Natural Tooth Color Research Articles

Comparison of the color of natural teeth measured by a colorimeter and Shade Vision System

Objectives The objectives were to measure the difference in the color and color parameters of natural teeth measured by a tristimulus colorimeter (CM, used as a reference) and Shade Vision System (SV), and to determine the influence of color parameters on the color difference between the values measured by two instruments. Method Color of 12 maxillary and mandibular anterior teeth was measured by CM and SV for 47 volunteers (number of teeth = 564). Color parameters such as CIE L *, a * and b * values, chroma and hue angle measured by two instruments were compared. Chroma was calculated as C a b * = ( a * 2 + b * 2 ) 1 / 2 , and hue angle was calculated as h° = arctan( b */ a *). The influence of color parameters measured by CM on the color difference ( Δ E a b * ) between the values measured by two instruments was analyzed with multiple regression analysis ( α = 0.01). Results Mean Δ E a b * value between the values measured by two instruments was 21.7 (±3.7), and the mean difference in lightness (CIE L *) and chroma was 16.2 (±3.9) and 13.2 (±3.0), respectively. Difference in hue angle was high as 132.7 (±53.3)°. Except for the hue angle, all the color parameters showed significant correlations and the coefficient of determination ( r 2) was in the range of 0.089–0.478. Based on multiple regression analysis, the standardized partial correlation coefficient ( β) of the included predictors for the color difference was −0.710 for CIE L * and −0.300 for C a b * ( p < 0.01). Conclusion All the color parameters showed significant but weak correlations except for hue angle. When lightness and chroma of teeth were high, color difference between the values measured by two instruments was small. Clinical accuracy of two instruments should be investigated further.

Selecting Nanotechnology‐Based Composites Using Colorimetric and Visual Analysis for the Restoration of Anterior Dentition: A Case Report

Currently it is possible to use direct composites and layering techniques to replicate the complex internal structures, visible shape, color, and surface anatomy of natural teeth. To do so, however, requires dentists to understand the principles of nature and the science of dental materials to determine the most suitable restorative material for a specific indication. By incorporating relatively new technologies--colorimetric analysis, which provides computerized shade guide definitions of a tooth and essential information to verify shade mapping, and a new nanotechnology-based direct composite--into composite layering techniques, dentists can more predictably replicate the esthetics of natural teeth. This article presents a case in which both technologies, used in combination with a composite layering technique, contributed to the esthetic and functional restoration of the maxillary central incisors.

Intrarater repeatability of shade selections with two shade guides

Statement of problem. Color research has shown that shade guides do not always represent the color of natural teeth. Moreover, visual evaluation has been found to be unreliable and inconsistent. Purpose. This investigation evaluated the effects of 2 shade guides on the intrarater repeatability (reliability) of prosthodontists and general practitioners with regard to shade selection. Material and methods. Ten prosthodontists and ten general practitioners (all men, 35-45 years old) with an average practice experience of 14 years participated in this study. Examiners were tested to eliminate color blindness. Each clinician used Vita Lumin Vacuum and Vitapan 3D-Master shade guides to determine the shades of the maxillary right canines of 20 patients following a standard protocol. The identification codes of the shade tabs were masked to prevent shade memory. All teeth were polished before each shade selection, and the selection process was standardized for controlled lighting and procedures. Shade selections were randomly repeated 1 month later by the same practitioners on the same group of patients in accordance with the same shade-selection protocol. Analysis of variance and t tests for individual comparisons among means were performed (P<.05). Results. Significant interactions were found between the effects of shade guide system and specialty training on intrarater repeatability (P<.0001, analysis of variance). The intrarater repeatability of prosthodontists was significantly higher than that of general practitioners when the Vita Lumin Vacuum shade guide was used (P<.0001, t test). Use of the Vitapan 3D-Master shade guide significantly improved the intrarater repeatability of general practitioners compared with the Vita Lumin Vacuum shade guide (P<.0005). This improvement was not significant, however, among prosthodontists (P=.2861). Conclusion. Within the limitations of this study, the prosthodontists demonstrated superior intrarater repeatability in shade selection, especially when the Vita Lumin Vacuum shade guide was used. Use of the Vitapan 3D-Master shade guide notably improved intrarater repeatability among the general practitioners. (J Prosthet Dent 2003;89:50-3.)

The repeatability of an intraoral dental colorimeter

Statement of Problem. Characterizing and reproducing color remain one of the most challenging aspects of dentistry. A relatively new intraoral colorimeter measures the color of natural teeth and metal-ceramic restorations and prints out a color recipe for the Vintage Halo Porcelain System. The reliability of the colorimeter is unknown. Purpose. The purpose of this study was to evaluate the reliability of a contact dental colorimeter and to correlate the shade registered by the colorimeter with the shade selected by experienced clinicians. Material and Methods. In part I of the study, 2 examiners (A and B) took 2 colorimeter measurements from the maxillary right central incisors of 11 subjects. The examiners were blinded to their own data and those of other investigators. The readings were repeated 3 weeks later with the same protocol. The Cronbach α reliability coefficient was used to analyze the collected data. In part II of the study, 2 experienced clinicians (examiners D and E) selected a shade from the classic Vita Lumin Vacuum shade guide for the maxillary right central incisors of the same 11 subjects. The clinicians were blinded to each other's selections and the colorimeter readings. It should be noted that the manufacturer of the colorimeter uses the terms shade, value, and hue to represent chroma, value, and hue, respectively, as defined in the Glossary of Prosthodontic Terms (J Prosthet Dent 1999;81:39-110). Results. The reliability analysis results for each of the combined trials for shade, value, and hue were all >.94. The interexaminer reliability α values were >.9 for shade and value and.64 to.74 for hue. The interexaminer α represented the value range of each of 4 measurements. The intraexaminer reliability α values for shade, value, and hue were.99,.95, and.96 for examiner A and.99,.93, and.97 for examiner B, respectively. In part II of the study, the colorimeter agreed with itself 82% of the time, whereas clinicians agreed with each other on the selected shade 73% of the time. Selections made by the colorimeter and the clinicians matched 55% to 64% of the time. Conclusion. Within the limitations of this study, the colorimeter reliably measured the color of natural teeth. (J Prosthet Dent 2002;88:585-90.)

A New All-ceramic Zirconium Post and Core System

Purpose : A study was done to investigate the use of a newly developed esthetically and mechanically superior all-ceramic zirconium post and core system (CosmoPost®, Ivoclar, Liechtenstein). Fabrication techniques and clinical cases are discussed.Materials and Methods : CosmoPost®s are cylindrical conical-shaped posts made of ZrO2-TZP and are marketed with corresponding rotary drilling and trimming instruments. The ceramic cores can be fabricated by either direct or indirect methods.Results : The authors have used zirconium all-ceramic posts and cores since 1997 to improve esthetics and to treat cases of dental metal allergy. Results at achieving natural tooth color and translucency have been evaluated as excellent. No failures of crowns, post and cores have been observed up to the present.Conclusion : Good esthetic results and improvements in the oral soft tissue in cases of dental metal allergy can be achieved using the newly developed all-ceramic post and core.

In vitro chemical stain removal by 'whitening' toothpastes

This paper: Background A considerable number of toothpastes are available as tooth whitening products. Most appear to contain ingredients that might remove extrinsic stains rather than change natural tooth colour. Extrinsic stain removal could be achieved by physical or chemical means. Aim The purpose of this study was to measure the chemical stain removal properties of a range of whitening toothpaste products and experimental formulations using a standardised method in vitro. Materials and method 5 separate studies were conducted involving a total of 39 agents of which 28 were whitening products, 7 were experimental formulations, 2 were oxidising mouthrinses used as positive controls, 1 was a popular fluoride toothpaste product as a benchmark control, and 1 was water as the negative control. The formulations and controls varied in each study. The stain model was saliva/chlorhexidine/tea stain developed on optically clear acrylic to an optical density of at least 2.0. Groups of stained specimens were exposed to standard slurries or solutions of each test agent for 1 minute periods up to 5 minutes. Optical density readings were taken at each 1 minute time point. Analyses were based on per cent stain remaining after 5 minutes and time to 75% stain remaining. Results 3 toothpaste products achieved 100% stain removal by 5 minutes; 2 of these in 3 out of 4 studies in which they were used. 4 experimental formulations also achieved 100% stain removal. In general agents with high total stain removal also had short times to 75% stain remaining. The majority of agents tested had low total chemical stain removal and prolonged times to 75% stain remaining. A few agents were little different from water and several similar in effect to the conventional fluoride toothpaste. This method in vitro tests agents under the best case scenario conditions for chemical stain removal. Conclusion Only a small number of the whitening toothpaste products have good chemical stain removal potential; the majority are unlikely to achieve their claimed benefits through chemical stain removal. There is clearly a need for further data on the actual effects of such products using both methods in vitro and particularly in vivo or in situ.

Color and translucency of in vivo natural central incisors

Statement of problem: The range of shades in shade guides is not consistent with natural teeth, and there is no information on the color and translucency of the natural tooth for all age groups. Therefore, it is important to obtain a database of the characteristics of the natural tooth from a wide age group. Purpose: This study obtained information on color and translucency of natural teeth for all age groups, and attempted to clarify the difference of the color and translucency between natural teeth and VITA Lumin Vacuum shade guide. Material and methods: Natural central incisors of 87 subjects (42 men and 45 women; age range from 13 to 84 years) and 16 shades of VITA Lumin Vacuum shade guide were evaluated. Color and translucency of 5 sites, each 1.0 mm in diameter, on the surfaces of individual teeth were measured for L*, a*, and b*, using a color computer according to CIELAB color spaces. Results: At the center site, negative correlation was found between age and L*, with positive correlation between age and b*. Both a* and b* of the natural tooth increased when moving in the direction of the cervical site, but translucency decreased in the direction of the root. The a* value for the natural tooth was significantly higher than those for VITA Lumin Vacuum shade guide. Conclusion: This study found that the older the subject, the darker and more yellow the color at the center site of the natural tooth. Both reddish and yellowish colors of natural teeth tend to increase from the incisal to cervical, whereas translucency decreases. Red-green chromaticity of VITA Lumin Vacuum shade guide was not distributed to cover the natural tooth. (J Prosthet Dent 2000;83:418-23.)

ステイニング法における材料の厚さ，背景およびセメント色調の影響

The purpose of this study was to evaluate the influence of ceramic thickness, background and cement color on the color of all-ceramic crowns using the staining technique. Ceramic specimens of three different thicknesses (1.0, 1.5, 2.0 mm) were fabricated with Dicor, Empress T2, Empress O1 and Empress O2 by using surface staining. Three backgrounds (porcelain, Type IV gold alloy and gold-silver-palladium alloy) and two resin cements (universal and brown color) were used for the study. The color of ceramic specimens was measured with a small area colorimeter and evaluated by the CIE L*a*b* color system.Ceramic thickness had the greatest influence on the color of ceramic specimens. Both lightness and yellowness decreased as the ceramic thickness increased. The background color had an influence on the lightness and yellowness of ceramic specimens when the ceramic specimens were 1.0 mm in thickness. However, cement color had little influence on the color of ceramic specimens. These results suggested that both ceramic thickness and background color are important factors for reproducing natural tooth color by using the staining technique.

Color of natural tooth crown in Japanese people

The aim of this study was to investigate the color of the natural maxillary incisor tooth from Japanese people of all age groups. These results were compared with the Trubyte Bioblend shade guide. The subjects of this study were in the age range of 13–84, 42 male and 45 female making 87 people in total. Areas with 1.0-mm diameter at five sites were measured along the tooth axis for L*,a*,b*, according to CIELAB color spaces using a Spectroradiometric Color Computer. At the incisal site, two significant positive correlations were found between age and a* (r = 0.376, p < 0.001), and b* (r = 0.483, p < 0.001). At the center site, a significant negative correlation (r = −0.418, p < 0.001) was found between age and L*, but positive correlation (r = 0.497, p < 0.001) was found between age and b*. At the cervical site, a significant negative correlation (r = −0.326, p < 0.01) was found between age and L*, but positive correlation (r = 0.702, p < 0.001) was found between age and b*. Near the root, particularly, the values of a* were greater than those suggested by the Trubyte Bioblend shade guide. In conclusion, as the Trubyte Bioblend shade guide does not match the natural tooth color in red-green chromaticity near the root, it is significant for us in dentistry to develop new shade guides that match the Japanese people based on the data collected. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 43–48, 2000

歯冠色の構築からみたオールセラミッククラウンの特徴

A lot of all-ceramic crown systems have been developed in the last decade. Current all-ceramic crown systems show great mechanical strength compared with previous porcelain crowns. With regard to color reproduction of esthetic and natural tooth color, all-ceramic crown systems have an advantage due to the lack of a metal frame. This paper describes colorimetric indications related to the following points for color reproduction of all-ceramic crowns.·oe Color space of natural tooth color·oe Tooth color as the turbid-media·oe Color reproduction with stratiformed ceramic layer·oe Colorimetric properties of ceramic crown·oe Color adjustability of luting resin cements·oe Application of CCM for color reproduction

ＩＰＳ Ｅｍｐｒｅｓｓの色調に関する研究 各種接着性レジンセメントによる色調の影響について

IPS Empress®, an all-ceramic crown system, achieves natural tooth color appearance, however, because of the light transmission itself, abutment tooth color is influenced by the final restoration.This paper describes the effect of color blocking and changing through background color when using nine adhesive resin cements (50 and 100μm) and four ceramic ingots (TI, TII, OI and OII), which have different light transmission with a thickness of 1.5 mm in the middle coronal tooth portion, in the staining technique. The results were as follows:1. The effect of color blocking was significantly improved when only using JO (IMPERVA DUAL Opaque) and PO (PANAVIA 21 Opaque) cementation insertion.2. According to the increase in thickness of resin cement of all specimens, the value of L* tended to decrease as the luminosity decreased, the value of a* did not significantly change, and the value of b* tended to increase and there was a tendency to become more yellow.3. As the effect of color blocking, specimens using Oil ingot with low light transmission had the highest value. As the influence of thickness through the resin cementation, T I ingot with higher light transmissionhad a significantly improved value.

オールセラミッククラウンの色調に関する研究 レイヤリング法について

Three types of shade A system of dentin porcelain VITA for layering (2 D, 3 D, and 3.5 D) and 5 types of enamel porcelain (N, 1 E, 2 E, 3 E, and 4 E) in the layering method, in which more emphasis is put on cosmetic appearance, were evaluated. The thickness of the porcelain was varied and color tone in the abutment teeth color sample was changed, i.e., natural teeth (A 2, A 3, and A 3.5), 2 types of gold alloy and palladium alloy (Au and Pd) as casting metal core, and discolored teeth influenced the color tone of IPS EMPRESS crown. The conclusion were as follows:1. Lightness difference When the ratio of the thickness of dentin and enamel samples was varied within the range of 1.5 mm (two-thickness samples), the lightness difference tended to decrease when thickness of the dentin sample was increased, while no interruption of color tone was observed.2. Color difference1) The smaller the shade number was, the higher the color difference was between Au and Pd samples and natural tooth color sample, and the color difference decreased when the dentin sample was thicker. Almost all two-thickness samples showed the value of 1.2 or more, i.e., within the criterion for color difference, and it was evaluated as “detectably different.”2) In the color difference between discolored tooth sample and natural tooth color sample, the smaller the shade number was, the higher the color difference was. The color difference decreased as dentin sample became thicker. In all of the two-thickness samples, the value was 1.2 or more, thus falling within the criterion for color difference in the present study. Some of the two-thickness samples showed a color difference of 3.3 or more. Thus some samples were evaluated as “extremely different.”

ポーセレンラミネートベニアクラウンの色彩学的研究 視感色濃度θによる色調評価

Restoration of discolored teeth to a more natural color provides the patient with not only a harmonious oral appearance, but also a feeling of self-esteem and psycological satisfaction. Porcelain laminate veneer crowns, which do not require much tooth reduction, have drawn much attention as a type of prosthesis which is capable of restoring discolored teeth while maintaining its original occlusion. However, due to the thinness of the laminate veneer crowns, it is difficult to hide the original color of the tooth abutment while giving it a semi-transparent natural appearance. Thus a more objective method of evaluating the color of discolored teeth by using a non-contact type spectrophotometer was undertaken, and the measured color was evaluated in terms of the CIELab system, Munsell system, and a new index involving color depth which will be referred to as the Rabe θ value.Results indicated that it is possible to identify the color of teeth using the Rabe θ value, and that color variation between those teeth having natural tooth color to those having discoloration are clearly distinguishable by means of this index. Futhermore, by measuring the Rabe θ value of a tooth before and after placement of a porcelain laminate veneer crown, it was possible to determine the absolute color value of the tooth itself.

非接触型微小面積測色用分光光度計の開発

A method of applying the CCM system to reproduce natural tooth color in metal ceramic restorations was successfully undertaken by a newly modified spectrophotometer and measuring system.The spectrophotometer utilizes bidirectional (45/0) geometry and a telephoto camera lens capable of measuring small areas (1×2mm) of the tooth and gingiva by the “noncontact” method. Furthermore, color measurements were automatically done by means of a scanning program.The standard deviation (S. D.) of the reflectance factors, measured 10 consecutive times, was under 0.16, and the color difference dE was around 0.21. Both the measuring data of the Munsell color chips by this spectrophotometer and integrating sphere spectrophotometer Macbeth CE 3000 were nearly identical.It was concluded that this newly modified spectrophotometer could measure small areas of the tooth efficiently, and also be beneficial for use in dental clinics and research.

ラミネートベニア補綴における色彩学的研究 正常歯および変色歯の色調について

Since the ideal color mathching has not certainly been attained in laminate veneer restoration, it might be partly due to the insufficient knowledge about color of natural and discolored tooth. To overcome the problem, it would be important to examine the color difference between natural and discolored tooth. The left upper anterior teeth color were measured in the mouth by a small area colorimeter and evaluated by CIE L*a*b*color system. The following conclusions were obtained.1. Discolored anterior tooth was darker and more reddish than natural anterior tooth.2. Concerning the type of anterior teeth, the respective tendency of L*a*b*was the same between discolored and natural teeth.3. Concerning each part of the same tooth, the respective tendency of L*and b*was the same between discolored and natural teeth.4. The color difference (ΔEab*) compared between each type of anterior tooth, those of discolored tooth were little greater than those of natural tooth.5. The color difference (ΔEab*) compared between each part of tooth, those of discolored tooth were much greater than those of natural tooth.

The influence of porcelain powder blending on color: A clinical and laboratory study using a custom shade analysis system

D entists attempting to produce esthetic metal-ceramic restorations are often frustrated with the difficulty of selecting a suitable color from the existing shade guides. The range of color in human teeth has been measured by spectrophotometcr,‘*’ and color guides based on the Munsell color order systems have been developed. Clark’s system3 used only three basic Hues, 19 Value steps, and six Chroma steps, available from 13 porcelain powders. Hayashi’s guide represented 125 locations equally spaced ,within the color space from Japanese people.’ Lemire and E;urk2 developed a color guide having a configuration similar to the Munsell color wheel. The Value scale was represented by two tiers of color chips. Three basic Hues were used, with one side yellow/red and the other yellow. As the color chips in the tier extend outward, Hue remains constant while Chroma increases and Value decreases. Logical arrangement allows interpolation among shades. Binns4 compared existing color guides with the color range of natural teeth and indicated that although the guides were logically arranged, they did not cover the range of natural tooth color. Boone, in the United Kingdom, developed the Spectratone custom shade analysis system (Dental Ventures of America, Inc., Anaheim Hills, Calif.) for Spectratone porcelain to simplify color selection and accuracy. The system is based on the four primary colors of opalescent, yellow, pink, and gray, which by precise mixing to the desired combination can achieve a wide range of dentin colors (Hue) with precise strength of color (Chroma) and lightness or darkness (Value). By first selecting the correct Hue, the:n Chroma and Value, an accurate color match can be established in only three steps. Modification can then be made in either direction. The relationship of the enamel and dentin porclains must be accurately conveyed to the ceramist. The color can be

The use of a direct bonded microfilled composite resin veneer

This technique creates a direct bonded microfilled composite resin veneer that replicates the complex color distribution and surface texture of the natural tooth structure. Duplicating the complexity of natural tooth color can be repeated by recording the different layers of color used in their sequence of placement.

Spectrophotometric study of the relationship between body porcelain color and applied metallic oxide pigments

I t is unlikely that anyone is able to measure objectively a porcelain restoration by a number that represents how lifelike it appears. The restorative dentist must assess the elements that cause the subjective impression of “naturalness” in a tooth to fabricate a restoration that will produce the natural effect. The dentist relies on external and internal tinting techniques to modify the color of existing porcelain restorations. The color of natural teeth in vitro has been measured objectively in several studies, some using a spectrophotometer.le3 The colors of both available dental porcelains and shade guides have similarly been measured.’ In the final analysis, however, the dentist’s subjective judgment determines the color of a restoration. To discuss color from an objective point of view, a

Color of Dental Restorative Resins

The color of 7 composite resins, an unfilled restorative resin, and 3 glaze coatings was determined by reflection spectrophotometry and visually with Munsell color tabs. Statistically significant correlations existed between comparable parameters of the spectrophotometric and Munsell data. There was observable color variations among the 11 resins studied, but only 3 materials were within the range for natural tooth color.

Porcelain as an Esthetic Restorative Material

Baked porcelain has been used as a restorative material for both the replacement of missing teeth and the restoration of lost tooth structure since the turn of the twentieth century. To date, no substitute has equalled its physical and esthetic properties. The development of translucent porcelains has extended the range of color selection for porcelain restorations. The main disadvantage of porcelain as a restorative material has been its vulnerability to fracture under excessive stress. Current techniques of bonding porcelain to metal make it more resistant to fracture. Natural-appearing full porcelain veneer crowns can be produced by maintaining the specific color indicated in each of the three color band areas of the teeth, namely the gingival, central and incisal. When the correct hue is laid in each of the three color band areas, with the natural tooth's dentin as a base, the optimum in natural tooth color can be attained. Mixing colors together or tiering one color on top of another will produce a different color. This is a basic and fundamental fact. In order to reproduce natural tooth appearance when bonding porcelain to metal, the color of the metal must be obliterated and the bonding mineral must duplicate the color of the patient's underlying dentin,