier transform infrared spectroscopic (FTIR) analysis, and emission factors were calculated. Dangerous concentrations of hydrogen fluoride (HF) were observed, reaching up to 50 ppm from the combustion of single LIB cells. Large amounts of combustible electrolyte solvents and light hydrocarbons were released in some cases, depending on cell combustion behavior. Electrolyte solvents, hydrogen chloride (HCl), and particles were released earlier than other species and should be targeted for early TR detection. Gas emissions were correlated with cell state of charge (SOC) and combustion behavior. Cells at high SOCs had higher peak concentrations of HF, HCl, CO, and flammable hydrocarbons, and these peaks happened sooner after cell failure than for low-SOC tests. Full article

This study aimed to address the clinical challenge of secondary caries prevention in dental restorations. Leveraging the sustained fluoride-releasing capacity of calcium fluoride (CaF₂) and the broad-spectrum antibacterial activity of zinc oxide (ZnO), we designed and synthesized a novel core–shell CaF₂@ZnO nanoparticle filler to synergistically enhance the functional performance of dental resin composites. The filler was successfully prepared via a co-precipitation-hydrothermal method, and its well-defined core–shell architecture was systematically confirmed using XRD, SEM, and TEM. When incorporated into the resin matrix at 10 wt.% loading, the composite containing CaF₂@30ZnO demonstrated optimal overall performance. Notably, this formulation enabled sustained fluoride ion release, potent antibacterial efficacy, and excellent in vitro cytocompatibility. Collectively, these findings demonstrate that the CaF₂@ZnO nanofiller confers multifunctional benefits—including improved mechanical integrity, long-term fluoride release stability, and targeted antibacterial action—thereby holding significant promise for clinical application in mitigating secondary caries around resin-based restorations. Full article

Background/Objectives: Electrolytes used in in vitro corrosion testing critically determine the behavior inferred for metallic dental implants, yet formulations and their justifications are inconsistently reported across the literature. This review compiles and compares electrolytes employed to simulate the oral cavity and the bone–implant interface, linking their chemical composition to the corrosion mechanisms they target. Methods: This structured narrative review synthesized peer-reviewed literature on simulated electrolytes used for in vitro corrosion testing of metallic dental implants and implant-related alloys. Literature was identified using database searches and targeted reference screening, with emphasis on artificial saliva formulations, physiological simulated fluids, challenge chemistries, protein-containing media, hydrodynamic conditions, and microbiological models. Relevant formulations were standardized to grams per liter and grouped according to application domain and targeted corrosion mechanisms. Results: The analysis maps electrolyte selection to corresponding corrosion modes, including uniform dissolution, pitting, crevice, galvanic, and microbiologically influenced corrosion. Consolidated composition tables highlight how pH, halide concentration, calcium–phosphate balance, proteins, gas control, and flow conditions modify passive-film stability and metal-ion release. Dental-specific gaps are identified, notably the lack of a standardized fluoride–pH matrix and limited guidance for microbiome-integrated assays. Conclusions: Aligning electrolyte formulations with the research question enhances reproducibility and mechanistic interpretation. However, current in vitro corrosion data should be interpreted cautiously because quantitative links between simulated-fluid testing and clinical outcomes such as peri-implantitis, peri-implant bone loss, and implant failure remain insufficiently established. The adoption of shared reporting standards, dynamic programmable chemistries, and interoperable datasets may improve the translational value of future corrosion studies. Full article

Background: Corrosion of orthodontic archwires raises biocompatibility concerns; yet, comparative multi-element data across manufacturers remain scarce. Methods: Ni, Cr, Fe, and Ti release was quantified by ICP-OES from SS and NiTi rectangular archwires (0.43 × 0.64 mm) from four manufacturers (Ormco, 3M Unitek, Dentaurum, and American Orthodontics) and immersed in artificial saliva (pH~7.0) and fluoride-containing saliva (+0.05% NaF) at six time points (days 1–35). Release was normalised to wire mass (mg g⁻¹). Non-parametric tests were applied. Results: NiTi wires released significantly more Ni than SS wires in +NaF at all time points (p = 0.029). An exploratory manufacturer effect on Ni release from NiTi was detected (Kruskal–Wallis H = 12.99, p = 0.005); American Orthodontics exceeded Dentaurum and Ormco. Ormco SS released ~3-fold more Fe than other SS wires (H = 13.68, p = 0.003). Ti was detectable exclusively in NiTi wires in +NaF; all specimens were below LOQ in pH~7.0. Cr release was uniformly low (0.017–0.023 mg g⁻¹). Conclusions: Manufacturer identity influences Ni and Fe release independently of alloy type. Fluoride selectively disrupts the NiTi passive film. These exploratory findings, derived from a single-specimen pilot design, may inform clinical material selection in nickel-sensitive patients pending replication. Full article

Flotation tailings, the primary solid waste generated during gold extraction, may pose issues such as land occupation, environmental pollution, and geological hazards in open-pit mining areas. This study systematically investigated the environmental characteristics, long-term pollutant release patterns, and migration risks associated with flotation tailings by taking a specific backfill project as a case study and employing short-term leaching tests, long-term column leaching experiments, and multi-model numerical simulations. Short-term leaching tests indicated that tailings leachate exhibited weak alkalinity (pH 8.21−8.45) with low pollutant leaching concentrations, meeting the fundamental requirements for open-pit backfilling. Notably, leaching characteristics varied significantly among tailings from different sources, and an extended storage duration enhanced chemical stability. Long-term leaching tests identified nine characteristic pollutants, including fluoride and sulfate, with their release patterns categorized into three types: continuous slow release, initial rapid leaching, and delayed/complex release. Furthermore, simulation results from the HYDRUS and MODFLOW/MT3DMS models indicated that the maximum predicted concentrations of characteristic pollutants in the surrounding soil and groundwater will remain at low levels for 50 years post-backfilling. The site’s “micro-to-weakly permeable” strata exhibited significant pollutant retention capabilities. Based on these experimental and simulation results, a three-tier risk management system—”source control, process monitoring, and end-point surveillance”, was developed to provide technical support for the long-term environmental safety of the flotation tailings backfill project. This study revealed the environmental risk characteristics associated with the storage of flotation tailings, including land occupation, environmental pollution, and the potential for geological hazards in open pits. Furthermore, the leaching characteristics, long-term release patterns, and migration mechanisms of tailings used to backfill open pits have been elucidated, providing theoretical references and practical guidance for similar solid waste resource recovery and backfilling projects. Full article

Objectives: This study characterised the bioactive properties (i.e., ion release, pH rise, and apatite formation) of a newly developed Voco Profluorid + BioMin F varnish. Three additional varnishes were investigated for comparison: Clinpro™ White Varnish (3M™, St. Paul, MN, USA), MI Varnish (GC, Tokyo, Japan), and Profluorid varnish (VOCO GmbH, Cuxhaven, Germany). The Clinpro™ White and MI varnishes were chosen for comparison due to their similar composition of active ingredients. Profluorid served as a standard fluoride-only varnish reference. Methods: Dental varnish ingredients were characterised using ATR-FTIR, XRD, and ¹⁹F and ³¹P MAS-NMR. Coated coverslips were immersed in Tris buffer and artificial saliva (pH 4.0 and 7.0) for 2–24 h. Ion release was analysed using ICP-OES and a fluoride ion-selective electrode whilst monitoring pH changes. Post-immersion, coverslips were analysed by XRD and MAS-NMR to assess possible apatite formation. Results: XRD and ¹⁹F MAS-NMR detected NaF in all four varnishes. BioMin F varnish showed a ³¹P peak matching BioMin F glass, with an additional brushite peak, indicating partial reaction of the bioactive glass (BAG) with rosin resin water. All varnishes released fluoride and calcium, but only BioMin F and MI varnishes released phosphate, which is essential for the formation of calcium fluorapatite. Post-immersion analysis confirmed fluorapatite formation in BioMin F and, to a lesser extent, the Profluorid varnish. No apatite formation was observed in the other two varnishes. MI varnish exhibited calcium fluoride formation before and after immersion, as evidenced by XRD and ¹⁹F MAS-NMR analysis. Conclusions: The novel BioMin F varnish potentially promotes remineralisation by providing a sustained and slow release of therapeutic ions that are essential for the formation of fluorapatite. Full article

Secondary caries and biofilm accumulation remain major causes of failure in provisional crowns and restorations, highlighting the need for multifunctional resin coatings with antibacterial and remineralizing capabilities. This study aimed to develop a novel bioactive and antibacterial resin-based surface coating incorporating 10% dimethylaminododecyl methacrylate (DMADDM), 20% nanoparticles of amorphous calcium phosphate (NACP), and/or 20% calcium fluoride nanoparticles (nCaF₂) within a urethane dimethacrylate/triethylene glycol divinylbenzyl ether (UDMA/TEG-DVBE) matrix. Coatings were evaluated for degree of conversion (DC), flow, shear bond strength, brushing wear resistance (10,000 cycles), and calcium (Ca), phosphate (PO₄), and fluoride (F) ion release up to 70 days. All groups achieved clinically acceptable polymerization, with the lowest DC at 50%. NACP-containing coatings significantly increased shear bond strength to 18.3 ± 2.8 MPa, representing a ~170% increase compared with the experimental control (6.8 ± 2.1 MPa) and exceeding the ISO 10477 minimum threshold of 5 MPa. After brushing simulation, experimental coatings demonstrated low wear depth (0.93–1.19 µm), which was ~40% lower than the commercial control (1.85 ± 0.40 µm). Sustained ion release was achieved for 70 days, with 20% NACP-formula releasing 1.22 mmol/L Ca and 0.90 mmol/L PO₄, while the dual NACP–nCaF₂ formulation provided simultaneous Ca (0.62 mmol/L) and F (0.33 mmol/L) release. The developed coatings demonstrated promising physicochemical properties, bonding performance, wear resistance, and sustained remineralizing ion release, supporting their potential application as therapeutic surface coatings for provisional restorations. Full article

Advances in dental material science over recent decades have significantly improved the mechanical, physical, esthetic, and adhesive properties of restorative systems. As clinical performance and durability have reached high standards, research has progressively shifted from purely mechanical replacement toward the development of bioactive materials capable of interacting beneficially with biological tissues. Rather than functioning solely as passive restoratives, contemporary materials are increasingly designed to contribute to disease prevention and tissue repair. Bioactive functionality encompasses both bioprotective and biopromotive effects, including antimicrobial activity, reinforcement of the dental substrate, promotion of remineralization, modulation of inflammatory responses, and stimulation of regenerative pathways. In this context, the surface pre-reacted glass ionomer (S-PRG) particle has emerged as a multifunctional bioactive technology. Its unique three-layer structure enables sustained release of multiple ions, fluoride, strontium, boron, sodium, silicate, and aluminum, associated with mineralization, biofilm inhibition, inflammatory regulation, and activation of cellular signaling pathways. An integrative review was conducted through a literature search in PubMed, SciELO and Scopus using the descriptors “Surface-reaction-type prereacted glass ionomer” and “S-PRG.” Experimental studies evaluating antimicrobial, anti-inflammatory, remineralizing, cellular, or regenerative effects of S-PRG-containing materials were considered eligible. A total of 49 studies met the inclusion criteria and were analyzed through descriptive synthesis. The available evidence indicates that the biological activity of S-PRG-containing materials extends beyond caries prevention, including modulation of inflammatory responses, enhancement of mineralization processes, and stimulation of cellular pathways related to tissue repair. These findings highlight the potential of S-PRG technology as a promising strategy for the development of restorative materials with regenerative and preventive properties. Full article

Glass ionomer cements (GICs) are considered functionally biomimetic as they participate in ion-exchange processes that partially resemble the behavior of natural enamel and dentin, chemically bond to dental hard tissues, and release fluoride. While GICs are designed to interact with aqueous oral environments, their exposure to dietary beverages may affect their esthetic stability and water-related behavior within the oral environment. For biomimetic restorative materials to perform successfully in the oral environment, they must maintain not only bioactive properties but also esthetic stability and resistance to water-related degradation during exposure to dietary beverages. This study evaluated beverage-induced color changes, water sorption, and water solubility of six GICs following their immersion in coffee, tea, berry juice, cola, and distilled water (n = 5 per material per solution). Color measurements were recorded at baseline and after 2, 4, 6, and 8 weeks using a spectrophotometer, and color change (ΔE) values were calculated using the CIE L*a*b* system. Specimen mass was measured at baseline, after 8 weeks of immersion and then after 4 weeks of desiccation. Data were analyzed using repeated-measures Analysis of Variance (ANOVA) and Fisher’s least significant difference post hoc tests (α = 0.05). The results showed time, material, and solution significantly affected ΔE (p < 0.001). Tea produced the greatest discoloration overall, followed by coffee. ChemFil exhibited the greatest staining susceptibility, while Fuji II showed the lowest staining susceptibility. Water sorption and solubility were material- and solution-dependent. Clinically relevant discoloration of GICs was found when immersed in common beverages over time, with tea showing the strongest staining effect. These findings indicate that although GICs exhibit biomimetic characteristics through their interaction with tooth structures and aqueous environments, their long-term esthetic stability and resistance to environmental challenges should also be considered when selecting restorative materials for clinically visible areas. Full article

Biofouling remains a critical challenge in membrane bioreactors (MBR), which is primarily caused by the production of extracellular polymeric substances (EPS) as an initial step in biofilm formation. This still limits their widespread application in wastewater treatment. In the past decades, much research has been carried out to understand and consequently reduce biofouling in MBR. More recent studies have focused primarily on inhibiting the release of EPS by applying quorum quenching (QQ) to control biofouling in MBR. This study presents the first investigation of the QQ potential of Rubellimicrobium mesophilum and its effects on biofilm inhibition by EPS reduction, which is demonstrated for MBR operated with submerged flat sheet (PTFE, PS) and hollow fibre polyvinylidene fluoride (PVDF) membranes operated in parallel for 114 days. The QQ effect has a significant impact on the reduction in biofilm thickness on PTFE membranes by 45% and on PS membranes by about 47%, respectively. Additionally, the performance of PVDF was improved by 287.5%. Similarly, the total protein concentration on the PTFE membranes was reduced by 57%, while on the PS membranes, the reduction was 78%. In mixed liquor, protein reduction was 55%, indicating its effectiveness in controlling biofouling over extended operation. The biofilm formation was monitored by measuring the biofilm thickness via fluorescence microscopy and by analyzing the protein and sugar content of the developing biofilm and of the mixed liquor. All parameters indicated decreasing biofilm formation with increasing amounts of entrapped QQ bacteria, while the removal efficiency of organic compounds and ammonia remained similar between all MBRs. Full article

The exceptional stability of C-F bonds renders PFAS highly persistent in aqueous environments, posing significant challenges for conventional treatment technologies. While plasma-based technologies show promise, their efficiency is often limited by poor gas–liquid mass transfer in bulk liquid. Here, an in-house constructed ultrasonic atomization–dielectric barrier discharge (UEN-DBD) system was developed to promote PFAS degradation under non-thermal plasma conditions. Ultrasonic atomization generated microdroplets, which promoted PFAS enrichment at the surface of microdroplets and facilitate interactions with plasma-generated reactive species. Using perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) as model compounds, degradation behavior was evaluated over an initial concentration range of 0.01–1.0 ppm. At 0.01 ppm, degradation efficiencies of 96.06% for PFOA and 94.86% for PFOS were achieved within 5 min. Electron paramagnetic resonance (EPR) spectroscopy confirmed the formation of oxidative radicals (·OH) and suggested a mixed redox environment involving reactive species, potentially including superoxide (O₂·⁻) or hydrated electrons (e_aq⁻), in the discharge-treated system. High-resolution mass spectrometry results are consistent with a stepwise chain-shortening pathway dominated by successive –CF₂– scission, while fluoride-release measurements provided supporting evidence for partial defluorination. These findings advance the understanding of plasma-assisted PFAS degradation at the gas–liquid interface and provide a basis for the further development of plasma-assisted PFAS treatment strategies. Full article