Search Results (219)

Background/Objectives: Immediate dentin sealing (IDS) has been widely investigated in sound dentin; however, its efficacy on demineralized dentin remains insufficiently explored. This in vitro experimental study aimed to evaluate the shear bond strength (SBS) of indirect composite resin restorations bonded to demineralized dentin using IDS, assessed at 24 h and after 6 months of aging. Methods: Twenty-five extracted premolars were randomly divided into five groups: (1) control (no sealing), (2) IDS applied to sound dentin (sound-IDS), (3) IDS applied to demineralized dentin (carious-IDS), (4) delayed dentin sealing (DDS) on sound dentin (sound-DDS), and (5) DDS on demineralized dentin (carious-DDS). SBS values were analyzed using a three-way analysis of variance (ANOVA) with dentin condition (sound vs. demineralized), aging time (24 h vs. 6 months), and sealing strategy (control, IDS, DDS) as independent variables. Statistical analyses were performed using SigmaPlot 12.0, with significance set at p < 0.05. Results: The results showed that IDS led to significantly higher SBS than DDS (p < 0.05). Bond strength was significantly influenced by dentin condition (p < 0.05), and all interactions between variables—particularly between dentin condition and sealing strategy, and between aging time and treatment—were statistically significant (p < 0.001). Overall, bond strength was higher at 24 h than after 6 months. IDS showed optimal performance in sound dentin, while DDS resulted in better long-term outcomes in demineralized dentin. Conclusions: These findings suggest that DDS may be the more effective approach in cases of carious or demineralized dentin. Full article

Recently, 3D-printed resins have been introduced as materials for definitive indirect restorations. Herein, a comparative assessment of the bond strengths of 3D-printed resins to a resin cement was performed. Methods: four definitive restorative materials were selected, i.e., a Feldspar ceramic (VITA Mark II, VM), a polymer-infiltrated ceramic network (VITA Enamic, VE), a nanohybrid resin composite (Grandio Bloc, GB), and one 3D-printed resin (Crown Permanent, CP). VM and VE were etched and silanized, GB was sandblasted, and CP was glass bead blasted; for one further experimental group, this was followed by sandblasting (CPs). A resin cement (RelyX Unicem) was then used for bonding, and then a notched shear bond strength test (nSBS) was performed. Failure modes were observed and classified as adhesive, cohesive, or mixed, and SEM representative images were taken. Data were statistically analyzed with one-way ANOVA, Tukey, and Chi-square tests. Significant differences were detected in nSBS among materials (p < 0.001). The highest nSBS was found in VM (30.3 ± 1.8 MPa) a, followed by CP^b, GB^bc, CP^bc, and VE^c. Failure modes were significantly different (p < 0.001), and with different prevalent failure modes. The bond strength for 3D-printed permanent resin materials was shown to be lower than that of the felspathic ceramic but comparable to that of the resin block and PICN substrates. Full article

Introduction: Digital planning and evolution of technology is allowing dentistry to be more efficient in time than before. In orthodontics the main purpose is to obtain fewer patient visits and to reduce the bonding time. For that, indirect bonding planned with CAD-CAM softwares is used to obtain a shorter treatment period, in general, and less chair-time. This waste of chair-time should also be reduced in other fields of dentistry such as endodontics, surgery, prosthodontics, and aesthetics. Methods: A total of 504 teeth were embedded into epoxy resin models mounted as a dental arch. Customized lingual multibracket appliances were bonded by a current adhesion protocol. After that, they were debonded, the polishing of cement remnants was performed with three different burs and two drills. The polishing time of each group was recorded by an iPhone 14 chronometer. Results: Descriptive and comparative statistical analyses were performed with the different study groups. Statistical differences (p < 0.005) between diamond bur and tungsten carbide and white stone burs and turbine were obtained, with the first being the slowest of them. Discussion: Enamel roughness was widely studied in orthodontics polishing protocol as the main variable for protocols establishment. However, in lingual orthodontics, due the difficulty of the access to the enamel surfaces, the protocol is not clear and efficiency should be considered. It was observed that the tungsten carbide bur is the safest bur. It was also recommended that a two-step protocol of polishing by tungsten carbide bur be followed by polishers. Conclusions: A tungsten carbide bur mounted in a turbine was the most efficient protocol for polishing after lingual bracket debonding. Full article

Limited recovery of the viscoelastic properties of aged asphalt on RAP surfaces at ambient temperature reduces interface fusion and bonding with new emulsified asphalt, degrading pavement performance and limiting large-scale promotion and high-value applications of the emulsified asphalt cold recycled mixture (EACRM). Therefore, a cold regenerant was independently prepared to rapidly penetrate, soften, and activate aged asphalt at ambient temperature in this paper, and its effects on the volumetric composition, mechanical strength, and pavement performance of EACRM were systematically investigated. The results showed that as the cold regenerant content increased, the air voids, indirect tensile strength (ITS), and high-temperature deformation resistance of EACRM decreased, while the dry–wet ITS ratio, cracking resistance, and fatigue resistance increased. Considering the comprehensive pavement performance requirements of cold recycled pavements, the optimal content of the activated cold regenerant for EACRM was determined to be approximately 0.6%. Full article

Biomimetic restorative protocols aim to preserve natural tooth structure while enhancing restoration longevity. This in vitro study aimed to evaluate the shear bond strength (SBS) in the repair of additively and subtractively manufactured CAD/CAM materials using bulk-fill resin composites and to assess the effect of thermocycling. Forty rectangular specimens (14.5 × 7 × 3 mm) were prepared from Grandio Blocs (GB, VOCO) and VarseoSmile Crown^Plus (VS, BEGO), and thermocycled (5000 cycles, 5–55 °C, 20 s dwell time). All surfaces were roughened with 50 μm Al₂O₃. Samples were repaired using VisCalor (VCB, VOCO) and Charisma Bulk Flow One (CBO, Kulzer) composites (n = 10 per group) with their respective adhesives. Each group was further divided into immediate and post-thermocycling subgroups. All specimens were tested under shear force until failure, and failure types were examined under a stereomicroscope. Representative samples were examined by SEM to evaluate filler morphology. Statistical analysis was performed with SPSS v23 (p < 0.05). No statistically significant differences in SBS were found between groups (p > 0.05). Mean SBS values were highest in VS-CBO and lowest in GB-CBO. Cohesive failures were more frequent in immediate groups, while adhesive failures predominated after thermocycling. Bulk-fill composites did not influence the repair bond strength of indirect materials. Thermocycling affected the failure type, though not the SBS values. Full article

Objectives: This study investigated the use of artificial intelligence (AI) in the design of lingual bracket indirect bonding trays and its association with bracket transfer accuracy using three-dimensional (3D) printing. Methods: Digital impressions of patient’s dental arches were captured using an intraoral scanner, and orthodontic setups were virtually constructed. Brackets were virtually positioned in their ideal locations using the digital setups guided by virtual archwire templates. Indirect bonding trays were automatically generated using the AI-powered Auto Creation function of the Medit Splints application, which analyzes anatomical features to streamline design. Bracket transfer accuracy was evaluated in vivo by comparing planned and actual bracket positions across grouped and individual tray configurations. Linear and angular deviations were measured using conventional 3D inspection software. Results: Most bracket transfer errors were within clinically acceptable thresholds, although torque accuracy remained suboptimal. Grouped trays generally exhibited greater precision than individual trays in several dimensions. Conclusions: These findings support the application of AI-assisted design tools to enhance digital workflows and improve consistency in appliance fabrication. Full article

The natural and sustainable ability of earthen building materials makes them highly valuable. Bio-stabilization involves using biological materials or processes in earthen construction to enhance the performance and characteristics of earthen materials. The main objective of bio-stabilization is to substitute high-energy-intensive building materials with more green, thermally efficient substitutions, ultimately reducing indirect emissions. The large-scale use of earth presents a viable alternative due to its extensive availability and, more importantly, its low embodied energy. The aim of this work is to investigate the thermal conductivity of earth stabilized with Opuntia Ficus-Indica (OFI), a natural biopolymer, and to assess how these properties vary based on mix design. A comparative analysis is performed to evaluate the thermal performance of bio-based polymer-stabilized earthen materials (S-30, S-40, D-30, and D-40) alongside natural biopolymer-stabilized earth (OFI-30 and OFI-40) under dry conditions, employing an experimental method. A scanning electron microscope was employed to examine the microstructure of bio-stabilized earthen materials from the samples. Statistical analysis was conducted on the collected data using ANOVA with a significance level of 0.05. The Tukey test was applied to identify specific mean pairings that demonstrate significant differences in the characteristics of the mixtures at each replacement level, maintaining a confidence interval of 95%. The experimental and statistical findings reveal that the OFI-30, D-40, and S-40 mixtures exhibit strong bonding with earthen materials and high thermal performance compared to all other mix designs in environmental samples. Additionally, these mix designs show further improvement in thermal performance in the dry conditions. Full article

In order to shorten the curing time of the cement-treated aggregate base, provide a stable paving base for an asphalt mixture, and finally, achieve rapid traffic reopening during the maintenance of the pavement (milling and resurfacing of the base layer), sulphoaluminate cement (SAC) was used to prepare cement-treated aggregate with high early strength. As a result, the SAC was first optimized by adding several cement admixtures (i.e., polycarboxylic water reducer, borax, lithium carbonate, and calcium formate) based on hydration kinetics, setting time, compressive strength, and morphology tests. Then, the optimized SAC was used to prepare the sulphoaluminate cement-treated aggregate (SACTA). The test results show that the addition of compound retarder and compound early strength agent in SAC could delay the hydration, reduce microcracks, and ensure required setting time and high early strength. Compared with ordinary Portland cement-treated aggregates (OPCTAs) with the same cement content, the 1 d unconfined compressive strength and indirect tension strength of SACTAs increased by 87.7–184.6% and 133.8–263.6% respectively. The SACTA had smaller total drying shrinkage strain and better anti-scouring performance than OPCTA when using the same cement content. Besides, the 1 d interfacial bonding strength between SACTA and OPCTA was 0.18 MPa, which was higher than the indirect tension strength of OPCTA. The findings in this study indicate that the prepared SACTA could be used for rapid traffic opening during road maintenance. Full article

A comprehensive investigation of the chemical bonding, electronic structure, and spectroscopic properties of the lanarkite-type Pb₂SO₅ (PSO) structure was conducted, for the first time, using density functional theory simulations. Thus, different functionals, PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP, and B3LYP, were used, and their results were compared to predict their fundamental properties accurately. All DFT calculations were performed using a triple-zeta valence plus polarization basis set. Among all the DFT functionals, PBE0 showed the best agreement with the experimental and theoretical data available in the literature. Our results also reveal that the [PbO₅] clusters were formed with five Pb–O bond lengths, with values of 2.29, 2.35, 2.57, 2.60, and 2.79 Å. Meanwhile, the [SO₄] clusters exhibited uniform S–O bond lengths of 1.54 Å. Also, a complete topological analysis based on Bader’s Quantum Theory of Atoms in Molecules (QTAIM) was applied to identify atom–atom interactions in the covalent and non-covalent interactions of the PSO structure. Additionally, PSO has an indirect band gap energy of 4.83 eV and an effective mass ratio ($m_h^{*}$/$m_e^{*}$) of about 0.192 (PBE0) which may, in principle, indicate a low degree of recombination of electron–hole pairs in the lanarkite structure. This study represents the first comprehensive DFT investigation of Pb₂SO₅ reported in the literature, providing fundamental insights into its electronic and structural properties. Full article

Background: The 2C protein of foot-and-mouth disease virus (FMDV), a member of helicase superfamily 3 (SF3), drives viral genome replication and serves as a critical target for antiviral drug development. Methods: A fluorescence resonance energy transfer (FRET)-based high-throughput screening (HTS) platform was developed to identify 2C helicase inhibitors. Primary screening evaluated 4424 compounds for helicase inhibition. Molecular docking analyzed inhibitor interactions with the N207 residue within the catalytic core and helicase inhibition assays classified the inhibitor type (mixed, competitive, noncompetitive). Differential scanning fluorimetry (nanoDSF) quantified 2C thermal destabilization. Antiviral activity was assessed via indirect immunofluorescence, RT-qPCR, and plaque reduction assays. Results: Six compounds inhibited 2C helicase activity at >620 μM. Molecular docking revealed hydrogen bonding, hydrophobic interactions, and π-cation stabilization at the catalytic core. 2-MPO and MPPI were classified as mixed-type inhibitors, 5-TzS⁻ and 2-PyOH as competitive, and DCMQ/Spiro-BD-CHD-dione as noncompetitive. NanoDSF showed a ΔT_m ≥ 1.5 °C (2.5 mM compounds), with reduced destabilization in N207A mutants. Antiviral assays identified 2-MPO and MPPI as optimal inhibitors. MPPI achieved effective FMDV suppression at 160 μM, exhibiting two orders of magnitude higher potency than 2-MPO (400 μM). Conclusions: The established FRET-based HTS platform targeting 2C helicase facilitates anti-FMDV lead discovery, while 2C inhibitors may serve as an effective therapeutic strategy against other picornaviruses. Full article

The aim of this study is to develop a simple and reliable laboratory testing procedure for evaluating the bond strength of cement–formation sheaths that considers cement slurry composition and contamination as well as formation strength and formation surface conditions (roughness and contamination). Additionally, a simple and practical empirical correlation is developed for predicting cement–rock bond strength based on the routine mechanical properties of hard-set cement and formation rock. Cement slurries composed of Yamama cement type 1 and 25% local Saudi sand, in addition to 40% fresh water, are used for all investigations in this study. Oil well cementing is a crucial and essential operation in the drilling and completion of oil and gas wells. Cement is used to protect casing strings, isolate zones for production purposes, and address various hole problems. To effectively perform the cementing process, the cement slurry must be carefully engineered to meet the specific requirements of the reservoir conditions. In oil well cementing, the cement sheath is a crucial component of the wellbore system, responsible for maintaining structural integrity and preventing leakage. Shear bond strength refers to the force required to initiate the movement of cement from the rock formation or movement of the steel casing pipe from the cement sheath. Cement–formation sheath bond strength is a critical issue in the field of petroleum engineering and well cementing. Cement plays a crucial role in sealing the annulus (the space between the casing and the formation) and ensuring the structural integrity of the well. The bond strength between the cement and the surrounding geological formation is key to preventing issues such as fluid migration, gas leaks, and wellbore instability. To achieve the study objectives, sandstone and sandstone–cement composite samples are tested using conventional standard mechanical tests, and the results are used to predict cement–formation sheath bond strength. The utilized tests include uniaxial compression, direct tensile, and indirect tensile (Brazilian) tests. The predicted cement–rock sheath bond strength is compared to the conventional laboratory direct cement–formation sheath strength test outcomes. The results obtained from this study show that the modified uniaxial compression test, when used to evaluate cement–formation shear bond strength using cement–rock composite samples, provides reliable predictions for cement–formation sheath bond strength with an average error of less than 5%. Therefore, modified uniaxial compression testing using cement–rock composite samples can be standardized as a practical laboratory method for evaluating cement–formation sheath bond strength. Alternatively, for a simpler and more reliable prediction of cement–formation sheath bond strength (with an average error of less than 5%), the empirical correlation developed in this study using the standard compressive strength value of hard-set cement and the standard compressive strength value of the formation rock can be employed separately. For the standardization of this methodology, more generalized research should be conducted using other types of oil well cement and formation rocks. Full article

Carbon is one of nature’s basic elements, hosting a tremendous number of allotropes benefiting from its capacity to generate $sp$, $s{p}^2$, and $s{p}^3$ hybridized carbon–carbon bonds. The exploration of novel carbon architectures has remained a pivotal focus in the fields of condensed matter physics and materials science for an extended period. In this paper, we, by using first-principles calculation, carry on a detailed investigation an an all-$s{p}^3$ hybridized carbon structure in a 20-atom tetragonal unit cell with $P{4}_3{2}_{1}2$ symmetry ($D_4^8$, space group No. 96), and call it T20 carbon. The equilibrium energy of T20 carbon is −8.881 eV/atom, only 0.137 eV/atom higher than that of diamond, indicating that T20 is a superstable carbon structure. T20 is also a superhard carbon structure with a large Vicker’s hardness about 83.5 GPa. The dynamical stability of T20 was verified by means of phonon band spectrum calculations. Meanwhile, its thermal stability up to 1000 K was verified via ab initio molecular dynamics simulations. T20 is an indirect band-gap insulator with approximately 5.80 eV of a band gap. This value is obviously greater than the value in the diamond (5.36 eV). Moreover, the simulated X-ray diffraction pattern of T20 displays a remarkable match with the experimental data found in the milled fullerene soot, evidencing that T20 may be a potential modification discovered in this experimental work. Our work has given a systematical understanding on an all-$s{p}^3$ hybridized superstable and superhard carbon allotrope with large band gap and provided a very competitive explanation for previous experimental data, which will also provide guidance for upcoming studies in theory and experiment. Full article

Background/Objectives: Sandblasting build-ups before applying the acid and adhesive significantly improves the bond strength. The aim of this study is to evaluate, for the first time, the effectiveness of an Er:YAG laser used in QSP mode to treat the surface of build-ups before the adhesive cementation sequence. Methods: This ex vivo study was conducted on 12 intact, undecayed extracted teeth kept hydrated in NaCl 0.9% solution. A cavity was created in the center and reconstructed with composite resin (build-up). Then, samples were prepared with burs and divided into three groups: control group G1, prepared only with burs; group G2, in which surfaces were treated with a sandblaster (2.5 bar, 10 mm from composite surface, aluminum oxide, 10 s); and group G3, treated using an Er:YAG laser (QSP modality, 1 W, 10 Hz, 100 mJ). The surface roughness of the build-ups was measured using a CCI MP-L digital optical profiler (Taylor Hobson, Leicester, UK), and surface morphology was studied using the Quanta™ 250 FEG (FEI, Hillsboro, OR, USA) ESEM instrument. Results: Regarding enamel, mean surface roughness in G1 vs. G2 was not statistically significant (p = 0.968); meanwhile, differences between the Er:YAG laser group (G3) and G1 or G2 were significant (G3 vs. G1 p < 0.001; G3 vs. G2 p < 0.001). Regarding dentin, G1 vs. G2 was significant (p = 0.021); differences between G3 and G1 or G2 were extremely significant (G3 vs. G1 p < 0.001; G3 vs. G2 p < 0.001). The same trend was detected for resin. Conclusions: An Er:YAG laser in QSP mode used on the build-up surface for indirect adhesive restorations is innovative and should be investigated with further studies. However, it seems extremely effective with increased roughness, the absence of a smear layer and characteristics potentially favorable for good adhesion for all substrates (enamel, dentin, resin). Full article

This study examines how bonding social capital (BSC) is related to depression symptoms (Dsym) in university students, focusing on the mediating roles of socio-emotional support, instrumental support, self-efficacy, self-esteem, and academic stress. A cross-sectional design was employed, with data collected from 217 undergraduate students (from an initial sample of 250) using validated questionnaires. Data were analyzed using partial least squares structural equation modeling (PLS-SEM) to evaluate direct and indirect relationships. The key findings indicate that BSC has an indirect, relevant, and significant negative effect on Dsym (H5) (β = −0.201, 95% CI [−0.266, −0.216]) through six routes, involving enhanced self-esteem and reduced academic stress. The model highlights self-esteem as a critical mediator between social capital and mental health outcomes. With strong predictive validity (R² ≥ 0.1, Q² > 0, PLS-SEM RMSE < LM), the study provides a framework for potential interventions. The theoretical contributions include distinguishing social capital from support and prioritizing self-esteem over self-efficacy in depressive pathways. Although the cross-sectional design limits causal inferences, the model advances systemic approaches to student mental health, highlighting the need for longitudinal validation in diverse contexts. Full article

Background: This study investigated the pathways through which various psychological problems occurring across the perinatal period influence mother–child bonding within the first 18 months postpartum, with a particular focus on the relationship between perinatal and postpartum depression and childbirth-related posttraumatic stress symptomatology. Methods: A multi-stage longitudinal design included three assessment points: recruitment and initial assessment in the third trimester of pregnancy (T1), a second assessment at 8 months postpartum (T2), and a final assessment at 18 months postpartum (T3). A total of N = 51 mothers completed all three waves (total follow-up period per participant: approximately 21 months). Sociodemographic data were collected, and all assessments were completed online. Results: Our findings revealed significant indirect effects, linking higher levels of perinatal depressive symptoms in the third trimester with mother–child bonding difficulties at 18 months postpartum. This association was mediated by both greater childbirth-related posttraumatic stress symptoms and elevated postpartum depressive symptoms at 8 months. Conclusions: These preliminary results highlight how complex perinatal factors at different stages (i.e., during pregnancy and early postpartum) influence mother–child bonding at 18 months postpartum. Understanding these pathways is essential in order to inform targeted interventions and to promote optimal maternal mental health and bonding outcomes. Full article