Lowest ΔE Research Articles

Effect of ambient lighting conditions on tooth color quantification in cross-polarized dental photography: A clinical study

Statement of problemLimited data are available in the dental literature regarding the effect of ambient lighting on the consistency of color quantification in cross-polarized photography. PurposeThe purpose of this clinical study was to investigate the effects of ambient lighting conditions and postprocessing photograph calibration on color quantification in cross-polarized dental photography. Material and methodsTwelve volunteers with intact maxillary central incisors were recruited. Cross-polarized photographs were captured under light-emitting diode (LED), fluorescent ceiling, and natural lighting. The photographs were repeated after a 1-week interval, yielding a total of 72 photographs. The average Commission Internationale de l’Eclairage L∗a∗b∗ coordinates of the right central incisor were obtained with a software program before and after calibration by using a neutral gray reference card. The color difference (ΔE) values were calculated for each participant between the repeated photographs under the change and no change in illumination both before and after calibration. A 3-way repeated measures ANOVA was used to compare these values (α=.05). ResultsA statistically significant 3-way interaction was found between the illuminant type, change in illumination, and calibration (P<.001); however, all the ΔE values were within a clinically acceptable threshold (ΔE≤3.7). Before calibration, when photographs were captured under no change in illumination, LED lighting was found to have a significantly lower ΔE than fluorescent (P=.008) and natural and fluorescent lightings (P=.011), but when there was a change in illumination, no significant differences (P>.05) were found. After calibration, all the ΔE values were ≤1 and significantly lower than the values before calibration (P<.001). ConclusionsBoth the ambient illuminant type and change in illumination had minimal effects on ΔE. Calibration through the use of a neutral gray reference card was found to result in reduced and imperceptible color change (ΔE≤1) for all illuminant types.

Effect of Novel Cycloaliphatic Comonomer Incorporation on the Color Stability of Thermo-polymerized Denture Base Resin.

Background:Denture during its in vivo service encounters myriad food pigments and numerous physico-mechanical dynamic changes. Denture discoloration is one of the unresolved problems that should be unraveled to satisfy the esthetic demands of the patients.Aim:This study aims to evaluate the color stability of a novel denture base copolymer with 10% and 20% (vol/vol) concentration of cycloaliphatic comonomer.Materials and Methods:Control group (G0) comprises specimens made without cycloaliphatic comonomer. The specimens of trial groups G10 and G20 were fabricated with 10% and 20% cycloaliphatic comonomer, respectively. For each group, thirty specimens (n = 30) were made. The specimens (n = 10) were immersed in three food colorant solutions (erythrosine, tartrazine, sunset yellow) for 56 days after artificial thermal aging. Ultraviolet-visible spectrophotometer was employed to measure the tristimulus values and calculate the color change (ΔE) of the specimens prior to and following rapid thermal aging or immersion of the specimens in the food colorants.Results:G0 showed the highest ΔE and G20 exhibited the least with each colorant. G10 had an intermediate imperceptible ΔE with each colorant. Also, significant differences (P = .000) existed between the food colorants within each group. The highest ΔE value was observed with sunset yellow and the lowest ΔE with tartrazine with each group.Conclusion:The addition of cycloaliphatic comonomer in denture base acrylic resins improved the color stability. The new copolymer with 20 Vol.% comonomer exhibited the highest color stability with all the food colorants.

Banana liqueur made with yacon syrup: evaluation of stability during maturation

Abstract The aim of this work was to evaluate the stability during maturation of banana liqueurs made with yacon syrup and sucrose. Thus, 20 °GL and 30 °Brix liqueurs were produced using yacon and sucrose syrups at concentrations of 42.8 and 45.0 °Brix. The liqueurs were subjected to two procedures as following: heat treatment at 70 °C for 20 min (tranchage), followed by storage at room temperature for 10 days (T42-T and T45-T); no heat treatment and storage at 50 °C for 10 days (T42-50 and T45-50). The color and turbidity of liqueurs were evaluated daily within 10 days of storage. The alcohol content was evaluated every 2 days. The total color difference (ΔE) was calculated in relation to color at time zero for each treatment. The T42-50 treatment had the lowest turbidity at the end of maturation. The T45-T treatment presented the lowest ΔE value at the end of maturation. The alcohol contents regarding the liqueurs were the same as those contents after elaboration as well as did not change over the maturation time for all treatments.

Optimization of fortified sponge cake by nettle leaves and milk thistle seed powder using mixture design approach.

Powdered nettle leaf and milk thistle (MT) seed were added to the cake batter with certain percentages selected by the Design‐Expert v. 10 software (0–25, 25–0, 18.75–6.25, 6.25–18.75, and 12.5–12.5). Addition of nettle and MT seeds to the cake reduced the moisture content, volume, and springiness and increased hardness of the samples. 12.5% nettle‐12.5% MT seed had the least hardness and the highest amount of springiness and cohesiveness. The highest BI, WI, SI, L*, a*, and b* and the lowest ΔE were observed in 12.5% nettle‐12.5% MT seed and 25% MT seed samples, respectively. Antioxidant activity and antimicrobial properties were increased in all samples compared to the control sample, so that 6.25% nettle‐18.75% MT exhibited the highest antioxidant activity and antimicrobial properties. The highest levels of quercetin and silymarin were observed in 25% nettle and 25% MT seeds, respectively. In the sensory evaluation, 12.5% nettle‐12.5% MT seed took the best scores regarding flavor, texture, color, and overall acceptance. Based on the lowest hardness, 13.65% nettle‐11.34% MT seed was determined as optimized points by the software, which was equivalent to desirability of 0.72. The optimum sample contained 62.90 mg quercetin and 886.70 mg silymarin. According to the HPLC analysis results, consumption of 10 optimal cakes daily could theoretically decrease the blood sugar level, which requires further studies. The remaining amount of quercetin and silymarin in 2.5 g of nettle leaves and 2.5 g of MT seeds after heating was 11 and 19 mg, respectively. In other words, heat did not have much effect on the destruction of quercetin and silymarin.

Jackfruit (Artocarpus heterophyllus Lam) leaf as a new source to obtain protein hydrolysates: Physicochemical characterization, techno-functional properties and antioxidant capacity

Physicochemical, techno-functional properties and antioxidant capacity of Jackfruit leaf protein concentrate (LPC). And its hydrolysates were evaluated. LPC was obtained using the isoelectric precipitation method assisted by high hydrostatic pressure. LPC and its hydrolysates with pepsin (H-Pep) and pancreatin (H-Pan) at different interval times were characterised by colour, foaming and emulsifying properties. The antioxidant capacity through in vitro tests, such as DPPH+ and ABTS+ radical scavenging activity was also evaluated. The degree of hydrolysis (DH) for H-Pep and H-Pan ranged from 1.78 to 3.44 to 6.12–9.21%. The enzymatic hydrolysis significantly increased (p < 0.05) the L* value of all the hydrolysates concerning the LPC. However, the H-Pep presented lower ΔE (p < 0.05) regarding the H-Pan, this could be related to the high L* values presented in the samples. The solubility of the hydrolysates was significantly higher (p < 0.05) than the LPC in all the tested pH (2.0–10.0) values (except for H-Pep at pH 10.0), reaching solubility values of 19–41 and 60–98% from pH 4.0 to 10.0 for H-Pep and H-Pan, respectively. The increase of solubility was associated with high emulsifying and foaming properties compared with LPC. The best emulsifying and foaming properties were presented at 180 and 60 min of H-Pan, respectively. The antioxidant capacity revealed that the H-Pan at 120 min of proteolysis exhibited high antioxidant properties. The values for DPPH+ and ABTS+ were 72.38% at 0.1 mg/mL and 98.20% at 0.8 mg/mL, respectively. The results suggest that type of enzyme and hydrolysis time determined the physicochemical, techno-functional properties, and antioxidant capacity of hydrolysates.

Effect of bleaching protocols on surface roughness and color change of high- and low-viscosity bulk-fill composite resins.

The aim of this in vitro study was to evaluate the effect of bleaching protocols on the surface roughness (Ra), color change and surface micromorphology of a low-viscosity bulk-fill composite (Filtek Bulk Fill Flow, 3M ESPE), a highviscosity bulk-fill composite (Filtek Bulk Fill, 3M ESPE) and a conventional nanoparticulate composite resin (control) (Filtek Z350 XT, 3M ESPE). Forty samples of each composite (disks 5 mm in diameter and 2 mm thick) were randomly divided into four groups (n=10), according to bleaching protocol: a) 10% carbamide peroxide gel (Opalescence, Ultradent Products) (2 h/ day, for 14 days); b) 40% hydrogen peroxide gel (Opalescence Boost, Ultradent Products) (three bleaching sessions, once a week, 45 min/session); c) whitening rinse (Listerine Whitening Extreme, Johnson &amp; Johnson) (2 min/day, for 14 days); and d) distilled water (control). The samples were submitted to triplicate readings (Ra and color [CIELAB parameters]) before and after contact with bleaching protocols. Micromorphology was analyzed in a scanning electron microscope (SEM). Ra and color parameters (ΔL, Δa, Δb and ΔE) were analyzed by generalized linear models (α=0.05). The Ra of the high-viscosity bulk-fill was significantly higher than that of the other composites (p&lt;0.05). Ra increased significantly (p&lt;0.05) and surface became more irregular (SEM analysis) in all the composite resins, regardless of the bleaching protocol (p&lt;0.05). The high-viscosity bulk-fill composite resin group had significantly lower ΔE (p&lt;0.05) than the nanoparticulate composite resin group immersed in distilled water. It was concluded that the characteristics of each resin significantly influenced the Ra more than the bleaching protocol. The high-viscosity bulk-fill resin presented minor color change.

The effect of surface treatments on the color stability of CAD-CAM interim fixed dental prostheses

Statement of problemAdditive manufacturing or 3D printing is gaining popularity in dentistry, including for interim fixed dental prostheses (IFDPs). However, evidence regarding the color stability of 3D-printed IFDPs is lacking. PurposeThe purpose of this in vitro study was to investigate whether different surface treatments could affect the color stability of milled and 3D-printed IFDPs after simulated physiological aging. Material and methodsForty milled IFDPs were fabricated with a 5-axis dental mill (DWX-51D; Roland DGA Corp) from polymethyl methacrylate disks (Temp Esthetic 98, A3.5, 98.5×16 mm; Harvest Dental Products, LLC). Forty 3D-printed IFDPs were fabricated with an in-office digital light processing 3D printer (MAX; Asiga) and light-polymerizing resin (NextDent Crown & Bridge A3.5; NextDent B.V). All milled and 3D-printed IFDPs were allocated into 4 different groups (n=10), according to different surface treatments: Control, Polish, Optiglaze, and Skinglaze. In the Control group, no surface treatment was applied to the IFDPs. For the Polish group, IFDPs were finished and polished with aluminum oxide finishers/polishers (Enhance PoGo Complete Kit; Dentsply Sirona). For the Optiglaze and Skinglaze groups, specimens were first finished and polished and prepared with additional light-polymerizing protective coatings (Optiglaze; GC America Inc, or New Outline Skin Glaze; anaxdent North America). Shade measurements were recorded with a digital spectrophotometer (Vita Easyshade V; VITA North America) before and after the thermocycling for the color stability comparisons. The effects of interim prosthesis type and surface treatments on ΔE∗, ΔL∗, Δa∗, and Δb∗ were examined using 2-way analysis of variance (ANOVA), and ΔE∗ was considered as the primary outcome variable. Post hoc pairwise comparisons were performed by using the Tukey honestly significant difference (HSD) method (α=.05 for all tests). ResultsMilled IFDPs had significantly smaller ΔE∗ than 3D-printed prostheses for the Control group only (P<.001). Within the milled IFDPs, Optiglaze group (mean ±standard deviation, 1.01 ±0.38) had significantly lower ΔE∗ than all the other surface treatments groups (Control group: 2.38 ±0.44, P<.001; Polish group: 1.83 ±0.51, P=.025; and Skinglaze group: 1.85 ±0.78, P=.021). Within the 3D-printed IFDPs, the Control group (3.83 ±0.71) had significantly larger ΔE∗ than all other surface treatments (Polish group: 2.66 ±0.89, P=.018; Skinglaze group: 1.40 ±0.73, P<.001; and Optiglaze group: 1.37 ±0.67, P<.001). The Polish group had significantly higher ΔE∗ than Skinglaze group (P=.009) and Optiglaze group (P=.007), while Skinglaze and Optiglaze groups were not significantly different from each other (P=1.000). ConclusionsFor the milled IFDPs, only the nano-filled, light-polymerizing protective coating significantly lowered color changes after thermocycling simulating 6 months of intraoral physiological aging. For the 3D-printed IFDPs, surface polishing and both light-polymerizing protective coating agents all significantly reduced color changes of the prostheses after thermocycling. The protective effect of light-polymerizing coating agents was more substantial.

Color Stability Assessment of Innovative Technique of Complete Denture Flasking using Silicone Mask Technique (Case-Control Study)

Background: Treatment challenges for completely edentulous patient have traditionally been described as a combination of esthetics, function and comfort. Some studies regarding complete denture esthetics were more important than function or comfort. Denture characterization is modification of the form of the denture base to produce a more natural appearance. Materials and Methods: Acrylic resin complete dentures had been divided into two groups according to flasking technique (group I as control group: conventional three pour flasking technique, group II as test group: silicone mask flasking technique). ΔE was calculated for both groups immediately and after seven days of exposure to different staining conditions (Smoke, Coffee and Tea). Results: Heat cured acrylic resin complete denture processed through silicone mask flasking technique showed statistically significant lower ΔE values (as P < 0.05) than conventionally processed heat cured acrylic resin complete denture. Conclusion: With the limitations of this study regarding color stability change (ΔE), depending on flasking technique; the conventional three pour flasking technique showed a higher amount of color change (lower color stability) than the silicone mask flasking technique regarding smoking, tea and coffee coloring agents.

Color Masking Ability of Lithium Disilicate Ceramic for Titanium Alloy Implant Abutments

The aim was to assess the acceptable thickness of monolithic Lithium Disilicate (LD) ceramic in masking of Titanium (Ti) implant abutment by comparison to Zirconium (Zr) crowns through color matching. Forty LD and 10 Zr copings (control) using Hot-pressing and CAD-CAM techniques were fabricated. A standard Ti abutment (Straumann, ITI, Basel, Switzerland) was used as foundation substrate. LD crowns were divided into different thickness [1.0 mm (n = 10), 1.2 mm (n = 10), 1.5 mm (n = 10) and 1.8 mm (n = 10)] and 10 Zr copings (control) had 0.5 mm thickness. Different crown materials and crown thicknesses resulted in 5 study groups designated as Zr-Ti-0.5, LD-Ti1.0, LD-Ti-1.2, LD-Ti-1.5 and LD-Ti-1.8. Specimens were cemented to Ti abutments and using a spectrophotometer the difference of color for specimen and controls was determined by comparing ΔL, Δa and Δb (CIELab color system) and an overall ΔE. These were statistically compared using analysis of variance and Tukey post hoc multiple comparisons. Among LD specimens with Ti abutments, lowest color difference was achieved for LD-Ti-1.8 (2.3 ± 0.31) and the highest color difference was for LD-Ti-1.0 (4.93 ± 0.45). The lowest ΔE was recorded for Zr copings (control), which was lower than (p &lt; 0 01) LD crowns of 1.0 and 1.2 mm thickness. LD crown thickness had a significant effect on ΔE (color difference) on Ti abutments. Masking of Ti abutments by 1.5 mm LD crowns was comparable to Zr specimens (control). Lithium disilicate crown of 1.5 mm thickness showed statistically comparable color stability to 0.5 mm Zr copings on Ti implant abutments.

Microwave drying of fish, chicken and beef samples.

In this study, the drying characteristics of fish, chicken and beef samples were investigated using microwave drying method. Each sample was dried using four different microwave powers of 90, 180, 270 and 360W. Drying time decreased as microwave power increased. Fish fillets were dried in a shorter time than chicken and beef samples. The experimentally obtained data were fitted to seven drying models. The logarithmic and Midilli et al. models were found to be the most appropriate in describing microwave drying behavior of meat samples. Effective moisture diffusion coefficients were computed and found between 1.74 × 10-7 and 16.4 × 10-7 m2s-1 for all the meat samples. The activation energies were found as 14.59W/g, 79.147W/g and 140.81W/g, for chicken, fish and beef meat samples, respectively. The highest and lowest energy consumptions were found in the chicken drying process at 90W (0.045 kWh) and fish drying process at 360W (0.018 kWh), respectively. The microwave power level are the main factors affecting the color change of material during drying process, where the highest and the lowest ΔE is obtained t chicken and fish samples, respectively.

Effects of Khat on Surface Roughness and Color of Feldspathic and Zirconia Porcelain Materials under Simulated Oral Cavity Conditions.

Background and Objectives: Khat chewing is considered as a daily habit that is practiced by more than five million people globally. The effect of khat chewing on the surface roughness and the color stability of natural teeth and the material used in the fabrication of dental prosthesis remains unknown. This study was conducted to explore and compare the effect of khat homogenate (KH) on the surface roughness (Ra) and the average color changes (ΔE*) amongst natural teeth and selected shades from different porcelain types, namely, feldspathic metal ceramic (MC) VM13, computer-aided design/computer assisted manufacture (CAD/CAM) feldspathic (Vitablocs Mark II), and multilayer zirconia (Ceramill Zolid PS) porcelains. Materials and Methods: Seventy samples were prepared from natural teeth, feldspathic MC, CAD/CAM Vitablocs Mark II, and zirconia porcelain. The Ra values were measured using a profilometer and expressed in micrometers, whereas the ΔE* values were measured using VITA Easyshade® V spectrophotometer for all samples before and after frequent immersion and thermocycling in KH for 30 days. The surface topography was used to assess the materials surfaces (glazed or polished) after KH immersion by using a white light interferometry machine. Results: Results revealed that the Ra and the ΔE* values of the different types of tested porcelain were influenced by KH. The order of surface roughness values was glazed or polished MC > polished Zircon > polished Vitablocs Mark II > natural teeth. The lowest ΔE* values were recorded for glazed Vitablocs Mark II and MC, and the values could be arranged as polished zircon > natural teeth > glazed zircon > polished MC > polished Vitablocs Mark II. P values were significantly varied (<0.001) among all the tested groups, except the zircon group (>0.05) for both Ra and ΔE*. Conclusions: KH significantly affected both surface parameter and color of glazed or polished porcelain materials and natural teeth.

Physicochemical, thermal, mechanical, optical, and barrier characterization of chia (Salvia hispanica L.) mucilage-protein concentrate biodegradable films.

In thisstudy, the effect of chia mucilage (CM) and protein concentrate(CPC) contents on the physicochemical, thermal, mechanical,and opticalcharacteristics of developed films was evaluated. Films were prepared dissolving CM:CPC mixtures (1% w/v) in seven ratios (0:1, 1:4, 1:2, 1:1, 2:1, 4:1, 1:0). Microstructure of treatments with higher CM revealed the formation of polysaccharide granules. A semicrystalline behavior was manifested in 1:0, which decreased as CPC content in the formulations increased. Contact angle values obtained for 1:1 and 2:1 were the highest (61.24° and 62.44°), evidencing less affinity to water than other films. TGA analysis suggest that films showed thermal stability at less than 225 °C. Melting temperatures above 85 °C were found for all films in the evaluated range (50 °C to 200 °C) of DSC analysis. Higher CM concentrations in films increased the force required to break them (13.5MPa) and their elongation capacity (5.20%). As the CM ratio in formulations was increased, the color difference was lower (ΔE = 27.45), water vapor permeability was higher (10.9×10-11 g/m·s·Pa), but transparency was statistically the same for all treatments (6.62 to 7.26). After analyzing all films properties, 2:1 formulation corresponding to 25:75% w/v mixtures of CM:CPC would be the best option for use in food packaging.

Effect of carrier types on the physicochemical and antioxidant properties of spray-dried black mulberry juice powders

Effects of maltodextrin (MD) and four types of proteins, viz., whey protein isolate, egg albumin, soy protein isolate and pea protein on the physicochemical and antioxidant properties of spray-dried black mulberry juice powders were investigated. Generally, animal proteins were more effective than the plant ones in powder recoveries. Differential scanning calorimeter analysis revealed better compatibility of the mulberry juice-MD than that of juice-protein matrix. When the juice total soluble solid was replaced by protein at the same ratio, the spray-dried powders with animal protein involvements resulted in smaller particle size, lower moisture content, bulk density, total phenolic content, DPPH scavenging capacity but higher water solubility index (WSI) and total color difference (ΔE) as compared with the plant proteins. In addition, the spray-dried powders with MD as carrier showed lower hygroscopicity, ΔE and higher WSI as compared with the proteins. This work provided some fundamental knowledge and practical guidance in improving the powder recovery of spray drying of fruit juice.

Evaluation of Electrochemical Stability and Li-ion Interactions in Ether Functionalized Pyrrolidinium and Phospholanium Ionic Liquids

Potential electrolytes for lithium ion batteries (LIB) depicting high electrochemical stability and ionic conductivity still represents a great challenge. Herein, we investigate the reduction stability and Li+ cation interactions with substituted cyclic phospholanium (CylP5+) and pyrrolidinium (Pyr+) ionic liquids (ILs) with bis(trifluoromethanesulfonyl)imide (TFSI−) anion. The cations CylP5+ and Pyr+ are functionalized with varying chain lengths of alkyl and alkoxy substituents and their reduction potentials evaluated with respect to Li+/Li. CylP5+ cations, in general have better stability than Pyr+ based ILs, while the alkoxy substitution is found to lower the reduction stability compared to alkyl substituents in both ILs. Furthermore, the interaction energies between the substituent modified-cations (C), Li+ cation and the anion (A) were evaluated. The ion-pair (C-A) interaction energies on addition of Li+ cation is shown to decrease for both Pyr+ and CylP5+ cations with shorter alkoxy chain lengths, thereby implying faster diffusion of ions due to weaker interactions. Similarly, among the two cations, lowest ΔE were noted between alkoxy substituted [Li(CylP5)]2+ cation and TFSI−, signifying faster diffusion of ions in CylP5+ based electrolytes than that of Pyr+ based ILs. These results govern the synthesis of novel ILs with promising base cation and functionalization for LIB.

Comparative Study of the Hydrothermal Softening Characteristics of Heartwood and Sapwood

Abstract This study was conducted to investigate the hydrothermal softening characteristics of heartwood and sapwood from Catalpa bungei. The viscoelastic properties were investigated by dynamic mechanical analysis (DMA Q800) with a tension and submersion mode. Heartwood and sapwood specimens were tested under water-saturated conditions in the radial and tangential directions. The measured temperature ranged from 25°C to 79°C with three heating rates: 0.5°C/min, 1°C/min, and 2°C/min. The results show that heartwood specimens presented a higher storage modulus (E′) and a lower reduction of wood rigidity (ΔE′) than sapwood specimens. A difference was also observed in loss modulus (E″), and the glass transition temperature of lignin in heartwood specimens was nearly 2°C to 3°C lower than that in sapwood specimens. This could be caused by lower lignin content and higher levels of extractives of sapwood in comparison with heartwood. Additionally, a circular arc curve of E′ versus E″ was formed in heartwood specimens, irrespective of heating rate. These findings suggest that heartwood presented better hydrothermal softening characteristics than sapwood. Compared with the tangential specimens, the radial specimens revealed higher E′ and lower ΔE′, indicating that the radial specimens were less influenced by hydrothermal treatment.

A Systematic Review and Meta-Analysis of the Influence of Abutment Material on Peri-implant Soft Tissue Color Measured Using Spectrophotometry.

To systematically review the current literature on the influence of abutment material (metal vs ceramic) and soft tissue thickness on peri-implant soft tissue discoloration in partially edentulous patients restored with implant-supported single crowns. An electronic MEDLINE search was performed to identify randomized controlled clinical trials (RCTs) up to and including March 2017. The search was complemented by a manual search of related bibliographies. Selection of studies was made independently by two reviewers based on the inclusion criteria. Spectrophotometric data (ΔE values) and soft tissue thickness values were extracted, and, whenever applicable, a meta-analysis using a random-effects approach was performed. The search resulted in 208 titles and 30 abstracts. Full-text analysis was performed for 13 articles, resulting in 6 included RCTs. Meta-analysis of a total of 266 abutments revealed significantly lower ΔE values for ceramic abutments when compared to the overall metal abutments (z test value = 1.99, P = .05), with a mean difference of 1.41 (95% CI 0.02, 2.80). Nonsignificant differences were found between titanium and zirconia (z test value = 1.59, P = .11). Limited information on the correlation between soft tissue thickness and ΔE values was found. Hence, it was not possible to perform a meta-analysis of this question. The color outcome of the peri-implant soft tissue might be influenced by the abutment material. Ceramic abutments appear to provide an improved color matching between peri-implant soft tissues and soft tissues around natural teeth when compared to metallic abutments. These findings support the preference for all-ceramic or "white" abutments in esthetically demanding cases.

Influence of Different Cements on the Color Outcomes of Titanium-Based Lithium Disilicate All-Ceramic Crowns and Peri-implant Soft Tissue.

To evaluate the influence of different cements on the color outcomes of CAD/CAM lithium-disilicate implant crowns cemented to titanium-base abutments utilizing spectrophotometric analysis. A clinical situation with a missing lateral incisor was mimicked using a maxillary plastic model. Titanium-base-supported monolithic lithium disilicate crowns with identical designs were fabricated using a laboratory CAD/CAM system. The crowns were cemented with three provisional cements and with six definitive cements on both nonsandblasted and sandblasted titanium-base abutments for a total of 15 test groups. As a control group, identical crowns were attached with try-in paste on composite die abutments that duplicated the shape of the titanium-base abutments. The colors of the labial surfaces of the crowns and the peri-implant artificial soft tissue were measured with a spectrophotometer and recorded in CIE L*a*b* parameters. Color differences between the test and control groups were calculated as: ΔE = ([ΔL*]2 + [Δa*]2 + [Δb*]2)1/2. Kruskal-Wallis test was used to compare ΔE values across different groups. The median ΔE values reported for crowns cemented with different definitive cements on titanium-base abutments ranged from 1.4 to 2.9 for the crown surface and from 1.7 to 1.9 on the peri-implant artificial soft tissue; when the titanium-base abutments were sandblasted, the respective median ΔE values ranged from 0.8 to 4.0 and from 1.4 to 2.2. Ceramic crowns cemented with Multilink HO 0 cement presented significantly (P < .01) lower ΔE values than the other cement types for the crown surface independent of sandblasting and for the artificial soft tissue surface when the titanium abutments were sandblasted (P = .011). Within the limitations of this study, Multilink HO 0 (Ivoclar Vivadent) cement showed the most favorable masking ability and the most favorable color outcome among the evaluated definitive cements. Cements of more opaque shades appeared in general to be more favorable in terms of masking the gray color of the titanium-base abutments.

Tris(tropolonato) ruthenium as a hub for connecting π-conjugated systems.

In this study, the intramolecular electronic communication between π-conjugated moieties bridged by the tris-chelate [Ru(trop)3] (trop = tropolonate) framework has been investigated and compared with [Ru(acac)3] (acac = acetylacetonate) derivatives. Two types of π-conjugated groups, -C2SiMe3 and -C2Ph, which were each introduced at the 5-position of tropolonate, were found to behave almost independently in the resultant ruthenium complexes. In contrast, the cyclic voltammetry study of [Ru(trop)3] derivatives showed a clear decrease in ΔE, the difference in the potentials of the two redox couples, with an increase in the number of π-conjugated groups introduced into the [Ru(trop)3] framework. The lower ΔE values observed in [Ru(trop)3] derivatives compared to those in [Ru(acac)3] derivatives illustrated the non-innocent behavior of the tropolonate ligand, i.e., the mixing between the metal- and ligand-based frontier orbitals. This orbital mixing was exemplified in the oxidized [Ru(trop)3] derivatives, which showed a broad near-infrared (NIR) absorption. The increase in the red shift of the NIR absorption with the increasing number of terminal groups indicated intramolecular electronic communication between the terminal π-conjugated moieties. In contrast, no NIR absorption was observed upon oxidation of [Ru(acac)3] derivatives with -C2Ph groups. The lifetimes of the in situ formed [Ru(trop)3]+ and [Ru(acac)3]+ in acetonitrile solution were found to be several hours and minutes, respectively. Density functional theory calculations for [Ru(trop)3] and [Ru(acac)3] with terminal -C2Ph groups demonstrated that the spin densities in their mono-oxidized states were evenly distributed over the entire molecular framework and localized mainly on one ligand, respectively. These results confirmed that the mono-oxidized [Ru(trop)3]+ framework can behave as a hub and induce moderate intramolecular electronic communication between terminal π-conjugated groups.

Influence of electronic nicotine delivery systems (ENDS) in comparison to conventional cigarette on color stability of dental restorative materials.

Objective:The use of Electronic Nicotine Delivery Systems (ENDS) is increasing rapidly. However, its discoloring effect on dental restorations is not known. This study aimed to evaluate the effect of ENDS aerosol when compared to conventional cigarette smoke (CS) on the color stability of dental ceramic (DC) and resin composite (RC).Methods:This research project was conducted from November 2018 to May 2019. In this study 30 discs each for DC and RC materials were fabricated to be equally divided into groups of exposure to CS, ENDS aerosol and storage in distilled water (No smoke; NS) respectively (n=10). Specimens were exposed for a total of 7 days, with a rate of 10 cycles per day, each cycle represented 10 puffs. The color change was assessed using the CIELAB color space, by calculating ΔE. Data was analysed using ANOVA and multiple comparisons test.Results:Ceramic specimens in CS (2.422 ± 0.771) and ENDS (2.396 ± 0.396) groups showed comparable ΔE (color change) (p=0.992). Similarly, composite specimens in CS (42.871 ± 2.442) and ENDS (46.866 ± 3.64) groups showed comparable ΔE (p>0.05). NS specimens in both composite and ceramic samples showed lower ΔE than CS and ENDS specimens respectively.Conclusions:Aerosol from Electronic nicotine delivery systems (ENDS) showed similar discoloration levels as cigarette smoking (CS). The level of discoloration for ceramic samples for both ENDS and CS was below clinically perceptible levels (Mean ΔE < 2.5). Discoloration of composite resin due to CS and ENDS was visually perceptible (Mean ΔE > 4.0).

Evaluation of Dosidicus gigas Skin Extract as An Antioxidant and Preservative in Tuna Pâté.

A strategy for food preservation, based on a methanol–HCl squid skin extract (Dosidicus gigas) (JSSE), was evaluated at two concentrations in yellowfin tuna fish pâtés, which were stored at 4 and 8 °C for 20 day. The JSSE was characterized by determining its antioxidant and mutagenic activities. A yellowfin tuna pâté was elaborated, with and without the addition of the JSSE. An affective sensory analysis was performed to establish consumers’ preferences. During a 20-day storage period, the water activity (aw), pH, color difference (ΔE*ab), microbiological analysis, lipid oxidation and sensory quality attributes were evaluated, and the results were compared with the results of the butylated hydroxyanisole (BHA) and control treatments. The JSSE showed antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl (DPPH●+) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS●) radicals and did not induce mutation, according to the Ames’ Salmonella test, nor chromosomal abnormalities, according to the onion root-tip cell assay. The consumer analysis demonstrated a higher preference for the pâté with the added JSSE in seven out of the eight evaluated attributes. During storage, the JSSE neither had an impact on aw nor pH, maintained lower ΔE*ab values, inhibited the microbial activity and lipid oxidation (unlike the control pâté), and preserved the sensory quality attributes, unlike the BHA and control treatments. This study showed that the JSSE has biologically active pigments that can act as antioxidants and antimicrobials in yellowfin tuna fish pâtés.