Color alteration of the paint used for iris painting in ocular prostheses

The purpose of this study was to assess color alteration of the paints used for iris painting in artificial eyes. Five disks of heat cured acrylic resin were confectioned by microwave energy for each paint analyzed, in a total of 40 specimens. Each specimen consisted of a colorless acrylic resin disk and another of equal size, of scleral white colored acrylic resin, with the painting interposed between the two disks. The specimens were submitted to an accelerated aging process in a chamber under ultraviolet radiation for 1,008 hours. To assess color variation, a reflective spectrophotometer was used. The results were statistically analyzed by ANOVA and the Tukey test (p < 0.05). All the paints underwent chromatic alteration. The oil paint presented the highest resistance to accelerated aging.

Color stability after accelerated aging of two silicones, pigmented or not, for use in facial prostheses

One of the greatest challenges faced by buccomaxillofacial prosthetists is to reproduce the patient's exact skin color and provide adequate esthetics. To reach this objective, professionals must use materials with easy characterization and that maintain color over long periods of time. The objective of this study was, thus, to evaluate the color stability of two types of silicones, Silastic 732 and Silastic MDX4-4210. Twenty-four test specimens were made from each type of silicone and were divided into a colorless group and groups intrinsically pigmented with ceramics, cosmetics or iron oxide. The specimens were submitted to an accelerated system of aging for non-metallic materials. Readings were carried out initially and after periods corresponding to 163, 351, 692 and 1,000 hours of aging, using a reflection spectrophotometer analysis, and color alterations were calculated by the CIE L*a*b* system. The data were submitted to variance analysis and Tukey's test at a 5% level of probability. The results demonstrated that, irrespective of the period of time analyzed, all the materials underwent some type of chromatic alteration (ΔE > 0). The test specimens made with Silastic 732 and MDX4-4210, without pigmentation, presented the lowest color alteration values after 1,000 hours of aging. Of the pigments, ceramic presented the lowest color alteration values and cosmetic powder presented the highest values. Thus, it may be concluded that the materials without the incorporation of pigments presented similar color alteration values, and did not differ statistically. The cosmetic powder used in this study was the pigment that most altered the color of the test specimens. © 2009 Sociedade Brasileira de Pesquisa Odontológica.

Effect of accelerated aging on the microhardness and color stability of flexible resins for dentures

Acrylic resins have been widely used due to their acceptable esthetics and desirable characteristics such as easy handling, good thermal conductivity, low permeability to oral fluids and color stability. Flexible resins were introduced on the market as an alternative to the use of conventional acrylic resins in the construction of complete and partial removable dentures. Although these resins present advantages in terms of esthetics and comfort, studies assessing chromatic and microhardness alterations of these materials are still scarce in the related literature. The aim of this study was to evaluate the chromatic and microhardness alterations of two commercial brands of flexible resins in comparison to the conventional resin Triplex when submitted to accelerated aging. The resins were manipulated according to manufacturers' instructions and inserted into a silicone matrix to obtain 21 specimens divided into 3 groups: Triplex, Ppflex and Valplast. Triplex presented the highest microhardness value (p < 0.05) for all the aging periods, which was significantly different from that of the other resins, followed by the values of Valplast and Ppflex. Comparison between the flexible resins (Ppflex and Valplast) revealed a statistically significant difference (p < 0.05) as regards color. The flexible resin Ppflex and the conventional resin Triplex presented no statistically significant difference (p < 0.05) as regards aging. The accelerated aging significantly increased the microhardness values of the resins, with the highest values being observed for Triplex. Valplast presented the greatest chromatic alteration after accelerated aging.

Color polymorphism in Leptodactylus fuscus (Anura, Leptodactylidae): A defensive strategy against predators?

Color patterns are strongly related to defensive strategies in anurans. Some anurans present more than one morphotype. Leptodactylus fuscus, for example, present two morphotypes (with and without vertebral white line). The proportion of each pattern in nature is different, whereby there are always more individuals without stripes. Therefore, we speculated if this difference in the observed color pattern is due to unequal predation pressures (i.e. stronger over the striped morphotype), and/or if there is a genetic component related to autossomic heritage. To test the selective predation over the morphotypes, we prepared plasticine models of L. fuscus with both phenotypes and placed them in the field. We did not find evidence of predation selection and as we found significant relationships between the proportions of the phenotypes and Mendelian proportions, we suggest that the phenotypes observed in this species are genetically determined (involving dominant and recessive alleles) and may not have a defensive function.

Leaf spray fertilization of boron and zinc on productivity and fruit quality of Japanese pear tree

The cultivation of fruit plants from temperate climate in tropical or subtropical regions can be a good income alternative for the producer. However, due to the little existent information about cultivation of those fruit plants, the producers use imported techniques of other producing areas, or even an association of practices used for other fruit plants, pointing out the leaf spray fertilization of micronutrients without appropriate scientific base. In this context, the objective of this study was to verify the effect of the leaf spray fertilization of B and Zn on productivity and fruit quality of Japanese pear tree. The experiment was conducted from 2004 to 2005, in Ilha Solteira, in northwestern São Paulo State-Brazil. The climate is, according to the Köpppen Classification, tropical wet and dry (Aw). The 'Okusankichi' cultivar, grafted on Pyrus communis L. rootstock was used as well as doses of 110 g.ha-1 of B and 250 g.ha-1 of Zn in each application. The treatments were: T1. water, T2. boric acid, T3. zinc sulfate, T4. T2 + T3, T5. boric acid + urea + citric acid + EDTA, T6. zinc sulfate + urea + citric acid + EDTA, T7. T5 + T6, T8. boric acid + urea + citric acid + EDTA + sodium molibdate + sulfur + calcium chloride, T9. zinc sulfate + urea + citric acid + EDTA + Fe sulfate + Mn sulfate + Mg sulfate and, T10. T8+T9. A randomized blocks design was used and the averages were compared by Tukey test. In the first crop the mixture of boric acid with quelating agents were efficient to supply B to the plants and zinc sulfate plus quelating agents were efficient to increase Zn leaf content. However, the productivity and the fruit quality were not influenced by the leaf spray of B and Zn. In the second crop the leaf content of B and Zn and the productivity were not influenced by the leaf spray; the boric acid and the zinc sulfate with or without quelating agents increased the contents of total soluble solids and, the boric acid with or without quelating agents increased the contents of total titratable acidity.

Assessment of color fidelity of several composite resins compared to their Vita Classical shade registration

This study compared the color fidelity of different composite resins with their registration in the Vita Classical Shade Guide. Using a prefabricated Teflon mold, 120 specimens were divided into four groups fn - 30), according to the resin tested. Three subgroups (a = 10) were prepared for each resin group; these subgroups tested enamel shade, dentin shade, and enamel and dentin shade. Three measurements were performed to verily whether the tooth shade matched that of the Vita Classical Shade Guide. The color was evaluated and the shade variations were calculated. The data were submitted to a three-way AN OVA test (time, color match, and composite type), followed by Tukey's test. It was concluded that all composite resins showed color differences in relation to the Vita Classical Shade Guide.

Measuring and analyzing color and texture information in anatomical leaf cross sections: An approach using computer vision to aid plant species identification

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of tooth color after bleachingwith and without light-activation

Purpose: The use of different light sources as an adjunct to in-office bleaching has been questioned. Thus, the aim of this study was to evaluate the color changes of teeth after application of bleaching techniques with different products, with and without activation by a LED-laser system. Methods: Twenty-four bovine teeth surfaces were submitted to three bleaching techniques with two commercially available 35% hydrogen peroxide bleaching agents (n=8). The specimens were immersed in red wine for 48 h at 37°C and submitted to the bleaching techniques. Color changes were measured before and after staining as well as immediately after and 24 h after the bleaching treatments, with two different methods of color evaluation, software ScanWhite V1.1 and intra-oral spectrophotometer (Vita Easyshade). Data were analyzed by ANOVA and Kruskal-Wallis test. Results: The statistical analysis showed that there was no statistically significant difference at 5% of significance level between the different groups, independently of the evaluation time, evaluation methods or the use of LED-laser systems. Conclusion: The results suggested that the use of light in the bleaching techniques did not influence the color changes. Copyright: © 2011 Roberto et al.

Color stability of resins and nylon as denture base material in beverages

Purpose: Staining of prosthodontic materials may result in patient dissatisfaction and additional expense for replacement. This study aimed to determine the color stability of two heat-cured denture base acrylic (Lucitone 550, Vipi Cril) and one nylon denture base resin (Transflex) after immersion in beverages. Materials and Methods: Forty disks of each resin (20.0-mm diameter, 3.0-mm thick) were prepared and stored in distilled water for 24 hours at 37°C. During that time (T 0), the color of all specimens was spectrophotometrically measured. Each specimen was immersed in coffee, cola, red wine, and distilled water as a means of control. After 15-day (T 1) and 30-day (T 2) periods of immersion, the color of the specimens was measured again. The CIE (Commission Internationale de L' Eclairage) L*a*b* system was used to determine mean ΔE (color changes) values for each material and compared statistically with two-way ANOVA and Bonferroni intervals at 0.95. Results: In ΔET 0T 1 and ΔET 0T 2 the most severe staining was apparent with red wine (p < 0.001), followed by coffee (p < 0.01), when compared to the specimens stored in distilled water. Transflex also showed significant color change after immersion in cola (p < 0.01). In ΔET 1T 2 only red wine promoted significant staining of all resins (p < 0.0001). Conclusion: Chromatic changes were exhibited by specimens immersed in red wine, followed by coffee. For Transflex, cola also promoted color changes. The values of color changes converted to National Bureau of Standard units showed them to be perceivable to the human eye. © 2011 by the American College of Prosthodontists.

Color stability of composites: effect of immersion media.

Coloring in drinks decreases the color stability of composite restorations, reducing their longevity. The purpose of this in vitro study was to evaluate the effect of immersion media on color stability of seven different composite resins (Solidex - Shofu, Resilab-Wilcos, Signum - Heraeus, Epricord - Tokuyama, Adoro - Ivoclar Vivadent, Admira - Voco and Sinfony - 3MESPE). Seven resin-based composite specimens were prepared using a cylindrical teflon mold 2 mm thick and 10 mm in diameter Fifteen specimens of each resin were light-cured according to manufacturers' instructions and randomized into 3 groups (n= 5) according to immersion media: coffee, cola beverage and water A digital spectrophotometer Easy Shade (VITA) was used to evaluate the color changes at baseline and 7 days after immersion in each solution. Specimens were stored in the different staining media for 24 h/day during one week. The color differences were analyzed by two-way ANOVA and Tukey 's test (p< 0.05). Color change was observed after one week of immersion and there were statistical differences in staining, composite and interaction factors. The least staining was observed in Admira (deltaE= 3.934+/-0.814) and Resilab (deltaE= 3.993+/-0.735), followed by Adoro (deltaE= 4.044+/-1.001), Epri-cord (deltaE= 4.049+/-1.234), Signum (deltaE= 4.260+/-1.785), Solidex (deltaE=5,122+/-0.534) and Sinfony (deltaE=5.126+/-0.838). All of the composites tested except Adoro were susceptible to staining by substances present in coffee and cola, when stored in beverage for seven days. The lowest deltaE means were obtained with Admira.

Influence of different disinfecting solutions on the color change of artificial irises used in ocular prostheses

Making an artificial iris with an aesthetically acceptable color is an important aspect of ocular rehabilitation. This work evaluated the influence of different disinfecting solutions on changes to the color of artificial irises used in ocular prostheses. Fifty samples simulating ocular prostheses were produced with cobalt blue artificial irises and divided (n = 10) according to the disinfectant used: neutral soap, Opti-free, Efferdent, 1% hypochlorite, and 4% chlorhexidine. The samples were disinfected for 120 days and subjected to a color readings by spectrophotometry, using the CIE L*a*b* system, before the disinfection period (B), after 60 days of disinfectant exposure (T 1), and after 120 days of disinfectant exposure (T 2). Color differences (ΔE) were calculated for the intervals between T 1 and B (T 1B), and between T 2 and B (T 2B). The data were evaluated by analysis of variance and the Tukey Honestly Significantly Different (α = 0.05). All disinfectant groups exhibited color changes. The mean color change observed for all groups overall during T 2B (ΔE = 3.51) was significantly greater than that observed during T 1B (ΔE = 2.10). All groups exhibited greater color change for the b* values when compared to the a* and L* values. There were no significant differences between the disinfectant groups. It can be concluded that the time period of disinfection and storage significantly affected the stability of artificial iris color, independent of the disinfectant used. © 2012 Wiley Periodicals, Inc.