Perceptible Color Change Research Articles

Evaluation of some mechanical and optical properties of modified glass ionomer cement with TiO2 and SiO2 nanoparticles

BackgroundGlass ionomer cements with extended setting time and inferior mechanical properties present significant challenges for dentists in clinical practice. Thus, various alterations aimed to enhance their properties.Aim of the studyTo study the effect of adding TiO2 and SiO2 nanoparticles on properties of conventional glass ionomer cement.Methods2.5 wt% TiO2 and 2.5 wt% SiO2 were added to the glass ionomer cement (GC Gold Label Luting & Lining Cement, Japan). Microhardness, compressive strength, setting time and color changes were evaluated using Vickers hardness tester, Universal testing machine, Gillmore needle apparatus and spectrophotometer, respectively.ResultsData were analyzed using SPSS 18. Mean, SD, and confidence intervals were reported. Normality was checked using Kolmogorov–Smirnov test. The experimental group revealed a higher hardness value than the control group. Meanwhile, Compressive strength results revealed a higher value of the control group than experimental group. Setting time was longer for the experimental group, in the meantime no perceptible color change for the experimental group was recorded.ConclusionsAdding 2.5 wt% TiO2 and 2.5 wt% SiO2 to conventional glass ionomer had a positive effect on microhardness without affecting the perceptible color.

First Insight into Lignin Valorization as a Promising Biopolymer for the Modulation of the Physicochemical Properties of Port Wine.

Lignosulfonate (LS), kraft lignin (KL), and organosolv lignin (OL) were evaluated as potential modulating agents of the physicochemical properties of Port wine at two different concentrations for 7 and 30 days. KL and LS demonstrated the ability to remove proteins and potentiate the anthocyanin concentration. LS reduced the tannin content and the interaction of salivary acidic proline-rich proteins with wine phenolic compounds. None of the lignin promoted a perceptible color change; however, the yellowish color of KL and OL at 100 g/hL contributed to an increase in the yellow tones of wines. Lignin improved wine aroma by reducing the amount of unwanted volatiles by 30% and increasing the content of ethyl esters associated with fruity aromas by up to 60%. The results suggest that lignin, especially LS, can be employed as a modulating agent, positively impacting wine's physicochemical properties. This valorization of a byproduct opens up new opportunities for the wine industry.

Tooth Discoloration from 2 Silver Fluorides Used in Adults with Special Needs: A Randomized Trial.

Discoloration of carious lesions after application of silver diamine fluoride lowers patient acceptance and limits its wider use for caries arrest. To assess lesion and tooth color changes from 2 novel silver fluoride (AgF) products and its relationship to caries activity (clinical visuo-tactile scores) and bacterial load (using laser fluorescence with the DIAGNOdent). A split-mouth design was followed, with matched smooth surface carious lesions in the same arch in adults with special needs randomized for 1-min treatments with AgF/potassium iodide (KI) (Riva Star Aqua, SDI) and AgF/stannous fluoride (SnF2) (Caries Status Disclosing Solution; Whiteley). Standardized images taken at baseline, immediately postoperatively, and at 3-mo review were subjected to digital image analysis to calculate delta-E and to track changes in luminosity of carious lesions. Twelve participants were recruited in the study. A total of 56 teeth (28 pairs) were included. Significantly greater changes were seen in treated lesions than in the adjacent noncarious natural tooth structure, both immediately after treatment and at the 3-mo review (P < 0.0001). Color change and caries activity were not affected by tooth type, tooth location, plaque status, salivary status, or special needs condition. AgF/SnF2 caused transitory darkening immediately on application, while AgF/KI caused the immediate formation of yellow deposits (silver iodide). Both products caused significant darkening of treated lesions at 3 mo (P = 0.0009; P = 0.0361), with no differences between them (P = 0.506). Responding lesions showed larger and more perceptible color changes immediately after either AgF application (P = 0.002; P = 0.024). Both AgF products were highly effective for caries arrest in this patient population. Despite minor differences in the appearance of treated lesions at the time of application, both products lead to similar darkening of treated sites at 3 mo. This study shows the usefulness of silver fluoride used in conjunction with potassium iodide or stannous fluoride for achieving caries arrest in smooth surface lesions in adults with special needs. Patients need to be informed that long-term staining of the lesion occurs with both, similar to silver diamine fluoride.

Color stability of CAD-CAM hybrid ceramic materials following immersion in artificial saliva and wine.

To examine the color stability of 3D-printed and milled, interim, and definitive, restorative materials after immersion in artificial saliva and wine for 1, 3, and 6 months. The study used a 2 × 5 factorial design with 10 subgroups, including 2 immersion liquids (artificial saliva and wine) and 5 manufacturing technology and restorative material combinations (n = 10). Color measurements were taken using a contact-type digital spectrophotometer (CM-2600d Spectrophotometer; Konica Minolta Healthcare Americas Inc) before immersion and at 1 month (T1), 3 months (T3), and 6 months (T6) after immersion. The CIE2000 system was used to calculate quantitative measurements of color differences in ΔE00, and comparisons were made to the acceptability threshold (AT) and perceptibility threshold (PT). Repeated measures of ANOVA (α = 0.05) were used to compare differences in color changes between manufacturing technology/restorative material-immersion liquid combinations at T1, T3, and T6. To compare the effect of immersion liquid and time on the manufacturing technology/restorative material groups, the ΔE00 values were compared to the PT of 0.8 and the AT of 1.8. Wine caused significant color changes in ΔE00 values beyond the PT and AT values in all groups at all time intervals, except for the AT value of milled definitive crowns (hybrid nano-ceramic material). Wine immersion caused significant ΔE00 for all manufacturing technology/restorative material groups at all time intervals (1 month, 3 months, and 6 months) when compared to artificial saliva immersion (all p < 0.001). Upon exposure to artificial saliva, 80%-100% of samples from all groups remained within the acceptable and perceptible color change thresholds. The wine had significant chromogenic effects on all tested restorative materials, however, the milled definitive crowns (hybrid nano-ceramic material) showed the greatest color stability. For patients with heavy wine consumption, 3D-printed definitive crowns (hybrid ceramic-filled material) may show discoloration exceeding acceptable and perceptible color change limits.

The effect of speed sintering on the optical properties and microstructure of multi-layered cubic zirconia.

Speed sintering was introduced to fabricate time-efficient chairside restorations, however, its influence on the microstructure and optical properties of zirconia is still unclear. This study investigated the influence of speed sintering on the microstructure and optical properties of ultra-translucent multi-layered cubic zirconia. Ultra-translucent cubic zirconia (Katana™ UTML; Kuraray Noritake Dental Inc., Aichi, Japan) was cut into a total of 80 specimens, twenty within each layer of the blank. The specimens were divided into 2 groups: speed and conventional sintering. The translucency parameter, opalescence, chromaticity, and color difference were recorded using a spectrophotometer. Scanning electron microscope images were used for crystallographic analysis. One-way ANOVA and Tukey's post-hoc test (p < 0.05) were used for data analysis. Speed sintering significantly reduced the translucency and opalescence compared to conventional sintering excluding the opalescence of the dentin layer. Chromaticity significantly decreased with speed sintering in less chromatic layers and significantly increased in more chromatic layers. Mean color change ranged between 0.65 and 1.25 across different layers. Mean crystal size decreased with speed sintering. With speed sintering, translucency, and opalescence decrease while chromaticity increases in the more chromatic layers. Additionally, no clinically perceptible color change was found compared to conventional sintering.

Evaluation of gingival porcelains: Color change and surface properties.

This in vitro study aimed to evaluate the effect of thermal cycling (TC) on the color stability, translucency, and surface roughness of two different gingival porcelain materials. The gingival porcelains IPS e.max Ceram Gingiva (Ceram) and IPS InLine Gingiva (InLine) were tested. A total of 66 disc-shaped specimens were prepared and glazed using porcelain powders of G1, G3, and G5 colors. The samples were divided into two porcelain groups by their types and into three subgroups (n11) by their colors. Thermal cycling was performed at 6000 cycles simulating an oral environment of five years. The color and surface roughness measurements of the samples were made before and after the thermal cycling. Color measurements were made with a spectrophotometer. Surface roughness (mean surface roughness [Ra; μm]) was measured using a contact profilometer. Data before thermal cycling were evaluated using the Kruskal-Wallis test followed by the Dunn Bonferonni paired comparison test. Two-way ANOVA with repeated measurements and a pairwise comparison test with Bonferroni correction were used to evaluate the change in roughness and translucency parameter (TP) data between groups due to thermal cycling. The color change was below the clinically perceptible color change threshold (∆E00 = 2.1) in all groups after thermal cycling. However, all materials had significantly increased roughness (p<0.05). An increase in roughness was detected in the Ceram group and was higher than that in the InLine group. The change in the translucency parameters of the samples after thermal cycling was not statistically significant; a small increase was observed in all groups. The highest translucency values ​​were seen in the G1, G3, and G5 colors. Thermal cycling caused a significant increase in the roughness values ​​(Ra) of all materials and a minimal increase in their translucency. The color change of gingival porcelains after thermal cycling was less than the clinically perceptible threshold. This article is protected by copyright. All rights reserved.

Silver Diamine Fluoride Staining With Potassium Iodide: A Prospective Cohort Study

Staining after silver diamine fluoride (SDF) treatment limits treatment acceptability but is also used as a clinical indicator of lesion stability. Potassium iodide (KI) has been postulated to modify SDF staining. Understanding the natural history and resultant shade of SDF/KI-treated lesions will inform clinical decision-making. This study describes the change in colour of carious lesions in primary teeth treated with SDF and KI. One hundred carious lesions in primary teeth were treated with SDF+KI (Riva Star, SDI) and followed up over 6 months. Lesion shade was determined using standardised intraoral photography and broadly categorised into 4 shades: yellow, light brown, dark brown, and black. Lesions were digitally isolated, and colour was evaluated using CIELAB (L*: lightness, a*/b*: hue) and perceptible colour change (ΔE). One hundred valid observations were analysed on 129 lesions included in the study. Lesions were excluded if subsequently restored (n=15), teeth exfoliated (n=2), exhibited pulpal exposure (n=1), or failed to attend at follow-up visits (n=11). At baseline, the shade of carious lesions was yellow (n=22), light brown (n=19), dark brown (n=29), or black (n=30). The changes in shade between baseline and 6 months were clinically perceptible to the human eye, with the mean ΔE being 12.2 (SD=6.9). Neither tooth type, lesion severity, nor baseline shade was statistically associated with the degree of perceptible change at 6 months. Carious lesions exhibited clinically significant changes in colour after application of SDF+KI, primarily attributed to differences in L* of lesions over the 6 months.

Effect of coffee thermocycling on the surface roughness and stainability of denture base materials with different chemical compositions manufactured with additive and subtractive technologies.

To evaluate the effect of coffee thermocycling (CTC) on the surface roughness (Ra ) and stainability of denture base materials with different chemical compositions fabricated by using additive and subtractive manufacturing. Disk-shaped specimens were additively (FREEPRINT denture, AM) or subtractively (G-CAM, GSM and M-PM, SM) fabricated from three pink denture base materials in different chemical compositions (n = 10). Ra was measured before and after polishing, while color coordinates were measured after polishing. Specimens were subjected to CTC (5000 cycles) and measurements were repeated. Color differences (ΔE00 ) after CTC were calculated. Ra among different time intervals within materials was evaluated by using repeated measures analysis of variance (ANOVA), while 1-way ANOVA was used to evaluate the Ra of different materials within each time interval and the ΔE00 values. Color coordinates within each material were compared by using paired samples t-tests (α = 0.05). Ra before polishing was the highest for all materials (p < 0.001), while SM had its lowest Ra after CTC and AM had its lowest Ra after polishing (p ≤ 0.008). Before polishing, AM had the highest Ra among the materials (p < 0.001). After polishing, SM had higher Ra than AM (p < 0.001). After CTC, GSM had the lowest Ra (p ≤ 0.048). SM had the lowest (p ≤ 0.031) and AM had the highest (p < 0.001) ΔE00 . CTC decreased the a* and b* values of SM and AM (p ≤ 0.017), and increased the L* values of AM (p < 0.001). Polishing significantly reduced the surface roughness of all materials. CTC did not increase the surface roughness of materials above the clinically acceptable threshold. Only AM had perceptible color change when previously reported threshold values for denture base materials were considered. Tested denture base materials may have similar surface stability after coffee thermocycling. However, subtractively manufactured denture base materials may have improved color stability when subjected to long-term coffee consumption.

Comparative study of conventional frying and air frying on the quality of potatoes (Solanum tuberosum L.).

The human being has historically consumed fried foods for centuries; however, conventional frying has a disadvantage, immersion in vegetable and/or animal oils, which leads to the search for different options. This is why air frying is a good alternative, which still has a wide field of study. In this work, frozen French fries of a brand marketed in Mexico that were subjected to frying in canola oil and air frying were compared. They were evaluated through the change in the removed moisture content, water activity, color profile, hardness, fracturability, and surface damage by SEM, thermal analysis by MDSC, and chemical by FTIR-ATR spectroscopy. Air-fried French fries were found to contain about 48% less moisture, fewer perceptible color changes, and less surface damage translated into better crunchiness compared with conventionally fried. It was also found that the changes at the chemical level are smaller, mainly attributed to the absence of canola oil and that the thermal transitions are more stable in terms of temperatures and enthalpies, which makes it possible to emphasize that air frying is a good alternative for developing new fried products that allow expanding the variety of these in the market without sacrificing some quality attributes.

Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor.

This paper describes the synthesis and characterization of seven different copper(II) coordination compounds, as well as the formation of a protonated ligand involving all compounds from the same reaction. Their synthesis required hydrothermal conditions, causing the partial in situ transformation of 5-fluoro uracil-1-acetic acid (5-FUA) into an oxalate ion (ox), as well as the protonation of the 4,4'-bipyridine (bipy) ligand through a catalytic process resulting from the presence of Cu(II) within the reaction. These initial conditions allowed obtaining the new coordination compounds [Cu2(5-FUA)2(ox)(bipy)]n·2n H2O (CP2), [Cu(5-FUA)2(H2O)(bipy)]n·2n H2O (CP3), as well as the ionic pair [(H2bipy)+2 2NO3-] (1). The mother liquor evolved rapidly at room temperature and atmospheric pressure, due to the change in concentration of the initial reagents and the presence of the new chemical species generated in the reaction process, yielding CPs [Cu(5-FUA)2(bipy)]n·3.5n H2O, [Cu3(ox)3(bipy)4]n and [Cu(ox)(bipy)]n. The molecular compound [Cu(5-FUA)2(H2O)4]·4H2O (more thermodynamically stable) ended up in the mother liquor after filtration at longer reaction times at 25 °C and 1 atm., cohabiting in the medium with the other crystalline solids in different proportions. In addition, the evaporation of H2O caused the single-crystal to single-crystal transformation (SCSC) of [Cu(5-FUA)2(H2O)(bipy)]n·2n H2O (CP3) into [Cu(5-FUA)2(bipy)]n·2n H2O (CP4). A theoretical study was performed to analyze the thermodynamic stability of the phases. The observed SCSC transformation also involved a perceptible color change, highlighting this compound as a possible water sensor.

Antibacterial and fluorescent clear aligner attachment resin modified with chlorhexidine loaded mesoporous silica nanoparticles and zinc oxide quantum dots

ObjectivesTo develop an antibacterial and fluorescent clear aligner attachment resin via the incorporation of chlorhexidine loaded pore-expanded mesoporous silica nanoparticles (CHX@pMSN) and amino-silane functionalized zinc oxide quantum dots (aZnOQDs), and to evaluate its antibacterial activity, fluorescence capability, esthetic properties, mechanical performance and biocompatibility. MethodsCHX@pMSN and aZnOQDs were incorporated into the commercial resin composites (Filtek Z350 XT, 3M) at different mass fractions, control group: Filtek; fluorescent attachment resin (FAR): Filtek + 3 wt% aZnOQDs; antibacterial and fluorescent attachment resin (AFAR)-1: Filtek + 3 wt% aZnOQDs + 1 wt% CHX@pMSN; AFAR-2: Filtek + 3 wt% aZnOQDs + 3 wt% CHX@pMSN; AFAR-3: Filtek + 3 wt% aZnOQDs + 5 wt% CHX@pMSN. CHX release, antibacterial activity, fluorescence capability, color change, stain resistance, degree of conversion, depth of cure, polymerization shrinkage, water sorption and solubility, softening in solvent, flexural strength, flexural modulus, shear bond strength, and cytotoxicity were evaluated comprehensively. ResultsCHX could be continuously released from the AFAR groups for up to 30 days. CFU, MTT, lactic acid production, SEM and CLSM evaluation showed AFAR-2 and AFAR-3 could effectively inhibit S. mutans biofilms even after 1-month aging. Only AFAR-3 showed clinically perceptible color change and all the experimental groups were not more susceptible to staining. AFAR-1 and AFAR-2 could suppress polymerization shrinkage and enhance the resistance to degradation without compromising other properties, including degree of conversion, water sorption and solubility, flexural strength, flexural modulus, and shear bond strength. Depth of cure of all the four experimental groups was significantly decreased (p < 0.05) but still within the ISO standard. CCK-8 assay and live/dead cell staining denied the cytotoxicity of experimental resins. Fluorescence intensity tests showed that FAR and AFAR-2 could emit strong yellowish fluorescence under the excitation of ultraviolet for up to six months. ConclusionsAFRA-2 possessed long-term antibiofilm activity, strong fluorescence capability and satisfying biocompatibility without compromising esthetic and mechanical properties. This study proposed a new strategy for reducing bacteria accumulation around the attachment, which is also promising in helping orthodontists to remove the attachment thoroughly and precisely.

Effect of coffee thermocycling on the surface roughness and stainability of nanographene-reinforced polymethyl methacrylate used for fixed definitive prostheses

Statement of problemA nanographene-reinforced polymethyl methacrylate (PMMA) has been introduced for definitive prostheses. However, knowledge on the surface roughness and stainability of this material is lacking. PurposeThe purpose of this in vitro study was to compare the surface roughness and stainability of nanographene-reinforced PMMA with those of a prepolymerized PMMA and a reinforced composite resin after coffee thermocycling. Material and methodsDisk-shaped specimens (Ø10×1.5-mm) were prepared from 3 different A1-shade millable resins (prepolymerized PMMA [M-PM; PMMA]; nanographene-reinforced PMMA [G-CAM; G-PMMA]; reinforced composite resin [Brilliant Crios; RCR]). Surface roughness (Ra) values were measured before and after conventional polishing by using a noncontact profilometer. Initial color coordinates were measured over a gray background with a spectrophotometer after polishing. Specimens were then thermocycled in coffee for 5000 cycles. Measurements were repeated after coffee thermocycling, and color differences (ΔE00) were calculated. Ra values among different time intervals were analyzed by using either the Friedman and Dunn tests (RCR) or repeated measures analysis of variance (ANOVA) and Bonferroni corrected paired samples t tests (PMMA and G-PMMA), while Ra values within a time interval were analyzed by using either the Kruskal-Wallis and Dunn tests (before polishing) or 1-way ANOVA and Tukey HSD (after polishing) or Tamhane T2 tests (after coffee thermocycling). ΔE00 values were analyzed by using 1-way ANOVA and Tukey HSD tests, while color coordinates of the specimens after polishing and after coffee thermocycling were compared by using paired samples t tests (α=.05). ResultsAll materials had their highest Ra values before polishing (P≤.011), while differences after polishing and after coffee thermocycling values were nonsignificant (P≥.140). PMMA had higher Ra than RCR before polishing (P=.002), and RCR had higher values than G-PMMA after polishing and after coffee thermocycling (P≤.023). RCR had the highest ΔE00 (P<.001). Polishing increased the b∗ values of PMMA, and coffee thermocycling increased the a∗ values of G-PMMA and all values of RCR (P≤.012). ConclusionsThe tested materials had similar and acceptable surface roughness after polishing. The surface roughness of materials was not affected by coffee thermocycling. Considering the reported color thresholds, all materials had acceptable color change, but the computer-aided design and computer-aided manufacturing composite resin had perceptible color change after coffee thermocycling.

The effects of cement thickness and cement shade on the final color of lithium disilicate crowns.

The aim of this study is to evaluate the effect of resin cement color, cement thickness, and thermocycling on the final color of monolithic lithium disilicate crowns. A total of ninety prepared central incisors of typodont teeth were restored with lithium disilicate crowns which have different cement thicknesses (40 µm, 80 µm, and 120 µm) and cement shades (clear, yellow, and white). Color parameters of restorations were measured with a spectrophotometer in three different steps 1) before cementing 2) after cementing and 3) after thermocycling with 10000 cycles. Color differences (ΔE00) were calculated with the CIEDE2000 formula and evaluated according to perceptibility (0.8) and acceptability (1.8) thresholds. The ΔE00 data were analyzed by using two-way ANOVA before and after thermocycling (α = .05). There was no interaction between the cement shade and the cement thickness factors. After cementation, the mean ΔE00 was under the perceptibility threshold in the group of 40 µm cement thickness and clear cement while it was between the perceptibility and acceptability thresholds (0.8 < ΔE00 < 1.8) for all other groups. After thermocycling, the ΔE00 values were between the perceptibility and acceptability thresholds for all experimental groups. Although there were no significant differences among the groups, thermocycling increased the color difference values. The cementation of restorations with clear, yellow, and white resin cements resulted in color differences with uncemented restorations except for the group cemented with clear cement in 40 µm cement thickness. All study groups revealed perceptible color change after thermocycling.

Surface roughness and stainability of new-generation denture base materials after brushing and coffee thermocycling

Disk-shaped specimens were prepared from additively (NX and DT), subtractively (MZ), and conventionally manufactured denture base resins (CV). Surface roughness and color coordinates were measured after polishing, simulated brushing, and coffee thermocycling, while surface roughness was also measured before polishing. Polishing reduced the surface roughness of all materials. Brushing and coffee thermocycling increased the surface roughness of only DT. CV had the highest susceptibility to consecutive brushing and coffee thermocycling as it had the highest surface roughness, which was above the clinically acceptable threshold. All materials had similar stainability; only MZ had perceptible color change after brushing. Even though stainability of tested denture base resins was similar, additively or subtractively manufactured computer-aided design and computer-aided manufacturing (CAD-CAM) resins had smoother surfaces after brushing and coffee thermocycling, regardless of the material. Therefore, complete dentures made out of these CAD-CAM resins may have favorable surface properties in the long term.Graphical abstract

Effect of Polymerization on the Color of Resin Composites.

The initial shade of a resin-based restorative material should be the same as that after polymerization. In this study, the color changes of translucent and opaque composites from nine different brands were assessed after polymerization using a spectrophotometer and cross-polarization (CP) photography. Thirteen nano-hybrid (Essentia LE, GC Corp; Ceram.x Duo SphereTEC A2E/A2D, Dentsply Sirona; Harmonize A2E/A2D, Kerr Dental; IPS Empress Direct A2E/A2D, Ivoclar Vivadent; Mosaic EN/A2, Ultradent Products; Clearfil Majesty Es-2 A2E/A2D, Kuraray Noritake; Charisma Topaz A2/OL, Kulzer), two supra nano-hybrid (Estelite Asteria NE/A2B; Tokuyama), two nano-filled (Filtek Ultimate A2E/A2D; 3M) light-curing resin composites, and one micro-hybrid (Essentia MD, GC Corp) light-curing resin composite were tested. Disc-shaped specimens (n=5) were prepared using silicone molds (12 × 5 mm) and polymerized from both sides using an LED curing light (Elipar Deepcure S, 3M) at a light intensity of 1470 mW/cm2. Measurements were performed before and 1 day after polymerization using a contact-type dental spectrophotometer (Easy Shade 5, VITA Zahnfabrik, Bad Säckingen, Germany) and a combination of CP photography and Photoshop CC software (Adobe Inc, San Jose, CA, USA). Spectrophotometry and CP photography ΔE* values were calculated; the perceptibility threshold was a ΔE* value of 1.2. VITA spectrophotometry color change scores were also calculated and evaluated. The overall ΔE* values ranged between 0.34 and 12.56. Two-way analysis of variance (ANOVA) showed that color change was associated most strongly with composite brand (p<0.001), followed by shade (p=0.002). Color change (p=0.002) and degree of darkening/lightening (p<0.001) were significantly greater for dentin compared to enamel shades. Clearfil Majesty Es-2 (Kuraray Noritake) showed significant lightening, whereas all other composites showed darkening after polymerization. All composite brands presented perceptible (ΔE*≥1.2) color changes. Estelite Asteria (Tokuyama), Ceram.x Duo SphereTEC (Dentsply Sirona), and Harmonize (Kerr Dental) were considered the most reliable brands regardless of the shade. The spectrophotometry and CP photography methods were positively correlated (p<0.001). Also, CIEDE2000 and CIELCH (also referred to as CIE L*c*h) color systems were positively correlated based on the ΔE* values (p<0.001). Despite improvements in the chemical composition of, and fillers for, contemporary resin-based composites (RBCs), all tested composite brands showed perceptible color change after polymerization, except for some shades. Under the conditions in this study, it is preferable to polymerize the composite during the trial phase, before identifying the most appropriate shade. CP photography in combination with Photoshop analysis appears to be a reliable and promising approach for color evaluation.

The Effect of Home and In-Office Bleaching on Microhardness and Color of Different CAD/CAM Ceramic Materials.

The aim of this study is to assess the effect of different bleaching agents on microhardness and color of CAD/CAM ceramics including IPS e.max CAD (lithium disilicate), VITA ENAMIC (polymer-infiltrated ceramic), and Celtra Duo CAD (zirconia-reinforced lithium silicate). Materials’ samples were divided into three groups (n = 10) and each received a different bleaching treatment; 20% carbamide peroxide, 35% carbamide peroxide, and 40% hydrogen peroxide. A fourth group was stored in water acting as a control. Vickers microhardness and spectrophotometric color measurements were taken at baseline and after bleaching. IPS e.max CAD showed a significant reduction (about 14%), while VITA ENAMIC showed a significant increase (about 78%) in microhardness after bleaching (p ˂ 0.001). Celtra Duo CAD did not demonstrate a significant change in microhardness (p ≥ 0.609). The color difference (ΔEab) after bleaching was 0.29 (±0.08), 2.84 (±0.64), and 1.99 (±0.37) for IPS e.max CAD, VITA ENAMIC, and Celtra Duo CAD, respectively. It could be concluded that the effect of bleaching on color and microhardness was mainly material-dependent. Bleaching significantly affected the microhardness of IPS e.max CAD and VITA ENAMIC. The color difference was within the clinically imperceptible range for IPS e.max CAD, while VITA ENAMIC and Celtra Duo CAD demonstrated perceptible color change.

Color and surface stainability of additively and subtractively manufactured interim restorative materials against mouth rinses

Statement of problemInterim restorations are often used along with mouth rinses during the healing period following surgical procedures. However, evidence regarding the color and surface properties of digitally fabricated interim restorations after oral rinsing is lacking. PurposeThe purpose of this in vitro study was to evaluate whether different mouth rinses could affect the color and surface roughness of milled and printed interim restorations after simulated oral rinsing. Material and methodsDisk-shaped specimens (Ø15×2 mm; N=180) were fabricated by using conventional (Jet Tooth Shade), milled (Yamahachi PMMA Disk), and printed (NextDent C&B) resin materials. All resin specimens were divided into 3 different groups according to the rinsing material: distilled water, whitening mouth rinse (Listerine Healthy White), and conventional mouth rinse (Listerine Cool Mint). The specimens were further allocated into short- and long-term subgroups, and oral rinsing simulation was performed (n=10). Short-term rinsing simulated the conditions in a usual interim restoration period, and long-term rinsing was performed to evaluate the properties of the interim materials. The color differences (CIEDE2000, ΔE00) between the baseline and each time point were determined by using a spectrophotometer. The surface roughness of the tested specimens was measured by using a confocal laser scanning microscope. Kruskal-Wallis and Friedman tests with nonparametric pairwise comparisons were used to analyze the data (α=.05). ResultsOn simulation of a 6-month use of the mouth rinse, the color change in the milled resin did not differ from that in the conventional resin (P>.334), but the printed resin showed a significantly greater color change than the other resins (P<.007). The greatest color change with the printed resin was observed when a conventional mouth rinse was used. However, all color changes were below a perceptible threshold of 1.30. When daily rinsing for 14 years was simulated, all resin groups showed a perceptible color change when conventional mouth rinse was used, and the printed resin showed the greatest median ±interquartile range ΔE00 (2.24 ±0.2). In both short- and long-term simulations, the printed resin rinsed with the conventional mouth rinse showed significantly greater roughness than that rinsed with distilled water (P<.009). ConclusionsThe printed resin showed higher stainability than the conventional resin, and the color change was greatest with the conventional mouth rinse. However, in 6 months of daily mouth rinse simulation, all the tested resin materials exhibited imperceptible color change and clinically acceptable surface roughness.

The Effect of a Green Smoothie on Microhardness, Profile Roughness and Color Change of Dental Restorative Materials.

Acidic drinks are known to exert negative effects on the surface properties of dental restorative materials. However, the effect of increasingly popular green smoothie drinks has not been addressed so far. The present study investigated the effect of cyclic immersions (5 min daily over 30 days) in a green smoothie drink on the surface properties of contemporary dental restorative materials, including resin composites, an alkasite, and a glass hybrid. Vickers microhardness, profile roughness, and perceptible color change in the CIE L* a* b* color space were evaluated as clinically relevant properties of the material surface. After 30-day green smoothie immersion, microhardness values either decreased by 8–28% (for resin composites) or increased by up to 91% (for glass hybrid). The increase in profile roughness (Ra parameter) of smoothie-immersed specimens was 7–26 times higher compared to the control group. The perceptible color change (ΔE*) in the smoothie group was 3–8 times higher compared to the control group. Overall, this study demonstrated that daily exposure of dental restorations made from resin composites, alkasites, and glass hybrid materials to a green smoothie drink can significantly accelerate material degradation, which is reflected as surface softening, as well as higher roughness and higher perceptible color change.

A photo-reversible, sensitive, and selective sensor for copper ions in an aqueous medium

A naphthopyran derivative 3, 3-diphenyl-3H-benzo[f]chromen-5-ol having a suitably positioned hydroxyl group has been synthesized via condensation of naphthalene-2,3-diol with 1,1-diphenylprop-2-yn-1-ol. The naphthopyran derivative has been characterized by various techniques such as NMR, IR, HRMS, and single-crystal X-ray crystallography. The intermolecular short contacts have been quantitatively investigated. The suitably positioned OH group allowed complexation of metal ions with an optical signal. The screening of metal ions with naphthopyran derivative led to selective and sensitive binding of Cu2+ ions with a perceptible color change (colorless to light yellow). The metal binding by naphthopyran derivative was analyzed by using UV-vis spectrophotometry. The detection was also accomplished using digital colorimetry based on a paper-based device and solution method. Furthermore, calculations based on density functional theory were performed to inspect the formation of a complex and find a suitable complex geometry. The time-dependent theory was also used to compare the observed changes in the absorption spectra for a solution containing naphthopyran derivative and copper ions with the calculated excitation parameter, which provided further evidence of complex formation.

Highly sensitive visual colorimetric sensor for trichlorfon detection based on the inhibition of metallization of gold nanorods

In this study, a highly sensitive visual colorimetric sensor was designed for the detection of trichlorfon based on inhibiting ascorbate oxidase (AAO)-induced metallization of gold nanorods (Au NRs). Ascorbic acid (AA) can reduce silver ion (Ag+) to metal silver (Ag) that will be deposited on the surface of Au NRs, which results in the blue shift of longitudinal localized surface plasmon resonance (LSPR) peak of Au NRs, accompanying by perceptible color changes from red to cyan to red to yellow. In the presence of trichlorfon, the activity of AAO will be inhibited, resulting in less AA is hydrolyzed to dehydroascorbic acid (DHA), and therefore more Ag+ is reduced to Ag by AA. Under the optimized conditions, detection of trichlorfon has a wide linear range of 27.8–11111.1 μg/L with a limit of detection as low as 132.6 ng/L. Moreover, the sensor has a good sample spiked recovery (84.7–96.8%) for the determination of trichlorfon in lake water samples. The proposed method can achieve rapid analysis (about 10 min) of trichlorfon with simple operation when there are no other types of organophosphorus pesticides in the real samples.