Search Results (114)

In this study, the efficacy of super white cement (SWC) to improve organic soils was researched. For stabilization, 10%, 15%, and 20% proportions of SWC were added to organic soil. After improvement with SWC, Atterberg limit testing, standard Proctor tests, triaxial compression tests, and swelling and compressibility tests were performed on the organic soil. Proctor tests showed that stabilization of organic soil with SWC increased maximum dry density (MDD) and optimum moisture content (OMC) values. After stabilization, the unconfined compressional strength values of the soil increased. This increase continued until the 28th day and had a reducing trend after improvement with SWC, linked to time. In addition to the reaction between SWC and OS, the time-dependent behavior of OS also contributed to this behavior. With the increase in SWC proportions, the cohesion intercept and internal friction angle values rapidly increased until the 56th day. This increase began to reduce after the 56th day. After stabilization, the swelling percentage and compressibility values for the soil reduced. The addition of SWC within organic soil appeared to improve the engineering properties of the soil. 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

This research paper provides new insights into the impact of accelerated mineralization of alkaline waste materials on the physical and mechanical behavior of low-carbon cement-based mortars. Standardized eco-cement mortars were prepared by replacing Portland cement with 7% and 20% proportions of three alkaline waste materials (white ladle furnace slag, biomass ash, and fine concrete waste fraction) that had been previously carbonated in a static reactor at predefined humidity and CO₂ concentration. The mortars’ physical (total/capillary water absorption, electrical resistivity) and mechanical properties (compressive strength up to 90 d of curing) were analyzed, and their microstructures were examined using mercury intrusion porosimetry and computed tomography. The results reveal that carbonated waste materials generate a greater heat of hydration and have a lower total and capillary water absorption capacity, while the electrical resistivity and compressive strength tests generally indicate that they behave similarly to mortars not containing carbonated minerals. Mercury intrusion porosimetry (microporosity) indicates an increase in total porosity, with no clear refinement versus non-carbonated materials, while computed tomography (macroporosity) reveals a refinement of the pore structure with a significant reduction in the number of larger pores (>0.09 mm³) and intermediate pores (0.001–0.09 mm³) when carbonated residues are incorporated that varies depending on waste material. The construction and demolition waste (CCDW-C) introduced the best physical and mechanical behavior. These studies confirm the possibility of recycling carbonated waste materials as low-carbon supplementary cementitious materials (SCMs). Full article

Aim: hydraulic calcium silicate-based cements (HCSCs) are widely used in endodontics for vital pulp therapy and other clinical procedures due to their favorable physicochemical and biological properties. This study evaluates the biological properties of two HCSCs—MTA Flow™ and MTA Flow™ White (in a 3:2 liquid-to-powder ratio, thick consistency)—on human dental pulp stem cells (hDPSCs). Methodology: hDPSCs were exposed to leachates from MTA Flow™, MTA Flow™ White, and ProRoot^® MTA. pH changes, cytotoxicity, cell proliferation, cell morphology, and cell death (apoptosis/necrosis) were assessed in vitro. Results: MTA Flow™ White and ProRoot^® MTA leachates produced a strongly alkaline pH (~10–12) compared to the negative control, whereas MTA Flow™ leachate caused a smaller pH increase (~9.4). Freshly mixed cements showed moderate cytotoxicity (around 40–60% cell viability at 100% concentration), while hardened cement leachates did not significantly affect cell viability. At 100% concentration, MTA Flow™ and MTA Flow™ White leachates significantly inhibited hDPSC proliferation and caused cell death, but at lower concentrations (≤50%) they supported cell viability and proliferation comparable to ProRoot^® MTA. hDPSCs exposed to MTA Flow™ and MTA Flow™ White leachates appeared more elongated morphologically than those exposed to ProRoot^® MTA. Notably, cells treated with MTA Flow™ White leachates were significantly smaller than those treated with MTA Flow™. Conclusions: MTA Flow™ and MTA Flow™ White, used in 3:2 thick consistency, demonstrated biocompatibility comparable to ProRoot^® MTA in vitro. While 100% leachates showed moderate cytotoxicity, lower concentration dilutions (≤50%) supported hDPSC viability, proliferation, and morphology. These findings support their potential as safe alternatives for vital pulp therapy. Further in vivo studies and dynamic models are needed to confirm long-term biological performance. Full article

Fixed orthodontic appliances, which are cemented to tooth surfaces, complicate the maintenance of oral hygiene and create a rough surface that is favorable for bacteria attachment. Additionally, the presence of orthodontic appliances may conceive a unique environment that interacts with cariogenic microorganisms, fostering a distinct microbial ecosystem compared to that of the patients without orthodontic appliances, thus increasing the vulnerability of tooth surfaces to demineralization and caries formation. Silver (Ag) has shown strong antimicrobial effects and has been extensively investigated in the medical field. Here, we aim to review the antibacterial properties and potential side effects of silver nanoparticles (AgNPs) when incorporated into orthodontic bonding reagents. This valuation could contribute to the development of novel bonding reagents designed to prevent the formation of white spot lesions and caries during orthodontic treatments. Full article

Bioactive resin-based cements (RBCs) were recently introduced, but data on their color stability remain limited. This study analyzed the impact of thermal cycling on the color and whiteness of bioactive RBCs. Specimens (n = 10) were fabricated from Panavia SA Universal (PN), Predicta Bioactive Cement (PR), and ACTIVA BioACTIVE cement (AC). CIE Lab* values were registered at baseline and after 5000, 10,000, and 15,000 thermal cycles (5–55 °C). Changes in color (ΔE₀₀) and whiteness index (ΔWI_D) were calculated and compared. Material type and thermal cycling significantly affected ΔE₀₀ and ΔWI_D (p < 0.001). AC showed the highest ΔE₀₀ values at all stages (p < 0.001), with a progressive increase over time. PN differed significantly between early and later cycles (p < 0.05), while PR remained stable (p > 0.05). Analysis of color parameters indicated that AC underwent the most pronounced changes, particularly in Δa and Δb, while PN exhibited the greatest shift in Δb. For ΔWI_D, PR had significantly lower values than PN (p < 0.05) and AC (p < 0.001), with no difference between PN and AC (p > 0.05), and thermal cycling significantly affected all groups, with PR and AC differing across all stages (p < 0.05). Thermal cycling significantly influenced the color stability and whiteness of bioactive RBCs, with AC exhibiting the greatest changes over time, while PR demonstrated superior stability. Full article

Concrete printing technologies play a key role in the modernization of construction practices. One factor that mitigates their progress is the development of standards and characterization tools for concrete during printing. The aim of this work is to point out correlations between some printability descriptors of mortars and the data obtained from low-field nuclear magnetic resonance (NMR) relaxometry techniques. In this context, the superposed effects of an acrylic-based superplasticizer and calcium nitrate accelerator were investigated. The mortars under study are based on white Portland cement, fine aggregates, and silica fume at fixed ratios. Extrusion tests and visual inspection of the filaments evaluate the extrudability and the printing window. The selected compositions were also investigated via transverse $\left(T_2\right)$ and longitudinal $\left(T_1\right)$ NMR relaxation times. The results indicate that both additives increase the printing window of the mortar, while the accelerator induces a faster increase in specific surface area of capillary pores $\left(S/V\right)$ only after 30–60 min of hydration. Some correlations were found between the printing window and the range where the transverse relaxation rates $\left(1/T_2\right)$ and the pore surface-to-volume ratios $\left(S/V\right)$ increase linearly. This suggests some promising connections between NMR techniques and the study of structural buildup of cementitious materials. Full article

Titanium nitride (TiN) is a widely used industrial hard coating material, known for its excellent hardness and chemical stability. However, its relatively high coefficient of friction (COF) often leads to interfacial heat accumulation and adhesive wear during service, limiting its applicability in high-temperature tribological environments. To enhance its tribological performance, a TiN–WS₂ soft–hard composite coating was fabricated on cemented carbide substrates using reactive co-sputtering magnetron deposition. By adjusting the sputtering parameters and target power ratio, a synergistic deposition of the hard (TiN) and lubricating (WS₂) phases was achieved and compared with a pure TiN coating. The results revealed that the incorporation of WS₂ significantly reduced the COF at both room temperature (25 °C) and an elevated temperature (200 °C), with the average values decreasing from 0.61 to 0.39 at 25 °C and from 0.53 to 0.36 at 200 °C. A white light interferometry analysis showed that the TiN–WS₂ coating exhibited narrower wear tracks and less surface damage than TiN at elevated temperatures, demonstrating superior friction-reducing and wear-resistant capabilities. In terms of mechanical properties, the composite coating showed a reduction in the hardness, the reduced elastic modulus (Er), and the adhesion strength by 27.3%, 19.8%, and 9.5%, respectively, compared to pure TiN. These findings indicate that the introduction of a quantitatively controlled lubricating WS₂ phase allows for a balance between nanoscale hardness and wear resistance, offering promising potential for engineering applications under complex working conditions. Full article

The feasibility of producing high-quality zinc phosphate cement based on a frit-sintered mixture of ZnO, SiO₂, MgO, and Bi₂O₃ oxides, with the addition of phosphorous slag and an aqueous solution of orthophosphoric acid as the mixing liquid, was demonstrated. The raw materials used for zinc phosphate cement preparation were investigated using various physicochemical analysis methods. It was found that the phosphorous slag contains silicon oxide (37.6%), aluminum oxide (4.49%), calcium oxide (42.4%), magnesium oxide (2.19%), as well as fluorine (1.94%) and calcium fluoride (4.91%). The slag predominantly consists of an amorphous glassy phase with minor inclusions of crystalline components. During the sintering process, the addition of 1.5–3.0 wt.% phosphorous slag to the frit promotes the formation of low-melting eutectics due to the presence of fluorides, resulting in a 100 °C reduction in the sintering temperature. An optimal zinc phosphate cement powder composition was developed, comprising: ZnO—83.0%, MgO—9.0%, SiO₂—3.5%, Bi₂O₃—3.0%, and phosphorous slag—1.5%. The resulting sintered product exhibited a whiteness of 97.8%, which exceeds that of the reference sample by 2.6%. Upon mixing the powder with the mixing liquid, zinc ions are released first, initiating a chemical reaction that leads to the formation of zinc, magnesium, and aluminum phosphates. The compressive strength of the resulting composite cements ranged from 101.8 to 111.9 MPa, fully complying with the requirements for cement grade as specified in GOST 31578-2012. Full article

In the search for eco-friendly and resource-efficient alternatives to conventional building materials, agricultural residues are gaining increasing attention as reinforcements in cement-based composites. This study investigates the potential of walnut shell particles (WSPs), a lignocellulosic bio-product, as a sustainable reinforcing agent in walnut shell cement boards (WSCBs). Using super white cement (SWC) as a binder, boards were manufactured with WSP content ranging from 10% to 50% by weight, targeting a density of 1300 kg/m³, a 10 mm thickness, and a water-to-cement ratio of 0.6:1. The mixtures were cold-pressed at ambient temperature using a hydraulic press at 3 MPa for 24 h, followed by curing for 28 days under ambient conditions. Physical properties such as density, water absorption, and thickness swelling were assessed, along with mechanical performance, through flexural testing. Fracture surfaces and internal microstructures were examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Functional groups and chemical reactions were monitored using FTIR, while thermal analysis (TGA and DSC), as well as measurements of thermal conductivity and resistance, provided comprehensive insights into the thermal behavior, insulating performance, and energy efficiency potential of the boards. Results demonstrate that the board with 30% WSP exhibited an optimal balance of physical and mechanical properties, achieving a 24 h water absorption of 14.05% and a modulus of rupture (MOR) of 6.53 MPa, making it suitable for non-structural applications. The board with 50% WSP exhibited the best thermal insulation performance, with a low thermal conductivity of 0.079 W/m·K. These findings highlight the potential of recycled agricultural materials in enhancing building materials’ performance, contributing to sustainable, eco-friendly construction practices. Full article

When performing an apicoectomy avoiding the microleakage is desired. That is why materials used for this procedure should be resistant to washout. Washout refers to the tendency of freshly prepared materials to disintegrate upon contact with fluids. Background/Objectives: The aim of this paper is to provide a literature review on the washout resistance of bioactive root-end filling materials. Methods: This systematic review was conducted following the PRISMA 2020 guidelines. International databases (PubMed, Google Scholar, ScienceDirect, and Wiley Online Library) were searched, and articles published in the last 20 years were selected for analysis. The following keywords were used “antiwashout”, “washout resistance”, “washout in dentistry”, “root-end filling materials”, “calcium silicate-based cements”, “bioceramic materials”. A total of 6 in vitro studies that met all the inclusion criteria were included in the analysis. The overall risk of bias was low in all six studies. Results: Most tested bioceramic materials are Endocem, Capasio, and Ceramicrete-D. Generex-A, MTA-Plus, MTA-AW, Bioaggregate, and MTA HP usually demonstrate very good washout resistance. ProRoot and MTA Angelus performed differently depending on the test; however, generally they showed good washout resistance. The Biodentine material showed significant washout, and requires further research. There is still a lack of a unified method for washout evaluation in dentistry, which makes it difficult to compare different studies. Conclusions: The study the confirmed excellent washout resistance of EndoCem, Capasio, Ceramicrete-D, Generex-A, Bioaggregate, MTA-Plus, and MTA HP. ProRoot, MTA-Angelus, and MTA Angelus White exhibited lower washout resistance. Biodentine shows poor washout resistance, and requires further research. A unified method for assessing washout would be beneficial for comparing different studies. Full article

(1) Background: White spot lesions (WSLs) on enamel result from demineralization and are an early sign of dental caries. Glass ionomer cement (GIC) has been widely used for its remineralization potential, and zinc-containing GIC (zGIC) has been introduced to enhance this effect. However, its efficacy compared to conventional GIC (cGIC) remains unclear. This study aimed to evaluate and compare the remineralization effects of cGIC and zGIC on WSLs. (2) Methods: Thirty-six bovine enamel specimens were prepared, demineralized for four days, and divided into three groups: control, cGIC, and zGIC. Half of each specimen’s treated window was covered with varnish, and a two-week pH cycling protocol was conducted. Mineral density (MD) changes were assessed using microcomputed tomography (Micro-CT) at five time points: pre-demineralization, after demineralization, immediately after treatment, and 1- and 2-weeks post-treatment. Scanning electron microscopy (SEM) was also performed. (3) Results: MD values in the zGIC and cGIC groups were significantly higher than in the control group throughout every post-treatment assessment (p < 0.05). zGIC demonstrated significantly higher MD than cGIC (p < 0.05), and SEM images revealed inferior mineral deposition. (4) Conclusions: These findings suggest that zGIC is more effective in remineralizing WSLs than cGIC over two weeks. Full article

Objectives: This study evaluates the effectiveness of laser surface texturing (LST) using a Surface Transition Machine (STM) on pre-sintered zirconia, comparing its impact on surface characteristics and shear bond strength (SBS) with resin cement to conventional sandblasting techniques. Methods: Zirconia specimens were treated with either STM or sandblasting, followed by surface analysis through scanning electron microscopy (SEM) and White Light Interferometry (WLI), wettability assessment via contact angle measurements, and SBS testing with resin cement and a 10-MDP-containing primer. Results: SEM and WLI revealed significant surface alterations in STM-treated zirconia, producing microscale textures. STM-treated surfaces exhibited significantly lower contact angles (28.4 ± 10.0°) compared to untreated (78.2 ± 8.0°) and sandblasted (79.2 ± 5.7°) surfaces, indicating enhanced wettability (p < 0.05). SBS was highest in the STM with primer group (46.3 ± 8.3 MPa) and STM without primer (43.4 ± 4.3 MPa), both of which significantly outperformed sandblasting with primer (30.06 ± 3.09 MPa) and sandblasting alone (9.8 ± 3.7 MPa) (p < 0.05). Conclusions: These findings suggest that STM-based LST is a more effective method for improving zirconia surface characteristics and adhesion in dental restorations, simplifying bonding procedures, and potentially offering better clinical outcomes than conventional sandblasting. Full article

Zirconia restorations are widely used in dentistry due to their high esthetic expectations and physical durability. However, zirconia’s opaque white color can compromise esthetics. Therefore, zirconia is often veneered with porcelain, but fractures may occur in the veneer layer. Monolithic zirconia restorations, which do not require porcelain veneering and offer higher translucency, have been developed to address this issue. Zirconia exists in three main crystal phases: monoclinic, tetragonal, and cubic. Metal oxides such as yttrium are added to stabilize the tetragonal phase at room temperature. 3Y-TZP contains 3 mol% yttrium and provides high mechanical strength but has poor optical properties. Recently, 4Y-PSZ and 5Y-PSZ ceramics, which offer better optical properties but lower mechanical strength, have been introduced. This review examines the factors affecting the color change in monolithic zirconia ceramics. These factors are categorized into six main groups: cement type and color, restoration thickness, substrate color, sintering, aging, and zirconia type. Cement type and color are crucial in determining the final shade, especially in thin restorations. Increased restoration thickness reduces the influence of the substrate color while the sintering temperature and process improve optical properties. These findings emphasize the importance of material selection and application processes in ensuring esthetic harmony in zirconia restorations. This review aims to bridge gaps in the literature by providing valuable insights that guide clinicians in selecting and applying zirconia materials to meet both esthetic and functional requirements in restorative dentistry. Full article

The Spanish cement sector must adapt its production model to a green economy model. This study focuses on the use of new secondary main constituents (SMCs) suitable for a cement plant that specializes in sulfate-resistant (SR) cement production, defining a framework of technical conditions for their usage and their economic and environmental feasibility. Low-calcium-carbonate-content albero, steel slags, and iron silicate were the tested SMCs; however, they are not currently permitted in cement manufacture. CEM I 42.5 R-SR 3 (type I-SR) was mixed with 5%, 20%, and 30% of these new SMCs. XRF, XRD, leaching and other chemical tests, setting, and hardening tests were performed with no significant issues. Albero is the best option, on the whole, because of the following characteristics: availability, >100 Mt; proximity, 3 km; and acceptable compressive strength level. However, black slag cement with 30% SMC after 28 days shows the best performance, with a compressive strength of 41.3 MPa compared to 35.3 MPa for albero cement and 56.5 MPa for the type I-SR reference. Albero and steel slag at 30% content are the best option according to the cost savings of 32% (−31.5 EUR/t and −31.6 EUR/t, respectively) compared to the type I-SR reference. Regarding the carbon footprint, albero and steel slag at 30% content have the least impact, showing a 31% reduction (−254.8 kg CO₂/t and −255.2 kg CO₂/t, respectively) compared to the type I-SR reference. The studied SMCs meet the analytical conditions and—with the corresponding regulatory changes—offer potential cost savings for SR cement production, exhibiting a competitive advantage. Full article