Search Results (3,532)

Dental caries remains one of the most prevalent chronic diseases worldwide, driven by complex interactions among dietary, hygienic, and biological factors. This study introduces a hybrid predictive framework that integrates mathematical modelling and artificial intelligence (AI) to estimate individual caries risk based on daily sugar intake, oral hygiene index, salivary pH, fluoride exposure, age, and sex. A first-order balance differential equation was applied to simulate demineralisation–remineralisation dynamics, while a feed-forward artificial neural network (ANN) was trained on simulated and literature-derived datasets. The hybrid model demonstrated strong predictive performance, achieving 91.2% accuracy and an AUC of 0.98 in classifying individuals into low-, moderate-, and high-risk categories. Sensitivity analysis identified sugar intake and oral hygiene as dominant determinants, while fluoride and salivary pH showed protective effects. These findings highlight the feasibility of combining mechanistic and data-driven approaches to enhance early risk assessment and support the development of intelligent, personalised screening tools in preventive dentistry. Full article

Fluoride prophylaxis is a cornerstone in preventing dental caries, a disease for which orthodontic patients are at high risk due to the reduced effectiveness of home oral hygiene and increased plaque accumulation. Recent evidence defines caries as polymicrobial, involving Streptococcus mutans, Lactobacilli, and emerging species such as Selenomonas sputigena. This prospective, randomized, controlled study evaluated professional topical fluoride in the form of gel and varnish in 68 patients aged 8–17 years wearing fixed orthodontic appliances. Participants were divided into three equal groups: two intervention groups and one control group. Clinical parameters (DMFT, salivary pH, PCR%) and microbiological analyses of plaque and saliva (oral Streptococci, S. mutans, S. sputigena, Lactobacilli, total bacterial count) were assessed at baseline (T0) and after 4 months (T1), following professional hygiene and fluoride application for the intervention groups. At T1, salivary pH increased in the gel group, and PCR% decreased significantly in all groups, with the most pronounced decrease observed in the varnish group. PCR analysis showed a higher rate of S. mutans and S. sputigena negativization in intervention groups. Culture-based analyses revealed reductions in oral Streptococci and Lactobacilli in intervention groups, while levels increased in controls. Overall, both clinical and microbiological variables indicated improvements in the fluoride-treated groups compared to controls, highlighting the efficacy of professional fluoride prophylaxis in orthodontic patients. Full article

Epidemiological and geochemical evidence suggests that coal-burning fluorosis in Southwest China is mechanistically linked to the presence of fluoride-rich geochemical anomalies. However, the severity of dental fluorosis does not consistently align with the distribution pattern of fluoride geochemistry, suggesting that other factors may interfere with the dose–effect relationship of fluorosis. To investigate the potential biotoxicity impacts of fluoride, this study conducted an analysis of soil fluoride–selenium spatial correlation in the central areas of coal-burning fluorosis in China. The results revealed that 59.1% of soil fluoride contents were more than the average soil fluoride content of China (800 mg·kg⁻¹) and 77.9% of soil selenium contents were above 0.45 mg·kg⁻¹. Soil fluoride (1.11 × 10³ mg·kg⁻¹) and selenium contents (0.78 mg·kg⁻¹) were significantly high states, but agricultural products and drinking water sources showed relatively low levels, not significantly influenced by soil conditions. The severity of fluorosis was evaluated using Dean’s dental fluorosis index (DFI). The spatial association of soil selenium or fluoride with DFI suggested that there was a reverse relationship between soil selenium or selenium/fluoride and the DFI. The generalized additive model (GAM) showed the onset of DFI correlated with soil fluoride content, showcasing a distinctive “W” pattern, while DFI decreased steeply or gradually as soil selenium content or selenium/fluoride ratio increased. In conclusion, our findings suggest that the geochemical anomaly of soil fluoride likely contributes to the occurrence of fluorosis. However, the significantly elevated levels of soil selenium might alleviate the severity of dental fluorosis to some extent. Full article

Metarhizium anisopliae, an entomopathogenic fungus, can produce four extracellular proteases, subtilisin (Pr1), trypsin (Pr2), metalloproteases (Pr3), and cysteine proteases (Pr4), which are important for pathogenicity of M. anisopliae in target hosts. In order to understand their function in M. anisopliae pathogenicity, third-instar nymphs of Locusta migratoria were fed with a diet containing either conidia of M. anisopliae strain IPPM202 or in combination with one of the four inhibitors (TPCK: tosyl-phenylalanine chloromethyl-ketone, inhibitor of Pr1; EDTA: ethylenediaminetetraacetic acid, inhibitor of Pr3; APMSF: 4-amidinophenyl methanesulfonyl fluoride, inhibitor of Pr2; CI1: cathepsin inhibitor 1, inhibitor of Pr4). The effects on mortality, midgut integrity, and the gut enzymes peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and phenol oxidase (PO) were examined. The results indicated that exposure to IPPM202/TPCK and IPPM202/CI1 caused decreased mortality to L. migratoria with no loss of midgut epithelial cellular integrity. On the other hand, exposure to IPPM202/APMSF or IPPM202/EDTA mixtures resulted in higher mortality similar to PPM202, with severely damaged epithelial gut cells with fragmented microvilli, broken endoplasmic reticulum, and disrupted nucleus membrane. The activity of the protective enzymes POD, SOD, CAT, and PO all increased significantly when L. migratoria was treated with IPPM202 only, but decreased when any one of the inhibitors was added. We further concluded that TPCK, a subtilisin (Pr1) inhibitor, and CI1, a cysteine protease (Pr4) inhibitor, played important roles in the pathogenicity of the M. anisopliae strain IPPM202. Conversely, trypsin (Pr2) and metalloproteases (Pr3) did not have a role in the given process. We further concluded that trypsin (Pr2) and metalloproteases (Pr3) do not contribute to the fungal infection process, while the subtilisin (Pr1) inhibitor TPCK and cysteine protease (Pr4) inhibitor CI1 play critical roles in the pathogenicity of Metarhizium anisopliae strain IPPM202, thus providing a foundation for targeted biocontrol strategies. Full article

Breastfeeding based on the use of follow-on milk may contain traces of xenobiotic elements that could pose a risk to the health of the vulnerable population for which it is intended. Fluorine is a non-essential element that, at high concentrations, can produce adverse health effects such as dental fluorosis, decreased IQ (intelligence quotient), thyroid alterations, and kidney damage. Given the vulnerability of infants and the possible presence of fluoride in this type of product, the content of this anion was determined in a total of 46 samples of follow-on milk from different brands and types (starter, follow-on, and hydrolysate formulas) using a fluoride ion-selective electrode (EWI). The highest mean concentration of fluoride was recorded in the hydrolysate formulas (3.38 ± 2.78 mg/L). The dietary intake assessment indicated that some brands of hydrolyzed formulas could pose a health risk, providing up to 94.1% of the UL (upper level) with only one 90 mL serving in the 0–6-month age group. It is recommended that consumers be aware of the fluoride content in the water used to prepare bottles, as it can further increase total fluoride intake and therefore pose a risk to the health of infants. Full article

The morphology and composition of inorganic particles play a vital role in controlling the flame-retardant characteristics of polymers. Halogen-free flame-retardant polymers have also become a current research hotspot. Boron nitride (BN), phytic acid (PA), and chitosan (CS), a natural polysaccharide with a nitrogen content of approximately 6.8–7.5%, show great promise as flame retardants owing to their high thermal stability, P-based flame retardancy, and natural polysaccharide properties, respectively. In this study, BN (BN@PA-CS) particles coated with PA and CS were designed and prepared via a facile modification strategy. The effect of BN@PA-CS on the mechanical and flame-retardant properties of polyvinylidene fluoride (PVDF) was further investigated, and it was found that both characteristics were improved. Compared to pure PVDF, the PVDF composite films exhibited a significantly lower peak heat release rate and total heat release. With a BN@PA-CS content of 20%, the peak was the lowest at 18.25 W/g, corresponding to a decrease of 77.83%. This phenomenon may be attributed to the synergistic effect of the BN nanosheets and PA-CS in the BN@PA-CS particles. This work describes a facile and effective method of modifying the morphology and composition of inorganic particles, thereby controlling the properties of polymers, and provides a new approach to improving the safety of PVDF battery separators. Full article

Groundwater represents a critical global resource, increasingly threatened by overexploitation and pollution from contaminants such as arsenic (As), fluoride (F), nitrates (NO₃⁻), and heavy metals in arid to semi-arid regions like Mexico. Traditional Water Quality Indices ($WQIs$), while useful, suffer from subjectivity in assigning weights, which can lead to misinterpretations. This study addresses these limitations by developing a novel, objective Groundwater Quality Index ($GWQI$) through the seamless integration of Machine Learning (ML) models. Utilizing a database of 775 wells from the Mexican National Water Commission (CONAGUA), Principal Component Analysis (PCA) was applied to achieve significant dimensionality reduction. We successfully reduced the required monitoring parameters from 13 to only three key indicators: total dissolved solids (TDSs), chromium (Cr), and manganese (Mn). This reduction allows for an 87% decrease in the number of indicators, maximizing efficiency and generating potential savings in monitoring resources without compromising water quality prediction accuracy. Six $WQI$ methods and six ML models were evaluated for quality prediction. The Unified Water Quality Index (${WQI}_u$) demonstrated the best performance among the $WQIs$ evaluated and exhibited the highest correlation (R² = 0.85) with the traditional $WQI$ based on WHO criteria. Furthermore, the ML Support Vector Machine with polynomial kernel (svmPoly) model achieved the maximum predictive accuracy for ${WQI}_u$ (R² = 0.822). This robust $GWQI$-ML approach establishes an accurate, objective, and efficient tool for large-scale groundwater quality monitoring across Mexico, facilitating informed decision-making for sustainable water management and enhanced public health protection. Full article

As a favorable hydrophilic additive for antifouling modification of polyvinylidene fluoride (PVDF) membrane, titanium dioxide (TiO₂) nanoparticles have been applied for years. Sodium dodecyl sulfonate (SDS), a representative anionic surfactant, has been proven to benefit the dispersion of nano-TiO₂ via an electro-spatial stabilizing mechanism. In this study, various proportionally SDS-functionalized TiO₂ nanoparticles were adopted to modify PVDF membrane. Dispersion and stability of SDS-functionalized TiO₂ nanoparticles in casting solutions were evaluated by multiple light scattering technology. The properties and antifouling performance of PVDF/SDS-TiO₂ composite membranes were assessed. The uniformity of surface pores as well as structures on cross-section morphologies was modified. The finger-like structure of PVDF/SDS-TiO₂ composite membrane was adequately developed at the SDS/TiO₂ mass ratio of 1:1. The improved antifouling performance was corroborated by the increasing free energy of cohesion and adhesion as well as the interaction energy barrier between membrane surfaces and approaching foulants assessed by classic extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory, the low flux decline during bovine serum albumin (BSA) solution filtration process, and the high critical flux (38 L/(m²·h·kPa)) in membrane bioreactor. This study exploits a promising way to modify PVDF membrane applicable to the wastewater treatment field. Full article

Background and Objectives: Early Childhood Caries affect children’s quality of life and overall health. This study aimed to assess the involvement of dentists in implementing early preventive measures, including fluoride use, for children aged 6–33 months. Materials and Methods: a multiple-choice questionnaire was distributed in six German states, consisting of two sections: Section I covered participant demographics and Section II included items on dental preventive measures for children. The questionnaire was adapted from a validated German-language source, reviewed by five experts at Kiel University, and tested in a focus group of 30 dentists. Descriptive statistics (mean ± SD or median [IQR]) and Mann–Whitney U tests were used to assess pediatric dentists (PD) and general dentists (GP) involvement in early dental preventive measures. Results: A total of 511 eligible questionnaires were returned (mean age 47 ± 11 year, 63.8% females, 36.7% PD). Both GP and PD routinely recommended a diagnostic dental visit (1 = never, 5 = always), with PD reporting higher frequency (GP: 4 [3–5], PD: 4.5 [4–5]; p = 0.001). Parental training in oral hygiene was performed significantly more often by PD (p < 0.01). PD also recommended tooth brushing with fluoridated toothpaste after the eruption of the first tooth more frequently than GP (GP: 5 [3–5], PD: 5 [4–5]; p = 0.06). Surprisingly, fluoride-free toothpaste was still recommended by a relevant number of respondents in both groups. Conclusions: PDs showed greater involvement in early caries prevention than GP. While most recommended fluoridated toothpaste, many still advised fluoride-free options, highlighting gaps in guideline adherence. Full article

Cutting force measurement plays a fundamental role in machining research and industrial applications, but existing dynamometers present important trade-offs between cost, stiffness, and dynamic bandwidth. Strain gauge devices are inexpensive but too flexible for high-speed operations, whereas piezoelectric systems provide excellent accuracy and bandwidth at prohibitive costs. This work presents the design, construction, and validation of a novel plate dynamometer based on polyvinylidene fluoride (PVDF) sensors, aimed at providing an effective alternative having an intermediate cost and suitable for advanced milling applications. The device integrates eight symmetrically arranged PVDF films in a stiff steel structure, complemented by four accelerometers for inertial compensation. A finite-element analysis confirmed favorable stress distribution at the PVDF contact surfaces and high resonance frequencies (under ideal clamping conditions). Modal tests demonstrated that uncompensated PVDF signals offer limited bandwidth, but the application of the Universal Inverse Filter (UIF) extended the usable bandwidth to 5 kHz along direct directions and up to 0.3–4 kHz along cross directions, approaching the performance of piezoelectric reference devices. Milling tests under diverse cutting conditions further validated the new device. Overall, the proposed device bridges the gap between low-cost strain gauge and high-performance piezoelectric dynamometers, offering a versatile and promising solution for both laboratory research and industrial applications. Full article

Background/Objectives: Dental caries, one of the most common oral diseases worldwide, represents a major public health concern. Contemporary dentistry has established several non-invasive approaches and resin infiltration, as a micro-invasive path, in the treatment of white spot lesions (WSLs). This study aimed to evaluate the effect of different WSL treatments on enamel surface microhardness. Materials and Methods: Seventy-five intact human premolars extracted upon orthodontic indication and the demineralizing solution composed of acetic acid, monopotassium phosphate and calcium chloride with pH = 4.4 and exposure time 96 h were used. The samples were randomly divided into five groups (n = 15): I—intact enamel (control group); II—artificial white spot lesion; III—artificial WSL treated with fluoride varnish; IV—artificial WSL treated with casein phosphopeptide—amorphous calcium phosphate (CPP-ACP) paste; V—resin-infiltrated artificial WSL. The surface microhardness was determined using the Oliver–Pharr method and a spherical indenter (Shimadzu Indenter, Kyoto, Japan). One-way analysis of variance (ANOVA) followed by a Post Hoc test (Bonferroni) was used with a level of significance set at p < 0.05. Results: Resin-infiltrated white spot lesions showed comparable microhardness mean value as the control group: 68.23 (±21.45) and 63.57 (±18.89), respectively (p > 0.05). Also, resin infiltration increased enamel microhardness compared to WSL values, with a statistically significant difference (p < 0.05). Fluoride varnish and CPP-ACP treatment resulted in equivalent values (50.84 ± 14.35 and 50.99 ± 15.31, respectively). Conclusions: Different WSL treatments (fluoride varnish, CPP-ACP and resin infiltration) produced comparable enamel microhardness values. Among the tested agents, resin infiltration resulted in higher microhardness values, while fluoride varnish and CPP-ACP demonstrated equivalent outcomes. Full article

As an emerging platform for high-precision sensing, integrated silicon-waveguide-based cavity optomechanical devices face a critical fabrication challenge in the co-fabrication of silicon-on-insulator (SOI) micromechanical structures and optical waveguides: the silicon oxide (SiO₂) layer beneath the waveguides is susceptible to etching during hydrofluoric acid (HF) release of the microstructures, leading to waveguide collapse and significantly reducing production yields. This study proposes a novel selective protection process based on a magnesium fluoride (MgF₂) thin film to address the critical challenge of long-range waveguide collapse during hydrofluoric acid (HF) etching. By depositing a MgF₂ protective layer over the waveguide regions via optical coating technology, localized protection of specific SiO₂ areas during HF etching is achieved. The experimental results demonstrate the successful release of silicon waveguides with lengths of up to 5000 μm and a significant improvement in production yield. This work provides a compatible and efficient strategy for the fabrication of robust photonic–microelectromechanical integrated devices. Full article

Brick tea is a type of post-fermented food that involves microorganisms. Long-term consumption of brick tea exposes consumers to high fluoride levels, which can adversely affect their health. This study explored the feasibility of selective defluorination of Qingzhuan brick tea through membrane separation technology, and pilot production was conducted to produce defluorinated instant brick tea. The concentration of tea polyphenols increased by more than 10 times after nanofiltration, demonstrating the high selectivity of nanofiltration membranes toward fluoride. Defluorination trends were studied at different initial material concentrations (0.5–4%) and operating pressures (0.1–0.5 MPa) under cyclic defluorination. Defluorinated instant brick tea products were also industrially prepared using 300- (DF-300) and 1000-Da (DF-1000) membranes, followed by vacuum freeze-drying. The DF-1000 and DF-300 products exhibited a defluorination rate of 51.46% and 67.96%, respectively. The products have excellent characteristics in terms of color, aroma, and flavor quality, as well as solubility. Gas chromatography–mass spectrometry indicated that the volatile components in the defluorinated instant brick tea were slightly different from those in the original tea, but the key aroma and flavor characteristics of the defluorinated brick tea remained unchanged. Membrane separation provides technical support for the large-scale production of low-fluoride post-fermented tea. Full article

Background/Objectives: Adhesion to caries-affected dentin remains challenging due to its altered structure and composition. Remineralizing agents have been proposed to strengthen this substrate and improve bonding. This study evaluated the effect of three remineralization treatments, CPP-ACP, self-assembling peptide P11-4, and silver diamine fluoride (SDF), on the microtensile bond strength (μTBS) of universal adhesive systems applied to caries-affected dentin, using both etch-and-rinse and self-etch strategies. Methods: Seventy human molars were sectioned and artificially demineralized to simulate caries-affected dentin. Samples were divided into ten groups: four untreated and six treated with CPP-ACP (MI Paste™), P11-4 (Curodont™ Protect), or SDF (Riva Star™). Universal adhesives were applied via etch-and-rinse or self-etch mode, followed by composite restoration. Microtensile bond strength was measured using a universal testing machine, and results were statistically analyzed with ANOVA and t-tests (p < 0.05). Results: Untreated caries-affected dentin showed significantly lower μTBS than sound dentin (C3: 18.3 ± 5.4 MPa vs. C1: 41.3 ± 2.7 MPa). Remineralization agents improved μTBS considerably. CPP-ACP achieved the highest recovery (S1: 31.8 ± 2.6 MPa; S2: 29.2 ± 4.6 MPa), nearing sound dentin levels. P11-4 yielded moderate gains (S3: 24.4 ± 6.5 MPa; S4: 24.1 ± 4.7 MPa), while SDF provided the lowest, yet significant, improvements (S5: 23.7 ± 7.5 MPa; S6: 21.3 ± 5.3 MPa). Etch-and-rinse generally produced higher μTBS than self-etch, but differences were not statistically significant (p > 0.05). Conclusions: Pre-treatment of caries-affected dentin with CPP-ACP, P11-4, or SDF enhances universal adhesive bond strength, with CPP-ACP showing the most pronounced effect. Remineralization protocols represent a valuable adjunct in restorative procedures involving compromised dentin. Full article

The thermal behavior of 3D-printed polyvinylidene fluoride (PVDF)-based composites enhanced with carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and their hybrid formulations was investigated under Joule heating at applied voltages of 2, 3, and 4 V. The influence of filler type and weight fraction on both electrical and thermal conductivity was systematically assessed using a Design of Experiments (DoE) approach. Response Surface Methodology (RSM) was employed to derive an analytical relationship linking conductivity values to filler loading, revealing clear trends and interaction effects. Among all tested formulations, the composite containing 6 wt% of GNPs exhibited the highest performance in terms of thermal response and electrical conductivity, reaching a steady-state temperature of 88.1 °C under an applied voltage of just 4 V. This optimal formulation was further analyzed through multiphysics simulations, validated against experimental data and theoretical predictions, to evaluate its effectiveness for potential practical applications—particularly in de-icing systems leveraging Joule heating. The integrated experimental–theoretical–numerical workflow proposed herein offers a robust strategy for guiding the development and optimization of next-generation polymer nanocomposites for thermal management technologies. Full article