Perceptual Color Research Articles

Feature Weighted Cycle Generative Adversarial Network with Facial Landmark Recognition and Perceptual Color Distance for Enhanced Face Animation Generation

We propose an anime style transfer model to generate anime faces from human face images. We improve the model by modifying the normalization function to obtain more feature information. To make the face feature position of the anime face similar to the human face, we propose facial landmark loss to calculate the error between the generated image and the real human face image. To avoid obvious color deviation in the generated images, we introduced perceptual color loss into the loss function. In addition, due to the lack of reasonable metrics to evaluate the quality of the animated images, we propose the use of Fréchet anime inception distance to calculate the distance between the distribution of the generated animated images and the real animated images in high-dimensional space, so as to understand the quality of the generated animated images. In the user survey, up to 74.46% of users think that the image produced by the proposed method is the best compared with other models. Also, the proposed method reaches a score of 126.05 for Fréchet anime inception distance. Our model performs the best in both user studies and FAID, showing that we have achieved better performance in human visual perception and model distribution. According to the experimental results and user feedback, our proposed method can generate results with better quality compared to existing methods.

Hybrid method for enhancement of low-resolution ancient Kannada Stone Inscription images

In this paper, we proposed the hybrid-based method for the enhancement of low-resolution Kannada Stone Inscription images. To test the performance of the proposed method, a total of 110 low-resolution samples of Kannada stone inscription images were collected from internet sources for the experimental setup due to the non-availability of the standard datasets for the Kannada stone inscriptions. The collected data set samples from the internet were complex in nature to read the contents present on stone images. The experimental workflow of the proposed method is to separate the text and non-text regions from the stone inscription images using a proposed technique for setting the coordinates. Then, the preprocessing process starts to filter out the noises and other unwanted regions found in the image foreground region using the median filtering composition method. Finally, the hybrid approach is implemented using a Fuzzy adaptive thresholding technique for the elimination of the background region of the input image and smooth enhancement of Kannada stone inscription images due to enormous challenges related to perspective distortion, diverse lighting conditions, the minimal disparity between the foreground and background, a lack of standardized text size and shape, reduced perceptible colour contrast, and associated noises. Hence, we obtained an enhancement accuracy of 78.18% using a hybrid method. The obtained accuracy is more acceptable compared to existing methods found in the global literature and is also carried out during the experimental study. The novelty of the paper is working on low-resolution ancient Kannada stone inscription images and a hybrid approach to enhance the quality of the original input image.

The learnability of natural concepts

According to a recent proposal, natural concepts are represented in an optimally designed similarity space, adhering to principles a skilled engineer would use for creatures with our perceptual and cognitive capacities. One key principle is that natural concepts should be easily learnable. While evidence exists for parts of this optimal design proposal, there has been no direct evidence linking naturalness to learning until now. This article presents results from a computational study on perceptual color space, demonstrating that naturalness indeed facilitates learning.

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.

Effects of Homophone Priming on the Decision-Making in Perceptual Color Recognition of Mandarin Speakers

This study delves into the nuanced interactions between language, cognition, and perception by examining the impact of homophones on decision-making and perceptual color recognition among native Mandarin speakers. Drawing on theories of linguistic relativity and cognitive processing, this research hypothesized that homophonic primes would subtly influence both decision-making processes and color recognition tasks. Participants were assigned at random to surveys where they were unknowingly exposed to stimuli with and without homophonic primes before engaging in color recognition tasks involving subtle shade differentiations. Contrary to initial expectations, statistical analysis revealed no significant differences in decision-making accuracy between conditions, suggesting that homophones may not overtly affect conscious decision-making processes in our bilingual cohort. However, intriguing variations emerged in the perceptual color recognition task, where participants exposed to homophonic primes showed tendencies to perceive color shades more similarly compared to those in the control condition. This finding implies a potential cognitive load effect or subtle priming influence on perceptual categorization tied to linguistic structures. The implications of these findings challenge traditional views on language's role in shaping cognitive processes, highlighting the complexity of how linguistic structures such as homophones may operate at subconscious levels. The study contributes to ongoing debates in cognitive science and linguistics by underscoring the need for nuanced approaches to understanding cross-linguistic cognitive mechanisms. Future research should further explore the Whorfian hypothesis within bilingual contexts, considering additional variables such as language proficiency and cultural influences to elucidate the intricate relationship between language and cognition.

Digital photometric analysis as a non-invasive method to determine gingival phenotype: A comparative study

ObjectiveIdentification of periodontal phenotype is critical in clinical practice. Thick and thin tissues respond differently to inflammation, and trauma. It significantly influences the outcomes of restorative treatment, regenerative therapy, and success of implants and periodontal surgery. Periodontal phenotype can be assessed via invasive or non-invasive methods. This study aimed to establish the reliability of non-invasive methods in determining gingival phenotypes in comparison with validated methods. MethodsThis preapproved cross-sectional observational study was conducted at Batterjee Medical College in Saudi Arabia. The participants were conveniently sampled based on the inclusion criteria. The clinical study utilized Colorvue® biotype probes to evaluate gingival tissue phenotype in the region of interest, intraoral digital scanner (IOS) (iTero® scanner), and digital photography. Densitometric acquisition of photographs and intraoral scans was performed using Adobe Photoshop to quantify three-dimensional color measurements expressed in Delta E values (ΔE). Furthermore, patient-reported experience measures (PREMs) were used to evaluate anxiety and pain perception. Values of p < 0.05 were considered statistically significant. ResultsThe analysis of color difference values (ΔE) revealed significant variations in color perception across methods for the thin, medium and very thick groups, indicating perceptible color differences (p < 0.001). The assessment of anxiety levels indicated a statistically significant decrease in stress levels in favor of the IOS method for the medium phenotype. Furthermore, perceived pain was significantly lower with the IOS method than with the probing method for all phenotypes. ConclusionDensitometric analysis of standardized clinical photographs and intraoral scans of the marginal gingiva offers a promising, non-invasive, less stressful, and virtually non-painful method of periodontal phenotype evaluation with reliable numerical outputs. Furthermore, these data may be used to feed AI systems, where machines can learn to recognize color differences and possibly deduce phenotype assessments.

Efficient Computation of Geodesics in Color Space.

Although scientists agree that a perceptual color space is not Euclidean and color difference measures, such as CIELAB's ∆E2000, model these aspects of color perception, colormaps are still mostly evaluated through piecewise linear interpolation in a Euclidean color space. In a non-Euclidean setting, the piecewise linear interpolation of a colormap through control points translates to finding shortest paths. Alternatively, a smooth interpolation can be generalized to finding the straightest path. Both approaches are difficult to solve and are compute intensive. We compare the 11 most promising optimization algorithms for the computation of a geodesic either as the shortest or as the straightest path to find the most efficient one to use for colormap interpolation in real-world applications. For two control points, the zero curvature algorithms excelled, especially the 2D relaxation method. For multiple control points, only the mimimal curvature algorithms can produce smooth curves, amongst which the 1D relaxation method performed best.

Division and spreading of attention across color.

Biological systems must allocate limited perceptual resources to relevant elements in their environment. This often requires simultaneous selection of multiple elements from the same feature dimension (e.g. color). To establish the determinants of divided attentional selection of color, we conducted an experiment that used multicolored displays with four overlapping random dot kinematograms that differed only in hue. We manipulated (i) requirement to focus attention to a single color or divide it between two colors; (ii) distances of distractor hues from target hues in a perceptual color space. We conducted a behavioral and an electroencephalographic experiment, in which each color was tagged by a specific flicker frequency and driving its own steady-state visual evoked potential. Behavioral and neural indices of attention showed several major consistencies. Concurrent selection halved the neural signature of target enhancement observed for single targets, consistent with an approximately equal division of limited resources between two hue-selective foci. Distractors interfered with behavioral performance in a context-dependent fashion but their effects were asymmetric, indicating that perceptual distance did not adequately capture attentional distance. These asymmetries point towards an important role of higher-level mechanisms such as categorization and grouping-by-color in determining the efficiency of attentional allocation in complex, multicolored scenes.

Color-appearance-matched data in high-dynamic-range luminance conditions

We report color-appearance-matched data under high-dynamic-range luminance conditions. The experimental method and apparatus proposed in a previous study [J. Opt. Soc. Am. A 36, 1940 (2019)JOAOD60740-323210.1364/JOSAA.36.001940] were used to measure perceptual color shifts in the R, G, B, Y, RB, BG, GY, and YR groups of 16 samples under four dual-illumination conditions at luminance levels of (300 and 4500cd/m2), (20 and 300cd/m2), (80 and 4500cd/m2), and (20 and 4,500cd/m2). We observed a decrease in lightness for all samples, and hue shifts toward blue in R, red in reddish YR, and green in BG samples when the luminance changed from low to high. Correlated changes in lightness and chroma, that is, an increase in lightness change and a decrease in chroma change under the highest luminance contrast (20 and 4500cd/m2), were observed for the Y, GY, and YR samples.

Evaluation and Comparative Analysis of Coronal Tooth Discoloration Induced by Four Endodontic Biomaterials Utilized in Regenerative Endodontic Procedures: An Ex-vivo Study.

This study aims to compare and evaluate the changes in color caused by four different biomaterials utilized as intracanal coronal barriers in the regenerative endodontic procedure at varying intervals of time. A total of 100 extracted mandibular single-rooted premolars were taken. Samples were standardized, and access cavity preparation was done. All the canals were instrumented and irrigated thoroughly. They were divided into five groups: A, B, C, D, and E (n=20), i.e., the control group, gray mineral trioxide aggregate (MTA), white MTA, Biodentine, and calcium hydroxide. Each group was further subdivided into two subgroups (n=10), where one subgroup was prepared with normal saline and the other was prepared with platelet-rich fibrin (PRF). Digital photographs were taken at baseline, immediately after the placement of biomaterials, after 72 hours, seven days, and sixmonths, using a DSLR camera. The color evaluation was done using the Adobe Photoshop 2021 software using the CIE L*a*b color system. The data obtained were recorded and statistically analyzed using IBM SPSS Statistics for Windows, Version 23 (Released 2015; IBM Corp., Armonk, New York). Continuous variables were analyzed using a one-way ANOVA test and post-hoc analysis. The P-value was set to be significant at <0.05. Statistically significant variation was obtained in all four experimental groups regarding change in color (ΔE) over periods of 72 hours, seven days, and six months. At six months, all the experimental groups presented with a perceptible color variation (ΔE>3.3). The color change was significant after six months in all groups. Biodentine produced the least color alteration, whereas gray MTA produced the highest.

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.

Effect of Simulated Gastric Juice on Color Stability of Different Artificial Teeth

Objective: The current study aimed to evaluate the gastric juice effect on the artificial teeth discoloration in patients with gastroesophageal reflux disease (GERD) under in vitro conditions.&#x0D; Methods: Three different artificial teeth (Ivostar, Vivodent PE, Phonares II) were used in the study (n=12). A spectrophotometer (VITA Easyshade Compact; VITA Zahnfabrik, Bad Säckingen, Germany) was used for initial color measurements after keeping the specimens in distilled water for 24 h. Then, they were immersed in 5% hydrochloric acid (HCl) at 37°C (pH=2) for 91 h and the color measurements were&#x0D; repeated. The CIEDE2000 formulation was used to calculate the color changes. The statistical analysis was performed with one-way ANOVA and Tukey HSD tests.&#x0D; Results: Although the color differences of Vivodent PE and Phonares II materials did not exhibit a statistically significant difference (p=.95; p &gt; .05), there was a significant difference between Ivostar and other materials (p=.02, p=.01). The 50:50% detection threshold (PT) was exceeded with Vivodent PE and Phonares II materials, while the 50:50% acceptability threshold (AT) was exceeded with Ivostar material.&#x0D; Conclusion: After exposure to gastric acid, all groups exhibited perceptible color differences. In the group of acrylic resin artificial teeth, the color difference was above acceptability threshold and would be better to improve. While the acrylic resin artificial teeth exhibited the highest discoloration, artificial teeth containing nanohybrid composite resin showed the least discoloration. These should be considered in&#x0D; the selection of artificial teeth in patients with GERD.

Effect of thermal treatment on selected bioactive compounds and physicochemical properties of a blackberry-soy-flaxseed beverage

Three prototypes of a blackberry-soy-flaxseed beverage were formulated and processed by pasteurization (71.1 °C, 3 s) or commercial sterilization (heating to 87 °C followed by immediate hot-fill). The effects of heat exposure on selected bioactive compounds (total phenolics, ellagitannins, anthocyanins, isoflavones and lignans) and physicochemical properties (pH, °Brix, turbidity, viscosity and color) were evaluated. Bioactive compounds were quantified by HPLC-DAD analytical methods. No significant changes (p > 0.05) were observed in the contents of total phenolic compounds, ellagitannins, cyanidin-3-glucoside, isoflavones (daidzein and genistein), or lignans, regardless of the heat regime applied or the beverage formulation. The pH and soluble solids were similar among the three beverages and did not change after heat treatments. The content of cyanidin-3-malonyl-glucoside, a polyphenol, significantly decreased (p < 0.05) by 35–45% with the hot-fill process in all beverage prototypes. Turbidity was not significantly affected by the type of heat treatment, but the viscosity of the hot-filled beverages was significantly higher (p < 0.05) than that of the pasteurized and non-pasteurized prototypes. No significant differences (p < 0.05) in color parameters L*, a*, and b* were observed. Total color difference (DE*) values indicated differences in perceivable color among samples of the same beverage exposed to the heat processing regimes. DE* values for prototype 1 processed by pasteurization and commercial sterilization were distinct from non-pasteurized beverage. DE* values for prototypes 2 and 3 processed by pasteurization were distinct from those of the non-pasteurized beverage. Pasteurization allowed higher retention of bioactive compounds and had a lower impact on the physicochemical properties of the blackberry-soy-flaxseed beverage.

Effects of post-fermentation addition of green tea extract for sulfur dioxide replacement on Sauvignon Blanc wine phenolic composition, antioxidant capacity, colour, and mouthfeel attributes

This study examines the feasibility of replacing SO2 in a New Zealand Sauvignon Blanc wine with a green tea extract. The treatments included the control with no preservatives (C), the addition of green tea extract at 0.1 and 0.2 g/L (T1 and T2), and an SO2 treatment at 50 mg/L (T3). Five monomeric phenolic compounds were detected in the green tea extract used for the experiment, and their concentrations ranged in the order (−)-epigallocatechin gallate > (−)-epigallocatechin > (−)-epicatechin > (−)-epicatechin gallate > gallic acid. At the studied addition rates, these green tea-derived phenolic compounds contributed to ∼70% of the antioxidant capacity (ABTS), ∼71% of the total phenolic index (TPI), and ∼ 84% of tannin concentration (MCPT) of the extract dissolved in a model wine solution. Among wine treatments, T1 and T2 significantly increased the wine's colour absorbance at 420 nm, MCPT, gallic acid and total monomeric phenolic content. TPI and ABTS were significantly higher in wines with preservatives (i.e., T2 > T1 ≅ T3 > C, p < 0.05). These variations were observed both two weeks after the treatments and again after five months of wine aging. Additionally, an accelerated browning test and a quantitative sensory analysis of wine colour and mouthfeel attributes were performed after 5 months of wine aging. When exposed to excessive oxygen and high temperature (50 °C), T1 and T2 exhibited ∼29% and 24% higher browning capacity than the control, whereas T3 reduced the wine's browning capacity by ∼20%. Nonetheless, the results from sensory analysis did not show significant variations between the treatments. Thus, using green tea extract to replace SO2 at wine bottling appears to be a viable option, without inducing a negative impact on the perceptible colour and mouthfeel attributes of Sauvignon Blanc wine.

Effect of various staining beverages on the color stability of CAD/CAM PMMA denture teeth: An in vitro study.

This study aimed to compare the color change of computer-aided design (CAD)/computer-aidedmanufacturing (CAM)polymethyl methacrylate (PMMA)denture teeth and conventional acrylic teeth after immersion in three staining beverages (coffee, red tea, and cola) for a day, 7 days, and 30 days. Group 1: Conventional acrylic teeth (n = 32). Group 2: Milled CAD/CAMteeth out of PMMA disc (n = 32). The specimens of each material were further divided into four subgroups: (1) Control group, distilled water (n = 16). (2) Red tea solution (n = 16). (3) Coffee solution (n = 16). (4) Cola (n = 16). The color change ( ) was assessed using a spectrophotometer at four time points: at the baseline (t0 ), on the 1st day (t1 ), on the 7th day (t2 ), and the 30th day (t3 ) of immersion. Kolmogorov-Smirnov test was applied, followed by performing independent samples t test, one-way analysis of variance and post-hoc Tukey tests to compare the color change values at different time points. The mean score of NBS values of the coffee solution indicates perceivable color change at the end of the 30th day in the conventional acrylic teeth group. It was 0.843 ± 0.395 at t1 , then increased to 1.017 ± 0.477 at t2 and to 2.259 ± 1.059 at t3 . There is a statistically significant difference (p < 0.05) in color change values between both tooth types at the end of the 30th day of immersion in red tea solution and a statistically significant difference at the end of the 7th day (p < 0.05) and the 30th day (p < 0.05) of immersion in coffee solution. CAD/CAMPMMA teeth are more color stable than conventional acrylic teeth after 30 days of immersion in coffee and red tea solution.

History constrains the evolution of efficient color naming, enabling historical inference

Color naming in natural languages is not arbitrary: It reflects efficient partitions of perceptual color space [T. Regier, P. Kay, N. Khetarpal, Proc. Natl. Acad. Sci. U.S.A. 104, 1436-1441 (2007)] modulated by the relative needs to communicate about different colors [C. Twomey, G. Roberts, D. Brainard, J. Plotkin, Proc. Natl. Acad. Sci. U.S.A. 118, e2109237118 (2021)]. These psychophysical and communicative constraints help explain why languages around the world have remarkably similar, but not identical, mappings of colors to color terms. Languages converge on a small set of efficient representations.But languages also evolve, and the number of terms in a color vocabulary may change over time. Here we show that history, i.e. the existence of an antecedent color vocabulary, acts as a nonadaptive constraint that biases the choice of efficient solution as a language transitions from a vocabulary of size [Formula: see text] to [Formula: see text] terms. Moreover, as efficient vocabularies evolve to include more terms they explore a smaller fraction of all possible efficient vocabularies compared to equally sized vocabularies constructed de novo. This path dependence of the cultural evolution of color naming presents an opportunity. Historical constraints can be used to reconstruct ancestral color vocabularies, allowing us to answer long-standing questions about the evolutionary sequences of color words, and enabling us to draw inferences from phylogenetic patterns of language change.

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.

E-cigarettes and heated tobacco products impact on dental color parameters

ObjectivesAbstaining from tobacco smoking may not only improve general health, but also reduce teeth staining and restore teeth whiteness. Compared with conventional cigarettes, E-cigarettes (ECs) and heated tobacco products (HTPs) may offer substantial reduction in exposure to pigmented tar-like compounds of cigarette smoke. It is possible that improvements in dental color indices may be observed in those who have stopped smoking combustible cigarettes by switching to tar-free nicotine delivery products. MethodsThis cross-sectional study evaluated and compared dental color parameters by digital spectrophotometry among five different groups: individuals who currently smoke ; individuals who used to smoke but have quit ; individuals who have never smoked ; exclusive users of electronic cigarettes (former smokers) ; and exclusive users of heated tobacco products (former smokers) . ResultsDental whiteness in current cigarette smokers was notably worse compared with never and former smokers, (13.38 Whiteness Index for Dentistry (WID) units vs. 19.96 and 16.79 WID units). Remarkably high WID values (i.e., whiter teeth) were also observed in ECs (16.72 WID units) and HTPs users (17.82 WID units). Compared to current smokers, difference in dental whiteness for ECs and HTPs users was visually noticeable (ΔWID difference being on average > 2.90 units). The colour differences measured as delta E*(ΔE*) were all visually detectable except for the comparison between ex-smokers and ECs users for which no perceptible color difference was observed (0.415). ConclusionExclusive use of ECs and HTPs is associated with better dental color measurements than current smoking, suggesting that tar-free nicotine delivery technologies are unlikely to have negative effects on dental appearance. Clinical significanceUse of alternative nicotine delivery systems may be associated with cosmetic benefits with important implications for those smokers perceiving dental aesthetics as a significant problem. For these an oral-based narrative may be a much more significant reason to refrain from smoking than the fear of developing smoking-related diseases in future.