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PubMed2004

Shading Vita YZ substructures: influence on value and chroma, part I.

All-ceramic restorations should reproduce as well as possible the color of the natural teeth to create a restoration in accordance with the esthetic wishes and ideas of the patient. The basic color of zirconium oxide is white to ivory. The color can be partially adapted by veneering it with ceramic materials. However, it would be better if the substructure could already be adapted to the basic color shade of the neighboring teeth. In this study, the influence of differently shaded frameworks made of Y-TZP by Vita and 3M ESPE and by Enrico Steger (without, with 0.5 mm, or with 1.0 mm ceramic veneer with Base Dentin) on the brightness, saturation, and color shade (= value, chroma, and hue) was measured and assessed with the aid of a spectral photometer (EasyShade, Vita) in a clinical case in the mouth and on the model. By adaptation to the basic shade, the shading of substructures made of Y-TZP can help to reduce the necessary layer thickness of the veneer ceramic to achieve the desired color and should be performed in the future as a matter of routine. In this way, more substance can be conserved when restoring the teeth without having to accept an impairment of the esthetic result.

Color↗
PubMed1998

Acceptability of shade differences in metal ceramic crowns.

STATEMENT OF PROBLEM: Application of technology that quantify color and color differences is currently used in esthetic restorative materials research. However, parameters for the size of perceptible and acceptable color differences in metal ceramic crowns have not been determined. PURPOSE: The CIELAB colorimetric system was used to study the relationship between instrumentally measured color differences (delta E) and human observer assessment of color differences in metal ceramic crowns. MATERIAL AND METHODS: Subjects were shown pairs of metal ceramic crowns whose color difference varied from indistinguishable to obvious. The subjects attempted to discern a difference in each pair's color and indicated the clinical acceptability of the shade difference between the crown pairs. RESULTS: Correlations between instrumental and visual assessment of color differences in these crown pairs did not agree in all dimensions of color space. Thresholds acceptability of color differences were 1.1 delta E units for red-varying crowns and 2.1 delta E units for yellow-varying crowns. Thresholds for perceptibility judgments were significantly lower than thresholds for acceptability judgments. CONCLUSIONS: Acceptability thresholds were found to be dependent on chromaticity. Observers were more sensitive and critical of crowns whose color differed in redness as opposed to crowns whose color differed to the same extent in yellowness.

Chi-Square Distribution↗
PubMed2004

Clinical strategies for success in proximoincisal composite restorations. Part I: Understanding color and composite selection.

The restoration of proximoincisal (Class IV) defects with direct resin-based composites requires attention to many technical and artistic details. This article is the first of a series of two articles that aim at presenting clinical strategies for optimal success when direct resin-based composites are used for the restoration of moderate or large proximoincisal defects. Concepts of natural anatomy, color as it relates to dental structures, and composite selection are discussed in this article and are illustrated with a preclinical exercise and two clinical cases in which these concepts are applied.

Acrylic Resins↗
PubMed2003

Spectrophotometric analysis of all-ceramic materials and their interaction with luting agents and different backgrounds.

In this study, two All-Ceramic (AC) materials--Empress 2 (EMP) (Ivoclar Vivadent AG, Schaan, Liechtenstein) and In-Ceram ALUMINA (ICA) (Vita Zahnfabrik, Bad Säckingen, Germany)--were analyzed, along with the effects of 3 luting agents-viz. Zinc Phosphate cement (ZNPO, PhospaCEM PL, Ivoclar Vivadent AG, Schaan, Liechtenstein), Glass Ionomer Cement (GIC, Ketac-Cem Radiopaque, ESPE Dental AG, Seefeld, Germany), and Compolute (COMP, ESPE Dental AG, Seefeld, Germany)--on the final color, using the CIELab system. Color differences (DeltaL, Deltaa, Deltab, and DeltaE) were calculated for samples with luting agents and for samples without luting agents with standard white and black backgrounds, with the use of a spectrophotometer, Luci 100 (Dr. Lange, Berlin, Germany). One-way ANOVA for DeltaL, Deltaa, Deltab, and DeltaE within both the AC systems, with and without luting agents, showed significant contributions of the background (p < 0.05). EMP was seen to be more translucent than ICA. Darker ceramics showed less color variation. Luting agents altered the final color of the restoration. ZNPO was least translucent, followed by GIC and COMP. Marginal increases in thicknesses of ICA samples (0.4 mm) do not show a statistically significant color difference. No method exists to predict the outcome of an AC restoration based on consideration of the luting agent and the background color.

Analysis of Variance↗
PubMed1995

Shade match of tooth-colored restorative materials based on a commercial shade guide.

Many restorative materials are claimed by their manufacturers to match the Vita shade guide. To verify this claim, 40 dental personnel were asked to color match five different restorative materials to their respective Vita shade tabs according to a 5-point scale (1 = very poor color match; 5 = excellent color match). Three shades were chosen for each restorative material (a mid-Value shade as well as the highest Value shade and the lowest Value shade present in each system). Pooled scores indicated that the resin composite materials had significantly better overall shade match than did the other materials evaluated and that one resin-modified glass-ionomer cement had significantly better shade match than did the "compomer" and another resin-modified glass-ionomer cement. Only 11% of the scores for all material and shade combinations were given a good or excellent rating (score greater than 3). Shade match to the Vita shade guide was not material dependent but tended to differ among the different Value shades evaluated.

Analysis of Variance↗
PubMed1995

Color stability of facial prostheses.

The limited service of facial prostheses is the result of degradation of the elastomer and color instability. Deterioration may be caused by many factors, which include environmental exposure and changes in humidity. This investigation assessed the efficacy of an additive, intrinsic, broad-spectrum ultraviolet light absorber on the color stability of a pigmented facial elastomer. Samples were weathered artificially and outdoors at exposure levels of radiant energy of 150 to 450 kJ/m2. The samples changed color slightly but perceptibly. Artificial aging caused a greater change than outdoor aging. The ultraviolet light absorber UV-5411 did not protect the samples from color changes.

Absorption↗
PubMed2004

[A preliminary study on the color effect of IPS Empress all-ceramic veneers].

OBJECTIVE: To evaluate the opaquing capacity, color compatibility and stability of IPS Empress all-ceramic veneers. METHODS: A total of 86 IPS Empress all-ceramic veneers were made for 18 patients. The patients were divided into three groups: Group A was tetracycline teeth, 64 veneers for 5 patients; Group B was non-tetracycline teeth, 22 veneers for 13 patients; Group C was 22 natural vital teeth with normal color as control group. Before and after veneers were inserted, ShadeEye NCC was employed to obtain L * a * b * values of each tooth. The values of cemented veneers used as the baseline, the L * a * b * values of each veneer were measured half a year, 1 year, and 2 years after restoration respectively. All L * a * b * values at different evaluation times were analyzed by SPSS 10.0. RESULTS: Before and after veneers were restored, the L * a * b * values of both Group A and Group B were significantly different, the color difference being 5.01 and 4.15 respectively. The color difference between Group A and selected shade guides was 2.45. Compared with the baseline value, the L * value of Group A significantly decreased 2 years after restoration, but the DeltaE of different evaluation times was not significantly different. The color difference between Group B and Group C was 0.22 and there was no significant color difference after restoration. CONCLUSIONS: IPS Empress all-ceramic veneers have excellent opaquing capacity, color compatibility and stability to non-tetracycline teeth. To tetracycline teeth IPS Empress all-ceramic veneers have a certain opaquing capacity, but they cannot completely match with shade guides; the L * value is significantly different after restoration and further studies are needed to evaluate its color effect.

Adolescent↗
PubMed2004

[The study on color space of the VINTAGE & UNIBOND standard color].

OBJECTIVE: To research the color space of the standard color board, guide the clinic work of color match, and establish an foundation for deeper researching. METHODS: Through taking analysis of reflecting spectrum and spectral tristimulus, each parameter of the color on standard board was found out. The color difference between border upon colors on board was worked out through matching the color parameters. The number of color space between each border upon color on standard color board, divided by deltaE = 1.5, was found. RESULTS: The number of color space between each border upon color was 3-6. The color space was bigger in group B, but smaller in group D. The color space was bigger in high lightness area, but smaller in low lightness area. CONCLUSION: Some color space has been found between standard color borders of VINTAGE and UNIBOND. Color of natural teeth is unable to be completely included into standard color border, especially in clinical care.

Colorimetry↗
PubMed1996

Masking severely tetracycline-stained teeth with ceramic laminate veneers.

When the primary restorative objective is the reinstatement of vital natural tooth color, dark tetracycline-stained teeth still represent the ultimate challenge for ceramic laminate veneers. Masking severe stain with opaquing composite resins is a significant advancement; however, the procedure requires additional chairtime, is technique sensitive (to avoid excessive opacity), and involves removal of additional tooth structure. The learning objective of this article is to describe and compare two different methods for masking tetracycline-stained teeth. The article illustrates the natural tooth color derived from ceramic laminate veneers when bonded to opaque composite resins in the maxillary arch, and compares it to a new ceramic veneer formulation in the mandibular arch, which masks the stain, eliminates the need for subopaquing with composite resins, and resembles the qualities of natural tooth color.

Anti-Bacterial Agents↗
PubMed1995

Science, art and nature: a case report.

The ceramo-metal restoration still forms the backbone of modern restorative dentistry, despite many new systems. This article discusses a unique ceramo-metal system, its advantages, and clinical and technical applications teamwork between the dentist and the technician is emphasized. IPS Classic (Ivoclar Williams) is a ceramic system with several exclusive features. It encompasses Color Visions, a computer-generated shade system, and the IPS Impulse modifier system allows the ceramist unlimited creativity in color development.

Dental Porcelain↗
PubMed1994

Influence of colorants on crystallization and mechanical properties of lithia-based glass-ceramics.

OBJECTIVES: The objective of the present study was to test the hypothesis that colorants such as AgNO3 and FeCl3 act as conucleating agents with P2O5 in the Li2O-Al2O3-CaO-SiO2 system and that the addition of either colorant and P2O5 produces a greater effect on crystallization and selected mechanical properties than the use of P2O5 alone. METHODS: Microstructural effects were observed by SEM and optical microscopy. Mechanical properties were determined to monitor the effects of structural changes after crystallization. These include controlled-flaw flexure strength, fracture toughness (KIC), and Vickers hardness (VHN). RESULTS: Based on a glass composition of 27.84 mol% Li2O, 2.45 mol% Al2O3, 5.88 mol% CaO, and 63.84 mol% SiO2 (LACS), the mechanical properties of LACS glass-ceramics were influenced by P2O5, the colorant type, and the colorant concentration. The mean strength of the glass-ceramic disks without P2O5 increased with AgNO3 concentration to a peak value of 188 MPa at a concentration of 0.78 mmol%. The maximum value of controlled-flaw flexure strength increased from 120 MPa for one of the FeCl3 groups to 188 MPa for one of the AgNO3 groups. The maximum fracture toughness of glass-ceramic disks without P2O5 (2.45 MPa.m1/2) was associated with a AgNO3 concentration of 0.58 mmol%. This value was significantly greater (p < 0.05) than that of the corresponding group (1.90 MPa.m1/2) which also contained P2O5. There was no significant change in KIC of glass-ceramic specimens containing P2O5 as the AgNO3 concentration increased. The increase in controlled-flaw flexure strength and fracture toughness of specimen groups containing 0.58 to 0.78 mmol% AgNO3 support its use as a colorant and as a nucleating agent in LACS glass-ceramics. SIGNIFICANCE: The development of tougher, higher strength glass-ceramics can be controlled by the use of colorants that are also effective as nucleating agents. Although certain colorants are believed to act synergistically when used in combination with known nucleating agents to enhance the fracture toughness of glass-ceramics, this effect was not observed in this study for the combined use of AgNO3 and the classical nucleating agent, P2O5. In fact, the colorant used in this study (AgNO3) was more effective than P2O5 as a nucleating agent for lithia-based glass-ceramics.

Ceramics↗
PubMed2004

In vitro evaluation of color change in maxillofacial elastomer through the use of an ultraviolet light absorber and a hindered amine light stabilizer.

STATEMENT OF PROBLEM: External prostheses composed of silicone elastomers exhibit an unwanted color change over time. PURPOSE: This study evaluated color stability when an ultraviolet light absorber and hindered amine light stabilizer were mixed in the maxillofacial elastomer containing either organic or inorganic pigments. MATERIAL AND METHODS: The materials used were an RTV silicone elastomer, 1 natural inorganic dry-earth pigment (burnt sienna) and 2 synthesized organic pigments (hansa yellow and alizarin red), ultraviolet light absorber (UVA) and hindered amine light stabilizer (HALS). Specimens (n=160) were fabricated in a custom mold and randomly assigned and exposed to weathering sites in Miami and Phoenix for approximately 3 months. Eight test groups (2 of each 4 material types with or without additives) of 10 specimens each were assigned to each site. L*, a*, b* readings were obtained before and after weathering from a spectrocolorimeter. Nonpigmented elastomers served as the control. Three-factor ANOVA was conducted to examine interaction effects between weathering sites, specimen type, and the presence of additive (alpha=.05). Overall color change (Delta E) and change in color coordinates (Delta L*, Delta a*, Delta b*) of specimen groups with and without additive were analyzed with independent sample t tests. RESULTS: In specimen groups with the additives (UVA and HALS), color change decreased significantly (P<.05) in burnt sienna and hansa yellow in Phoenix and in the control and hansa yellow in Miami. Additives did not affect color change in the alizarin red group. CONCLUSION: UVA and HALS were shown to be effective in retarding color change in some circumstances.

Absorption↗
PubMedDate not supplied

Efficacy of a computerized shade selection system in matching the shade of anterior metal-ceramic crowns--a pilot study.

OBJECTIVE: The purpose of this study was to determine whether anterior crowns fabricated using a computerized shade selection system (ShadeScan, Cynovad) (experimental procedure) match adjacent teeth better than anterior crowns fabricated using conventional shade prescription and clinical slides (control). METHOD AND MATERIALS: Five subjects who required a crown to restore a maxillary central incisor were selected. Two metal-ceramic crowns were fabricated for each incisor, 1 using the experimental procedure and 1 using the control method. The shade selection method to be used for the first and second crowns was randomly assigned. The duration of each procedure was recorded. Each restoration was tried-in in a double-blind manner and evaluated for its level of match to adjacent teeth using modified Ryge criteria. Data were analyzed within each subject using descriptive statistics and paired t test (alpha = .05). RESULTS: In 40% of the cases, both procedures did equally well. In the remaining 60% of the cases the control procedure (two-thirds of the cases) performed better than the experimental procedure (one-third of the cases). Duration of the control procedure was 14.4 +/- 5 minutes, and the experimental procedure was 5.2 +/- 3.3 minutes. A paired t test showed the difference was significant (P = .0045). CONCLUSION: The level of matching of crowns fabricated with the ShadeScan system was not different from crowns fabricated using the control. However, it took significantly less time to record the shade with the ShadeScan system.

Color↗
PubMedDate not supplied

Changes in translucency and color of particulate filler composite resins.

PURPOSE: The purpose of this study was to examine changes in translucency and color of particulate filler composite resins that can be fabricated into metal-free crowns. MATERIALS AND METHODS: Eight types of materials were used in this study. The particulate filler composite resins were represented by Artglass, BelleGlass, Estenia, Gradia, and Targis. Herculite XRV and Solidex were the conventional composite resins for crowns and fixed partial denture facings, and Empress was the ceramic material. Disks with a thickness of 1.0 mm were fabricated from each material and subjected to an accelerated test by immersion in 60 degrees C distilled water for up to 8 weeks. Color measurements were made before and after water immersion. Changes in translucency were evaluated by determining the contrast ratio, and changes in color were evaluated by determining color difference. RESULTS: After water immersion, Targis and Solidex demonstrated a significant increase in contrast ratio (6% to 7%) and a decrease in translucency. A color difference of more than 2.0, a visually perceptible value, was found for Targis, Gradia, and Solidex. However, the maximum color difference for these was 3.0, a value that would be considered clinically acceptable. CONCLUSION: Within the limitations of this study, the particulate filler composite resins were stable in both translucency and color.

Aluminum Silicates↗
PubMed1995

IPS Classic. Science, art and nature: a case report.

The ceramo-metal restoration still forms the backbone of modern restorative dentistry, despite many new systems. This article discusses a unique ceramo-metal system, its advantages, and clinical and technical applications; teamwork between the dentist and the technician is emphasized. IPS Classic (Ivoclar Williams) is a ceramic system with several exclusive features. It encompasses Color Visions, a computer-generated shade system, and the IPS Impulse modifier system allows the ceramist unlimited creativity in color development.

Aluminum Silicates↗
PubMed2002

Shade-match perception of porcelain-fused-to-metal restorations: a comparison between dentist and patient.

BACKGROUND: Patient satisfaction with the shade match of restorations has not been appraised carefully in the dental literature. This study compared patients' and a prosthodontist's satisfaction with the shade o f existing porcelain-fused-to-metal, or PFM, restorations. METHODS: The authors selected a convenience sample of 212 patients for this study. Patients and a prosthodontist were asked independently, under standardized conditions, to express their satisfaction with the shade match of the patient's restoration. Kendall's tau-b statistic was used to measure the strength of the association between the shade satisfaction rating of the patient and that of the prosthodontist. The authors also examined patient satisfaction with respect to sex, treatment location and clinician. RESULTS: The prosthodontist was less satisfied than the patient with the shade match in a significant number of cases. The authors found no difference in patient satisfaction with respect to sex. They did find that patients were more satisfied with the shade match of restorations placed by a prosthodontist or placed under the supervision of a prosthodontist than they were with restorations placed by general practitioners. CONCLUSIONS: Patients were more satisfied with the shade match of their PFM restorations than was the prosthodontist. Patients also were more satisfied with restorations placed by a prosthodontist or placed under the supervision of a prosthodontist in a hospital or academic setting. Clinical Implications. Patient satisfaction with shade match is important when constructing or replacing a restoration, and the level of satisfaction might be different from that of the clinician. When selecting restoration shades, clinicians should take into consideration the opinions of their patients.

Adult↗
PubMedDate not supplied

Color stability of visible light-cured, hard direct denture reliners: an in vitro investigation.

PURPOSE: Previous studies have disclosed the unsatisfactory color stability of autopolymerizing, hard direct denture reliners (HDDR). The present study investigated the color stability of the newly introduced visible light-cured and dual-cured HDDRs. MATERIALS AND METHODS: Five HDDRs were evaluated after 1 hour, 1 day, 7 days, and 30 days of immersion in coffee, tea, and water. Color measurements were obtained with a tristimulus colorimeter, and color differences (delta E*) were calculated. RESULTS: After 30 days of immersion one visible light-cured material exhibited the highest delta E* value (17.8). The other materials showed acceptable color stability in water and coffee. However, tea strongly affected their color. CONCLUSION: Reliners, staining solutions, and immersion time are significant factors that affect color stability. After 7 days of immersion, all of the materials showed perceptible color differences. Tea exhibited higher staining capacity than coffee.

Analysis of Variance↗
PubMed1993

Color mixing in dental porcelain.

For esthetic reasons, pigments and opacifiers are added to porcelains used in restorative dentistry. The purpose of this study was to use Kubelka-Munk theory (Kubelka and Munk, 1931) to predict and analyse the colors of porcelains modified by the addition of two pigments and an opacifying agent. The base porcelain was composed of 88% potassium feldspar, 6% quartz and 6% kaolin. The porcelain was modified by the addition of a yellow (Pr-Zr-Si) or a brown (Fe-Cr-Zn) stain and an opacifier (10% SnO in base porcelain). After firing at 1200 degrees C for 30 min, reflectance spectra of the various combinations were obtained with a spectrophotometer. Reflectance spectra, except at low wavelengths, were influenced by increased scattering due to the addition of the opacifier. Calculated values from Kubelka-Munk theory for absorption coefficients and scattering coefficients with appropriate correction factors were compared with the values from the reflectance spectra of the combinations. In general, good agreement was obtained if the scattering coefficient of the opacifier is set equal to 1.0. Using the L*a*b* transform of the CIE color space, it was found that this transform provided uniform color intervals for equal changes in pigment concentration.

Analysis of Variance↗