Search Results (593)

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

This study investigates the effectiveness of geopolymer-based binders for the stabilization of silty sand, aiming to improve its strength and durability under cyclic environmental conditions. A composite binder consisting of Ground Granulated Blast-furnace Slag (GGBS) and Recycled Glass Powder (RGP), modified with nano poly aluminum silicate (PAS), was used to treat the soil. The long-term performance of the stabilized soil was evaluated under cyclic wetting–drying (W–D) conditions. The influence of PAS content on the mechanical strength, environmental safety, and durability of the stabilized soil was assessed through a series of laboratory tests. Key parameters, including unconfined compressive strength (UCS), mass retention, pH variation, ion leaching, and microstructural development, were analyzed using field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Results revealed that GGBS-stabilized specimens maintained over 90% of their original strength and mass after eight W–D cycles, indicating excellent durability. In contrast, RGP-stabilized samples exhibited early strength degradation, with up to an 80% reduction in UCS and 10% mass loss. Environmental evaluations confirmed that leachate concentrations remained within acceptable toxicity limits. Microstructural analysis further highlighted the critical role of PAS in enhancing the chemical stability and long-term performance of the stabilized soil matrix. Full article

The main aim of this study was to evaluate the influence of heat and surface treatment on the physicochemical properties of samples produced using Direct Metal Sintering incremental technology from Ti64ELI titanium powder. Two groups of samples were selected for the study: sandblasted and mechanically polished samples. Each group consisted of samples in the initial state and after heat treatment carried out at temperatures of 800 °C, 910 °C, and 1020 °C. The article presents the results of microscopic metallographic observations, wettability and surface topography, hardness, and resistance to pitting corrosion in Ringer’s solution, together with microscopic evaluation of the surfaces before and after testing. Based on the test results, both heat and surface treatments were found to alter the functional properties of the printed samples. All the tested samples show hydrophilic properties. Heat treatment at 1020 °C produces the best resistance to pitting corrosion. This information is important when selecting the mechanical properties of the biomaterial and the physicochemical properties of the surface for a specific type of stabilizer. The choice of appropriate heat treatment and surface treatment of the implant will also depend on the length of time the implant remains in the body. Full article

This study developed a full solid waste-based cementitious material (ISWs-CM) using steel slag (SS), ground granulated blast furnace slag (GGBFS), phosphorus slag (PS), carbide slag (CS), and desulfurized gypsum (DG) to completely replace cement. A two-layer optimization strategy, combining three chemical moduli and simplex lattice experiments, was employed to determine the proportion and to investigate the impact of proportions on the uniaxial compressive strength of mortar. As an application case, the ISWs-CM with the optimal proportion was employed to stabilize aeolian sand, and its effectiveness as a cement substitute and the underlying mechanisms were investigated. The results indicated that the ISW proportion that maximized the strength of the mortar was SS:GGBFS:PS:CS = 5:20:20:40. The strength of the mortar was enhanced when the proportion of GGBFS exhibiting the highest reactivity was increased and also increased initially and then decreased with an increase in CS when the dosage of GGBFS was fixed. The aeolian sand stabilized by ISW-CM exhibited higher strength than that stabilized with cement. The greater number and variety of hydration products resulted in denser connections and encapsulation of sand particles, which highlights the synergistic effect of ISWs and the potential of ISW-CM as a cement replacement across diverse applications including aeolian sand stabilization. Full article

Zirconia restoration debonding is one of the common issues in its dental applications because of its dense and chemically inert structure that is difficult to bond to. In this study, plasma treatment of zirconia was performed to improve its bond strength and longevity with dental resin cement. Sandblasted zirconia specimens were treated using argon cold atmospheric plasmas (CAPs), followed by applying a thin layer of 10-MDP primer, dental resin cement with light curing. Micro-shear bond strength (µSBS) test results showed that 300 s of CAP treatment significantly increased the initial µSBS to 38.3 ± 5.6 MPa as compared with the 21.6 ± 7.9 MPa without CAP treatment. After 30 days of storage in 37 °C deionized (DI) water, CAP-treated zirconia specimens had 191.2% higher bond strength than the bonded specimens without plasma treatment. After 1000 cycles of thermal cycling (TC) between 5 °C and 55 °C, the CAP-treated zirconia specimens gave 30.5% higher bond strength than the bonded specimens without plasma treatment. Surface–water contact angle measurements indicated that the zirconia surface became much more hydrophilic but showed rapid hydrophobic recovery within the first hour of CAP treatment, indicating the importance of promptly applying the primer after the plasma treatment. These findings suggest that the argon CAP technique is effective in the surface preparation of zirconia for enhancing bond strength and longevity with dental cement. Full article

Background/Objectives: The increasing clinical integration of 3D-printed definitive resins requires a comprehensive understanding of their physicochemical properties and adhesive behavior. However, there is limited evidence regarding the optimal surface treatment and bonding strategies for clear aligner composite attachments on these materials. This study aimed to characterize a 3D-printed definitive resin, evaluate the effects of surface treatments on its surface topography, and compare the shear bond strength (SBS) of the bonded attachments using different adhesive systems, both before and after thermocycling. Methods: A total of 120 rectangular specimens were fabricated from a 3D printed dental resin (Crowntec^®, SAREMCO Dental AG—Mexico City, Mexico). For physicochemical characterization, six samples underwent scanning electron microscopy/energy-dispersive spectroscopy, X-ray diffraction, and thermogravimetric analysis. To evaluate surface topography, 42 polished specimens were assigned to three groups: untreated (control), etched with 4% hydrofluoric acid (HFA), or sandblasted with 50 µm Al₂O₃ (AA). Each group was subdivided for SEM observation and surface roughness (Ra) measurement. For SBS testing, 72 additional samples received the same surface treatments and were further subdivided according to the adhesive system: Transbond™ XT Primer (TXT) or Single Bond Universal (SBU). Results: The AA group showed the highest Ra (2.21 ± 0.30 µm), followed by HFA (0.81 ± 0.20 µm) and control (0.07 ± 0.30 µm) (p < 0.001). The highest SBS was observed in the AA + SBU group, followed by AA + TXT. Conclusions: Sandblasting with Al₂O₃ particles, combined with a universal adhesive, significantly improved bond strength, suggesting a viable protocol for 3D printed definitive composites in aligner attachment applications. Full article

In railways, problems in braking and traction can be caused by so-called low-adhesion conditions. Adhesion is increased by sanding, where sand grains are blasted towards the wheel–rail contact. Despite the successful use of sanding in practice and extensive experimental studies, the physical mechanisms of adhesion increase are poorly understood. This study combines experimental work with a DEM model to aim at a deeper understanding of adhesion increase during sanding. The experimentally observed processes during sanding involve repeated grain breakage, varying sand fragment spread, formation of clusters of crushed sand powders, plastic deformation of the steel surfaces due to the high load applied and shearing of the compressed sand fragments. The developed DEM model includes all these processes. Two types of rail sand are analysed, which differ in adhesion increase in High-Pressure Torsion tests under wet contact conditions. This study shows that higher adhesion is achieved when a larger proportion of the normal load is transferred through sand–steel contacts. This is strongly influenced by the coefficient of friction between sand and steel. Adhesion is higher for larger sand grains, higher sand fragment spread, and higher steel hardness, resulting in less indentation, all leading to larger areas covered by sand. Full article

Ceramic dental prosthetics with internal metal structures are made from a cobalt–chromium alloy that is coated with ceramic. This study aims to validate surface treatments for the metal that enhance the adhesion of the ceramic coating under masticatory forces. Surface conditioning is performed using mechanical methods, like sandblasting (SB), and thermal methods, such as oxidation (O). The ceramic coating is applied to the metal component following the conditioning process, which can be conducted using either a single method or a combination of methods. Each conditioned sample undergoes characterization through various techniques, including drop shape analysis (DSA), scanning electron microscopy (SEM), X-ray diffraction (EDX), and atomic force microscopy (AFM). After the ceramic coating is applied and subjected to thermal sintering, the metal–ceramic samples are mechanically tested to assess the adhesion of the ceramic layer. The research findings, illustrated by scanning electron microscopy (SEM) images of the metal structures’ surfaces, indicate that alloy powder particles ranging from 10 to 50 µm were either adhered to the surfaces or present as discrete dots. Particles that exceed the initial design specifications of the structure can be smoothed out using sandblasting or mechanical finishing techniques. The energy-dispersive spectroscopy (EDS) results show that, after sandblasting, fragments of aluminum oxide remain trapped on the surface of the metal structures. These remnants are considered impurities, which can negatively impact the adhesion of the ceramic to the metal substrate. The analysis focuses on the exfoliation of the ceramic material from the deformed metal surfaces. The results emphasize the significant role of the sandblasting method and the micro-topography it creates, as well as the importance of the oxidation temperature in the treatment process. Drawing on 25 years of experience in dental prosthetics and the findings from this study, this publication aims to serve as a guide for applying the ceramic bonding layer to metal surfaces and for conditioning methods. These practices are essential for enhancing the adhesion of ceramic materials to metal substrates. Full article

This in vitro study aimed to compare the effects of various surface treatments and hydrothermal aging on the phase composition, microstructure, and compressive strength of dental zirconia (ZrO₂). Forty-eight zirconia cubes (8 × 8 × 8 mm) were fabricated using CAD/CAM from two materials: infrastructure zirconia (Group S1) and super-translucent multilayered monolithic zirconia (Group S2). Four samples of each material were analyzed in their pre-sintered state (S1-0, S2-0). The remaining specimens were sintered and assigned to sub-groups based on surface treatment: untreated, sandblasted with 30 µm or 50 µm Al₂O₃, polished, or polished and glazed. Characterization was performed using EDX, SEM, XRD with Rietveld refinement, Raman spectroscopy, and compressive testing before and after accelerated hydrothermal aging, according to EN ISO 13356:2015. EDX revealed a higher yttria content in monolithic zirconia (10.57 wt%) than in infrastructure zirconia (6.51 wt%). SEM images showed minimal changes in polished samples but clear surface damage after sandblasting, which was more pronounced with larger abrasive particles. XRD and Raman confirmed that sandblasting promoted the tetragonal (t-ZrO₂) to monoclinic (m-ZrO₂) phase transformation (t→m), amplified further by hydrothermal aging. The polished groups showed greater phase stability post-aging. Compressive strength decreased in all treated and aged samples, with monolithic zirconia being more affected. Polished samples displayed the best surface quality and structural resilience across both materials. These findings underline the impact of clinical surface treatments on zirconia’s long-term mechanical and structural behavior. Full article

As a promising and sustainable construction material, alkali-activated slag lightweight high-strength concrete (AAS-LWHSC) may be influenced by lightweight aggregate (LWA) content. In this study, the effects of hollow glass microspheres (HGM) replacing granulated ground blast furnace slag (GGBFS) under varying LWA dosages on the workability, dry apparent density, mechanical properties, and microstructure of AAS-LWHSC were investigated. The results indicated that the dry density of concrete was significantly reduced by HGM, while the “ball-bearing” effect of HGM was observed to enhance workability at a dosage of 6%. The 7-day mechanical properties of AAS-LWHSC were found to decline progressively with increasing HGM content. However, at the shale ceramsite sand replacement rates of 35% and 65%, the incorporation of 6% HGM slightly improved the 28-day mechanical properties. Due to the absence of the water-releasing effect from shale ceramsite, the pozzolanic reactions of HGM were restricted, resulting in coarse hydration products and a reduction in the mechanical performance of AAS-LWHSC. Full article

Background: Traditional sandblasted large-grit acid-etched (SLA) surface treatments frequently utilize alumina (Al₂O₃) blasting, which may leave residual particles embedded in implant surfaces, potentially compromising biocompatibility and osseointegration. This study investigates a contamination-free alternative: titanium dioxide particle (TiO₂) blasting followed by hydrochloric acid (HCl) etching, aimed at generating a cleaner, hierarchical micro–nano-textured surface. Methods: Grade IV titanium disks were treated either with TiO₂ sandblasting alone or with an additional HCl etching step. Surfaces were analyzed via atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle measurements, and profilometry. hFOB osteoblasts were cultured to assess adhesion, proliferation, metabolic activity, and morphology. Results: The combination treatment produced a more homogeneous micro–nano structure with significantly increased roughness and a cleaner surface chemistry. Osteoblast proliferation and metabolic activity were notably improved in the TiO₂ and HCl group. SEM imaging showed a more organized cytoskeletal structure and pronounced filopodia at 72 h. Conclusions: Titanium blasting combined with HCl etching yields a cost-effective, contamination-free surface modification with promising early-stage cellular responses. This approach represents a safer and effective alternative to conventional SLA treatment. Full article

Objectives: In the animal model, we aim to evaluate the bone behavior in two innovative and different laser-treated (L1–L2) titanium implants compared to sandblasted and acid-etched (SBAE) used as control. Materials and Methods: A total of twenty-seven dental implants (8.5 × 3.3 mm) used for the study (Sweden & Martina, Due Carraie Padova-Italy) were placed in three Pelibuey female sheep. Implant surface profilometric, contact angle and EDX analysis were detected. After 15, 30 and 90 days, histological, histomorphometric, SEM-EDX analysis and Bone-to-implant Contact (BIC), Dynamic Osseointegration Index (DOI) and Bone Quality Index (BQI) (as Calcium and Phosphorous atomic percentages ratio) were performed. Results: All surfaces showed relevant profilometric and wettability differences. After 15 days, BIC₁₅ showed great differences in L2 (42.1 ± 2.6) compared to L1 (5.2 ± 3.1) and SBAE (23.3 ± 3.9) as well as after 30 days (L2 (82.4 ± 2.2), L1 (56.2 ± 1.3) and SBAE (77.3 ± 0.4)). After 90 days, relevant lower BIC₉₀ values were detected in L1 (68.4 ± 0.2) compared to L2 (86.4 ± 0.1) and SBAE (86.2 ± 0.6). The DOI showed higher rates of bone growth in L2 after 15 (DOI₁₅ = 2.81) and 30 days (DOI₃₀ = 2.83), compared to L1 (DOI₁₅ = 0.38, DOI₃₀ = 3.40) and SBAE (DOI₁₅ = 1.55, DOI₃₀ = 2.58). The DOI₉₀ drastic slowdown in SBAE (0.96), L1 (0.76), and L2 (0.95) confirmed the Early Osseointegration (EO) as a crucial phase. Moreover, before loading, the lower global BQI in L1 (Ca 44.43 ± 0.08–P 46.14 ± 5.15) and SBAE (Ca 45.31 ± 2.08–P 48.28 ± 1.12) compared to L2 (Ca 79.81 ± 2.08–P 81.85 ± 3.14) allows to assert that osseointegration process and bone healing could not be considered complete if compared to the native bone. Conclusions: The BIC, DOI, and BQI results showed that osseointegration is a dynamic process, confirming the crucial role of surface characteristics able to influence it, especially the early osseointegration (EO) phase. The short-time L2 implants’ higher bone quantity and quality results, compared to L1 and SBAE, suggested the fundamental role of this innovative laser-obtained surface in “secondary stability” and predictable long-term clinical outcomes. Full article

This study delves into the delamination-driven nonlinear buckling characteristics of metal–composite cylindrical shells with different interfacial strengths. Although surface treatments are known to affect bonding performance, their specific influences on the delamination buckling behavior of metal–composite cylindrical shells remain underexplored. Accordingly, sandblasting and polishing processes were employed to the fabrication of single-lap shear specimens. The topography of the treated surface was then characterized through scanning electron microscopy, optical profilometry, and contact angle measurements. For topography characterization and performance tests, sandblasted and polished metal–composite cylindrical shells were fabricated for hydrostatic tests. A cohesive zone model was used to analyze the influences of interfacial strength on the nonlinear buckling characteristics of metal–composite cylindrical shells, and the modeling results were validated by benchmarking them with experimental results. Subsequently, a detailed parametric study was conducted to investigate the effects of cohesive zone parameters and geometric imperfection on the load-bearing capacity of the shells. The new findings reveal that among the fabricated steel specimens, the specimens subjected to 80-mesh sandblasting exhibited the highest bond strength in single-lap shear tests, with the bond strength being 2.56 times higher than that of polished specimens. Moreover, sandblasted metal–composite cylindrical shells exhibited a 55.0% higher average collapse load than that of polished metal–composite cylindrical shells. Full article

Preparing a bioactive surface with a hierarchical micro/nanostructure can improve the osseointegration of titanium implants. In this study, titanium was sand blasted and etched in H₂SO₄ solution to obtain micro-rough morphology. The samples were then hydrothermally treated in the concentrated CaHPO₄ solution at 120–200 °C for 24 h to grow films consisting of anatase TiO₂ and hydroxyapatite nanoparticles (size 80–240 nm). The hydrothermally calcified (200 °C) sample exhibited much better corrosion resistance in the salt solution, as well as similar cellular viability and a higher alkaline phosphatase level in the cell tests using MC3T3-E1 cells, in comparison with the polished titanium sample. The hybrid treatment is a facile and effective method to a form bioactive surface with a hierarchical micro/nanostructure on titanium. Full article

The aim of this work is to investigate the effect of curing temperature and time on the development of compressive strength in geopolymer mortars produced using ground granulated blast-furnace slag (GGBFS) and fly ash (FA). Considering curing circumstances, both the activation energy and the reference temperature could be used properly to build a reliable anticipated model for predicting the compressive strength of geopolymer-based products (mortar and concrete) using maturity-based techniques. In this study, the compressive strength development of geopolymer mortar made from (FA) and (GGBFS) under varying curing conditions. The mortar was prepared using an alkali solution of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) in a 1:1 ratio, with NaOH molarity of 12. Specimens were cast following ASTM C109 standards, with a binder/sand ratio of 1:2.75, and compacted for full densification. FA-based mortar was cured at 40 °C, 80 °C, and 120 °C, while GGBFS-based mortar was cured at 5 °C, 15 °C, and 40 °C for durations of 0.5 to 32 days. Compressive strength was evaluated at each curing period, and data were analyzed using ASTM C1074 procedures alongside a computational model to determine the best-fit datum temperature and activation energy. The Nurse-Saul maturity method and Arrhenius equation were applied to estimate the equivalent age and maturity index of each mix. A predictive model was developed for geopolymer concrete prepared at an alkali-to-binder ratio of 0.45 and NaOH molarity of 12. The final equation demonstrated high accuracy, offering a reliable tool for predicting geopolymer strength under diverse curing conditions and providing valuable insights for optimizing geopolymer concrete formulations. Full article