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Polymers Mar 2022Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space...
Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress-strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress-strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress-strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress-strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.
PubMed: 35267864
DOI: 10.3390/polym14051041 -
Scientific Reports Dec 2022To investigate the effect of resin cements on the color stability and translucency of ceramic laminate veneers used for diastema closure. Sixty resin abutments were...
To investigate the effect of resin cements on the color stability and translucency of ceramic laminate veneers used for diastema closure. Sixty resin abutments were prepared for ceramic laminate veneers and divided into six groups according to the ceramic type (lithium disilicate, zirconia-reinforced lithium silicate, and translucent zirconia) and the cement type (Variolink Esthetic LC and RelyX Veneer). Color coordinates and translucency were analyzed after cementation and after soaking in the coffee solution. Differences in color and translucency were estimated, and results were statistically assessed (α = 0.05). Ceramic materials showed a significant impact on color changes after soaking in coffee within Variolink Esthetic groups. Translucent zirconia showed the highest color change, followed by zirconia reinforced lithium silicate and lithium disilicate. Ceramic materials showed a significant impact among the RelyX Veneer groups. A significant interaction in color changes was found between ceramic types and cement types after cementation, and after soaking in coffee was found. All groups showed a clinically acceptable difference in translucency parameters after soaking in coffee. The resin cement affects the color and translucency of ceramic laminate veneers used for diastema closure, and ceramic laminate veneers bonded with Variolink Esthetic LC resin cement are more translucent, while ceramic laminate veneers bonded with RelyX Veneer resin are more resistant to coffee staining. The lithium disilicate laminate veneer is more resistant to coffee staining than zirconia reinforced lithium silicate and translucent zirconia laminate veneers used for diastema closure.
Topics: Humans; Color; Resin Cements; Diastema; Lithium; Coffee; Materials Testing; Ceramics; Resins, Plant
PubMed: 36543821
DOI: 10.1038/s41598-022-26581-5 -
Materials (Basel, Switzerland) Jul 2020The aim was to evaluate the translucency, opalescence, and fluorescence of highly translucent zirconia, lithium disilicate, and bovine teeth. One mm-thick specimens of...
The aim was to evaluate the translucency, opalescence, and fluorescence of highly translucent zirconia, lithium disilicate, and bovine teeth. One mm-thick specimens of five monolithic zirconia systems, two glass-ceramics, and bovine enamel/dentin were investigated. A spectrophotometer (Ci7600) was used to measure the CIELab color coordinates, and the translucency and opalescence values were obtained. For evaluating the fluorescence emission, the differences in spectral reflectance by the UV component of illumination were calculated. The microstructures of ceramic specimens were examined with a scanning electron microscope and the chemical compositions were determined with an X-ray fluorescence spectrometer. Mechanical properties were appraised with three-point bending strength, indentation fracture toughness, and Vickers hardness. Data were analyzed using a one-way ANOVA, followed by Tukey's multiple comparison test (α = 0.05). A higher yttria content (5 mol%) significantly improved the translucency of zirconia ceramics, while they were less translucent than lithium disilicate ( < 0.05). Lowering the alumina content below 0.05 wt.% enhanced the translucency ( < 0.05), but a small amount of alumina was still required to obtain full densification. 0.05 wt.% Fe was used to increase the chroma of zirconia specimens without compromising their mechanical properties. The Er-containing zirconia specimen showed a maximal fluorescence emission at 430 nm. The degree of opalescence was affected by the microstructures of ceramic materials. The microstructure, incorporation of a secondary phase, and sintering behavior can have a strong impact on the final mechanical and optical properties of dental ceramics. Addition of small amounts of metal oxides can affect the translucency, opalescence or fluorescence qualities of zirconia.
PubMed: 32751942
DOI: 10.3390/ma13153395 -
Dental Materials Journal Jun 2019The purpose was to evaluate the bond strength between adhesive cement and translucent zirconia in comparison to conventional zirconia. Four brands of translucent...
The purpose was to evaluate the bond strength between adhesive cement and translucent zirconia in comparison to conventional zirconia. Four brands of translucent zirconia (BruxZir HT, Lava™ Plus, Prettau Anterior, and Prettau Zirconia) and one conventional zirconia (Kavo Everest ZS) were evaluated. Specimens were divided into groups depending on the pretreatment of the cementation surface of the zirconia: as-produced, hydrofluoric acid treatment, or sandblasted. The groups underwent three different procedures of artificial aging: water storage (24 h), 5,000 thermocycles, or long-term aging, (water storage 150 days including 37,500 thermocycles) before shear bond strength testing. Sandblasting treatment increased the bond strength significantly for all the brands of zirconia, irrespective of artificial aging procedures, in comparison to the control group. Bond strength between adhesive cement to translucent zirconia is equivalent to conventional zirconia. Sandblasting creates a cementation surface that is more durable than as-produced or hydrofluoric-acid-treated, irrespective of type of zirconia.
Topics: Ceramics; Dental Bonding; Dental Stress Analysis; Materials Testing; Methacrylates; Resin Cements; Shear Strength; Surface Properties; Zirconium
PubMed: 31105161
DOI: 10.4012/dmj.2018-194 -
Head & Face Medicine Nov 2018Color change of dental materials over time because of staining agents has important effects on the long-term prognosis of dental esthetic treatments. In the present...
BACKGROUND
Color change of dental materials over time because of staining agents has important effects on the long-term prognosis of dental esthetic treatments. In the present study, staining resistance of an interpenetrating network composite material with different translucency levels (translucent and high translucent) and various surface procedures for finishing were investigated.
METHODS
Same shade CAD/CAM interpenetrating network composite specimens having two different translucency levels were prepared using by a water cooling cutting saw. Specimens were grouped and different finishing procedures were performed. Then, specimens were kept in distilled water, red wine and coffee for different periods. Color was evaluated before and after exposure to staining liquids using a clinical spectrophotometer.
RESULTS
In the 7 days Glaze group (ΔE > 2.2), color difference was only perceivable in the specimens kept in red wine. In the 28 days red wine high translucent groups, only the high translucent Clinical group showed a clinically acceptable (ΔE < 2.2) color change. In the translucent groups kept in red wine, only the translucent Glaze group showed a clinically perceivable color change (ΔE > 2.2). In the 28 day measurements, all the translucent groups showed a clinically perceivable color change (ΔE > 2.2). Of the translucent groups kept in coffee for 28 days, it was observed that only the translucent Clinical group demonstrated a clinically non-perceivable color change (ΔE < 2.2).
CONCLUSIONS
All the translucent groups kept in red wine showed a clinically perceivable color change after 28 days. Only the high translucent Clinical Kit group showed a clinically acceptable color change. Among high translucent and translucent specimens kept in coffee only the translucent Clinical group showed a clinically acceptable color change after 28 days.
Topics: Coffee; Color; Composite Resins; Computer-Aided Design; Dental Materials; Esthetics, Dental; Materials Testing; Spectrophotometry; Staining and Labeling; Surface Properties; Wine
PubMed: 30477522
DOI: 10.1186/s13005-018-0184-2 -
Journal of International Oral Health :... Apr 2013Sclerosis of dentinal tubules may be a response to pathological or physiological insult in the crown & root. The mechanism by which apical translucency is produced is... (Review)
Review
BACKGROUND
Sclerosis of dentinal tubules may be a response to pathological or physiological insult in the crown & root. The mechanism by which apical translucency is produced is still uncertain. The increase in size of the apical zone of sclerotic dentin in human teeth has been used often in forensic science as a method of age estimation. However, only few studies have been done to compare percentage of translucency between vital and non-vital teeth. Conflicting concepts exist regarding the amount of translucent dentin in the vital & non vital teeth and correlation of this variation with age of the subject.
AIMS
To investigate the amount and distribution of apical translucent dentin in group-matched vital and non-vital teeth.
MATERIALS AND METHODS
Study was conducted on 70 extracted teeth, which were subjected for vitality test before extraction, and divided into two groups (vital & non-vital teeth) with a minimum of 35 teeth in each group. Ground sections of 150µ thickness were observed under Stereomicroscope and photographed. The distribution of area and length was measured on the images captured, using PROPLUS IMAGE ANALYSIS SOFTWARE version 4.1.0.0 software.
RESULTS AND CONCLUSIONS
The present study revealed significant differences (p < 0.05) in apical translucency of dentin, when both vital and non-vital teeth types were compared. There was more apical translucency present in non-vital when compared with vital teeth at any given age. Key words: Apical translucency; vital teeth; non-vital teeth. How to cite this article: Selvamani M, Madhushankari G S, Basandi P S, Donoghue M, Nayak V, Diwakar G. Effect of Vitality on Translucent Dentine - A Study. J Int Oral Health 2013; 5(2):1-7.
PubMed: 24155584
DOI: No ID Found -
Influence of yttria content and surface treatment on the strength of translucent zirconia materials.The Journal of Prosthetic Dentistry Apr 2023Newly developed translucent zirconia materials have been used for anterior monolithic complete coverage restorations. Surface treatments can improve adhesion, as well as...
STATEMENT OF PROBLEM
Newly developed translucent zirconia materials have been used for anterior monolithic complete coverage restorations. Surface treatments can improve adhesion, as well as decrease or increase the strength of ceramics. However, information on the influence of surface treatments on the strength of translucent zirconias is sparse.
PURPOSE
The purpose of this in vitro study was to measure and characterize the effects of different surface treatments, including airborne-particle abrasion, on the strength of different translucent 4 mol% and 5 mol% yttria-stabilized zirconia materials.
MATERIALS AND METHODS
Disks (N=160) made from 4 types of translucent yttria-stabilized zirconia materials were surface-treated in 4 ways: Control groups were hand-polished with 2000-grit silicon carbide abrasive paper; as-machined; glass bead airborne-particle abraded; and alumina airborne-particle abraded. The biaxial flexural strength was measured by using a piston-on-3-ball test in a universal testing machine. The simple main effects of material type and surface treatment and their interaction on biaxial flexural strength were evaluated with 2-way ANOVA (α=.05). A priori, 1-way ANOVA and the Tukey multiple comparisons tests were used within material and treatment types (α=.05). Surface morphology was assessed by using scanning electron microscopy. Translucency, absolute transmittance, was measured by using a spectrophotometer.
RESULTS
Two-way ANOVA revealed that the effects of zirconia type, surface treatment, and their interaction all significantly affected biaxial flexural strength (P<.001). One-way ANOVA revealed that the 4Y material was stronger than all 5Y materials, regardless of surface treatment; all 5Y materials were ranked from strongest to weakest as polished; as-machined, or glass bead abraded; and alumina abraded. The 4Y material was stronger when alumina abraded than when glass bead abraded. Scanning electron microscopy showed that as-polished surfaces were smoother than all others; as-machined and glass bead abraded surfaces displayed little difference; alumina abraded was the roughest; and differences among materials were not discerned. The 1-way ANOVA and multiple comparisons testing showed that the 4Y material had less absolute transmittance, approximately 5% less, than all the 5Y materials.
CONCLUSIONS
Zirconia material type and surface treatment influenced the strength of translucent zirconia materials; a 4 mol% zirconia material was stronger than 5 mol% zirconia materials for all surface treatments tested; airborne-particle abrasion using alumina had a slight strengthening effect on a 4 mol% zirconia but had a weakening effect on 5 mol% materials; airborne-particle abrasion by using alumina produced the roughest surfaces on all materials; and the 4 mol% material was slightly less translucent than the 5 mol% materials.
Topics: Dental Materials; Materials Testing; Surface Properties; Aluminum Oxide
PubMed: 34452741
DOI: 10.1016/j.prosdent.2021.07.001 -
The Pan African Medical Journal 2014
Topics: Female; Humans; Knee; Lymphangioma, Cystic; Skin Neoplasms; Young Adult
PubMed: 25977737
DOI: 10.11604/pamj.2014.19.374.3074 -
Materials (Basel, Switzerland) Sep 2023Amid chairside CAD/CAM materials, the use of lithium-based silicate glass-ceramics (LSGC) has been steadily increasing. This review aims to report on the translucency of... (Review)
Review
Amid chairside CAD/CAM materials, the use of lithium-based silicate glass-ceramics (LSGC) has been steadily increasing. This review aims to report on the translucency of these materials and the variables used to measure it. An electronic search was performed within the PubMed database within the period between 2 June 2011 and 11 September 2022. English-language papers investigating the translucency of IPS e.max CAD, Celtra Duo, Suprinity PC, Initial LiSi Block, Amber Mill, N!ce, and CEREC Tessera LSGC CAD/blocks were included in the search strategy. After an initial retrieval of 160 papers, the application of exclusion criteria, and the screening of abstracts and then of full texts, 33 papers were included in the study. The retrieved materials, with different degrees of translucency (LT, HT), were IPS e.max CAD (n = 33), Suprinity PC (n = 8), and Celtra Duo (n = 1). Concerning the examined colors, the most used was A2 (n = 20), followed by A1 (n = 8) and A3 (n = 2). The translucency parameter (TP) was the most used method (n = 30) with respect to the contrast ratio (CR) (n = 11) to assess translucency. Five papers measured both. Several specimens' thicknesses (0.5-4 mm) were investigated, with 1 mm (n = 23) being the most frequently analyzed. While a general tendency could be identified, conflicting results among different papers were reported.
PubMed: 37834578
DOI: 10.3390/ma16196441 -
Acta Stomatologica Croatica Dec 2020To examine the effect of two aging protocols on the chemical and phase composition as well as the surface state of monolithic translucent zirconia ceramics.
OBJECTIVES
To examine the effect of two aging protocols on the chemical and phase composition as well as the surface state of monolithic translucent zirconia ceramics.
MATERIAL AND METHODS
Translucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (no treatment, K1, K2; glazed, G1-G8; polished, P1-P8) underwent testing in order to examine how the two aging protocols (three-hour hydrothermal degradation in an autoclave at 134 °C and 2 bars: G1-G4, P1-P4, and sixteen-hour chemical degradation in four-percent acetic acid at 80 °C (ISO 6872): G5-G8, P5-P8) affect chemical composition, particularly the share of stabilizing yttrium oxide (Energy Dispersive X-Ray Fluorescence - EDXRF), phase composition (X-ray diffraction - XRD) and surface state in terms of roughness and gloss.
RESULTS
Aging protocols did not affect the tested chemical composition stability of specimens and a high share of stabilizing yttrium-oxide (≥10% of total content), which correlates with the absence of monoclinic phase. A decrease in gloss on all specimens is statistically significant. Chemical degradation substantially increased the surface roughness of tested specimens.
CONCLUSIONS
Translucent monolithic zirconia demonstrated a stable chemical composition and resistance to tetragonal-to-monoclinic transformation. Surface gloss was significantly reduced, especially in polished specimens. Contrary to glazed specimens, the tested polished specimens manifested an increase in surface roughness. Glazing the surface of translucent monolithic zirconia produces better esthetic, tribological and hygienic effects than polishing.
PubMed: 33642598
DOI: 10.15644/asc54/4/1