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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 -
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 -
European Journal of Dentistry Oct 2022This study investigated the effect of hydrothermal aging on surface roughness and translucency of various translucent zirconia materials.
OBJECTIVE
This study investigated the effect of hydrothermal aging on surface roughness and translucency of various translucent zirconia materials.
MATERIALS AND METHODS
Four types of zirconia were tested. Group 1 was translucent zirconia with no cubic structure. Group 2, 3, and 4 included cubic-containing zirconia with different amounts of cubic structures (less than 30%, 30-50%, and more than 50%, respectively). Each group contained 15 disk-shape specimens with dimensions of 15 mm in diameter and 1 mm in thickness. As-sintered surface roughness, translucency parameter, and contrast ratio were evaluated in the two different sessions, before and after aging.
STATISTICAL ANALYSIS
Two-way repeated measures ANOVA with Bonferroni test was used to analyze statistically significant difference in those tested parameters. Phase structure before and after aging was analyzed by X-ray diffraction analysis (XRD).
RESULTS
Groups 1 and 2 showed significant increased surface roughness after aging while groups 3 and 4 showed no alteration of surface. There was no effect of aging on translucency in all groups. After aging, group 1 and 2 presented monoclinic structure (16.63 and 5.01%, respectively).
CONCLUSION
Hydrothermal aging caused phase transformation and increasing surface roughness in group 1 and 2 but did not affect translucency in all groups.
PubMed: 34891182
DOI: 10.1055/s-0041-1736415 -
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 -
The Journal of Advanced Prosthodontics Oct 2022The purpose of this study is to evaluate translucency and masking ability of translucent zirconia compared to conventional zirconia and lithium disilicate materials.
PURPOSE
The purpose of this study is to evaluate translucency and masking ability of translucent zirconia compared to conventional zirconia and lithium disilicate materials.
MATERIALS AND METHODS
Three types of zirconia blocks with different yttria contents (3Y, 4Y, 5.5Y) and LS blocks (Rosetta SM) were used. Ten specimens for each group were fabricated with 10 mm diameter, with both 0.8 mm and 1.5 mm thicknesses (± 0.02 mm). All groups of zirconia specimens were sintered and polished according to the manufacturer's instructions. To calculate the translucency parameter (TP), CIELAB value was measured with a spectrophotometer on black and white backgrounds. To investigate the color masking abilities, background shades of A2, normal dentin, discolored dentin, and titanium were used. The color difference (ΔE) was calculated with the CIELAB values of A2 shade background as a reference compared with the values in the various backgrounds. One-way ANOVA and Bonferroni tests were conducted ( < .05).
RESULTS
The TP values of zirconia specimens increased as the yttria content increased. All materials used in the study were able to adequately mask normal dentin shade (ΔE < 5.5), but were incapable of masking severely discolored dentin (ΔE > 5.5). On the titanium background, all materials of 1.5 mm thickness were able to mask the background shade, but with a thickness of 0.8 mm, only 3Y-TZP and 4Y-PSZ were able to mask titanium background.
CONCLUSION
All zirconia materials and lithium disilicate specimens used in this study were unable to adequately mask the shade of severely discolored dentin. It is recommended to use 3Y-TZP or 4Y-PSZ with a sufficient thickness of 0.8 mm or more to mask titanium.
PubMed: 36452362
DOI: 10.4047/jap.2022.14.5.324 -
Poultry Science Jan 2023The eggshell quality declined with extending of chicken laying cycles. Eggshell quality is a crucial feature that not only affects consumer preference, but also... (Review)
Review
The eggshell quality declined with extending of chicken laying cycles. Eggshell quality is a crucial feature that not only affects consumer preference, but also influences producers' economic profitability. The eggshell ultrastructure consists of mammillary, palisade, and vertical crystal layers. Any defect in shell structure results in a reduction in eggshell quality. Speckled, translucent, pimpled, and soft eggshells are common defects that cause significant financial losses for farmers and food security concerns for consumers. Therefore, reducing the faulty eggshells is critical for poultry production. Defective eggshell quality has been attributed to hereditary factors and external environmental stimuli. As such, improvements can be carried out through selective breeding and environmental control of components such as temperature, moisture, and diet formula balance. In this review, the molecular mechanisms of the main eggshell quality defects (speckled, translucent, pimpled, broken, and soft-shell eggs) and the relevant improvement methods are detailed. We hope this review will serve as a useful resource for poultry production management and effectively increasing eggshell quality.
Topics: Animals; Chickens; Egg Shell; Ovum; Poultry; Diet
PubMed: 36399932
DOI: 10.1016/j.psj.2022.102283 -
Nigerian Journal of Clinical Practice Aug 2022Evaluation of the optical properties of restorative materials is an important parameter for identifying clinical success. The aim of this study was to compare the...
BACKGROUND AND AIMS
Evaluation of the optical properties of restorative materials is an important parameter for identifying clinical success. The aim of this study was to compare the translucency of contemporary resin-matrix ceramics (RMCs) and to evaluate the effect of cement shade on the final color of RMCs indicated for laminate veneers and full crowns.
MATERIALS AND METHODS
A hundred A2 shade RMC specimens were fabricated by using Mazic Duro (MD), CAMouflage NOW (CN), KZR-CAD HR2 (KZR), Grandio Block (GB), and Brilliant Crios (BC) at 0.7-mm and 1.5-mm thicknesses (n = 10). A2 shade composite resin was used for the foundation structure. Twenty resin-cement specimens were prepared from A2 and translucent shades at 0.1-mm thickness. Interchangeably, the foundation-cement-resin matrix ceramic assemblies were created with optical gel. The color coordinates were recorded using a spectrophotometer. After calculating translucency parameter (TP) and color difference (ΔE) values, data were analyzed statistically (P = 0.05).
RESULTS
TP values were influenced by RMC type and thickness. TP values of RMCs can be listed in descending order as MD>GB = CN>BC=KZR. ΔE values were significantly influenced by all parameters and their interactions. MD exhibited higher ΔE values among tested RMCs. The effect of A2 cement was not perceived visually while TR cement demonstrated visually perceptible but clinically acceptable values for both laminate veneers and full crowns. As the material thickness decreased, the TP and ΔE values increased in all RMCs.
CONCLUSIONS
Clinicians should carefully prefer cement shade and RMC material by contemplating their impact on the optical properties particularly when the restoration is thin.
Topics: Ceramics; Color; Glass Ionomer Cements; Humans; Materials Testing; Prosthesis Coloring; Resin Cements; Surface Properties
PubMed: 35975382
DOI: 10.4103/njcp.njcp_172_22