Effects of immersion media and repolishing on color stability and superficial morphology of nanofilled composite resin

This study evaluated the influence of fluoride mouth rinses and repolishing on the superficial morphology and color stability of nanofilled resin. About 150 specimens were prepared and polished using aluminum oxide discs for 15 s with a pressure of 2 kg. The experimental groups were divided according to the immersion medium (artificial saliva, 0.5% sodium fluoride, Fluordent Reach, Oral B, Fluorgard) and repolishing procedure (without and with). The specimens were continuously immersed for 1 week. Thereafter, half of each sample was repolished. A color reading was performed after 24 h of immersion in the artificial saliva baseline, after continuous immersion, and after repolishing. The superficial morphology was examined using scanning electron microscopy (SEM) in a qualitative way. Color change (∆E) data were submitted to a mixed analysis of variance using a Shapiro-Wilk test (p>0.05 for the different immersion media) and Sidak's test (p<0.05 for the differences between groups). In the interaction between the repolishing and the immersion media, Fluorgard showed a statistical difference between the ∆E values with and without repolishing (p<0.0001). On the SEM observations, both Fluordent Reach and Fluorgard caused degradation of the superficial resinous matrix of the composite after continuous immersion. This matrix was removed after repolishing.

Effect of finishing and polishing on color stability of a nanofilled resin immersed in different media

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Surface properties and color stability of an acrylic resin combined with an antimicrobial polymer

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biological associations of color variation in the Indo-Pacific swimming crab Charybdis hellerii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Long-term clinical evaluation of the color stability and stainability of acrylic resin denture teeth

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

Effects of short-term immersion and brushing with different denture cleansers on the roughness, hardness, and color of two types of acrylic resin

Purpose: To investigate the cumulative effects of brushing (B) or immersion (I), using different cleansing agents, on the surface roughness, hardness and color stability of a heat-polymerized denture resin, Lucitone 550 (L), and a hard chairside reline resin, Tokuyama Rebase Fast II (T). Methods: A total of 316 specimens (10 x 2 mm) were fabricated. The specimens (n= 9) were divided into brushing or immersion groups according to the following agents: dentifrice/distilled water (D), 1% sodium hypochlorite (Na0C1), Corega Tabs (Pb), 1% chlorhexidine gluconate (Chx), and 0.2% peracetic acid (Ac). Brushing and immersion were tested independently. Assays were performed after 1, 3, 21, 45 and 90 blushing cycles or immersion of 10 seconds each. Data were evaluated statistically by repeated measures ANOVA. Tukey's honestly significant difference (HSD) post-hoc test was used to determine differences between means (a= 0.05). Results: For L there was no statistically significant difference in roughness, except a significant decrease in roughness by brushing with D. T showed a significant effect on the roughness after 90 immersions with Ac. Hardness values decreased for L when specimens were immersed or brushed in Na0C1 and Pb. The hardness of T decreased with increases in the repetitions (immersion or brushing), regardless of the cleaning method. Values of color stability for L resin showed significant color change after brushing with and immersion in Ac and Pb. Brushing with D exhibited a higher incidence of color change. For T there were no significant differences between cleaning agents and repetitions in immersion. A color change was noted after three brushings with the Ac, Chx, and D. Brushing with dentifrice decreased roughness of L. Immersion in or brushing with Na0C1 and Pb decreased the hardness of L. For T, hardness decreased with increases in immersions or brushing. Color changes after the immersion in or brushing with cleaning agents were clinically acceptable according to National Bureau of Standards parameters for both resins.

Color masking of developmental enamel defects: a case series

Developmental defects involving color alteration of enamel frequently compromise the esthetic appearance of the tooth. The resin infiltration technique represents an alternative treatment for color masking of these lesions and uniformization of tooth color. This technique is considered relatively simple and microinvasive, since only a minimal portion of enamel is removed. This article illustrates the color-masking effect with resin infiltration of fluorosis and traumatic hypomineralization lesions with a case series. The final esthetic outcomes demonstrated the ability of the resin infiltrant to mask the color of white developmental defect lesions, resulting in satisfactory clinical esthetic improvements. However, in more severe cases, the color-masking effect was not complete.

Effect of hydrogen peroxide concentration on enamel color and microhardness

Objectives: The aim of this study was to investigate the effect of hydrogen peroxide gels with different concentrations (20%, 25%, 30%, and 35%) on enamel Knoop microhardness (KNIT) as well as on changes in dental color (C).Methods: Cylindrical specimens of enamel/dentin (3-nun diameter and 2-nun thickness) were obtained from bovine incisors and randomly divided into six groups (n=20), according to the concentration of the whitening gel (20%, 25%, 30%, 35%, control, thickener). After polishing, initial values of KNH0 and color measurement, assessed by spectrophotometry using the CIE L*a*b* system, were taken from the enamel surface. The gels were applied on the enamel surface for 30 minutes, and immediate values of KNHi were taken. After seven days of being stored in artificial saliva, new measures of KNH7 and color (L-7* a(7)* b(7)*, for calculating Delta E, Delta L, and Delta b) were made. Data were submitted to statistical analysis of variance, followed by Tukey test (p<0.05).Results: Differences in gel concentration and time did not influence the microhardness (p=0.54 and p=0.29, respectively). In relation to color changes, Delta E data showed that the 35% gel presented a higher color alteration than the 20% gel did (p=0.006).Conclusion: Bleaching with 35% hydrogen peroxide gel was more effective than with the 20% gel, without promoting significant adverse effects on enamel surface microhardness.

Color tunability in green, red and infra-red upconversion emission in Tm3+/Yb3+/Ho3+ co-doped CeO2 with potential application for improvement of efficiency in solar cells

The preparation of Tm3+/Yb3+/Ho3+ co-doped CeO2 prepared by the precipitation method using ammonium hydroxide as a precursor is presented. By X-ray diffraction the materials show the phase-type of fluorite structure and the crystallite sizes were calculated by the Scherrer's equation. No other phase was observed evincing that the rare earth ions were inserted into the fluorite phase as substitutional or interstitial dopants. The microstrain calculated by the Williamson-Hall method do not show significant changes in their values, indicating that the inclusion of rare earths does not causes structural changes in the CeO2 used as a host matrix. All material showed intense upconversion emission at red and green region under excitation with diode laser at 980 nm. The color of emission changes from green to red with increasing excitation power pump. The materials showed suitable photoluminescent properties for applications as a laser source, solar cells, and great emitter at 800 nm. (C) 2014 Elsevier B.V. All rights reserved.

Effect of different solutions on color stability of acrylic resin-based dentures

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

Development of the color scale of perceived exertion: preliminary validation

This study developed a Color Scale of Perceived Exertion (RPE-color scale) and assessed its concurrent and construct validity in adult women. One hundred participants (18-77 years), who were habitual exercisers, associated colors with verbal anchors of the Borg RPE scale (RPE-Borg scale) for RPE-color scale development. For RPE-color scale validation, 12 Young (M = 21.7 yr., SD = 1.5) and 10 Older (M = 60.3 yr., SD = 3.5) adult women performed a maximal graded exercise test on a treadmill and reported perceived exertion in both RPE-color and RPE-Borg scales. In the Young group, the RPE-color scale was significantly associated with heart rate and oxygen consumption, having strong correlations with the RPE-Borg scale. In the Older group, the RPE-color scale was significantly associated with heart rate, having moderate to high correlations with the RPE-Borg scale. The RPE-color scale demonstrated concurrent and construct validity in the Young women, as well as construct validity in Older adults.

Effect of polymerization methods and thermal cycling on color stability of acrylic resin denture teeth

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

Composite resin color stability: influence of light sources and immersion media

This study evaluated the influence of light sources and immersion media on the color stability of a nanofilled composite resin. Conventional halogen, high-power-density halogen and high-power-density light-emitting diode (LED) units were used. There were 4 immersion media: coffee, tea, Coke® and artificial saliva. A total of 180 specimens (10 mm x 2 mm) were prepared, immersed in artificial saliva for 24 h at 37±1ºC, and had their initial color measured with a spectrophotometer according to the CIELab system. Then, the specimens were immersed in the 4 media during 60 days. Data from the color change and luminosity were collected and subjected to statistical analysis by the Kruskall-Wallis test (p<0.05). For immersion time, the data were subjected to two-way ANOVA test and Fisher's test (p<0.05). High-power-density LED (ΔE=1.91) promoted similar color stability of the composite resin to that of the tested halogen curing units (Jet Lite 4000 plus--ΔE=2.05; XL 3000--ΔE=2.28). Coffee (ΔE=8.40; ΔL=-5.21) showed the highest influence on color stability of the studied composite resin. There was no significant difference in color stability regardless of the light sources, and coffee was the immersion medium that promoted the highest color changes on the tested composite resin.

Effect of postpolymerization method on the color stability of composite resins submitted to ultraviolet aging

The aim of this research was to evaluate the effect of postpolymerization method on the color stability of resin-based composites. Samples of direct and indirect restorative materials were polymerized with two photo-curing units (Visio photo-curing oven system and LED Elipar Freelight 2). All samples were submitted to an initial chromatic analysis using a spectrometer and submitted to ultraviolet-accelerated artificial aging. The direct material showed less color change than the indirect material, independent of the photo-activation method used. Samples photo cured with the LED system showed less change than those photo cured with the Visio system. The postpolymerization oven did not improve the color stability of direct and indirect resin-based composites.