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PeerJ 2024Juniper () is a common forest tree species in Saudi Arabia. The decline in many populations of . in Saudi Arabia is mainly due to seed dormancy and loss of natural...
PURPOSE
Juniper () is a common forest tree species in Saudi Arabia. The decline in many populations of . in Saudi Arabia is mainly due to seed dormancy and loss of natural regeneration. This study assessed the effects of chemical and hormonal treatments on seed germination and seedling growth in juniper plants.
METHODS
The seeds were subjected to either chemical scarification with 90% sulfuric acid and 20% acetic acid for 6 min or hormonal treatment by seed soaking in two concentrations (50 and 100 ppm) of three growth regulators, namely, indole acetic acid (IAA), gibberellins (GA), and kinetin, for 72 h. A control group without any seed treatment was also prepared. The experiments were performed in an incubator maintained at room temperature and under a light and dark period of 12 h for 6 w. The germinated seeds for each treatment were counted and removed from the dishes. The selected germinated seeds from different treatments were planted in a greenhouse and irrigated with tap water for another 6 weeks. The hormone-treated seedlings were sprayed with their corresponding hormone concentrations 1 w after planting.
RESULTS
The highest percentage of seed germination was significantly recorded after seed soaking in 50 ppm GA, whereas treatment with IAA (100 ppm) resulted in the best seedling growth. Seedlings treated with the three phytohormones showed a significant increase in photosynthetic pigments, total soluble sugars, proteins, percentage of oil, IAA, GA, and kinetin contents of juniper seedlings compared with the control value, whereas abscisic acid content was decreased compared with chemical treatments.
CONCLUSION
The investigated different treatments had an effective role in breaking seed dormancy and improving seedling growth of . , which is facing a notable decline in its population worldwide. Moreover, such an effect was more pronounced in the three phytohormones that succeeded in breaking dormancy and growth of the plant than in the other treatments.
Topics: Seedlings; Juniperus; Germination; Plant Growth Regulators; Kinetin; Seeds; Hormones; Dental Porcelain; Titanium; Metal Ceramic Alloys
PubMed: 38618572
DOI: 10.7717/peerj.17236 -
Dental Materials : Official Publication... May 2024This 3D finite element analysis study aimed to investigate the effect of reinforcing CAD-CAM bars on stress distribution in various components of a posterior composite...
OBJECTIVES
This 3D finite element analysis study aimed to investigate the effect of reinforcing CAD-CAM bars on stress distribution in various components of a posterior composite bridge.
METHODS
A virtual model mimicking the absence of an upper second premolar was created, featuring class II cavity preparations on the proximal surfaces of the adjacent abutment teeth surrounding the edentulous space. Five distinct finite element analysis (FEA) models were generated, each representing a CAD-CAM reinforcing bar material: 3-YTZP (IPS. emax ZirCAD MO; Zr), lithium disilicate (IPS e.max CAD; EX), nano-hybrid resin composite (Grandio Blocs; GB), Fibre-reinforced composite (Trilor; Tri), and polyetheretherketone (PEEK). A veneering resin composite was employed to simulate the replacement of the missing premolar (pontic). In the FEA, an axial force of 600 N and a transverse load of 20 N were applied at the center of the pontic. Subsequently, maximum von Mises (mvM) and maximum principal stresses (σmax) were computed across various components of the generated models. Additionally, shear stresses at the interface between the CAD-CAM bars and the veneering resin composite were determined.
RESULTS
CAD-CAM materials with high modulus of elasticity, such as Zr and EX, exhibited the highest mvM stresses and shear stresses while transferring the lowest stress to the veneering resin composite in comparison to other materials. Conversely, PEEK demonstrated the lowest mvM stresses but produced the highest stresses within the veneering resin composite. There was a uniform distribution of mvM stresses in the remaining tooth structure among all groups, except for a noticeable elevation in the molar region of Zr and EX groups.
SIGNIFICANCE
Reinforcing CAD-CAM bar materials with a high modulus of elasticity, such as Zr and EX, may result in debonding failures at the connector sites of posterior composite bridges. Conversely, GB, PEEK, and Tri have the potential to cause fracture failures at the connectors rather than debonding.
Topics: Finite Element Analysis; Computer-Aided Design; Composite Resins; Benzophenones; Dental Stress Analysis; Polyethylene Glycols; Materials Testing; Humans; Dental Materials; Ketones; Biomechanical Phenomena; Polymers; Dental Porcelain; Dental Veneers; Imaging, Three-Dimensional
PubMed: 38609774
DOI: 10.1016/j.dental.2024.04.001 -
Journal of Clinical and Experimental... Mar 2024The aim of this systematic review is to determine the effectiveness of self-etching primers in comparison to the conventional protocol with hydrofluoric acid and silane... (Review)
Review
BACKGROUND
The aim of this systematic review is to determine the effectiveness of self-etching primers in comparison to the conventional protocol with hydrofluoric acid and silane treatment for bonding lithium disilicate ceramics.
MATERIAL AND METHODS
The formulated PICO question for this research was: "Does self-etching silane primer surface treatment in lithium disilicate ceramics present a similar bond strength value compared to conventional hydrofluoric acid and silane treatment?". Combinations of words and appropriate truncations were adapted for each database. For the selection, duplicate articles were systematically eliminated using Mendeley software. The Cohen's Kappa statistic was then computed, RoBDEMAT questions were addressed, and the meta-analyses were conducted using RevMan 5.4, at a significance level of 5%.
RESULTS
Two independent reviewers conducted a blind and independent analysis of 190219 articles from PubMed, Scopus, Web of Science, and OpenGrey. Subsequently, they extracted data from 21 studies for the systematic review and in 16 the meta-analysis. In all in vitro studies, the most frequently cited concentration of hydrofluoric acid was 5%. In the meta-analysis, no statistical differences were observed between the two treatments concerning bond strength.
CONCLUSIONS
Self-etching silane primers demonstrate promising results in lithium disilicate bonding, suggesting their potential as an alternative surface treatment to hydrofluoric acids + silane. Lithium disilicate, Hydrofluoric acid, Dental Porcelain, Ceramics, Silanes.
PubMed: 38600931
DOI: 10.4317/jced.61369 -
Scientific Reports Apr 2024The present study aims to examine the characteristics of a composite material composed of glass/madar fibers and porcelain particles, which are reinforced with epoxy. A...
The present study aims to examine the characteristics of a composite material composed of glass/madar fibers and porcelain particles, which are reinforced with epoxy. A compression molding technique achieves the fabrication of this composite. A comprehensive characterization was conducted by employing a mixture of analytical techniques, including X-ray Diffraction (XRD), mechanical testing, Scanning Electron Microscopy (SEM), Dynamic Mechanical Analysis (DMA), and Thermogravimetric Analysis (TGA). The composition of the composite was determined using X-ray diffraction (XRD) analysis, which demonstrated the successful integration of porcelain fillers. The material exhibited notable mechanical properties, rendering it appropriate for utilization in structural applications. The utilization of SEM facilitated the examination of the microstructure of the composite material, thereby providing a deeper understanding of the interactions between the fibers and the matrix. DMA results revealed the glass/madar composite contained 4.2% higher viscoelastic properties when the addition of porcelain filler, thermal stability was improved up to the maximum temperature of 357 °C. This study provided significant insights into the properties of a hybrid epoxy composite consisting of glass/madar fibers reinforced porcelain particles.
PubMed: 38600087
DOI: 10.1038/s41598-024-53178-x -
Journal of Pharmacy & Bioallied Sciences Feb 2024Surface roughness and hardness are key factors that influence the clinical performance and durability of denture teeth. Understanding variations in these properties...
BACKGROUND
Surface roughness and hardness are key factors that influence the clinical performance and durability of denture teeth. Understanding variations in these properties among different denture teeth materials can assist in selecting the most suitable materials for optimal patient outcomes. This study aimed to investigate the surface roughness and hardness of four commonly used denture teeth materials: acrylic resin, composite resin, porcelain, and nanohybrid composite.
MATERIALS AND METHODS
Ten specimens were prepared for each denture teeth material, resulting in a total of 40 specimens. Surface roughness was assessed using a profilometer, and measurements were recorded in micrometers (μm). Hardness was determined using a Vickers hardness tester, and results were expressed as Vickers hardness numbers (VHN). The surface roughness and hardness data were analyzed using appropriate statistical tests (e.g., analysis of variance), with significance set at < 0.05.
RESULTS
The results revealed significant differences in both surface roughness and hardness among the different denture teeth materials ( < 0.05). Acrylic resin exhibited the highest surface roughness (mean ± standard deviation: 3.45 ± 0.78 μm) and the lowest hardness (mean ± standard deviation: 45.6 ± 2.3 VHN). Composite resin demonstrated intermediate values of surface roughness (mean ± standard deviation: 1.87 ± 0.54 μm) and hardness (mean ± standard deviation: 65.2 ± 3.9 VHN). Porcelain demonstrated the smoothest surface (mean ± standard deviation: 0.94 ± 0.28 μm) and the highest hardness (mean ± standard deviation: 78.5 ± 4.1 VHN). Nanohybrid composite displayed surface roughness and hardness values similar to composite resin.
CONCLUSION
This study demonstrated significant variations in surface roughness and hardness among the different denture teeth materials evaluated. Acrylic resin exhibited the roughest surface and lowest hardness, while porcelain demonstrated the smoothest surface and highest hardness. Composite resin and nanohybrid composite exhibited intermediate values. These findings provide valuable insights for prosthodontic practitioners in selecting denture teeth materials based on specific clinical requirements, aiming to achieve optimal aesthetics, reduced plaque accumulation, and improved wear resistance.
PubMed: 38595483
DOI: 10.4103/jpbs.jpbs_644_23 -
The Journal of Prosthetic Dentistry Jun 2024Additive (AM) and subtractive (SM) manufacturing have become popular for fabricating occlusal devices with materials of different chemical compositions. However,...
Effect of material and antagonist type on the wear of occlusal devices with different compositions fabricated by using conventional, additive, and subtractive manufacturing.
STATEMENT OF PROBLEM
Additive (AM) and subtractive (SM) manufacturing have become popular for fabricating occlusal devices with materials of different chemical compositions. However, knowledge on the effect of material and antagonist type on the wear characteristics of occlusal devices fabricated by using different methods is limited.
PURPOSE
The purpose of this in vitro study was to evaluate the effect of material and antagonist type on the wear of occlusal devices fabricated by using conventional manufacturing, AM, and SM.
MATERIAL AND METHODS
Two-hundred and forty Ø10×2-mm disk-shaped specimens were fabricated by using heat-polymerized polymethylmethacrylate (control, CM), AM clear device resin fabricated in 3 different orientations (horizontal [AMH], diagonal [AMD], and vertical [AMV]), SM polymethylmethacrylate (SMP), and SM ceramic-reinforced polyetheretherketone (SMB) (n=40). Specimens were then divided into 4 groups based on the antagonists: steatite ceramic (SC); multilayered zirconia (ZR); lithium disilicate (EX); and zirconia-reinforced lithium silicate (ZLS) used for thermomechanical aging (n=10). After aging, the volume loss (mm) and maximum wear depth (μm) were digitally evaluated. Data were analyzed with 2-way analysis of variance and Tukey honestly significant difference tests (α=.05).
RESULTS
The interaction between the device material and the antagonist affected volume loss and maximum depth of wear (P<.001). AMH had volume loss and depth of wear that was either similar to or higher than those of other materials (P≤.044). When SC was used, CM had higher volume loss and depth of wear than AMV, and, when EX was used, AMD had higher volume loss and depth of wear than SMP (P≤.013). SC and ZR led to higher volume loss of CM and AMH than EX and led to the highest depth of wear for these materials, while ZR also led to the highest volume loss and depth of wear of AMD and AMV (P≤.019). EX led to the lowest volume loss and depth of wear of AMV and SMP and to the lowest depth of wear of AMH (P≤.021). Regardless of the antagonist, SMB had the lowest volume loss and depth of wear (P≤.005).
CONCLUSIONS
AMH mostly had higher volume loss and depth of wear, while SMB had the lowest volume loss, and its depth of wear was not affected by the tested antagonists. ZR mostly led to higher volume loss and maximum depth of wear, while EX mostly led to lower volume loss and maximum depth of wear of the tested occlusal device materials.
Topics: Materials Testing; Dental Materials; Polymethyl Methacrylate; Zirconium; Ceramics; Humans; In Vitro Techniques; Occlusal Splints; Dental Restoration Wear; Dental Prosthesis Design; Benzophenones; Dental Porcelain; Polymers; Surface Properties; Polyethylene Glycols; Ketones
PubMed: 38594086
DOI: 10.1016/j.prosdent.2024.03.026 -
Materials Today. Proceedings Sep 2023Studies have reported challenges of debonding of dental zirconia crowns to from luting cement and prepared teeth. The aim of the study was to explore the application of...
Studies have reported challenges of debonding of dental zirconia crowns to from luting cement and prepared teeth. The aim of the study was to explore the application of dental glazing systems for enhancing the bonding of zirconia dental ceramics to luting resin cement. Commercial glaze powder and liquid (Vita Akzent) and experimental mica-based glaze powders were used for the study. X-ray diffraction analysis of the glaze powders (XRD) and Fourier Transform InfraRed Spectroscopy (FTIR) was done on the glaze liquid. Sandblasted sintered dental zirconia (Katana, Noritake) were the control samples. Glazed zirconia samples were coated with commercial glaze and experimental glaze powders which were further etched with 5% hydrofluoric acid. Shear bond strengths of sandblasted and glazed zirconia samples to resin composites were evaluated. XRD of commercial and experimental glaze powders revealed a broad peak confirming the amorphous nature of glass and FTIR analysis of the glaze liquid revealed symmetrical stretching (CH-CH) of the alcohol group indicating a mixture of -butane and ethanol. Glazed and etched zirconia showed significantly higher shear bond strength to resin cement compared to sand-blasted zirconia. The study confirms the glassy nature of dental glaze powders and the presence of ethanol-based mixtures in the commercial glaze liquid. Glazing systems have the potential to be explored for enhancing the bonding of non-etchable zirconia ceramics to resin cement and tooth substrates.
PubMed: 38590583
DOI: 10.1016/j.matpr.2023.04.308 -
Dental Materials Journal Jun 2024This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto...
This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto zirconia frameworks with mechanical retentive devices. Three different zirconia frameworks were assessed: attaching mechanical retentive devices on glaze and opaque porcelain materials (GL and OP groups, respectively), and no attaching mechanical retentive devices (ND group). The frameworks were layered using feldspathic porcelain (FP veneer) and indirect composite resin (IC veneer). Fracture load of the specimens was measured. In FP veneer, the GL group recorded the highest fracture load. In the IC veneer, the GL and OP groups had significantly higher fracture load than the ND group. The fracture resistance of IZCs can be enhanced by applying glaze material before attaching mechanical retentive devices for porcelain layering. The mechanical retentive devices effectively yielded mechanical interlocking between the zirconia frameworks and the IC veneer in GL and OP groups.
Topics: Zirconium; Materials Testing; Crowns; Dental Restoration Failure; Dental Stress Analysis; Dental Porcelain; Dental Prosthesis, Implant-Supported; Dental Veneers; Composite Resins; Surface Properties
PubMed: 38583996
DOI: 10.4012/dmj.2023-188 -
Dental Materials Journal Jun 2024This study was to evaluate the effect of different water amounts and hydrolysis times of silane coupling agent on shear bond strength between lithium disilicate glass...
Effect of the difference water amounts and hydrolysis times of silane coupling agent on the shear bond strength between lithium disilicate glass ceramic and composite resin.
This study was to evaluate the effect of different water amounts and hydrolysis times of silane coupling agent on shear bond strength between lithium disilicate glass ceramic (LDS) and composite resin. Fourteen groups (n=7) of different water amounts (90, 50 and 10%v/v) and hydrolysis times (5, 19, 75 and 300 s) of experimental silane coupling agent that were prepared for silanization, non-silanization and commercial silane coupling agent (CSC) groups. Two-way analysis of variance (ANOVA) revealed no interaction between water amounts and hydrolysis times of ESC on shear bond strength between LDS and composite resin. One-way ANOVA exhibited the highest shear bond strength and the highest mean percentage in mixed failure mode in the 50%v/v group. Molecular analysis of C and Si indicated that nuclear magnetic resonance spectra of M2 and M3 hydrolysis species were found in 50%v/v group. The presenting of M2 and M3 which was predominant factor contributing to the highest shear bond strength.
Topics: Shear Strength; Hydrolysis; Ceramics; Silanes; Dental Porcelain; Materials Testing; Water; Composite Resins; Dental Bonding; Dental Stress Analysis; Surface Properties; Magnetic Resonance Spectroscopy; Time Factors
PubMed: 38583995
DOI: 10.4012/dmj.2023-190 -
Dental Materials : Official Publication... May 2024Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and... (Review)
Review
OBJECTIVES
Lithium silicate-based glass ceramics have evolved as a paramount restorative material in restorative and prosthetic dentistry, exhibiting outstanding esthetic and mechanical performance. Along with subtractive machining techniques, this material class has conquered the market and satisfied the patients' needs for a long-lasting, excellent, and metal-free alternative for single tooth replacements and even smaller bridgework. Despite the popularity, not much is known about the material chemistry, microstructure and terminal behaviour.
METHODS
This article combines a set of own experimental data with extensive review of data from literature and other resources. Starting at manufacturer claims on unique selling propositions, properties, and microstructural features, the aim is to validate those claims, based on glass science. Deep knowledge is mandatory for understanding the microstructure evolution during the glass ceramic process.
RESULTS
Fundamental glass characteristics have been addressed, leading to formation of time-temperature-transformation (TTT) diagrams, which are the basis for kinetic description of the glass ceramic process. Nucleation and crystallization kinetics are outlined in this contribution as well as analytical methods to describe the crystalline fraction and composition qualitatively and quantitatively. In relation to microstructure, the mechanical performance of lithium silicate-based glass ceramics has been investigated with focus on fracture strength versus fracture toughness as relevant clinical predictors.
CONCLUSION
Fracture toughness has been found to be a stronger link to initially outlined manufacturer claims, and to more precisely match ISO recommendations for clinical indications.
Topics: Ceramics; Silicates; Materials Testing; Glass; Surface Properties; Dental Materials; Crystallization; Lithium Compounds; Dental Porcelain
PubMed: 38580561
DOI: 10.1016/j.dental.2024.03.006