Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Prosthesis Coloring”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Motif expressing soft print lenses. Effect on visual function].

BACKGROUND: Contact lenses which change the structure and color of the iris are used not only for many therapeutic situations but also for cosmetic reasons. The purpose of this study was to investigate whether such lenses cause impairment of visual functions. MATERIAL AND METHODS: In healthy volunteers with an uncorrected visual acuity of 20/20 a clear soft-fitting lens and a special effect soft contact lens (Crazy lens, Bach Optic, Cologne) were tested in changing sequence. The following parameters were studied: visual acuity, contrast sensitivity (MCT 8000, VisTech Cons., Dayton, Ohio), Goldmann visual field, mesopic vision (Nyktometer, Rodenstock, Munich), and subjective wear comfort on a scale from 1 (excellent) to 10 (poor). Statistical analysis was performed using the Wilcoxon test and the Mann-Whitney U-test. RESULTS: Nine volunteers with a mean age of 29.9 +/- 5.1 years were analyzed. Visual acuity was reduced to 0.9 +/- 0.23 in the Crazy lens group compared to 1.2 +/- 0.13 in the clear lens group. Mesopic vision without glare was reduced from 1:2.5 to 1:7.4. Goldmann visual field displayed a significant constriction of following isopters: III/4, I/4, and I/3. Contrast sensitivity was significantly reduced in a photopic condition with and without glare and in a scotopic condition without glare; there was, however, an increase in contrast sensitivity in a scotopic condition with glare. Furthermore a decrease in wear comfort from 2.8 +/- 1.4 with the clear fitting lens to 5.7 +/- 2.1 with the print-lens was found. CONCLUSION: The tested special-effect contact lenses are associated with a reduction of many visual functions, including visual acuity and contrast sensitivity. This may interfere in some wearers with the ability to drive a car.

Adult↗
PubMed1994

Influence of P205, AgNO3, and FeCl3 on color and translucency of lithia-based glass-ceramics.

OBJECTIVES: The objective of this study was to characterize the influence of various metals, metal compounds, and P2O5 as a nucleating agent on the color and translucency of a Li2O-Al2O3-CaO-SiO2 glass-ceramic. METHODS: Glass frits of Li2O-Al2O3-CaO-SiO2 (LACS), LACS with 1 mol% P2O5 (LACSP), and/or LACS with one of 16 colorants were melted, poured into a cylindrical graphite mold, cut into disks, annealed, nucleated, crystallized, and annealed again. Ten translucency measurements of each of five disks were made using a tristimulus colorimeter and a D65 standard CIE illuminant. The color of each disk was analyzed using the CIE L*a*b* color space system (1976) as a function of colorant, colorant concentration, and P2O5. RESULTS: Mean L* values of glass-ceramic disks ranged from 63.5 for LACS containing 6.2 mmol% FeCl3 (LACSP-6.2Fe) to 84.1 for LACS. No significant difference (p > 0.05) was found between the mean L* values for LACS, LACSP, and LACS with 0.19 mmol% AgNO3 (LACS-0.19Ag). The mean contrast ratio of glass-ceramic specimens ranged from 0.42 (LACS and LACS-1.0Fe) to 0.98 (LACS-0.78Ag). Mean color difference values varied from 5.8 (LACSP-1.0Fe vs. LACS) to 36.3 (LACSP-0.78Ag vs. LACSP). SIGNIFICANCE: The results of this study indicate that, because certain colorants in glass-ceramics affect opacity as well as hue and chroma, the development of glass-ceramics should be simplified by: 1) employing a nucleating agent that does not affect hue or chroma significantly, 2) controlling fixed levels of translucency consistent with mechanical and physical property requirements, and 3) varying the hue and chroma by means of colorants that do not affect the crystallization process. This implies that the volume fraction and mean size of crystals must be controlled, since the translucency or opacity of glass-ceramics is associated with scattering of light at the interfaces between adjacent crystals, and between crystals and the glass phase because of differences in refractive indices (McMillan, 1979a).

Analysis of Variance↗
PubMed1999

Color stability of denture base acrylic resins in three food colorants.

STATEMENT OF PROBLEM: Three commonly used artificial dyes in food technology are erythrosine, tartrazine, and sunset yellow. PURPOSE: The color stability of 5 commercially available denture base acrylic resins (QC-20, Meliodent, Trevalon, Trevalon High, and Lucitone) was studied in vitro. METHODS: The specimens were exposed to 3% erythrosine, tartrazine, and sunset yellow solutions at 23 degrees C +/- 1 degrees C. Color changes were determined with a computer-controlled spectrophotometer. Five specimens from each material were processed, and initial color measurements were made after 1, 3, and 6 months of exposure to the staining solutions. Finally, the color stability was quantitatively measured again, and color differences (DeltaE) were calculated. RESULTS: For the observations made in 1, 3, and 6 months intervals, the specimens that exhibited the least color change were in the sunset yellow solution. The greatest color changes observed according to the National Bureau of Standards unit system were Lucitone (2.71) in erythrosine solution, Lucitone (2.54), QC-20 (1.71) in tartrazine solution, and QC-20 (1.66) in sunset yellow solution. The changes in the other acrylic resins in the 3 solutions were slight and at trace level. CONCLUSIONS: All materials tested were acceptable from the standpoint of color stability for long-term exposure to these food colorants.

Acrylic Resins↗
PubMed1998

Light transmittance characteristics of light-cured composite resins.

OBJECTIVES: The purpose of this study was: (1) to examine the light transmittance characteristics of various shades of light-cured composite resins, and (2) to evaluate the effect of light transmittance characteristics on the color of the resins. METHODS: Eleven shades of two composite resins were used. Specimens with four different thicknesses (0.5, 1.0, 2.0 and 3.0 mm) were prepared. The transmittance at wavelengths from 400 to 700 nm was measured. Also, the color values and the color differences among thicknesses of a specimen on the CIE L*a*b* color system were determined by a digital chroma meter. The differences in the transmittance, color values and color difference were determined by using a one-way analysis of variance (ANOVA) combined with a Tukey multiple-range test. RESULTS: Significant differences were found in the wavelength dependence of transmittance between the two materials, and among shades of each material. The transmittances of the darker shades of one material were significantly lower at lower wavelengths than the other shades, but were nearly equal or significantly higher at higher wavelengths. There was a significant correlation between the changing ratio of transmittance and the color difference. Two materials showed significant differences in delta a* and delta b* of the chromatic component of color difference. SIGNIFICANCE: The results of this study indicate that light transmittance characteristics, including the wavelength dependence, play an important role for the color of a composite resin. The significant difference in light transmittance characteristics among materials and shades will affect their clinical appearance.

Analysis of Variance↗
PubMed2000

Evaluating porcelain color match of different porcelain shade-matching systems.

PURPOSE: This in vitro study was designed to evaluate the new ShadeEye-EX Chroma Meter and a new visual porcelain shade-matching system (Vitapan 3-D Master, Omega 900) in comparison to the traditionally used visual porcelain shade-matching system (Vita Lumin Vacuum, VMK 68). MATERIALS AND METHODS: Shade matches and porcelain fabrications on individualized shade tabs were carried out. The fabricated porcelain tabs were evaluated against the respective natural tooth using the United States Public Health Service (USPHS) criteria to determine clinically acceptable match. The tabs also were ranked according to the final-color match to the corresponding natural tooth. RESULTS: The percentage of clinically acceptable color matches were as follows: Vita Lumin Vacuum (46.67%), ShadeEye-EX (40%), and Vitapan 3-D Master (56.67%). The generalized estimating equation (alpha = 0.5) showed no statistically significant difference between systems in obtaining a clinically acceptable match (p = .5729). The chi-squared test (alpha = 0.5) showed no statistically significant difference between systems in terms of rank order (p = .5017). The two new systems do not produce color match that is better than the conventional visual porcelain shade-matching system.

Chi-Square Distribution↗
PubMedDate not supplied

Translucency parameter of colorants for maxillofacial prostheses.

The masking power of various generic, dry mineral earth, and flocking colorants dispersed in medical-grade silicone elastomer was investigated. Reflectance measurements were made by diffuse reflectance spectrophotometry using black and white backings. These data were reduced to optical scattering and absorption coefficients through the use of the Kubelka-Munk reflectance theory. The color difference between a 0.13-cm-thick layer of the colored elastomer placed on an ideal black backing and this layer on an ideal white backing was calculated and established as a translucency parameter. Using analysis of variance and stepwise comparison testing, significant differences were found among the translucency parameters of the colorants. Since these colorants differ substantially in their ability to mask underlying colors and since the translucency of maxillofacial material is an important aspect of color measurement and natural appearance, differences in these colorants go beyond their obvious differences in color.

Absorption↗
PubMedDate not supplied

Using a computer color-matching system in color reproduction of porcelain restorations. Part 3: A newly developed spectrophotometer designed for clinical application.

This paper reports the development of a newly modified, noncontact spectrophotometer for clinical use. The instrument is capable of accurately measuring the color within small areas (1 x 2 mm) of a tooth. This spectrophotometer used a 45 degree/0 degree geometry, a 150W halogen lamp, and fiberoptics to focus the light, together with a lens having a focal point distance of 85 mm. A movable platform was added to the apparatus to automatically scan and measure the color of specific areas. Short-term repeatability indicated the color difference delta E to be approximately 0.15.

Color↗
PubMedDate not supplied

The in vitro color stability of acrylic resins for provisional restorations.

This study made an in vitro comparative evaluation of the color variation of four types of acrylic resin for provisional fixed prostheses, as determined using computerized spectrophotometry, before and after a 20- and 30-day cycle of immersion in four staining solutions. The four acrylic resins used for provisional fixed restorations were: Cold Pac, Trim, Protemp, and Mixacryl II. Thirty-two specimens for each resin were divided into four subgroups of eight elements, immersed in the four staining solutions (synthetic saliva, synthetic saliva and tea, synthetic saliva and coffee, and synthetic saliva and chlorhexidine in 0.12% water solution), and then placed into four thermostatic baths at 37 degrees C +/- 1 degree C. All specimens were measured for each resin before immersion (baseline). After 20 and 30 days, the specimens were analyzed by computerized spectrophotometry and compared. All data were analyzed with analysis of variance for repeated measures (P < .05). Only the Cold Pac resin was color stable in all staining solutions, while the others showed color changes from the different staining solutions.

Acrylic Resins↗
PubMed2000

Double-layer porcelain veneers: effect of layering on resulting veneer color.

STATEMENT OF PROBLEM: Densely sintered aluminum oxide veneered with feldspathic porcelain seems to be a promising technology for the fabrication of porcelain laminate veneers, which provide both strength and esthetics. To effectively use this approach for porcelain veneers, practitioners should know how the resulting color is affected by adding a layer of veneering porcelain onto the aluminum oxide. PURPOSE: This study compared changes in CIE L*a*b* color coordinates of simulated stained teeth when covered with the aluminum oxide core disks alone and after the disks had been veneered with 3 different shades of porcelain. MATERIAL AND METHODS: Fifteen aluminum oxide disks were divided into 3 groups. Each of 5 disks was veneered with porcelain of the Vita shades A1, A2, and B4, respectively. The colors of the substrate covered with the nonveneered disks and the veneered disks were measured separately, and the color differences were calculated. Measurements of the disks on a white background were also performed and used as controls. The extracted data were compared with Vita shade values available from the literature. RESULTS: Statistically significant differences in color coordinates of dark substrates were recorded between the substrate covered by an aluminum oxide disk and the addition of veneering porcelain to the aluminum oxide disks. Veneering the aluminum oxide disks with A1, A2, and B4 porcelain produced significant differences in the resulting color when placed on a dark substrate. The direction of the color modifications correlated with values obtained from the literature. The resulting color was also affected by the color of the underlying structures. CONCLUSION: Although aluminum oxide alone does have a degree of masking capability, the resulting color of porcelain veneers with the use of this material can successfully be modified with the veneering porcelain.

Aluminum Oxide↗
PubMed1995

Development and assessment of an objective method of colour change measurement for acrylic denture base resins.

Current standard specifications for the laboratory evaluation of denture base materials require subjective assessment of colour stability. This study evaluates a new objective measurement technique for translucent denture base materials, by comparing quantitative data with the results obtained from a standard subjective method. Preliminary work on three representative commercial acrylic materials resulted in the selection of a white background for the quantification of colour change of these translucent materials. One half of each sample was exposed to artificial sunlight for 24 h. The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photo-electric colorimeter. Significant changes in the b* and E* values (P < 0.01) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials.

Acrylic Resins↗
PubMed2002

Curing-dependent changes in color and translucency parameter of composite bleach shades.

PURPOSE: The goal of this study was to evaluate curing-dependent changes in color and translucency parameter (TP) values of composite bleach shades. MATERIALS AND METHODS: Thirty bleach shades of microhybrid and microfill composites were analyzed. Specimens (n = 5) were made as disks, 10 mm in diameter and 2 mm thick, using cylindrical molds. Specimens were polymerized for 60 seconds using a light-curing unit. Data were collected before and after composite curing using a spectrophotometer and analyzed using the appropriate color-difference metric equations. RESULTS: L*a*b* ranges (maximum minus minimum values) for microhybrids were 17.7, 2.91, and 7.97, respectively. Corresponding ranges for microfills were 14.4, 1.26, and 4.27, respectively. Curing-dependent color differences varied from 3.7 to 12.0 deltaE* units, whereas TP values of cured resin composites varied from 2.0 to 7.1. Light-curing caused increase of microhybrid TP values (+0.7) and decrease of microfill TP values (-0.7). Color differences were found to be acceptable for five of six composite pairs of the same shade designation (each of them made by the same manufacturer) in post-curing measurements against white background. CLINICAL SIGNIFICANCE: Curing-dependent color and TP changes indicate that dentists should use cured composite for matching of shade and translucency. Tested materials became less saturated, with microhybrids becoming darker and microfills becoming lighter after polymerization. Light-curing caused an increase in translucency of microhybrids and a reduced translucency in microfills.

Color↗
PubMedDate not supplied

The importance of laboratory communication in modern dental practice: stone models without faces.

The development of advanced communication technology has enabled clinicians and ceramists to deliver improved dental care to their patients. This article highlights the importance of communication between the clinician, laboratory technician, and patient for the fabrication and delivery of aesthetic restorations. The use of stone models, photography, shade prescriptions, and occlusal relationships is demonstrated as a means to achieve this objective. These principles are illustrated in the restoration of a patient who presented for aesthetic enhancement of the anterior maxilla.

Color↗
PubMed1999

Use of a common shade guide to test the perception of differences in the shades and value by members of the dental team.

PURPOSE: Commercial shade guides are frequently used for treatments where the shades of teeth are being reproduced or altered. Where differences between shade tabs and the natural teeth are small, difficulty is often experienced in determining the closest match. The purpose of this investigation is to discover whether the claimed colour differences between individual shades of one commonly used guide can be determined subjectively in clinical circumstances. BASIC PROCEDURES: Seventy dental team professionals made shade comparisons in an idealized colour-matching environment using shade guides as supplied by the manufacturer. Their arrangements by 'value' were recorded and unidentified shade tabs were matched with those on a complete guide. MAIN FINDINGS: The results showed that discrepancies existed between nominated and perceived colours, for the shade determination system tested. The shade-guide manufacturer's recommended arrangement of shade tabs ranked according to colour 'value' did not correspond to subjective perception of 'value' ordering under the conditions of the study. PRINCIPAL CONCLUSIONS: There may be no practical clinical advantage in having shades which cannot be distinguished. This study indicates that colour differences between shade tabs are not clearly perceived by members of the dental team. A careful reduction of the number of tabs in the guide tested might simplify shade selection procedures and help to standardise shade-taking.

Color↗