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PubMed2006

Comparison of the shade matching ability of dental students using two light sources.

STATEMENT OF PROBLEM: Shade selection is affected by a host of variables, including lighting. PURPOSE: The purpose of this study was to assess the ability of dental students to match shades under natural lighting and using a light-correcting device, specifically to determine whether there are differences based on: (1) year in school, (2) gender of student, and (3) light source. MATERIAL AND METHODS: A 14-item shade matching quiz (SMQ) and a questionnaire were field tested. No major modifications were made to SMQ or questionnaire. Demographic information included year in school, age, gender, previous experience, and Ishihara's Tests for Color-Blindness. The SMQ was administered on separate occasions during the spring and summer, under natural light (SMQ-NL) and using the light-correcting device (SMQ-CL). For each of the 14 items, students (n=216) were to select the matching shade tab from 5 preselected tabs. Statistical analyses included ANOVAs, paired t tests, and independent t tests (alpha=.05). RESULTS: A total of 165 male and 51 female students participated, with an average age of 26 years. SMQ scores of 10 color-deficient students were excluded. There were no significant differences in SMQ-NL and SMQ-CL among the first through fourth year students (ANOVA), nor between men and women (t tests). The SMQ scores were significantly higher with the light-correcting device than with natural light: 11.4 +/- 1.9 and 10.4 +/- 2.0, respectively (paired t test, P<.001). With and without the light-correcting device, the Vita C shades were less likely to be matched than the Vita A or B shades (paired t tests, P<.001). CONCLUSIONS: Dental students' shade matching abilities were better with a light-correcting source than under natural light. Gender and experience were not found to be factors in matching shades. The Vita C shades were least likely to be matched.

Adult↗
PubMed1998

Color stability of provisional resin restorative materials.

STATEMENT OF PROBLEM: Use of temporary crowns and fixed partial dentures is especially relevant when the treatment plan requires restorations for long interim periods, and the in-service discoloration of provisional restorative materials is a major drawback. PURPOSE: This study evaluated the discoloration effect of coffee and tea on some materials that are commonly used in the fabrication of provisional restorations. MATERIAL AND METHODS: Six commercially available provisional resins (Jet, Caulk TBR, Protemp Garant, Luxatemp Solar, Provipont DC and SR-Ivocron-PE) were evaluated after 1 day, 7 days, and 30 days of immersion in various staining solutions. Color measurements were obtained by using a Dr Lange Micro Color tristimulus colorimeter and color differences (delta E*) were estimated. RESULTS: The 2 chemically activated resins (Jet and Caulk TBR) and the heat-cured resin (SR-Ivocron PE) exhibited the least color changes, whereas the Provipont-DC resin was the least color stable. After immersion for 30 days, the combination with the coffee solution resulted in unacceptable discoloration for all the tested materials. CONCLUSIONS: Provisional restorative materials, staining solutions, and immersion time were significant factors that affected color stability. After immersion for 7 days, all materials showed observable color changes. The composite-based materials, especially light-curing composites, were the least color stable. The coffee solution exhibited more staining capacity than the tea solution.

Analysis of Variance↗
PubMed1998

Evaluation of visual and instrument shade matching.

STATEMENT OF PROBLEM: Visual color matching to determine shades in dentistry is inconsistent and unreliable. If accurate, instrumental measurement of tooth color would provide objective, quantified data to match natural teeth to clinical shade guides. PURPOSE: This study evaluated and compared the ability of a new computerized colorimeter and a simple visual test to match ceramic shade guide teeth. MATERIAL AND METHODS: Thirty-one (n = 31) observers with normal color vision were allowed unlimited time to match one set of Vita Lumin shade guide teeth to the corresponding shade guide teeth of a second Vita Lumin shade guide. The same test was administered to 14 of the observers several months later to determine within-subject variability. A computerized colorimeter (Colortron II) equipped with a positioning guide was used to measure the middle third of each shade guide tooth. Through a "match tool" present in the computer's software, readings from one shade guide were matched with readings of the other shade guide by using CIELAB measurements and DeltaE values. The mean number of correct matches by the colorimeter and of correct matches in visual test were compared with a 1-tailed t test. Repeatability for both tests was determined with a paired t test. RESULTS: The Colortron II instrument correctly matched 8 of the 16 tabs (50% correct), whereas visual matching by examiners averaged 7. 7 of 16 correct matches (48% correct) (standard deviation 2.7). No statistically significant differences existed between the 2 methods. The colorimeter demonstrated 100% repeatability and the visual test demonstrated fair repeatability (correlation coefficient r =.60). CONCLUSIONS: Shade determination by visual means was inconsistent. Accuracy of a new colorimeter in matching porcelain shade guide teeth was only slightly better.

Ceramics↗
PubMed1999

Five-year color changes of light-cured resin composites: influence of light-curing times.

OBJECTIVES: The purpose of this study was to investigate the influence of light-curing times on the color changes of light-cured resin composites, over specified periods of time. METHODS: Silux Plus (3M Dental Products) light-cured resin composite disks (shades: U, Y, DY, L, G, UO, YO), 10 mm in diameter and 1 mm in thickness were prepared with 20, 40, and 120 s of light exposure through a 1 mm thick glass plate. The specimens were stored in artificial saliva at 37 degrees C. Colorimetric values of the specimens immediately after curing and after every 6 months for 5 years were measured backed by a light trap, and a white colored plate using a fast spectrophotometer. The CIE 1976 L*a*b* color system was used for the determination of the color difference. RESULTS: For specimens backed by a white colored plate, the delta E*ab of all shades increased for 3 years and 6 months to 5 years, to the time elapsed during all curing times. However, the a*b* values to the time elapsed differed among the shades and light curing times. In the 20 and 120 s curing time groups, the opacity% of all shades increased for 4 or 5 years to the time elapsed. SIGNIFICANCE: The modes of color changes of Silux Plus resins differed among the shades and light curing times.

Analysis of Variance↗
PubMedDate not supplied

Human-eye versus computerized color matching.

This project compared the difference in color matching between human-eye assessment and computerized colorimetry. Fifty dental personnel were asked to color match Vita Lumin shade tabs to seven different randomly arranged test tabs from the Z100 shade guide. All evaluators were blinded to the shades of the test tabs and were asked to match only body shade of the Vita Lumin tab to the middle third or body of each test tab. The results obtained were subsequently computed into L*a*b* values and compared with results obtained by computerized colorimetry. Results indicate that the difference in color matching between human-eye assessment and computerized colorimetry is shade dependent. Discrepancy was significant for b* coordinates for shades A1 and B2 and L* and b* coordinates for shade C4. For all shades evaluated, color difference between human-eye and computerized color matching is perceivable under clinical settings, as delta E values are greater than 3. There is a need for correction factors in the formal specification of the color-matching software due to the discrepancy between human-eye and computerized colorimetric color matching.

Color↗
PubMed2000

Tooth colour analysis by a new optoelectronic system.

The difficulties in assessing and comparing tooth shades are well documented. This pilot study introduces an alternative method of photoelectric tooth colour measurement, the silicon photodiode array apparatus. This apparatus was used to determine colorimetric values for samples of acrylic resin teeth and the results compared with colour values obtained using a conventional photoelectric tristimulus colorimeter. Whilst a significant difference was found between some colorimetric data produced by the two types of apparatus for the same sample these differences existed purely at the mathematical level and would not be perceived by a human observer.

Acrylic Resins↗
PubMed2003

Dimensions of color: creating high-diffusion layers with composite resin.

The objective of this article is to provide the clinician with fundamental principles for achieving success with directly placed composite resin restorations in posterior teeth. It describes the adhesive technique and protocol for the development of tooth-colored composite restorations in the posterior dentition by integrating the concepts of function, form, and color. A case presentation demonstrates the anatomical stratification and proper placement of tints and opaquers for the development of the direct posterior composite resin-bonded restoration. Used with an understanding of tooth morphology, restorative material selection, color options, and the physical properties of light, these techniques allow optimally esthetic restorations to be predictably achieved.

Color↗
PubMed2003

Simplified techniques for the placement of stratified polychromatic anterior and posterior direct composite restorations.

Although many tooth-colored indirect restorative materials are available, dentists frequently employ direct composite resins as a primary tooth-colored restorative material. Direct resin systems that are suited for stratification, or layering of various opacities and colors of dental composite, offer dentists the opportunity to accurately reproduce natural teeth in ways that rival the esthetics of most indirect systems. This article presents a simplified version of the classical three-layered technique originally described by Dietschi, and demonstrates the application of a recently introduced composite resin system.

Adult↗
PubMed2003

Color matching with composite resin: a synchronized shade comparison.

While traditional shade guides have been developed to facilitate shade selection for various restorative procedures, these tools are often fabricated according to the properties of porcelain materials rather than composite resin options. Contemporary composite resin restorations are often fabricated using incorrect guides that can compromise the final result. This article describes a predictable procedure for shade determination, shade mapping, and custom shade tab fabrication for predictable restoration using direct composite resin materials.

Color↗
PubMedDate not supplied

Optimizing shade match using all-ceramic and composite materials.

Aesthetic management of the anterior dentition often requires the restorative team to use materials of varying color properties. The utilization of shade-selection devices to assist in color interpretation along with dental photography can improve communication between dentist and technician. Additionally, a shade guide system that addresses the four components of color in both ceramics and composites can have a profound impact on the predictability of matching different restorative materials. This article addresses several key elements that should be considered when utilizing different restorative media.

Color↗
PubMed1994

[Color determination in dental ceramics].

Determining the appropriate color of an esthetic restoration is an important step in dental treatment. In this study instead of a shade guide the validity of a recently available objective colorimeter Castor has been investigated. A porcelain-fused-to-metal porcelain (PFM) (Biodent B2), the sinter-porcelain Mark II and the glass-porcelain Dicor have been spectrometrically studied, as well as a Vita shade guide. The Castor equipment has been used for all measurements. The lightness (L*) of the PFM porcelain was not altered by the glaze firing, whereas the red-green-values (a*) tended towards red and the blue-yellow-values towards blue. Total color value (E*) and lightness (L*) of Mark II and Dicor decreased with rising thickness of the samples. At and above a thickness of 1.5 mm, the background had only marginal influence on the L*a*b*-values. It was noticed, that the order by decreasing lightness within the shade guide did not meet official manufacturer declarations, whereas color intensity correlated evidently with the specification. The Castor equipment for color determination is an interesting innovation in dentistry. For the first time and in an economic reasonable frame it permits objective evaluation of color characteristics, such as lightness (L*), red-green (a*) and yellow-blue (b*).

Color↗
PubMed1996

Color differences between resin composites and shade guides.

The color of manufacturers' shade guides was compared with the color of the actual resin composites. Five light-activated resin composite products were evaluated. Resin specimens and shade guides of same thickness were measured with a spectrophotometer. Color differences (delta E* values) were more than perceptible in all products. The mean delta E* values were least in Z100 and greatest in Herculite XR. Generally, the L* and b* values of the shade guides were higher than those of the resin composites. Some colors showed color differences greater than the acceptable level.

Color↗
PubMedDate not supplied

Gold color in dental alloys.

This article will help the dental laboratory with alloy selection by exploring how the relationship among color, ductility and strength applies to gold and how color can be quantified. Because higher quality materials translate into higher profits, upselling to the dentist and patient is also discussed.

Color↗
PubMed1998

Shade selection: problems and solutions.

This article introduces shade selection as an act of communication rather than a quasi-science that has failed for generations. The use of three simple items: the Pensler Shield, the Kodak Color Viewing Light Selector Card (P3-180), and a patient-oriented prescription form solve the major problems in shade selection. Shade selection must be taught with an understanding of the psychology of vision and a communication of what you think you see.

Color↗
PubMed2005

Discoloration of dental resin composites after immersion in a series of organic and chemical solutions.

The objective of this study was to evaluate the color change of dental resin composites following a series of immersion treatments, especially in organic substances. The color of four resin composites was measured according to the CIELAB color scale relative to the standard illuminant D65. Color was measured at baseline, and after sequential immersion in the following substances: Step 1, porcine-liver esterase (a substitute for a salivary esterase); Step 2, organic substances (mucin and serum) and phosphate-buffered saline (PBS) as a control; Step 3, chemical alteration agents [chlorhexidine (CH) and carbamide peroxide (CP)]; and Step 4, 2% methylene blue. Porcine-liver esterase caused color changes (DeltaE(ab) (*)) of 0.7-1.1 from the baseline. Organic substances caused color changes of 0.4-1.8 from the baseline, and color changes in organic substances were not significantly higher than those in PBS (p > 0.05), except for one composite. Combined treatment with mucin (or serum) with CH (or CP) did not produce significantly higher color changes compared to controls (p > 0.05). Mucin-treated composites showed generally lower methylene blue staining compared to serum and PBS groups. Although combined treatment of organic substances and chemical agents resulted in various discolorations of resin composites, chemical alteration of organic substances did not produce higher color change compared to PBS controls.

Animals↗
PubMed2000

Color stability of new-generation indirect resins for prosthodontic application.

STATEMENT OF PROBLEM: Several new-generation indirect resins are being advocated for full contour restoration of teeth. Previous indirect resin systems have failed in this application, due in part to color instability. PURPOSE: This study evaluated and characterized the color stability of various new-generation indirect resins (ceramic-polymers) when subjected to accelerated aging. MATERIAL AND METHODS: Four new-generation indirect resin systems, 1 direct resin system, and 1 dental porcelain control were subjected to accelerated aging for a period of 300 hours. Initial specimen color parameters were determined in the Commission International de l'Eclairage Lab (CIELAB) color order system with a colorimeter. Color changes (DeltaE) were calculated between baseline color measurements and measurements made after 150 and 300 hours of accelerated aging. Color difference data were subjected to a 1-way analysis of variance to examine the interaction between material and time interval of aging. Where significant interactions occurred, a least-squared means test was performed to identify differences in the color stability between the materials (P </=.05). RESULTS: After 300 hours of accelerated aging, color changes of the indirect resins ranged between 0.62 and 3.40 DeltaE units. Two of the products tested demonstrated color stability that was not significantly different from the porcelain control. CONCLUSION: All the indirect resins tested demonstrated color stability at or below a quantitative level that would be considered clinically acceptable. Color changes of ceramic-polymers occurred because of changes in chroma, rather than alterations in lightness.

Analysis of Variance↗