-
Ultrasound in Obstetrics & Gynecology :... Apr 2019
Topics: Female; Fetus; Humans; Microarray Analysis; Nuchal Translucency Measurement; Pregnancy
PubMed: 30938480
DOI: 10.1002/uog.20253 -
Journal of Oral and Maxillofacial... 2021Ghost cells (GCs) have been a curious topic since a great deal of time. Extensive research has been done to deduce the true characteristics and formation of these cells....
Ghost cells (GCs) have been a curious topic since a great deal of time. Extensive research has been done to deduce the true characteristics and formation of these cells. GCs are balloon-shaped, elliptical, pale eosinophilic epithelial cells with pyknotic nuclei, leaving only a faint outline. In routine H and E staining, these cells give shadowy appearance and hence are also called shadow cells or translucent cells. The present article is an attempt to describe in detail about the origin, microscopic appearance, staining property, immunohistochemistry profile and diagnostic importance of GCs.
PubMed: 34349436
DOI: 10.4103/jomfp.jomfp_112_21 -
Dental Materials Journal Jan 2020This review describes low temperature degradation (LTD), discoloration, and erosion of high translucent dental zirconia and discusses its chemical durability in... (Review)
Review
This review describes low temperature degradation (LTD), discoloration, and erosion of high translucent dental zirconia and discusses its chemical durability in comparison with other CAD/CAM materials. The LTD of zirconia strongly depended on the firing temperature, yttria content, surface treatment, and heat treatment. Glass ceramics for CAD/CAM were remarkably etched in a lactic acid at 60°C, KOH solution at 60°C, and saline solution at 90°C, whereas zirconia showed no changes in these solutions. Glass ceramics and hybrid resins for CAD/CAM showed significant discoloration in a red wine and rhodamine B solution at 37°C, whereas zirconia showed no discolorations in either solution. It was concluded that high translucent dental zirconia has the highest chemical durability among dental CAD/CAM materials.
Topics: Ceramics; Computer-Aided Design; Dental Materials; Dental Porcelain; Materials Testing; Surface Properties; Zirconium
PubMed: 31511477
DOI: 10.4012/dmj.2019-109 -
Journal of Vision Aug 2021Translucency is an optical and a perceptual phenomenon that characterizes subsurface light transport through objects and materials. Translucency as an optical property... (Review)
Review
Translucency is an optical and a perceptual phenomenon that characterizes subsurface light transport through objects and materials. Translucency as an optical property of a material relates to the radiative transfer inside and through this medium, and translucency as a perceptual phenomenon describes the visual sensation experienced by humans when observing a given material under given conditions. The knowledge about the visual mechanisms of the translucency perception remains limited. Accurate prediction of the appearance of the translucent objects can have a significant commercial impact in the fields such as three-dimensional printing. However, little is known how the optical properties of a material relate to a perception evoked in humans. This article overviews the knowledge status about the visual perception of translucency and highlights the applications of the translucency perception research. Furthermore, this review summarizes current knowledge gaps, fundamental challenges and existing ambiguities with a goal to facilitate translucency perception research in the future.
Topics: Humans; Surface Properties; Visual Perception
PubMed: 34342646
DOI: 10.1167/jov.21.8.4 -
Journal of Applied Oral Science :... 2023The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental... (Review)
Review
The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.
Topics: Humans; Dental Materials; COVID-19; Ceramics; Computer-Aided Design; Dental Porcelain; Zirconium; Materials Testing; Surface Properties
PubMed: 36820784
DOI: 10.1590/1678-7757-2022-0421 -
Journal of Prosthodontic Research Aug 2021Purpose 1. to assess the ability of four brands of translucent monolithic zirconia with different thicknesses to mask discolored substrates; 2. to assess the influence...
Purpose 1. to assess the ability of four brands of translucent monolithic zirconia with different thicknesses to mask discolored substrates; 2. to assess the influence of glazing upon their color coordinates and masking properties.Methods Sixty samples of shade A1 (0.8, 1.5, and 2.0 mm thickness) from: ZirCAD/MT, Katana/HT, Vita YZ/HT, Cercon/HT were fabricated and glazed using a standardized laboratory procedure. CIE L*a*b* parameters were recorded on composite substrates, (IPS Natural Die Material Kit) (ND1=reference; ND2, ND3, ND4, ND5=test backgrounds), before and after glazing. The color changes of zirconia samples induced by glazing were analyzed. Masking properties was calculated as the color difference between CIE L*a*b* parameters of the samples placed on reference and test substrates with CIEDE2000(1:1:1) formula. The effect of material, thickness, substrate, and glazing on the color of monolithic zirconia was analyzed with ANOVA test and the multiple comparisons were analyzed with Tukey HSD tests (α=0.05).Results After glazing, lightness L* significantly increased, while chromatic coordinates a* and b* decreased (p<0.05). Significant differences in the masking properties of the four materials (p<0.001) were found, with IPS e.max ZirCAD/MT having the lowest masking effect (p<0.001). Thickness, substrate and glazing had a significant effect on the color masking properties of monolithic zirconia (p<0.001).Conclusions Masking properties of translucent zirconia were significantly influenced by the materials, the thickness and the color of the substrate; moreover, glazing improved the masking ability for all zirconia samples.
Topics: Ceramics; Color; Dental Porcelain; Materials Testing; Surface Properties; Zirconium
PubMed: 33116028
DOI: 10.2186/jpr.JPR_D_20_00039 -
Molecules (Basel, Switzerland) Mar 2022The aim of this article is to comprehensively review the revolution of dental zirconia (Zir), including its types, properties, applications, and cementation procedures.... (Review)
Review
The aim of this article is to comprehensively review the revolution of dental zirconia (Zir), including its types, properties, applications, and cementation procedures. A comprehensive search of PubMed and Embase was conducted. The search was limited to manuscripts published in English. The final search was conducted in October 2021. Newly developed monolithic Zir ceramics have substantially enhanced esthetics and translucency. However, this material must be further studied in vitro and in vivo to determine its long-term ability to maintain its exceptional properties. According to the literature, monolithic translucent Zir has had promising results and a high survival rate. Thus, the utilization of this material is indicated when strength and esthetics are needed. Both the materials and methods used for cementation of monolithic Zir have significantly improved, encouraging dentists to use this material, especially when a conservative approach is required. Zir restorations showed promising outcomes, particularly for monolithic Zir crowns supported with implant and fixed dental prostheses.
Topics: Zirconium
PubMed: 35268800
DOI: 10.3390/molecules27051699 -
PNAS Nexus Nov 2022Phenotypic heterogeneity is an important mechanism for regulating bacterial virulence, where a single regulatory switch is typically activated to generate virulent and...
Phenotypic heterogeneity is an important mechanism for regulating bacterial virulence, where a single regulatory switch is typically activated to generate virulent and avirulent subpopulations. The opportunistic pathogen can transition at high frequency between virulent opaque (VIR-O) and avirulent translucent subpopulations, distinguished by cells that form opaque or translucent colonies. We demonstrate that expression of 11 TetR-type transcriptional regulators (TTTRs) can drive cells from the VIR-O opaque subpopulation to cells that form translucent colonies. Remarkably, in a subpopulation of VIR-O cells, four of these TTTRs were stochastically activated in different combinations to drive cells to the translucent state. The resulting translucent subvariants exhibited unique phenotypic differences and the majority were avirulent. Due to their functional redundancy, a quadruple mutant with all four of these TTTRs inactivated was required to observe a loss of switching from the VIR-O state. Further, we demonstrate a small RNA, SrvS, acts as a "rheostat," where the levels of SrvS expression influences both the VIR-O to translucent switching frequency, and which TTTR is activated when VIR-O cells switch. In summary, this work has revealed a new paradigm for phenotypic switching in bacteria, where an unprecedented number of related transcriptional regulators are activated in different combinations to control virulence and generate unique translucent subvariants with distinct phenotypic properties.
PubMed: 36704122
DOI: 10.1093/pnasnexus/pgac231 -
Seminars in Fetal & Neonatal Medicine Jun 2014There have been tremendous advancements over the past three decades in prenatal screening for aneuploidy and we have changed our practice from screening by maternal age... (Review)
Review
There have been tremendous advancements over the past three decades in prenatal screening for aneuploidy and we have changed our practice from screening by maternal age alone to 'combined' first trimester screening and circulating cell-free fetal DNA. We currently use the nuchal translucency and biochemical markers of free β-hCG and PAPP-A to determine the risk of fetal aneuploidy. The primary goal is to identify higher risk women for fetal aneuploidy early in pregnancy and give them the option to pursue invasive testing in a timely manner if desired.
Topics: Adult; Aneuploidy; Down Syndrome; Female; History, 20th Century; Humans; Pregnancy; Pregnancy Trimester, First; Prenatal Diagnosis; Ultrasonography, Prenatal
PubMed: 24333205
DOI: 10.1016/j.siny.2013.11.013 -
Biomedicines Nov 2023Over the past two decades, dental ceramics have experienced rapid advances in science and technology, becoming the fastest-growing field of dental materials. This review... (Review)
Review
Over the past two decades, dental ceramics have experienced rapid advances in science and technology, becoming the fastest-growing field of dental materials. This review emphasizes the significant impact of translucent zirconia in fixed prosthodontics, merging aesthetics with strength, and highlights its versatility from single crowns to complex bridgework facilitated by digital manufacturing advancements. The unique light-conducting properties of translucent zirconia offer a natural dental appearance, though with considerations regarding strength trade-offs compared to its traditional, opaque counterpart. The analysis extends to the mechanical attributes of the material, noting its commendable fracture resistance and durability, even under simulated physiological conditions. Various zirconia types (3Y-TZP, 4Y-TZP, 5Y-TZP) display a range of strengths influenced by factors like yttria content and manufacturing processes. The study also explores adhesive strategies, underlining the importance of surface treatments and modern adhesives in achieving long-lasting bonds. In the realm of implant-supported restorations, translucent zirconia stands out for its precision, reliability, and aesthetic adaptability, proving suitable for comprehensive dental restorations. Despite its established benefits, the review calls for ongoing research to further refine the material's properties and adhesive protocols and to solidify its applicability through long-term clinical evaluations, ensuring its sustainable future in dental restorative applications.
PubMed: 38137337
DOI: 10.3390/biomedicines11123116