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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↗
PubMedDate not supplied

Color stability of resin cements after accelerated aging.

The color stability of both light- and dual-polymerized samples of three shades of three commercial resin cements was measured using a reflection spectrophotometer after accelerated aging over a period of 179 hours. Porcelite cement was the most color stable, followed by Optec and then 3M. The Optec and Porcelite cements changed color after accelerated aging, but with one exception the changes were not perceptible. Five of six 3M cements had perceptible color changes after accelerated aging, becoming darker and more yellow. The two lighter shades of Optec and 3M changed color more than the darker shade. Most differences between light- and dual-polymerized samples were significant but none was perceptible.

Analysis of Variance↗
PubMedDate not supplied

Comparison of aesthetic properties of tooth-colored restorative materials.

The objective of this study was to compare the aesthetic properties of color and translucency of Vita shade-based tooth-colored restorative materials, including composite resins, a polyacid-modified composite resin, and resin-modified glass-ionomer cements via clinical discrimination by human evaluators. The hue/chroma, value, and translucency of the five different materials chosen to represent the range of commercially available tooth-colored restoratives were graded by 40 dental personnel against the body of their respective Vita shade tabs using a five-point scale (1 = very poor; 2 = poor; 3 = average; 4 = good; 5 = excellent). Results confirm the clinical observation that the hue/chroma, value, and translucency of the different materials evaluated do not match the Vita shade guide to which they are supposedly keyed. The aesthetic properties of hue/ chroma, value, and translucency for the material evaluated were all shade dependent. Comparison of pooled results revealed that none of the materials had good or excellent ratings and that the composite resins had significantly better hue/ chroma, value, and translucency match to the Vita shade guide than the other materials evaluated.

Color↗
PubMedDate not supplied

The effect of core translucency on the aesthetics of all-ceramic restorations.

Recent advances in ceramic technology have revolutionized aesthetic dentistry. When treating a single anterior tooth in need of a full-coverage restoration, a multitude of options in restorative materials and techniques is available to the clinician. The learning objective of this article is to present and evaluate a selection of all-ceramic dental materials currently available for aesthetic full-coverage crown restorations. When selecting an all-ceramic system, there are several major factors to consider, including the inherent translucency of the ceramic material and of the adjacent dentition, the color of the prepared tooth, and the forces anticipated in that region. Preparation and restoration of discolored and nondiscolored tooth structure are reviewed. The techniques presented can be utilized to obtain predictable results in the anterior region for aesthetic all-ceramic full-coverage restorations.

Color↗
PubMed1997

Communication is vital to produce natural looking metal ceramic crowns.

Many in the dental profession believe that accurate shade matching of the single anterior tooth is impossible. Fabricating an anterior porcelain crown to accurately match surrounding teeth is the most difficult task in our industry. However, it is not impossible. For many years, I took custom shades for a large dental group, and while there were many successes, there were also many failures. In one incident, the dentist, his team and I all agreed on a Vita Lumin A-2 for a patient. I attended the try-in. To everyone's surprise, the crown did not match the patient's natural teeth. After taking a new shade and delivering the new crown, the shade matched more closely, but still "no cigar." This particular failure resulted in the loss of a patient. Unfortunately, this was one of several incidents involving a mismatched shade and unsatisfied patient. These experiences caused me to question the techniques I was using. From them, I developed a technique for taking shades which could be shared with others to eliminate the frustrations we have all encountered.

Color Perception↗
PubMedDate not supplied

Shade selection for single-unit anterior metal ceramic crowns: a 5-year retrospective study of 2,500 cases.

PURPOSE: The purpose of this study was to investigate the distribution of shades selected for metal ceramic crowns provided at a dental teaching hospital. MATERIALS AND METHODS: Data on the selection of shade for 2,500 metal ceramic crown units, placed over a 5-year period at the University Dental Hospital of Manchester, were collected and analyzed. Only those crowns placed adjacent to minimally restored vital teeth were included in the study. RESULTS: The results indicate that the most frequently chosen shades were in the mid-range of reddish-brown hue. Furthermore, shades in the reddish-grey range of hue were rarely chosen. The selection of more than one shade for a crown ("mixed shades") was generally restricted to the maxillary anterior teeth. CONCLUSION: Knowledge of the distribution of shades selected for permanently luted metal ceramic crowns may be a useful adjunct in shade selection, particularly for the inexperienced operator.

Adolescent↗
PubMed1997

Reconstruction of the constricted orbital cavity in patients with artificial anophthalmy.

In cases, in which not only the globe of the eye, but the whole conjunctival sack is missing and the eyelids are due to scarring attached either to the orbital tissues and/or to each other, it is not possible to insert a prosthesis. This is a major aesthetic defect. The cavity that allows artificial eye insertion can be formed by surgery. One of the best methods is the orbital cavity reconstruction developed and suggested by the Hungarian István Csapody. He constructed two instruments to perform the operation: a butterfly shaped marker to prepare skin graft with proper size and shape, and an adjustable cone formed spacer to keep the reconstructed socket open during the healing process. We use free autologous split skin graft to line the cavity. If the shapes of the eyelids are intact, and the color of the prosthesis matches the fellow eye and it fits perfectly, then the postoperative cosmetic result can be excellent.

Cicatrix↗
PubMed2003

A shade selection technique.

The purpose of this article is to present a variation on the standard technique of shade selection by use of the Vitapan 3-D master "tooth" guide and the Vitapan 3-D master "dentin" guide together. The dentin guide is used first to select the shade determinants, and the tooth guide is used to verify them.

Color↗