Search Results (999)

The peer-reviewed literature on the use of universal adhesives (UAs) with core build-up composite resins (CBCRs) is limited. UAs may enhance the polymerization of dual-cured composite resins, leading to increased microhardness due to the “touch-cure” effect. This study compared the dentin bond strengths and microhardness of CBCRs bonded with UAs. A total of 480 bovine incisors were randomly allocated into 20 groups (n = 24). Two dual-cured CBCRs, ParaCore (PrCore) and Gradia Core (GrCore), one light-cured CBCR, Clearfil Photo Core (PhotoCore), and Filtek Z250 (Z250) were evaluated. For the dual-cured CBCRs, the UAs from the respective manufacturers were mixed with a dual-cure activator (Act): One Coat 7 Universal (OC7+Act) and G-Premio Bond (GrPB+Act). Three additional UAs were evaluated: Tokuyama Universal Bond II (TUB), Scotchbond Universal Plus Adhesive (SBUP), and Scotchbond Universal Adhesive with Dual Cure Activator (SBU+Act). Shear bond strength was evaluated after 24 h. Additional specimens were prepared for Vickers microhardness (VHN) evaluation, with or without UA application to the bottom surface. Bond strengths ranged from 7.4 ± 4.0 to 37.0 ± 7.5 MPa. GrCore and PrCore showed higher bond strengths with SBU+Act than with their manufacturer-recommended adhesives. Dual-cured CBCRs exhibited lower dentin bond strengths and lower VHN than the light-cured composite resins, and the touch-cure effect was more effective for GrCore and PhotoCore. Full article

The optical stability of thin ceramic laminate veneers may be affected by both the adhesive interface and the underlying substrate. This in vitro study evaluated the influence of immediate dentin sealing (IDS) on the color stability of lithium disilicate laminate veneers bonded to sound and eroded dentin after accelerated aging. Forty bovine dentin specimens were allocated into four groups according to dentin condition and adhesive protocol: sound dentin without IDS, sound dentin with IDS, eroded dentin without IDS, and eroded dentin with IDS. Lithium disilicate disks were cemented using a light-cured resin cement. Color coordinates were measured with a spectrophotometer before and after thermocycling, and color change was calculated using the CIEDE2000 formula (ΔE₀₀). Changes in ΔL*, Δa*, and Δb* were also analyzed. Data were analyzed using two-way ANOVA and Tukey’s test (α = 0.05). IDS significantly increased ΔE₀₀ values (4.63 ± 0.89) compared with the NoIDS groups (2.51 ± 0.49) (p < 0.001), whereas dentin condition and the interaction were not significant. IDS also affected ΔL*, Δa*, and Δb*, with the greatest change observed for ΔL*. All groups exceeded perceptibility and acceptability thresholds. IDS increased color change in lithium disilicate laminate veneers after accelerated aging, regardless of dentin condition. Full article

Local drug delivery increasingly relies on injectable hydrogels that form directly at the x‘administration site, among which light-cured systems are of particular interest: irradiation converts a liquid precursor into a depot and can trigger drug release with high spatiotemporal resolution. The aim of this critical narrative review is to systematize the key design elements of such systems and to assess their path toward the clinic. We analyze the mechanisms of photoactivation, the role of wavelength, the natural, synthetic, and hybrid polymer matrices together with their tuning parameters, and the photoinitiators. The clinical and preclinical experience in dentistry, ophthalmology, regenerative medicine, and oncology is then considered separately. Finally, we address standardization through the Quality by Design concept. We show that, despite an extensive preclinical base, no photocrosslinkable injectable depot for drug delivery has yet been approved, whereas photopolymerization itself and the photoinitiators employed are already accepted in the clinic in adjacent fields. We conclude that clinical translation is defined by three tractable tasks: qualifying photoinitiators for the injectable route of administration, overcoming the limited depth of light activation, and standardizing characterization on the basis of Quality by Design. Full article

(1) Background: This study aimed to assess how two different adhesive solvent evaporation techniques affect the microtensile bond strength (µTBS) of a universal adhesive to dentin, as well as the enzymatic activity of dentinal matrix metalloproteinases (MMPs) at baseline and after 6-month aging under simulated pulpal pressure. (2) Methods: Middle-depth dentin surfaces of 32 sound extracted human molars were bonded under simulated pulpal pressure using a universal adhesive (Clearfil Universal Bond Quick) in either etch-and-rinse (ER) or self-etch (SE) mode. Two solvent evaporation approaches were compared: evaporation with a disposable air/water syringe (air) and with a disposable suction device (suction), yielding four experimental groups (n = 8): ER/air, ER/suction, SE/air, and SE/suction. After light-curing for 10 s, a 4 mm composite build-up was created. Specimens were stored in distilled water under simulated pulpal pressure at 37 °C for either 24 h (T0) or 6 months (T6) and then sectioned into sticks and subjected to µTBS testing. Fracture surfaces were examined by scanning electron microscopy (SEM). An additional subset of teeth from each group (n = 3) underwent in situ zymographic analysis, in which bonded sticks were ground and exposed to fluorescein-conjugated gelatin, with enzymatic activity quantified by confocal microscopy. Statistical analysis was performed at a significance threshold of p < 0.05. (3) Results: Air-drying yielded significantly higher µTBS values than suction drying, irrespective of adhesive application mode (p < 0.05). At T6, SE groups retained bond strength values comparable to baseline (p > 0.05), whereas ER groups showed a significant reduction in bond strength with aging (p < 0.05). The ER mode and suction were associated with significantly increased MMP activity at T0 (p < 0.05), while there were no differences between SE/ER at T6 (p > 0.05), and air increased MMP activity (p < 0.05). (4) Conclusions: When using an ethanol-based universal adhesive under pulpal pressure, evaporation with a disposable air syringe combined with the self-etch application mode appears to offer greater bonding reliability and stability. Full article

This in vitro study examined the effects of rapid high-intensity vs. conventional light-curing on real-time degree of conversion (DC) of conventional and fiber-reinforced resin composites. Two resin composites specifically designed for rapid high-intensity photo-polymerization (Tetric PowerFill, Tetric PowerFlow), two flowable fiber-reinforced composites (everX Flow, FibraFill Flow), and two condensable fiber-reinforced composites (everX Posterior, FibraFill DENTIN) were included. Photo-activation was performed using two protocols: 3 s at 3006 mW/cm² or 10 s at 1108 mW/cm². DC of 1.5 mm thick specimens (n = 6) was monitored for 5 min by real-time ATR-FTIR spectroscopy, and the maximum polymerization rate (R_DCmax) was determined. Data were analyzed using independent t-tests and ANOVA followed by Tukey’s post hoc test (α = 0.05). DC at the end of the 5 min observation period ranged from 33.7 ± 0.9% (FibraFill DENTIN, 3 s) to 59.2 ± 0.3% (Tetric PowerFlow, 10 s). All composites exhibited a significantly higher DC with the 10 s curing protocol compared with 3 s high-intensity light-curing. Within both curing protocols, Tetric PowerFlow, everX Flow, and everX Posterior achieved the highest DC values, whereas FibraFill DENTIN showed the significantly lowest DC. R_DCmax was significantly higher with the 3 s protocol than with 10 s light-curing for all materials, with the significantly highest values recorded for Tetric PowerFill and Tetric PowerFlow. FibraFill DENTIN and FibraFill Flow exhibited the significantly lowest R_DCmax for both curing protocols. In conclusion, 3 s high-intensity photo-activation increased the polymerization rate but simultaneously reduced the degree of conversion of conventional and fiber-reinforced flowable and condensable resin composites compared with a conventional 10 s light-curing regimen. Full article

Concrete mix design increasingly requires rapid screening of mixture proportions against mechanical and resource-efficiency targets. This study develops an explainable, cement-reduction-oriented computational screening framework based on the UCI Concrete Compressive Strength dataset. The dataset records Portland cement, fly ash, blast furnace slag, aggregates, water, superplasticizer, curing age, and compressive strength, but does not report clinker factor, material-specific emission factors, or durability performance. Cement dosage is therefore minimized only as a surrogate objective; the study does not claim quantified embodied-carbon optimization. A LightGBM surrogate was trained using raw mixture variables and domain-informed ratios. On the held-out test set, the model achieved an $R^2$ of 0.946 and a mean absolute error of 2.639 MPa. Shapley Additive Explanations were used to examine the statistical influence of mixture variables, with the water-to-binder ratio emerging as the dominant predictor. Constraint-filtered Monte Carlo sampling and non-dominated sorting were then used to screen Pareto-efficient binder allocations. For a 28-day target of 45 MPa, repeated searches identified candidates with a mean Portland cement dosage of $164.4 {\mathrm{kg/m}}^3$, 44.2% below the mean of empirical mixtures in the same strength band. The evaluated numerical modules were embedded in a Streamlit prototype in which a DeepSeek large language model performs only intent parsing and report generation. The main contribution is this tool-augmented separation of language interaction from deterministic engineering computation. The resulting mixtures remain computational candidates and should next be validated experimentally and assessed using material-specific life-cycle carbon and durability data. Full article

Background: Ultra-fast high-irradiance curing shortens exposure time, but its effects on conversion and polymer-network integrity may vary among bulk-fill resin composites. This in vitro study was designed as a materials-level investigation of irradiated-surface polymerization behavior. It evaluated irradiated-surface degree of conversion and polymer-network quality while deliberately excluding assessment of depth of cure or polymerization throughout the 4 mm bulk increment. Methods: Eighty disk specimens (6 mm × 4 mm) of Filtek One Bulk Fill, SDR Plus, Beautifil Bulk Flowable, and Beautifil Bulk Restorative (n = 10/material/protocol) were cured with a polywave LED at 1200 mW/cm² for 10 s or 3000 mW/cm² for 3 s. Degree of conversion (DC) was measured by ATR-FTIR on the irradiated (top) surface only. Ethanol-induced softening (ES%, Knoop-hardness reduction at the irradiated surface after 24 h ethanol immersion) served as an inverse, indirect indicator of polymer-network quality (cross-link density). Data were analyzed by two-way ANOVA and Tukey tests (α = 0.05); the DC–ES% relationship was examined by Pearson correlation at the individual-specimen level (n = 80). Results: Ultra-fast curing yielded higher pooled DC (66.30 ± 10.06%) than conventional curing (59.37 ± 7.96%; p < 0.001), but the effect was material-dependent: DC increased significantly for Filtek One Bulk Fill (p < 0.001) and Beautifil Bulk Flowable (p = 0.035), but not for SDR Plus or Beautifil Bulk Restorative. ES% was influenced mainly by material (p < 0.001) and less by curing protocol (p = 0.009). At the specimen level (n = 80), DC and ES% showed a weak but statistically significant negative correlation (r = −0.31, p = 0.006). Conclusions: Within the conditions of this study, irradiated-surface polymerization behavior under ultra-fast curing depended primarily on composite formulation, underscoring the need to evaluate both conversion efficiency and polymer-network quality when optimizing dental restorative materials. Because conversion was assessed only at the irradiated surface, these findings describe irradiated-surface behavior and do not provide evidence of adequate cure at the bottom of the 4 mm increment. Full article

Aim: This in vitro study investigated the effect of additional proximal post-curing on the microhardness of Class-II resin composite restorations. Methods: Thirty-two extracted human third molars received narrow (N) or wide (W) MO Class-II cavities with cervical margins extending below the cemento-enamel junction. Cavities were restored with Venus Diamond using an adhesive protocol and incremental layering. Specimens were assigned to four groups: N.O, N.OT, W.O, W.OT, representing cavity width (N/W) and curing protocol (O: occlusal light curing only, OT: occlusal plus proximal post-curing after matrix band removal). After 7 days of storage in artificial saliva, restorations were sectioned into three vertical planes, and Vickers microhardness (HV2/30 s) was measured. Results: The highest overall microhardness was observed in Group W.OT (81.35 HV2), whereas Group N.O showed the lowest values (73.14 HV2) (p < 0.05). Proximal post-curing significantly increased microhardness, with Group N.OT (78.34 HV2) exceeding both occlusal-only groups (W.O: 74.68 HV2; p < 0.05). In all groups, microhardness decreased with increasing restoration depth (p < 0.05), although this reduction was less pronounced after post-curing. Conclusions: Within the limitations of this in vitro study, proximal post-curing significantly increased polymerization depth and microhardness of Class-II resin composite restorations. Full article

This study evaluated the effects of thermocycling and staining on the optical behavior, chemical stability, and surface morphology of three commercial dental composites manufactured using different polymerization protocols: a light-cured composite (Omnichroma, OMNI) and two digital light-processed (DLP) 3D-printed composites intended for permanent (SprintRay CROWN, SPRINT) and temporary (GC Temp PRINT, TEMP) clinical applications. Disc-shaped specimens were subjected to thermocycling (0, 5000, 10,000, and 30,000 cycles) and immersion in coffee, Coca-Cola, or red wine for 1 and 7 days. Color change (ΔE₀₀) and translucency parameter (TP) were determined spectrophotometrically, while Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were employed to assess the polymerization efficiency (expressed as the relative conversion index) and surface morphology, respectively. Thermocycling induced material-dependent changes in color stability and translucency. After 30,000 cycles, ΔE₀₀ values reached 2.77 ± 0.89 for OMNI, 0.74 ± 0.34 for SPRINT, and 3.30 ± 0.89 for TEMP. SPRINT maintained the highest TP values throughout the aging protocol, ranging from 26.09 ± 0.33 to 23.81 ± 1.93, whereas OMNI and TEMP exhibited lower TP values. The most favorable optical performance and the highest resistance to beverage-induced coloration were detected for SPRINT, whereas TEMP showed the greatest susceptibility to aging- and staining-induced optical degradation. Red wine and coffee produced substantially greater color changes and reductions in translucency than Coca-Cola. AFM analysis demonstrated progressive surface degradation and increased roughness following prolonged thermocycling, highlighting the significant influence of material composition and manufacturing protocol on the long-term optical stability of the investigated dental composites. Full article

To address the key issues of uneven distribution of functional groups, large dispersion of holographic storage performance across different regions, and poor consistency of storage capacity in traditional PQ/PMMA holographic storage photopolymers, this paper introduces a low-viscosity reactive diluent, tripropylene glycol diacrylate (TPGDA), to modify the matrix. Leveraging the viscosity-reducing and double-bond crosslinking properties of TPGDA, the molecular diffusion behavior of the system was regulated. The effects of TPGDA doping ratio, the ratio of photosensitizer PQ to thermal initiator AIBN, and post-curing process on the holographic performance uniformity of the material were systematically investigated. The uniformity was quantitatively evaluated by the variance of diffraction efficiency at different points. Visible light absorption spectra and Fourier-transform infrared (FT-IR) spectroscopy were employed to reveal the modification mechanism from the perspective of functional group distribution. Actual-data read/write tests were conducted using a collinear holographic storage system. The experimental results show that the optimal TPGDA doping concentration is 40 wt%. For the optimized formulation TPGDA:MMA:AIBN:PQ = 8 g:12 g:0.20 g:0.18 g, the modified material achieves an average diffraction efficiency of 76.58%, and the diffraction efficiency variance decreases from 23.49 (pristine matrix) to 1.64, indicating a significant improvement in performance uniformity. Compared with pure PQ/PMMA, the modified material exhibits an approximately 1.95-fold increase in maximum diffraction efficiency, a 2-fold increase in recording rate, and a 1.6–1.75-fold increase in refractive index modulation. FT-IR spectroscopy confirms that TPGDA optimizes the spatial distribution uniformity of C=C and C=O functional groups. In collinear holographic measurements, the bit error rate (BER) variance of the modified sample is reduced by 40% relative to the pristine matrix, achieving homogeneous storage performance across the entire area while maintaining comparable signal-to-noise ratio (SNR) and BER. Additional short-time UV post-curing can further enhance the diffraction efficiency and refractive index modulation, and a thinner substrate can avoid performance fluctuations caused by incomplete thermal curing of thick samples. This study achieves directional optimization of the holographic uniformity of PQ/PMMA through reactive diluent viscosity reduction modification, providing a new strategy for the formulation design and engineering preparation of high-consistency holographic storage photopolymers. Full article

The method of how microcapsules and brass powder are added significantly affects the overall effectiveness of decorative coatings. An innovative self-repairing decorative coating for Basswood surfaces was created using melamine resin-coated water-based primer microcapsules as the repair agent under the coating process of “three coats of primer, two coats of topcoat, and introducing brass powder and microcapsules into the primer”. The optical and mechanical properties of this coating were significantly impacted by the curing temperature and brass powder content, respectively. The optical qualities, mechanical properties, liquid resistance, aging resistance, and self-repairing performance of the coating improved at higher curing temperatures under varying brass powder contents. The water-based acrylic wood coating obtained at 60 °C with 3% brass powder and 3% primer microcapsules, featuring a core-wall ratio of 0.58:1, provided the best overall qualities. It has a gloss of 34.1 GU, color difference of 0.00, visible light reflectance of 0.6038, visible light transmittance of 76.20%, color main wavelength of 589.79 nm, hardness of HB, impact resistance of 2 kg·cm, adhesion of grade 1, roughness of 1.125 µm, excellent aging and liquid resistance, and repair rate of 22.93%. This study provides an effective and new strategy for simultaneously improving the decorative, mechanical, and self-repairing properties of water-based wood coatings. Full article

Directing a stream of air across the tooth when light curing resin-based composites (RBCs) may affect their degree of conversion (DC), maximum rate of polymerization (RP_max), and in vitro intrapulpal temperature. Methods: Filtek One Bulk Fill and VisCalor bulk were preheated according to the manufacturer’s instructions and used to fill a Class I cavity in a molar at 32 °C. A stream of air at either 15 or 30 psi was directed across the tooth from an air-water syringe positioned 1 cm from the buccal surface. The RBCs were light-cured for 20 s using the Bluephase N, and the DC and RP_max were determined from real-time FT-IR data. A T-type thermocouple positioned inside the pulp chamber recorded the temperature. DC and RP_max data were analyzed using one-way ANOVA, whereas temperature was analyzed using two-way ANOVA, followed by Tukey post hoc tests. Results: Directing a stream of air at the tooth produced no significant differences in the DC and RP_max. The temperature change (ΔT) decreased compared to when no air was delivered. No significant difference in ΔT was found between the two air pressures. Conclusions: Directing a stream of air across the tooth when the preheated RBC was inserted did not affect the polymerization kinetics. The air stream reduced the temperature rise inside the pulp chamber as the RBC was light-cured. Clinical Significance: Directing a stream of air across the tooth at either 15 psi or 30 psi during light curing is an easy method to reduce the temperature increase inside the pulp chamber without affecting the polymerization kinetics of the evaluated preheated RBCs in this in vitro model. Full article

High-volume fly ash binder and aeolian sand have been widely used in the production of low-carbon ultra-high performance concrete (UHPC) owing to their environmental and economic benefits. However, such low-carbon UHPC still faces the volume stability issues, including autogenous shrinkage, drying shrinkage and early-age cracking. In this study, a superabsorbent polymer (SAP) was incorporated into low-carbon UHPC containing high-volume fly ash and aeolian sand to improve its volume stability through internal curing. The effects of SAP particle size and dosage on the mechanical properties and volume stability of low-carbon UHPC were investigated. Results showed that the addition of 0.3% SAP with a particle size of 180–600 μm significantly reduced shrinkage and early-age cracking while maintaining the compressive strength. Furthermore, the microstructure of low-carbon UHPC was characterized using advanced techniques to shed light on the underlying mechanisms. Full article

Coreless filament winding (CFW) enables the material-efficient digital fabrication of lattice fiber composite lightweight structures with high geometric freedom. However, the unconstrained formation of fiber bundle leads to variable cross-sectional shapes, rugged surfaces, and limited predictability of bundle-level geometry. This study evaluates an industrial epoxy spray coating and a custom epoxy immersion coating as post-processing technologies for improving the cross-sectional geometry of CFW fiber bundles at different compaction levels. Three groups of samples were compared: manually squeezed high-compaction elongated samples with immersion coating, wrapped medium-compaction circularized samples with spray coating, and low-compaction elongated samples with spray coating. Loop specimens were fabricated, modified after winding where applicable, cured, coated, sectioned into samples, and analyzed using digital light microscopy. Image-based analysis quantified layer thickness, coverage interruptions, roundness, ruggedness, roughness, second moments of area distribution, volumetric phase fractions, surface gain, mass gain, and simplified area-estimation errors. Wrapping was the most effective measure for improving global roundness and squeezing improved compaction without circularization. Coating reduced ruggedness in all groups, including the highly rugged low-compaction samples, where part of the contour regularization resulted from bridging indentations, causing higher surface than mass gain. Coating improved the mass-specific second moment in every sample group, with an anisotropy reduction in the immersion-coated sample group. Full article

Background: Traditional orthopaedic casting has remained the cornerstone of non-surgical fracture management for more than a century. Although plaster and fiberglass casts reliably stabilize fractures, they are associated with physical, psychological, emotional, social, and economic burdens that extend beyond bone healing. Children, older adults, and individuals with pre-existing vulnerabilities may be disproportionately affected. Despite increasing recognition of these complications, existing orthopaedic literature has historically prioritized radiographic healing and biomechanical stability, with limited synthesis of the broader multidimensional patient impact of traditional casting. Emerging technologies such as light-cured polymer mesh (LCPM) systems and 3D-printed lattice immobilizers have been developed to address these limitations and better align fracture care with patient-centered principles. Methods: A narrative review was conducted using a structured and transparent literature identification approach informed by PRISMA reporting principles; however, this study was not conducted as a formal systematic review and did not include risk-of-bias assessment or quantitative synthesis. A broad search of PubMed, Scopus, Web of Science, and Google Scholar was performed for studies published between January 2000 and July 2025. Search strategies combined MeSH terms and free-text keywords relating to orthopaedic casting, complications, psychosocial impacts, LCPM, and 3D-printed immobilizers. Following duplicate removal and a structured review process, 87 studies were included in the final narrative synthesis. Eligible studies included randomized controlled trials, observational studies, qualitative research, case series, and systematic reviews. Data were synthesized narratively across five domains: physical, psychological, emotional/social, economic, and technological alternatives. Results: Traditional plaster and fiberglass casts were consistently associated with musculoskeletal deterioration, joint stiffness, dermatological complications, and hygiene challenges. Psychological and emotional consequences included cast-induced anxiety, claustrophobia, depressive symptoms, and diminished autonomy. Social participation was frequently reduced due to mobility restrictions and perceived stigma, while economic impacts included hidden out-of-pocket expenses, caregiver burden, lost wages, and disparities in access to follow-up care. In contrast, emerging alternatives demonstrated promising advantages. LCPM systems improved ventilation, comfort, and hygiene, while reducing saw-related anxiety. Preliminary evidence suggests that both LCPM and 3D-printed systems may support improved patient experience and earlier return to selected activities, although larger comparative studies are needed to confirm effects on complication rates and long-term outcomes. Over time, these benefits may help offset higher upfront material costs. Conclusions: Fracture care should be evaluated not only by radiographic healing but also by patient-centered outcomes such as comfort, independence, and quality of life. Traditional casting imposes significant multidimensional burdens, whereas newer technologies such as LCPM and 3D-printed systems may offer a more holistic approach to immobilization while maintaining acceptable fracture stability in appropriately selected patient populations. While current evidence indicates potential physical, psychological, and economic advantages, large-scale comparative trials remain necessary to confirm long-term clinical, psychosocial, and cost-effectiveness outcomes across diverse populations. Future integration of emerging immobilization technologies into clinical practice may support more patient-centered, function-oriented, and cost-conscious approaches to fracture care. Full article