Three-Dimensional Optical Study on the Effects of Microwave Glazing on Surface Roughness of Zirconia-Reinforced Glass Ceramic.

BACKGROUND This 3-dimensional (3D) optical study aimed to evaluate the effects of microwave glazing on the surface roughness of zirconia-reinforced glass. Glazed surfaces of ceramic provide a smooth and esthetically superior restoration. There are many methods of glazing. However, this study aims to evaluate the effect of microwave glazing on ceramic restorations over conventional oven and hand polishing. MATERIAL AND METHODS A sample size of 90 ceramic material tiles was derived according to the standard sample size formula. The 3 dental ceramics used were IPS e.max CAD (lithium disilicate ceramic; IvoclarVivadent), Suprinity (zirconia-reinforced lithium silicate; VITA Zahnfabrik), and Celtra Duo zirconia-reinforced lithium silicate; Dentsply Sirona). Each group was further divided equally to undergo conventional oven glazing, hand polishing, and microwave glazing. The final glazed surfaces were then evaluated for surface roughness with the Ra parameter, using a Contour GT 3D Optical Microscope (Bruker) and 3D non-contact surface metrology with interferometry. RESULTS The ANOVA test for intergroup comparison showed microwave glazing was a significantly better glazing method than conventional oven and hand polishing (P<0.05). A statistically significant difference was shown between conventional and microwave glazing; however, the difference was greater between conventionally glazed and hand-polished specimens. Furthermore, a highly significant difference between microwave-glazed and hand-polished specimens was observed. CONCLUSIONS Results showed that irrespective of the ceramic, microwave-glazed ceramics were better than traditional oven-glazed ceramics, and hand-polishing resulted in a rougher surface than glazing. Irrespective of the surface treatment methods, IPS e.max CAD ceramic showed a relatively smoother surface than did Suprinity and Celtra Duo.

Fracture resistance and fractographic analysis of pressable glass-ceramics with different partial coverage designs for maxillary premolars.

BACKGROUND: Partial coverage concepts have met the main goal of conservative dentistry. Vonlays, which combine features of veneers and onlays, are a recent alternative to full coverage designs and overlay partial coverage restorations. This in vitro study was conducted to compare the fracture resistance of the newly introduced pressable zirconia-reinforced lithium silicate with pressable lithium disilicate ceramic and to determine the optimal preparation design for partial coverage on upper premolars. METHODS: Fifty-two duplicated epoxy resin dies were prepared following vonlay and overlay preparation guidelines. For each preparation (n = 26), the specimens were divided into two subgroups to be restored with lithium disilicate (IPS e.max Press) or zirconia-reinforced lithium silicate (Vita Ambria) (n = 13 each). Ceramic vonlays and overlays were bonded using dual cure resin cement, subjected to thermomechanical fatigue, and the load to fracture was tested by using a universal testing machine. The specimens were fractographically analyzed via scanning electron microscopy (SEM). The normality of the fracture resistance data was checked using the Shapiro‒Wilk test and Q‒Q plots, and two-way ANOVA was used to assess the effect of the type of preparation and ceramic material on the fracture resistance. RESULTS: The group of overlays restored with zirconia-reinforced lithium silicate showed the highest mean fracture load (1218.69 N), while the group of vonlays restored with lithium disilicate had the lowest mean fracture resistance (967.15 N). The effect of preparation design and material type on fracture resistance was significant for both factors, p = 0.003 and p < 0.0001, respectively. Different features of the fracture surfaces, such as arrest lines, hackles, and directions of crack propagation, were observed. CONCLUSIONS: Zirconia-reinforced lithium silicate exhibited greater resistance to fracture compared to lithium disilicate, making it a potential substitute for partial coverage restorations. Additionally, the overlay showed superior fracture resistance when compared to the vonlay preparation design.

The wettability of complete denture base materials constructed by conventional versus digital techniques: an in-vitro study.

BACKGROUND: Decreased salivary flow can make the patients uncomfortable with their complete dentures and affects the retention of the dentures. Milling and 3D printing have become an alternative to conventional denture construction techniques. The goal of this study was to evaluate the effect of conventional and digital techniques of the complete denture construction on the denture surface wettability with distilled water and saliva substitute before and after thermocycling. METHODS: A total of 30 specimens were utilized in the present study. Specimens were divided according to the construction techniques into 3 groups (n = 10 each). Group I: Heat-polymerized polymethylmethacrylate (PMMA) group, group II: Milled group, and group III: 3-dimensional (3D)-printed group. All the specimens were subjected to 2000 cycles of thermal aging in a thermocycler. The wettability of all specimens to water and saliva substitute was measured via a contact angle goniometer (Olympus TGHM, Rame-hart Inc, USA) before and after thermocycling. Descriptive statistical analysis, plots, and the Shapiro-Wilk test were used to verify normality for each variable. One-way ANOVA was used to compare the 3 study groups, while paired samples t-test was used to compare the differences within each group (P < .05). RESULTS: The smallest contact angle of drop of water to the denture base specimens before and after thermocycling were recorded in the milled group (53.0 ± 4.77 and 50.27 ± 2.30, respectively), followed by the heat polymerized PMMA group (85.65 ± 4.71 and 65.06 ± 2.27, respectively), and the 3D-printed group (91.34 ± 6.74 and 90.86 ± 8.57, respectively). While the smallest contact angle of drop of saliva substitute to denture base specimens was recorded in the milled group (56.82 ± 2.29 and 34.85 ± 7.51, respectively), followed by the 3D-printed group (72.87 ± 4.83 and 58.14 ± 9.58, respectively) and the heat polymerized PMMA group (83.62 ± 4.12 and 67.82 ± 4.93, respectively). There was statistically significant difference between the groups (P < .05). A significant decline in the average contact angle of drop of saliva has been reported in all groups after thermocycling. The contact angle values differed significantly between saliva substitute and distilled water in both 3D-printed and milled groups after thermocycling (P < .001). CONCLUSIONS: The milled denture base material presented the best wettability to water and saliva substitute than the 3D-printed and the heat-polymerized PMMA materials. Saliva substitutes improve the wetting ability of denture base materials manufactured by CAD/CAM compared with water.

Effect of carbamide peroxide treatment on the ion release of different dental restorative materials.

BACKGROUND: To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials. METHODS: In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer's instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05). RESULTS: It was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05). CONCLUSION: Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials.

A novel injectable boron doped-mesoporous nano bioactive glass loaded-alginate composite hydrogel as a pulpotomy filling biomaterial for dentin regeneration.

BACKGROUND: Different materials have been used as wound dressings after vital pulp therapies. Some of them have limitations such as delayed setting, difficult administration, slight degree of cytotoxicity, crown discoloration and high cost. Therefore, to overcome these disadvantages, composite scaffolds have been used in regenerative dentistry. This study aims to construct and characterize the physicochemical behavior of a novel injectable alginate hydrogel loaded with different bioactive glass nanoparticles in various concentrations as a regenerative pulpotomy filling material. METHODS: Alginate hydrogels were prepared by dissolving alginate powder in alcoholic distilled water containing mesoporous bioactive glass nanoparticles (MBG NPs) or boron-doped MBG NPs (BMBG NPs) at 10 and 20 wt% concentrations. The mixture was stirred and incubated overnight in a water bath at 50 0 C to ensure complete solubility. A sterile dual-syringe system was used to mix the alginate solution with 20 wt% calcium chloride solution, forming the hydrogel upon extrusion. Then, constructed hydrogel specimens from all groups were characterized by FTIR, SEM, water uptake percentage (WA%), bioactivity and ion release, and cytotoxicity. Statistical analysis was done using One-Way ANOVA test for comparisons between groups, followed by multiple pairwise comparisons using Bonferroni adjusted significance level (p < 0.05). RESULTS: Alginate/BMBG loaded groups exhibited remarkable increase in porosity and pore size diameter [IIB1 (168), IIB2 (183) (µm)]. Similarly, WA% increased (~ 800%) which was statistically significant (p < 0.05). Alginate/BMBG loaded groups exhibited the strongest bioactive capability displaying prominent clusters of hydroxyapatite precipitates on hydrogel surfaces. Ca/P ratio of precipitates in IIA2 and IIB1 (1.6) were like Ca/P ratio for stoichiometric pure hydroxyapatite (1.67). MTT assay data revealed that the cell viability % of human gingival fibroblast cells have declined with increasing the concentration of both powders and hydrogel extracts in all groups after 24 and 48 h but still higher than the accepted cell viability % of (˃70%). CONCLUSIONS: The outstanding laboratory performance of the injectable alginate/BMBGNPs (20 wt%) composite hydrogel suggested it as promising candidate for pulpotomy filling material potentially enhancing dentin regeneration in clinical applications.

Unveiling the Versatility of Coumarin-Integrated with Phenanthroline/Thiabendazole-Based EuIII Complexes for Smart LEDs, Vapoluminescence, and Bioimaging Applications.

Narrow band red-emitting phosphors based on organo-Eu(III) complexes prove their energetic features with surprising performance in smart red/white LEDs, sensing, and biological fields. In this report, a series of unique Eu(III) complexes have been synthesized with coumarin integrated with a class of phenanthroline(Phen)/thiabendazole(TBZ) based ancillary ligands and dibenzoyl methane (DBM)/2-theonyl trifluoroacetone (TTA) as an anionic ligand. The computational study reveals that the TBZ/Phen-based neutral ligands are superior energy harvesters to those other reported analogue neutral ligands. All the Eu-complexes demonstrated outstanding red emission due to electric dipole (ED) transition (5D0 → 7F2) in solid, solution, and thin film with high quantum yield (QY). Theoretical analysis (TD-DFT) and experimental findings describe that the energy transfer (ET) from the ligand's triplet level to the Eu(III) ion is completely occurring. The Eu(III) complexes can potentially be used to fabricate intense hybrid white and red LEDs. All of the fabricated red LEDs revealed high luminous efficiency of radiation (LER) values. The fabricated blue LED based hybrid white LEDs displayed remarkable performance with a low correlated color temperature (5634 K), high color rendering index 88%, and CIE values (x = 0.33; y = 0.342) for 3Eu. By interaction with acid-base vapors, Eu-complexes displayed effectively alterable on-off-on luminescence. Further, cellular imaging shows that Eu-complexes can be a potential biomarker for cancer cell lines.

Enhanced biomedical potential of polyurethane/hydroxyapatite composites through chemical modification: A comprehensive study on structure, morphology, and cytocompatibility for tissue regeneration.

Polyurethane/hydroxyapatite (PU/HA) composites are well-known for various biomedical applications. This study reports a chemical approach to improve the interaction between HA and PU matrix. HA was surface-modified with 1,6-hexamethylene diisocyanate (HMDI). First, an isocyanate-modified HA (IHA) was synthesized by hydro-thermal method. Second, IHA was incorporated into a separately synthesized thermoplastic PU by a solvent casting technique. A series of PU/IHA composites was prepared by varying PU᾿s soft and hard segments. The IHA was added to PU (5 and 10 %). The FTIR spectra exhibited characteristic bands of urethane and HA, confirming the synthesis of the composites. XRD study showed the crystallite size of IHA (20 Å) with hexagonal geometry and an amorphous to semicrystalline nature of composites. SEM showed that composites displayed porous and granular morphology. The TGA thermograms of the composites revealed the thermal stability up to 400 °C. The IHA addition considerably improved hydrophilicity and degradation of the composites in simulated body fluid (SBF). MTT assay revealed improved cytocompatibility (> 80 %) of the composites. These results demonstrated an appreciable improvement in structure, morphology, hydrophilicity, degradation, and cytocompatibility of PU/IHA composites by chemical modification of HA. Hence, these composites possess remarkable potential for biomedical applications such as tissue regeneration.

Effect of Silicon Nitride Coating on Titanium Surface: Biocompatibility and Antibacterial Properties.

In recent years, with the advent of a super-aged society, lifelong dental care has gained increasing emphasis, and implant therapy for patients with an edentulous jaw has become a significant option. However, for implant therapy to be suitable for elderly patients with reduced regenerative and immunological capabilities, higher osteoconductive and antimicrobial properties are required on the implant surfaces. Silicon nitride, a non-oxide ceramic known for its excellent mechanical properties and biocompatibility, has demonstrated high potential for inducing hard tissue differentiation and exhibiting antibacterial properties. In this study, silicon nitride was deposited on pure titanium metal surfaces and evaluated for its biocompatibility and antibacterial properties. The findings indicate that silicon nitride improves the hydrophilicity of the material surface, enhancing the initial adhesion of rat bone marrow cells and promoting hard tissue differentiation. Additionally, the antibacterial properties were assessed using Staphylococcus aureus, revealing that the silicon nitride-coated surfaces exhibited significant antibacterial activity. Importantly, no cytotoxicity was observed, suggesting that silicon nitride-coated titanium could serve as a novel implant material.

Bioinspired Functional Composites for Enhanced Thermally Conductivity via Fractal-Growth CuNP Fillers.

Thermal conduction for electronic devices has attracted extensive attention in light of the development of 5G communication. Thermally conductive materials with high thermal conductivity and extensive mechanical flexibility are extremely desirable in practical applications. However, the construction of efficient interconnected conductive pathways and continuous conductive networks is inadequate for either processing or actual usage in existing technologies. In this work, spherical copper nanoparticles (S-CuNPs) and urchin-inspired fractal-growth CuNPs (U-CuNPs), thermally conductive metal fillers induced by ionic liquids, were fabricated successfully through the electrochemical deposition method. Compared to S-CuNPs, the U-CuNPs shows larger specific surface contact area, thus making it easier to build a continuous conductive pathway network in the corresponding U-CuNPs/liquid silicone rubber (LSR) thermally conductive composites. The optimal loading of CuNP fillers was determined by evaluating the rheological performance of the prepolymer and the mechanical properties and thermal conductivity performances of the composites. When the filler loading is 150 phr, the U-CuNPs/LSR produces optimal mechanical properties (e.g., tensile strength and modulus), thermal conductivity (above 1000% improvement compared to pure LSR), and heating/cooling efficiency. The enhanced thermal conductivity of U-CuNPs/LSR was also confirmed through the finite element analysis (FEA) overall temperature distribution, indicating that U-CuNPs with larger specific surface contact areas exhibit more advantages in forming a continuous network in composites than S-CuNPs, making U-CuNPs/LSR a promising and competitive alternative to traditional flexible thermally interface materials.

Molecular Probe with Potential for Combined Boron Neutron Capture and Photothermal Antitumor Therapy.

Both boron neutron capture therapy (BNCT) and photothermal therapy (PTT) have been applied to tumor treatment in clinical. However, their therapeutic efficacy is limited. For BNCT, the agents not only exhibit poor targeting ability but also permit only a single irradiation session within a course due to significant radiation risks. In the context of PTT, despite enhanced selectivity, the limited photothermal effect fails to meet clinical demands. Hence, the imperative arises to combine these two therapies to enhance tumor-killing capabilities and improve the targeting of BNCT agents by leveraging the advantages of PTT agents. In this study, we synthesized a potential responsive agent by linking 4-mercaptophenylboronic acid (MPBA) and IR-780 dye that served as the agents for BNCT and PTT, respectively, which possesses the dual capabilities of photothermal effects and thermal neutron capture. Results from both in vitro and in vivo research demonstrated that IR780-MPBA effectively inhibits tumor growth through its photothermal effect with no significant toxicity. Furthermore, IR780-MPBA exhibited substantial accumulation in tumor tissues and superior tumor-targeting capabilities compared with MPBA, which demonstrated that IR780-MPBA possesses significant potential as a combined antitumor therapy of PTT and BNCT, presenting a promising approach for antitumor treatments.

Effect of adding sodium fluoride and nano-hydroxyapatite nanoparticles to the universal adhesive on bond strength and microleakage on caries-affected primary molars.

Evaluation of micro tensile bond strength (µTBS) and marginal leakage of sodium fluoride (NaF) and nano-hydroxyapatite (n-HA) modified universal adhesives (UAs) bonded using etch-and-rinse (ER) and self-etch (SE) bonding technique to the carious affected dentin (CAD). One hundred and twenty primary molars were prepared for CAD on the occlusal surface. The occlusal CAD surface was flattened and underwent a polishing procedure. The specimens were divided into six groups using a random allocation method based on the UAs applied and the mode of etching used (n = 20) Group A1: UAs (ER), Group B1: UAs (SE), Group A2: UAs (NaF) + ER, Group B2: UAs (NaF) + SE, Group A3: UA (n-HA) + ER and Group B3: UAs (n-HA) + SE. Composite restoration was placed and samples were thermocycled. Microleakage, µTBS, and failure mode assessment were performed using a dye penetration test, universal testing equipment, and stereomicroscope respectively. The µTBS and microleakage results (mean ± SD) were examined using analysis of the variance (ANOVA) and Tukey post hoc tests. Group B1 (UAs + SE) demonstrated the maximum scores of microleakage (25.14 ± 9.12 nm) and minimum recorded value of µTBS (14.16 ± 0.55 MPa). In contrast, Group A3 (UAs (n-HA) + ER) displayed a minimum value of marginal leakage (12.32 ± 6.33 nm) and maximum µTBS scores (19.22 ± 0.92 MPa). The outcomes of the intergroup comparison analysis showed that Group A2 (UAs (NaF) + ER), Group B2 (UAs (NaF) + SE), Group A3 (UA (n-HA) + ER) and Group B3 (UAs (n-HA) + SE) presented comparable outcomes of marginal seal outcomes and µTBS scores (p > 0.05). NaF and n-HA-modified UAs displayed favorable bond strength and minimum marginal leakage to the deciduous affected dentin surface.

Cyclic fatigue resistance of two pediatric rotary files manufactured with different heat treatments: an in-vitro study.

Nickel-titanium (NiTi) instruments offer many advantages during endodontic instrumentation; however, the fracture risk within the canal remains a concern. Manufacturers continuously develop and introduce instruments to the market with supposedly enhanced cyclic fatigue resistance and increased flexibility, achieved through different proprietary manufacturing processes, the details of which have not been made public. In recent years, two rotary systems specially designed for deciduous teeth have been commercially available, but information about their performance is lacking. This investigation aimed to identify which manufacturing process provides better cyclic fatigue resistance: the AF-H Wire technology used in the AF baby rotary files (AF-f) or the CM-Wire technology used in the i3 Gold deciduous teeth rotary files (i3G-f). Forty rotary International Organization for Standardization (ISO) 25/04 files were tested in artificial canals with a standard geometry of 60° angle and 2.5 mm radius until fracture. The number of cycles to fracture was calculated, and the length of the fragments was measured. A scanning electron microscope (SEM) was used to examine the fracture surfaces and fragments. Energy dispersive spectroscopy (EDS) was used to determine the percentage weight of NiTi in each file. The statistical analysis (Mann-Whitney test) showed that the cyclic fatigue resistance of the AF-f was significantly higher (p < 0.0001) than that of the i3G-f. Additionally, there was a significant difference (p = 0.0419) in the length of the fractured fragments. All instruments showed one or more types of manufacturing defects and presented similar NiTi percentages by weight. The manufacturing process is critical to cyclic fatigue resistance, and there seems to be responsible for the difference in cyclic fatigue resistance between these similar instruments.

Evaluation of nanohardness, elastic modulus, and surface roughness of fluoride-releasing tooth colored restorative materials.

Recently, interest in tooth-colored fluoride-releasing dental materials has increased. Although physical and mechanical properties such as surface hardness, elastic modulus and surface roughness of the restorative materials have been investigated, the effect of different immersion media on these properties is still controversial. The aim of this study was to evaluate the nanohardness, elastic modulus and surface roughness of the fluoride release of tooth-colored restorative materials after immersion in acidic beverages. Prepared samples of three restorative materials (a highly viscous glass ionomer (EQUIA Forte; GC, Tokyo, Japan), a compomer (Dyract XP; Dentsply, Weybridge, UK), and a bioactive restorative material (Activa BioACTIVE; Pulpdent, MA, USA)) were randomly divided and immersed in distilled water, a cola and an orange juice for one week. The HYSITRON T1 950 TriboIndenter device (Hysitron, USA) with the Berkovich diamond indenter tip was used for all measurements. The nanohardness and elastic modulus of the samples were measured by applying a force of 6000 µN to five different points on the sample surface. Surface roughness measurements were evaluated on random samples by scanning five random 40 × 40 µm areas. The properties were measured at the initial and one week after immersion. The values of nanohardness, elastic modulus and surface roughness were tested for significant differences using a two-way analysis of variance (ANOVA) with repeated measures (p < 0.05). Tukey's honest significant difference (HSD) test was used for multiple comparisons. AB (Activa BioACTIVE) had the highest initial mean values for nanohardness. After post-immersion, the highest mean value for elastic modulus was the initial AB value. The lowest mean value for roughness of 100.36 nm was obtained for the initial DX (Dyract XP) measurement. Acidic beverages had a negative effect on the nanohardness, elastic modulus and surface roughness of the restorative materials.

Effects of lactic acid etching on immediate and aged bond strength of resin-dentin bonding interface.

To investigate the effects of lactic acid etching on the immediate and aged bond strength of the resin-dentin bonding interface, the resin-dentin bonding interface was evaluated 24 hours and 6 months later. A total of 42 isolated third molars were randomly divided into 6 experimental groups according to different lactate concentration (35%, 40%, 45%) and acid etching time (30 s, 45 s), with 37% phosphoric acid etching 15 s as a control. In each group, dentin samples were etched under different acidic conditions and bonded with Adper Single Bond 2 (3M ESPE) as directed. The immediate group was immediately stored in deionized water at 37 °C for 24 h, and the aging group was stored in artificial saliva at 37 °C for 6 months. Immediate and aged bond strengths were measured by a micro-tensile tester, and the specimen fracture surface was observed under a microscope. 14 isolated third molars were randomly divided into 7 groups, and each group was etched with acid. Collagen fibers morphology in dentin was examined after gradient dehydration with ethanol by scanning electron microscopy (SEM). Statistically, there was no difference between the resin-dentin immediate bonding strength of 35% lactic acid for 30 s and 37% phosphoric acid for 15 s, but the aged bond strength was greater than that of the phosphoric acid group. According to scanning electron microscope observations, the collagen fiber morphology in 35% and 40% lactate etching dentin 30 s groups was relatively intact compared with other groups. In conclusion, 35% lactic acid etching of dentin 30 s ensures both immediate and aged resin-dentin bond strength.

Cytotoxicity of two fluoride-releasing adhesive tapes.

Sodium fluoride-polyvinyl alcohol (NaF-PVA) tape was developed to deliver fluoride to teeth by adding fluoride to polymer tape. Previous studies have demonstrated that tapes are effective and have antimicrobial properties. This study aimed to evaluate the cytotoxicity of two fluoride-releasing adhesive tapes. We investigated two polyvinyl alcohol (PVA) tapes: (i) a fluoride-PVA (F-PVA) tape, and (ii) a pullulan-incorporated F-PVA (PF-PVA) tape. The cytotoxicity test was conducted on human gingival fibroblasts (HGF) and human periodontal ligament (PDL) cells. Using an adhesive tape containing fluoride, we performed the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on these cells. Genetic analysis of the cells was performed to conduct a stability test on humans. In the MTT assay, PF-PVA had 66% greater cytotoxicity than control by PDL and 69% by HGF. F-PVA showed less cytotoxicity than PF-PVA by 29% in PDL and 33% in HGF. Gene ontology (GO) analysis and gene set enrichment analysis (GSEA) were performed as gene expression analyses. GO analysis indicated that PF-PVA displayed more expression changes of genes related to cytotoxicity than F-PVA. In addition, GSEA found more inflammatory response associations in PF-PVA than in F-PVA. MTT and genetic testing yielded comparable results.

Tough, Slippery, and Low-Permeability Multilayer Hydrogels Modified by Anisotropic Fiber Membrane for Soft Tissue Replacement.

Hydrogels with sustained lubrication, high load-bearing capacity, and wear resistance are essential for applications in soft tissue replacements and soft material devices. Traditional tough or lubricious hydrogels fail to balance the lubrication and load-bearing functions. Inspired by the gradient-ordered multilayer structures of natural tissues (such as cartilage and ligaments), a tough, smooth, low-permeability, and low-friction anisotropic layered electrospun fiber membrane-reinforced hydrogel was developed using electrospinning and annealing recrystallization. This hydrogel features a stratified porous network structure of varying sizes with tightly bonded interfaces, achieving an interfacial bonding toughness of 1.6 × 103 J/m2. The anisotropic fiber membranes, mimicking the orderly fiber structures within soft tissues, significantly enhance the mechanical properties of the hydrogel with a fracture strength of 20.95 MPa, a Young's modulus of 29.64 MPa, and a tear toughness of 37.94 kJ/m2 and reduce its permeability coefficient (6.1 × 10-17 m4 N-1 s-1). Meanwhile, the hydrogel demonstrates excellent solid-liquid phase load-bearing characteristics, which can markedly improve the tribological performance. Under a contact load of 4.1 MPa, the anisotropic fiber membrane-reinforced hydrogel achieves a friction coefficient of 0.036, a 219% reduction compared with pure hydrogels. Thus, the superior load-bearing and lubricating properties of this layered hydrogel underscore its potential applications in soft tissue replacements, medical implants, and other biomedical devices.

Effect of polishing process on torque loss ratio and microgap of selective laser melting abutment: an in vitro study.

BACKGROUND: The purpose of this in vitro study was to investigate the effect of polishing post-treatment process on the torque loss ratio and microgap of Selective Laser Melting (SLM) abutments before and after mechanical cycling test through improving the surface roughness of the implant-abutment interface. MATERIALS AND METHODS: Forty SLM abutments were fabricated, with 20 underwent minor back-cutting, designated as polishing, in the implant-abutment interface. The abutments were divided into three groups: SLM abutments (group A), original abutments (group B), and polished SLM abutments (group C), each containing 20 abutments. Surface roughness was evaluated using a laser microscope. Implant-abutment specimens were subjected to mechanical cycling test, and disassembly torque values were measured before and after. Scanning electron microscope (SEM) was used to measure microgap after longitudinal sectioning of specimens. Correlation between surface roughness, torque loss ratio, and microgap were evaluated. LSD's test and Tamhane's T2 comparison were used to analyze the data (α = 0.05). RESULTS: The Sz value of polished SLM abutments (6.86 ± 0.64 µm) demonstrated a significant reduction compared to SLM abutments (26.52 ± 7.12 µm). The torque loss ratio of polished SLM abutments (24.16%) was significantly lower than SLM abutments (58.26%), while no statistically significant difference that original abutments (18.23%). The implant-abutment microgap of polished SLM abutments (2.38 ± 1.39 µm) was significantly lower than SLM abutments (8.69 ± 5.30 µm), and this difference was not statistically significant with original abutments (1.87 ± 0.81 µm). A significant positive correlation was identified between Sz values and the ratio of torque loss after cycling test (r = 0.903, P < 0.01), as well as Sz values and the microgap for all specimens in SLM abutments and polished SLM abutments (r = 0.800, P < 0.01). CONCLUSION: The findings of this study indicated that the polishing step of minor back-cutting can lead to a notable improvement in the roughness of SLM abutments interface, which subsequently optimized the implant-abutment fit. It can be seen that the application of minor back-cutting method has advanced the clinical use of SLM abutments.

Evaluation of the physical properties of bromelain-modified biodentine for direct pulp capping.

BACKGROUND: This study aims to evaluate the compressive strength, solubility, radiopacity, and flow of Bromelain (BR)-modified Biodentine (BD) for direct pulp capping (DPC). This is suggested to determine the impact of BR on the physical properties of BD. METHODS: Eighty samples were prepared according to the ISO and ADA specifications and evaluated for compressive strength, solubility, radiopacity, and flow. The compressive strength was evaluated at 24 h and 21 days via a universal testing machine. The solubility was determined by weight loss after 24-hours immersion in deionized water. Radiopacity was assessed via X-ray with aluminum step-wedges, and flow was measured by the diameter of the discs under a standard weight. Independent sample t-tests were used to statistically assess the data. A significance level of 5% was considered. RESULTS: The compressive strength was 41.08 ± 1.84 MPa for BD and 40.92 ± 1.80 MPa for BR + BD after 24 h, and 88.93 ± 3.39 MPa for BD and 87.92 ± 3.76 MPa for BR + BD after 21 days, with no significant differences. Solubility was slightly greater in the BR + BD (2.75 ± 0.10%) compared to BD (2.62 ± 0.25%), but not significantly different. The radiopacity was similar between BD (2.82 ± 0.11 mm) and BR + BD (2.73 ± 0.10 mm). BR + BD resulted in significantly greater flow (9.99 ± 0.18 mm) than did BD (9.65 ± 0.27 mm) (p ≤ 0.05). CONCLUSION: BR-modified BD maintains BD's physical properties, with improved flow, making it a promising DPC agent that warrants further study.

A comparison of several separation processes for eggshell membrane powder as a natural biomaterial for skin regeneration.

BACKGROUND: Numerous studies have focused on skin damage, the most prevalent physical injury, aiming to improve wound healing. The exploration of biomaterials, specifically eggshell membranes (ESMs), is undertaken to accelerate the recovery of skin injuries. The membrane must be separated from the shell to make this biomaterial usable. Hence, this investigation aimed to identify more about the methods for membrane isolation and determine the most efficient one for usage as a biomaterial. METHODS AND MATERIALS: For this purpose, ESM was removed from eggs using different protocols (with sodium carbonate, acetic acid, HCl, calcium carbonate, and using forceps for separation). Consequently, we have examined the membranes' mechanical and morphological qualities. RESULTS: According to the analysis of microscopic surface morphology, the membranes have appropriate porosity. MTT assay also revealed that the membranes have no cytotoxic effect on 3T3 cells. The results indicated that the ESM had acquired acceptable coagulation and was compatible with blood. Based on the obtained results, Provacol 4 (0.5-mol HCl and neutralized with 0.1-mol NaOH) was better than other methods of extraction and eggshell separation because it was more cell-compatible and more compatible with blood. CONCLUSION: This study demonstrates that ESMs can be used as a suitable biomaterial in medical applications.

Effect of Active Oxygen Fluid (Blue®m) as a Root Canal Irrigant Against Enterococcus Faecalis.

PURPOSE: To evaluate the antimicrobial effect of a new active oxygen fluid (Blue®m) as a root canal irrigant against Enterococcus faecalis compared to sodium hypochlorite (NaOCl). MATERIAL AND METHODS: Forty-five extracted single-canaled human teeth were selected, received root canal preparation, autoclaved, and contaminated with Enterococcus faecalis. The specimens were randomly allocated into three groups: Group (A) served as the negative control, receiving irrigation with saline (n = 15); Group (B) was irrigated with 5.25% NaOCl (n = 15); and Group (C) was irrigated with 10 mL of Blue®m (n = 15). Microbial sampling from the root canals was performed before and after irrigation. The difference between the pre-irrigation and post-irrigation colony-forming units (CFU/mL) was calculated. The data was analysed using a one-way ANOVA followed by post-hoc Tukey tests. The significance level was set at 5%. RESULTS: Blue®m statistically significantly reduced the bacterial load compared to saline (p = 0.009), but NaOCl was most effective, outperforming both (p 0.0001). CONCLUSION: Irrigation with Blue®m demonstrated antibacterial efficacy against Enterococcus faecalis, but it was not as effective as NaOCl.