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PubMedDate not supplied

Effect of fluoride varnishes on color stability of esthetic restorative materials.

Fluoride varnish applications were applied to two hybrid resin composite materials, Z-100 (3M Dental Products, St Paul, MN, USA) and Esthet-X (Dentsply Caulk, Milford, DE, USA), shades A1 and A2 and a glass ionomer, GC Fuji IX GP Fast (GC Corporation, Tokyo, Japan), shade A2, to evaluate color stability. Specimens (12.6-mm dia x 2.3 mm) were prepared using a polyethylene frame, light-cured and polished through a 1-microm alumina finish. After the initial baseline color measurements, the discs were suspended in Fusayama artificial saliva (FAS) solution at 37 degrees C for 48 hours. Post immersion, the specimens were divided into five groups (n=15 each). The following fluoride varnishes were applied to four groups of test specimens: Duraphat (Colgate Oral Pharmaceutical, Inc, Canton MA, USA), Cavity Shield (OMNII Oral Pharmaceuticals, West Palm Beach, FL, USA), Duraflor (Pharmascience Inc, Montreal, Canada) and Fluor Protector (Vivadent, Ivoclar North America, Amherst, NY, USA). The varnish was allowed to dry for five minutes before immersion. The control group was not coated with varnish, although the specimens were immersed in FAS. All specimens were incubated in newly prepared FAS at 37 degrees C for 24 hours, cleaned with an electric toothbrush and the process repeated using newly prepared FAS. CIE L*a*b* color measurements were recorded five times: at baseline, after 48 hours FAS immersion, after cleaning the first and second fluoride varnish applications and after the final brushing using a commercial toothpaste (Crest). A Minolta CR-300 tristimulus colorimeter with an 8-mm aperture (Ramsey, NJ, USA) was used to record color measurements with the daylight (D65) setting. Calculations were performed for using CIE parameters deltaE*, deltaL*, delta a*, delta b*. Analysis of variance (ANOVA) and post-hoc test (Fisher's PLSD) were used for statistical analysis. After immersion in saliva, the tested glass ionomer (Fuji IX) produced the most significant color changes (deltaE*=1.19 and deltaL*=-1.03), indicating the effect of the color change was due to absorption. After fluoride varnish applications, Duraphat varnish produced significant changes in all tested materials and shades, resulting in color changes with deltaE greater than (>) 1 but less than (<) 3. These color changes are considered visually perceptible, yet have been reported in dental literature as clinically acceptable. Fluoride varnishes can be used without adversely affecting the color of restorative materials.

Absorption↗

PubMed2005

Color vision tests for aviation: comparison of the anomaloscope and three lantern types.

INTRODUCTION: A comparison of the results obtained with the Nagel anomaloscope and the Holmes-Wright Type A, Spectrolux, and Beyne aviation color vision lanterns was undertaken. The Joint Aviation Requirements (JAR) specify pass/fail limits for these four secondary color vision tests and the Ishihara screening test. The results for individuals on all five tests were studied. METHODS: The color vision of 55 color-vision deficient and 24 color-vision normal subjects, mostly applicant pilots, was assessed using a battery of tests, including the Ishihara plates, the Nagel anomaloscope, and three lanterns. The testing methods and characteristics of the lanterns and anomaloscope were compared. RESULTS: Of the color-deficient applicants, only deuteranomalous trichromats passed more than one of the four secondary JAR tests, but a pass on one test did not reliably predict a pass on another test. Three out of nine protanomalous trichromats passed the Nagel anomaloscope but failed all three lantern tests. Of the normal trichromats, 12 failed the anomaloscope and 12 failed the Beyne lantern. DISCUSSION: Variability in pass/fail results can be attributed to many factors apart from loss of chromatic sensitivity. Some normal trichromats can fail both the Ishihara screening and the secondary tests. The approved secondary test varies between countries and the outcome of regulatory assessment depends on the color vision test used. Since the flight safety consequences of the current situation cannot be ignored, the development of a less variable technique for color vision assessment that is accepted internationally, allied with a better understanding of color vision requirements, is needed.

Aerospace Medicine↗

PubMedDate not supplied

Two-year color changes of light-cured composites: influence of different light-curing units.

This study determined color changes in a composite cured with various types of curing units after two years. A hybrid (Clearfil AP-X) composite was cured with a conventional halogen, a high intensity halogen, a plasma arc and a light emitting diode unit. The specimens were stored in light-proof boxes after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after two years were measured using a colorimeter. The CIE 1976 L*a*b color system was used to determine color differences. Differences from baseline were calculated as deltaE*ab. Data were analyzed with two-way analysis of variance (p<0.05). The deltaE*ab values varied significantly, depending on the curing unit used. The specimens cured with a plasma arc curing unit induced significantly higher color changes than any other specimen and the color differences were also visually appreciable by the non-skilled operator (deltaE*ab >2.5). The specimens cured with a high intensity halogen curing unit produced the lowest color change; however, there were no statistically significant differences among the color changes of specimens cured with conventional halogen, high intensity halogen and the light emitting diode unit, and the color changes were not clinically relevant (deltaE*ab <2.5). The results of this study suggest that composite materials undergo measurable changes due to curing unit exposure. The specimens cured with a plasma arc light showed the highest color changes as compared to specimens cured with other curing units.

Analysis of Variance↗

PubMed2005

The color differences between different thicknesses of resin veneered over amalgam.

STATEMENT OF PROBLEM: Composites and compomers are popular in dental practice. However, little is known about their esthetic appearance as veneering restorative materials over amalgam restorations. PURPOSE: This in vitro study was designed to assess the color differences of composite and compomer restorative materials, placed in thicknesses of 1 mm and 2 mm over amalgam. MATERIAL AND METHODS: Thirty six cylindrical Teflon molds were filled with amalgam (13 mm diameter, 2 mm thickness) and stored at 37 degrees C and 100% relative humidity for 7 days. Nine veneers (for each thickness of 1 and 2 mm) were fabricated from four types of tooth-colored restorative material, Dyract AP (DYR), Compoglass F (COMP), Herculite XRV (XRV), and Vitalecense (VIT), over amalgam specimens using Teflon-split molds and following the manufacturers' instructions. A spectrophotometer was used to measure the color difference DeltaE* between the two thicknesses. RESULTS: Color difference DeltaE* values for 1 mm thickness veneers [XRV (2.52), Comp (5.46), VIT (6.73), and DYR (6.88)] were statistically significantly higher than the 2 mm thickness [XRV (1.32), Comp (3.24), VIT (4.89), and DYR (4.83)]. Although the XRV material had the lowest DeltaE* values, no statistically significant difference was found between the two thicknesses. The color measurements at L*, a*, and b* showed most materials became darker in color at either thickness. CONCLUSION: The thicker veneer specimens were found to be closer in color to the controls than the thinner specimens. Only XRV had color differences (DeltaE*) small enough to be considered clinically acceptable (2.52 and 1.32 at 1 mm and 2 mm, respectively). CLINICAL IMPLICATIONS: In this in vitro study the color of XRV was affected the least when veneered on amalgam. Opaquers may be needed to be used with thinner veneers to minimize the effect of amalgam background.

Analysis of Variance↗

PubMed1991

[A simple description of color adaptation in the red-green system].

The red/green-system is examined experimentally under adaptation to green and to magenta. The theoretical basis consists of Grassmann's laws and of a new linear opponent colors theory. Besides brightness, this opponent colors theory specifies the two chromatic axes yellow-blue and green-magenta within color space. An axiom is formulated for the description of color adaptation for the red/green-system. Two pairs of color vectors are assumed to be equivalent with respect to the red/green-system if the quotients of the respective red/green-coordinates of test vector and adaptation vector are identical. For both vectors the control of the other two opponent colors systems is presupposed. The axiom is tested for four green and four magenta adaptation vectors. Three observers take part in the experiment. For each observer an individual plane of constant brightness and his or her individual opponent colors axes are estimated experimentally. For both magenta and green adaptation the data agree well with the theoretical predictions. Thus they provide empirical support for the axiom. For the red/green-system color adaptation can be described very simply if the other two opponent colors systems are controlled.

Adaptation, Ocular↗

PubMed1986

[A new TV-bronchoscopy method using a video endoscope and digital processing of the endoscopic color image].

The TV-bronchoscope dose not have an image fiber bundle, which is instead replaced by a monochromatic C.C.D. (charge-coupled device). This system consists of a bronchofiberscope, a computer, a TV camera, a frame memory and a color CRT display. The enhancement of an endoscopic color image is one typical example of color image processing. Firstly a color image is divided into luminance information and color information, and only the former is processed for enhancement. The luminance information is filtered so as to eliminate the fiber bundle structure, and the spatial frequency band characterizing the structure is then emphasized. Finally the processed luminance information and the non-processed color information are combined to reconstruct the color image. In this way, a processed color image can be obtained without changing the color balance of the original image. Using this process, blood vessels and surface irregularities are emphasized by the newly developed digital processing method. We have applied it for localization of hilar-type early lung cancer, which progresses on the surface, and have obtained good results.

Bronchoscopes↗

PubMed1984

Color contrast perimetry.

A method for color perimetry is proposed in which colored test objects are presented in a white surround, so that the luminance of the object and its surround are identical. The color of the test object then may be varied in its degree of saturation, while maintaining a constant luminance. A color video instrument controlled by a microcomputer is used as a tangent screen. Foveally viewed, colored test objects are adjusted initially in luminance by heterochromatic flicker photometry to match the luminance of a white background at 100 apostilb. The relative foveal scotoma for blue light requires that test objects large enough to include the perifoveal retina be used for flicker photometry of blue test objects. Due to the progressively increasing threshold for luminance contrast detection in extrafoveal retina, differences in luminance between the colored objects and the white surrounding, as the test objects are moved into the extrafoveal visual field, appear to remain subthreshold. Test object detection can thus be expected to be a perimetric measure of color contrast detection, relatively unaffected by luminance contrast detection. This strategy should simplify the use of colored objects for clinical perimetric testing and should provide a specific test of color vision in the extrafoveal visual field.

Adult↗

PubMed1994

[Effects of color on implicit and explicit memory tests].

We report two experiments that explore why recent investigations of implicit memory did not find any effects of color information on test performance. The argument that previous failures to find effects of repetition priming were due to an arbitrary association between objects and colors was found to be wanting. To the contrary, both experiments showed no or small effects of repetition for objects paired with their prototypical colors. A second argument according to which subjects attend to the colors at encoding did not fare much better. More importantly, however, we found strong effects of repetition priming with a conceptual implicit memory measure, whereas previous research had relied exclusively on perceptual tests of implicit memory. In both experiments, the subjects were asked to choose a suitable color for each object at testing. No instructions about remembering the objects were given. The results demonstrated strong preferences for the previously seen colors in the color-choice task. Furthermore, this effect was present to the same extent with picture objects and with object names, corroborating the conceptual nature of the implicit memory measure. Finally, we observed many functional dissociations with explicit measures of memory for color information, demonstrating implicit use of memory in the conceptual choice-test for colors.

Attention↗

PubMed1993

[Clinical applications of color-Doppler: the parathyroid glands].

The high-resolution appearance of enlarged parathyroid glands is well known. Thus, real-time gray-scale US alone fails to provide, in ENT surgery, adequate sensitivity and specificity rates to differentiate between parathyroid glands, hypoechoic thyroid adenomas and other hypoechoic neck masses. Since parathyroid tissue, in both normal and enlarged glands, is hypervascular, color-Doppler US is used as a sort of non-invasive angiography to identify parathyroid glands. The combined use of B-mode and color-Doppler US allows the vascular features of thyroid masses to be satisfactorily demonstrated, with easy differentiation between enlarged parathyroid glands, featuring diffuse internal vascularization, and thyroid adenomas characterized by rounded peripheral vessels and also lymph nodes and cysts exhibiting different vascular patterns. We studied 25 patients with clinical and biochemical signs of hyperparathyroidism (19 primary and 6 secondary) submitted to surgery in the last 20 months. Every patient was scanned with both B-mode and color-Doppler US. At surgery, 19 parathyroid adenomas were found--16 of them correctly identified preoperatively with color-Doppler US and 3 false negatives (retrotracheal glands). Moreover, 1 false positive was observed due to a small Plummer's adenoma misdiagnosed as an intrathyroid parathyroid adenoma: both lesions had the same vascular pattern on US images. Sensitivity was 84.5% and specificity 93.7%. In secondary HPT patients, 23 hyperplastic glands were found at surgery--21 of them correctly identified preoperatively by color-Doppler US, with 2 false negatives. No false positive was found. Sensitivity was 87.5% and specificity 100%. Sensitivity does not differ very much from what reported in literature. Specificity is clearly increased by the use of color-Doppler US. The possible source of error represented by Plummer's adenomas lead us to investigate pulsed Doppler capabilities in differentiating Plummer's adenomas from PT glands, since color-Doppler findings were similar in the two conditions. Peak velocities recorded with both color and pulsed Doppler showed velocity to range 6 to 40 cm/s in parathyroid glands (mean +/- SD: 14.6 +/- 11.7) and 38 to 120 cm/s in thyrotoxic nodules (mean +/- SD: 78.4 +/- 23). The statistical analysis of the results showed a highly significant difference between the two groups of velocities. Peak velocities as recorded in the main, vessels of the parathyroid glands with color and pulsed Doppler were correlated with the activity of the parathyroid glands.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenoma↗

PubMed1996

Duplex and color Doppler flow sonography of occlusion and near occlusion of the carotid artery.

PURPOSE: To determine whether color Doppler flow imaging with the use of slow-flow sensitivity improves sensitivity and specificity in the differentiation of occlusion and near occlusion of the internal carotid artery. METHODS: Color Doppler and duplex sonography were performed in symptomatic patients who had angiographically confirmed occlusion and/or near occlusion of the internal carotid artery. The study consisted of two phases: in the first, we assessed the usefulness of color Doppler flow imaging by retrospectively reviewing the records of 35 patients with 36 angiographically confirmed occlusions or near occlusions of the internal carotid artery who were examined with color Doppler flow imaging at our institution during a period of 4 years; in the second phase, we incorporated color Doppler sonography into the routine scanning protocols of 39 patients with 41 occluded or nearly occluded internal carotid arteries seen over a period of 2 1/2 years. RESULTS: Overall, color Doppler imaging correctly showed all 34 of the near occlusions (sensitivity, 100%) and 36 of the 43 occlusions (specificity, 84%). Seven patients with angiographically confirmed occlusion had sonographic findings that suggested near occlusion. In the first phase, eight near occlusions were misinterpreted as occlusions with conventional duplex sonography, but were correctly shown with color Doppler flow imaging. In the second phase, sensitivity increased from 50% to 100% (18 or 18) because of better detection of the nearly occluded lumen. This was at the expense of a decrease in specificity (from 100% to 78%). owing to identification of apparent flow in the internal carotid artery on color Doppler flow images in five of 23 occlusions. CONCLUSION: Because of its ability to depict slow flow, color Doppler imaging with slow-flow sensitivity is superior to conventional duplex sonography for the noninvasive discrimination of occlusion from near occlusion of the internal carotid artery.

Arterial Occlusive Diseases↗

PubMed1997

[Potential uses of color Doppler in periskeletal soft tissue neoplasms].

Integrated imaging plays a fundamental role in the study of periskeletal soft tissue tumors, for both diagnosis and treatment planning. The steady and progressive technologic progress of color Doppler US equipment now permits the integration of conventional morphostructural parameters with the biofunctional data of lesion flow patterns and relative qualitative features. To assess color Doppler capabilities in differentiating benign from malignant soft tissue tumors, we reviewed the B-mode and color Doppler findings of 43 consecutive patients with a palpable periskeletal soft tissue mass. All patients were examined with a real time unit (Ultramark 9 HDI), with a broadband (5-10 MHz) linear transducer operating at 6.5 MHz for Doppler measurements. The PRF was set at 1500 to 800 Hz with 70% color gain; a 100 Hz wall filter was used. We kept the color box in the area of interest as small as possible to keep the frame rate high; pulsed Doppler studies were performed with a small sample volume and 2000 Hz PRF. The following signs were considered: morphostructural features; the presence/absence of color signals; the (peripheral/internal) site of vascular branches, their caliber and course; the number of afferent vascular poles; resistance index. As a rule, malignant masses tend to differ from benign masses for the presence of multiple vascular afferent branches, especially if they have an irregular pattern and caliber, and for the variability of the resistance index measured in different parts of the same mass. Further examinations, performed with second level imaging (CT and MRI) and microhistologic tests, respectively after biopsy and surgical resection, confirmed the high predictive value of color Doppler US, with only 1 false negative and 2 false positives; color Doppler sensitivity and specificity were 94.7% and 91.6%, respectively, which are higher values than those obtained with US alone (63% and 66.6%). Therefore, we believe that color Doppler US can be systematically applied to the study of periskeletal soft tissue masses, integrating conventional US for the correct selection of the patients to be submitted to second level investigations.

Adolescent↗

PubMed1996

[Color analysis of Vita shade guide].

In order to understand the reliability of the Vita Shade Guide and make it more resonably in applying, a series of tests were accomplished. Three Vita shade guides were selected in Beijing hospitals. By using the international color standard CIE1976LAB color system and CS-5 Spectrocolorimeter to measure, test and analyse the characteristics of the shade guides including the degree of color, color distribution, color stability and color difference. The results indicate: The tabs of each shade guide demonstrated the greatest color stability; most of the average color difference among the same number tabs of each guide are less than 1.5 NBS and the color range of shade guides are more limited than that of Chinese teeth crown.

China↗

PubMed1996

Preserved color imagery in an achromatopsic.

The loss of color vision secondary to central nervous system disease (achromatopsia) is thought to preclude visual imagery of colors. We report a patient with achromatopsia, secondary to bilateral temporo-occipital infarcts inclusive of the lingual and fusiform gyri, with preserved color imagery. Our findings, in conjunction with previous cases in the literature, are consistent with a single neural network for color processing in which a disconnection of internal activation from stored color representations produces impaired color imagery with preserved color perception, whereas a disconnection of visual input to these representations produces achromatopsia with preserved color imagery.

Cerebral Infarction↗

PubMed2006

Introducing a new computer-based test for the clinical evaluation of color discrimination.

PURPOSE: To evaluate the Portal color sort test (PCST), a new computer-based test of color vision, by comparing it with a series of clinical tests of color vision in normal and color deficient subjects. DESIGN: Prospective clinical laboratory study. METHODS: Fifty-nine subjects with normal trichromatic vision or with congenital color vision defects underwent a series of color vision tests that included the 15-plate Ishihara test, the D-15 Farnsworth-Munsell test (D-15), the Farnsworth-Munsell 100-Hue test (FM 100-Hue), and the PCST under rigorous standardized conditions, as recommended by the respective manufacturers. The PCST generates a numerical discrimination score comparable to the FM 100-Hue. RESULTS: To test validity, discrimination scores generated by the PCST were compared with scores on the FM 100-Hue. The Spearman rank correlation between discrimination scores on the FM 100-Hue and the PCST was 0.8 (P < .001). Reliability was assessed by asking patients to retake the PCST at a later sitting. Patients retaking the PCST achieved similar scores on their second sitting as on the first. The correlation in the score between the two tests was 0.7 (95% confidence interval [CI]: 0.4-0.9, P < .001). Median (quartiles) time to complete the PCST was 3.1 minutes. This was faster than the FM 100-Hue time (P < .001), but slower than both the Ishihara and the D-15 (both P < .001). CONCLUSIONS: This study suggests that the PCST, a test of color vision deficiency, can be used effectively and reliably as a tool for screening (comparable to the Ishihara plates and the D-15) and grading (comparable to the FM 100-Hue) color discrimination ability.

Adolescent↗

PubMedDate not supplied

Color constancy in natural scenes with and without an explicit illuminant cue.

Observers can generally make reliable judgments of surface color in natural scenes despite changes in an illuminant that is out of view. This ability has sometimes been attributed to observers' estimating the spectral properties of the illuminant in order to compensate for its effects. To test this hypothesis, two surface-color-matching experiments were performed with images of natural scenes obtained from high-resolution hyperspectral images. In the first experiment, the sky illuminating the scene was directly visible to the observer, and its color was manipulated. In the second experiment, a large gray sphere was introduced into the scene so that its illumination by the sun and sky was also directly visible to the observer, and the color of that illumination was manipulated. Although the degree of color constancy varied across this and other variations of the images, there was no reliable effect of illuminant color. Even when the sky was eliminated from view, color constancy did not worsen. Judging surface color in natural scenes seems to be independent of an explicit illuminant cue.

Analysis of Variance↗

PubMed1985

Performance of air traffic control tasks by protanopic color defectives.

Air traffic controllers perform a number of tasks which involve color identification, color discrimination, and color naming. Normal color vision is required for air traffic controllers, although the requirement is currently under review. The most critical task involving color is the distinction of red and black on flight strips; the distinction must be made reliably, quickly, and routinely for flight safety. In this study of four protanopes and three normals, all the protanopes were unable to make this distinction reliably under the lighting levels encountered at air traffic control (ATC) centers, whereas none of the normals had any difficulty. Protanopes also made numerous errors with other ATC tasks involving color. The use of a red filter, often recommended to aid color defectives, actually made performance worse and additionally compounded the usual protanopic loss of brightness for red light. When Snellen visual acuity was tested using the red filters, protanopes needed up to four times larger letters than the color normals. It is concluded that protanopes have inadequate vision for safe performance of some current ATC tasks.

Aviation↗

PubMed2006

Evaluation of cerebral dyschromatopsia using color afterimage.

Cerebral dyschromatopsia is traditionally evaluated by color discrimination tests such as the Farnsworth-Maunsell 100 Hue Test. These tests are also used to evaluate color-perception deficits caused by eye disease, and they do not tell us whether color perception is impaired in the eye or in the brain. Here, we used color afterimage to isolate color-perception deficits in the brain from those in the eyes, in a patient with cerebral dyschromatopsia. The results showed that the patient perceived color afterimage of yellow and blue with abnormal duration and chromaticity. On the other hand, the patient performed normally on the Farnsworth-Maunsell 100 Hue Test. We conclude that the color afterimage test would be useful to evaluate color perception in the brain.

Color Perception↗

PubMed1994

Comparison of transesophageal and transthoracic echocardiography with contrast and color flow Doppler in the detection of patent foramen ovale.

We directly compared the utility of agitated saline solution contrast echocardiography and color flow Doppler with both transthoracic and transesophageal echocardiography in the detection of patient foramen ovale (PFO). Forty-three patients referred for contrast echocardiography and transesophageal echocardiography were prospectively studied. Three were excluded because of technically inadequate contrast, and two were excluded because of hemodynamically significant atrial septal defect. The remaining 38 patients, who ranged in age from 19 to 73 years, were referred for cerebrovascular events (31), peripheral embolus (5), atrial septal aneurysm (1), and suspected atrial septal defect (1). With either contrast or color flow Doppler, PFO was detected by transthoracic imaging in 9 (24%) of 38 patients compared with 20 (53%) of 38 with transesophageal echo. PFO was present in 1 (3%) of 38 by TTE color flow, 9 (24%) of 38 by TTE contrast, 17 (45%) of 38 by TEE color flow, and 14 (37%) of 38 by TEE contrast. Discordant findings with TEE were the result of contrast-positive, color-negative results in 3 patients and color-positive, contrast-negative results in 6. With TEE contrast used as a diagnostic gold standard, other techniques detected PFO with the following sensitivities, specificities, and positive and negative predictive values: TEE color flow 79%, 75%, 65%, 86%, respectively; TTE contrast 50%, 92%, 78%, 76%, respectively; and TTE color flow 7%, 100%, 50%, 65%, respectively. Thus PFO is detected more frequently with TEE. TEE contrast and color flow Doppler yielded discordant findings in a minority of patients, probably as a result of intrinsic limitations in each technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗