The Science of Color, Light and Shade SelectionPresented byLisa Fedor James D.D.S.

OutlineLight and ColorDescription of LightQuality of lightDescription of ColorHue, Chroma, ValueMunsell Color SystemFactors influencing perception The eye (rods and cones)Deceptive color perceptionColor BlindnessShade selectionTechniques for determining shade / Shade guidesShade mapping

Visible electromagnetic energy whose wavelength is measured in nanometers (nm)

Without Light Color Does Not ExistWithout Light Color Does Not ExistA yellow object absorbs all lightwaves of all colors, but reflects yellow

ColorInfluenced by three main factorsPhysical properties of the objectAssessment of the observerNature of incident lightRelationship to other colored objects

LightPart of the electromagnetic spectrumThe eye is only sensitive to the visible portion of the spectrum (380 750nm)Different wavelengths constitute the different colors we perceive

Pure White LightRelatively equal quantities of electromagnetic energy over the VLS

When passed through a prism we see component colors of white light

Shorter wavelengths bend more than longer wavelengths380nm750nm + + + + + + =

Quality of Light / 3 TypesIncandescent Light Fluorescent Light Natural Daylight

Most dental offices are outfitted with incandescent and fluorescent lights

1. Incandescent LightEmits high concentration of yellow wavesNot suitable for shade matchingLow Color Rendering Index (CRI)

2. Fluorescent LightEmits high concentration of blue wavesNot suitable for shade matchingCRI =(50-80)

3. Natural DaylightNorthern daylight considered the best Closest to emitting the full spectrum of white lightUsed as the standard by which to judge other light sourcesCRI close to 100

Color Rendering IndexCRI = (0-100)Indicates how well a light source renders color as compared to a standard source (N. Daylight)Northern daylight (hence CRI) can be affected byTime of dayCloud coverHumidityPollution

CRI and Time of DayMorning and eveningShorter wavelengths scatter before penetrating atmosphereDaylight rich in yellow/orange, lacks blue/greenMid-dayHours around noon = idealIncident daylight is most balanced within VLSFull spectrum of colors visible

Color TemperatureAnother light source reference standardRelated to the color standard black body when heatedReported in degrees Kelvin (K)1000K red2000K yellow5555K white6500K northern daylight8000K pale blue

Dependent on four factors which influence CRI

ColorThe quality of an object or substance with respect to light reflected by the object, usually determined visually by measurement of hue, chroma and value

ColorInfluenced by three main factors1. Physical properties of the object

2. Assessment of the observer

3. Nature of incident light

Relationship to other colored objects

Subtractive ColorThese are the colors associated with the subtraction of lightUsed in pigments for making paints, inks, fabrics etc.

The primary subtractive colors are Red, Yellow, and Blue The secondary subtractive colors are Green, Purple and Orange

When subtractive primary colors are combined they produce black

Additive ColorThese are the color obtained by emitted light

Associated with television and computer displays

The primary additive colors are Red, Blue and Green

The secondary colors are Cyan, Yellow and Magenta

When additive primary colors are combined they produce white

Complimentary Colors

Three Attributes of ColorHueChromaValue

HueVariety of color (red, green, yellow, etc.)

Determined by wavelength of observed light within the VLS

Reflected wavelength determines hue

ChromaThe intensity or saturation of a hue

Low Chroma High Chroma

ValueThe relative darkness or lightness of a color, or brightness of an object Range = 0-10 (0=black, 10 = white)Amount of light energy an object reflects or transmits Objects of different hues / chroma can be identical valueRestorations too high in value are easily detectedLow Value High Value

Objects of different chroma / hue can be identical value

- Equal in Chroma / Variation in Value- Variation in Chroma / Equal in Value ChromaValueObjects of different chroma can be identical value

Objects of different chroma / hue can be identical value

Perception of Color

Color PerceptionRodsScotopic (gray scale) vision, interpret brightnessInterpret brightness, not colorHighest concentration on peripheral retina

ConesPhotopic (color) visionInterpret colorMore active under high light Highest concentration on central retina (macula), most color perceptive area of eye

Color AdaptationColor vision decreases rapidly as object is observedColor viewed dulls, while its compliment increases in intensityFatigueViewing a pale blue or gray surface between shade matching will restore color vision

MetamerismTwo colors that appear to be a match under a given lighting condition but have different spectral reflectance = metamers, the phenomenon is metamerism.Light Source #1Single Light SourceLight Source #2Light Source #3

Metamerism

Color BlindnessDefect in color vision8% males0.5% femalesSeveral variations existAchromatism complete lack of hue sensitivityDichromatism sensitivity to two primary huesAnomalous Trichromatism sensitivity to all three hues, with abnormality in retinal cones affecting one of primary pigments

Dentists should have their color vision evaluated. If any deficiency is detected, a dentist should seek assistance when selecting tooth shades.

Shade SelectionSubjective evaluation with considerable variationSubtle variations can exist without causing disharmony in smileRestoration contour Value of restorationProcess improved by applying principles of light and color

Principles of Shade SelectionTeeth to be matched must be cleanRemove bright colors from field of view- makeup / tinted eye glasses- bright gloves- neutral operatory wallsView patient at eye levelEvaluate shade under multiple light sourcesMake shade comparisons at beginning of appointmentShade comparisons should be made quickly to avoid eye fatigue

Commercial Shade GuidesMost convenient and common method of making shade selectionsGuides consist of shade tabsMetal backingOpaque porcelainNeck, body, and incisal colorSelect tab with the most natural intraoral appearance

Commercial Shade GuidesVita ClassicVitapan 3D MasterExtended Range Shade Guides

Vita Classic Shade GuideVery popular shade guideTabs of similar hue are clustered into letter groupsA (red-yellow) B (yellow)C (grey) D (red-yellow-gray)

Chroma is designated with numerical valuesA3 = hue of red-yellow, chroma of 3

Red/YellowYellowGreyGrey Red/Yellow

Vita Classic Shade GuideManufacturer recommended sequence forshade matchingHue SelectionChroma SelectionValue SelectionFinal Check / Revision

Vita Classic Step 1 (Hue Selection)Four categories representing hueA, yellow-redB, yellowC, grayD, red-yellow-grayOperator should select hue closest to that of natural toothUse area of tooth highest in chroma for hue selectionDifficult to select hue for teeth low in chroma

Vita Classic Step 2 (Chroma Selection)Hue selection has been made (B)Chroma is selected from gradations within the B tabsB1, B2, B3, B4Several comparisons should be madeAvoid retinal fatigueRest eyes between comparisons (blue-gray)

Vita Classic Step 3 (Value Selection)Use of second, value ordered shade guide is recommended

Value oriented shade guideB1, A1, B2, D2, A2, C1, C2, D4, A3, D3, B3, A3.5, B4, C3, A4, C4,

Value best determined by squinting with comparisons made at arms length Decreases lightDiminishes cone sensitivity, increases rod sensitivityTooth fading first has a lower value

Vita Classic Step 4 (Final Check / Revision)Potential ProblemFollowing value selection, tabs selected for hue and chroma may not coincide with shade tab selected for value

Vita Classic Step 4 (Final Check / Revision)Possible Findings / SolutionsValue of shade tab < natural teethSelect new shade tab with higher valueCannot increase value of restoration with extrinsic stainingWill only increase opacity, light transmisisonValue of shade tab > natural teethSelect new shade tab with lower value (or)Bridge difference with intrinsic or extrinsic staining

VITAPAN 3D-MASTER Shade Guide

Vita-3D Step 1Determine the lightness level (value) Hold shade guide to patients mouth at arms length Start with darkest group moving right to left Select Value group 1, 2, 3, 4, or 5

Vita-3D Step 2Select the chroma From your selected Value group, remove the middle tab (M) and spread the samples out like a fan Select one of the three shade samples to determine chroma

Vita-3D Step 3Determine the hue Check whether the natural tooth is more yellowish or more reddish than the shade sample selected

Vita-3D Step 4For more precise shade, intermediate levels for hue, value, and chroma can be given2.5M2 = value between 2M2 and 3m23M1.5 = chroma between 3M1 and 3M23M2 / 3L2.5 = hue between 3M2 and 3L2.5

Vita-3D Value ModificationFor more precise shade, intermediate levels for value, chroma, and hue can be given2.5M2 = value between 2M2 and 3M2

Vita-3D Chroma ModificationFor more precise shade, intermediate levels for value, chroma and hue can be given3M1.5 = chroma between 3M1 and 3M2

Vita-3D Hue ModificationFor more precise shade, intermediate levels for value, chroma and hue can be given3M2 / 3L2.5 = hue between 3M2 and 3L2.52.5Intermediate values should be noted on the laboratory communication form

Extended Range Shade GuidesMost shade guides do not cover all the colors in the natural dentitionSome porcelain systems extend the typical rangeBleached shades

Dentin shades

Custom shade guides

Shade MappingRecommended even when good custom shade match existsTooth is divided intoThree regionsNine segmentsEach region is matched independentlyFurther characterizations are sketched on diagram, may includeCraze linesHypocalcificationsProximal discolorationsTranslucency

SummaryAn understanding of the science of color and color perception is crucial to the success in the ever expanding field of esthetic restorative dentistry.

Although limitations in materials and techniques may make a perfect color match impossible, a harmonious color match impossible, a harmonious restoration can almost be achieved.

Shade selection should be approached in a methodical and organized manner.

This will enable the practitioner to make the best choice and communicate it accurately to the laboratory.

Thank You

I. LIGHT AND COLOR Without light color does not exist.An object we perceive as red absorbs all light waves (light waves of all colors) and reflects only the waves we interpret as red. (EXAMPLE)THE apparent color of an object is influenced by three factors..the physical properties of the objectthe nature of the incident light to which the object is exposedthe relationship to other colored objects (blue goves)the subjective assessment of the observerVariations in these factors can make a single tooth look very different among various observers.There is no standard for lighting in dentistryTHE apparent color of an object is influenced by three factors..the physical properties of the objectthe nature of the incident light to which the object is exposedthe relationship to other colored objects (blue goves)the subjective assessment of the observerVariations in these factors can make a single tooth look very different among various observers.There is no standard for lighting in dentistry

Pure white light consists of relatively equal quantities of electromagnetic energy over the VLR. When passed through a prism we see its component colors because the longer wavelengths are bent refracted) less than the shorter ones.Quality of LightMost common lights in dental offices are incandescent and fluorescent lights.Incandescent bulbs emit higher concentrations of yellow light wavesFluorescent bulbs give off higher concentrations of blue waves. Common fl bulbs (CRI= 50-80) therefore not suitable for shade matchingNatural daylight (northern) is closest to emitting the full spectrum white light and is often used as the standard for judging light from other sources. CRI close to 100Trying to find the ideal time location for shade matching may point towards the use of an artificial light. In these cases a color corrected fluorescent light is recommended. You want to have a CRI no less than 90, but hopefully more. Although daylight is often used as the standard against which other light sources are compared, never use direct sunlight to take shade. Its CRI is influenced byTime of day *Morning and evening incident daylight shorted blue and green waves are scattered and only the longer waves penetrate the atmosphere. Therefore daylight at dawn and dusk is rich in yellow and orange but is lacking in blues and greens.*Northern daylight around the noon hour on a bright day is considered ideal, because the incident daylight is most balanced within the VLS>HumidityCloud CoverPollution *Morning and evening incident daylight shorted blue and green waves are scattered and only the longer waves penetrate the atmosphere. Therefore daylight at dawn and dusk is rich in yellow and orange but is lacking in blues and greens.*Northern daylight around the noon hour on a bright day is considered ideal, because the incident daylight is most balanced within the VLS>

Trying to find the ideal time location for shade matching may point towards the use of an artificial light. In these cases a color corrected fluorescent light is recommended. You want to have a CRI no less than 90, but hopefully more. Color Temperature another light source reference standard. Related to the color of a standard black body when heated. Reported in degrees Kelvin (K)1000K red2000K- yellow5555K white8000K pale blueNorthern daylight has an average color temperature of 6500 degrees K, also dependent on the above 4 factors cited for CRI.THE apparent color of an object is influenced by three factors..the physical properties of the objectthe nature of the incident light to which the object is exposedthe relationship to other colored objects (blue goves)the subjective assessment of the observerVariations in these factors can make a single tooth look very different among various observers.There is no standard for lighting in dentistry

Almost everyone understands the concepts of the primary colors as they pertain to pigments. Red, yellow and blue are the primary pigment colors. Mixing yellow and blue yields green, blue and red yields magenta, etc.Subtractive colors are colors that are used in conjunction with reflected light. In this case the subtractive colors are blue red and yellow, (cyan, magenta and yellow where printing and coatings are concerned). These are the colors we are probably most familiar with the as the primary colors from school.

These are the colors that are associated with the subtraction of light and used in pigments for making paints, inks, colored fabrics, and general colored coatings that we see and use every day. All printing processes use subtractive colors in the form of cyan (blue) magenta (red) yellow and black. This is know as CMYK (cyan, magenta, yellow, black) the K stands for black in the printing process.If all three of the subtractive primary colors were combined together, they would produce black.Some examples where subtractive primary colours are used:textiles clothes furnishings printing paints colored coatings

Light behaves in a similar fashion, though it has a different set of primary colors. Red, green and blue are the primary colors of light.

Additive colors are colors that are used in conjunction with emitted light. In this case the additive primary colors are red, green and blue. These are the colors we are probably most familiar with in association with television, and computer displays.

These are the colors that are obtained by emitted light. The additive primary colors are red, green and blue. If all three of the additive colors were combined together in the form of light, they would produce white.Some examples where subtractive primary colors are used:television theatrical lighting computer monitors

complementary colors -- colors that are opposite from one another in their makeupHue a variety of color, shade or tint (EXAMPLE) red, yellow, green and is determined by the wavelength of the reflected and or transmitted light observed. Where the wavelength lies in the VLS determines the Hue of the color. The shorter the wavelength the closer the hue is to violet, longer the wavelength the closer the hue is to red.In the Munsell system there are 10 hue gradations. (Dont REALLY WANT OT GET INTO THIS?)Chroma- defined as the intensity of a hue. Another term for chroma is saturation, terms are used interchangeably in the dental literature, both mean strength of hue or concentration of pigment. (GOOD EXAMPLE take a container of water, add a drop of pigment, the result is a solution of low chroma, add another drop and the chroma intensifies, when solution is almost all ink a solution of high chroma has been reached)In the Munsell system chroma depends on hue and ranges form 10-14Achromatic shades have chroma near 0. The chroma of natural teeth range form 0.5-4.Value the relative lightness or darkness of a color or brightness of an object. This is a direct consequence of the amount of light energy the object reflects or transmits. It is the only dimension of color that may exist by itself. Light energy is measured in photons, objects of different hues can reflect equal number of photons and thus have the same value. (EXAMPLE try to tell the difference between two color sharing the same value in a black and white photograph). This also creates the myth that value is the amount of grayness in an object.Munsell method of describing value = ten gradations. 0 = black and 10 = white. Natural teeth range from 5.5-8.5.A restoration too high in value is easily detected by an observer and a common mistake in metal-ceramic prosthodonticsChroma vs. ValueThe Eye under low light conditions only rods are used (scotopic vision). Rods can interpret brightness but not color of objects. Color vision is dependent on cones, they become active under higher lighting conditions (Photopic vision). Dark adaptation is the change from photopic to scotopic vision, takes about 40 minutes.

The area with the most cones is the center of the retina, which is free of rods. Rods increase in concentration and predominate toward the periphery of the retina. Therefore the central field of vision is more color perceptive. There are three types of cones, those sensitive to red, green and blue light. Together these form an image in much the same way as the additive effect of the pixels in a television picture.

Color is also influenced by surrounding colors particularly complementary ones. When blue and yellow are placed side by side, their chroma may appear to be increased. The color of teeth can also look different if the patient is wearing brightly colored clothing or lipstick(LESSON DRAPE PATIENT IN LIGHT BLUE OR BLUE/GRAY COLOR< REMOVE BRIGHT FACIAL MAKEUP< SWITCH BRIGHTLY COLORED GLOVES FOR LIGHT NEUTRAL COLOR)Color Adaptation Color vision decreases rapidly as and object is observed. The original color appears to become less and les saturated until it appears almost gray. At the same time, the chroma (intensity) of complementary colors appears greater.This phenomenon suggests that operatory walls be painted pale blue (complementary to yellow) or that a pale gray-blue surface should be glanced at periodically while viewing color choices.(LESSON TAKE GLANCING LOOKS AT SHADE TABS< DONT STARE AT CHOICES> THEN LOOK AT COMP COLOR TO BRING BACK INTENSITY OF COLOR PERCEPTION MOST OFTEN FOUND IN TEETH ----yellow red).(EXAMPLE 3 objects appear to be an identical shade of purple, but they may in fact absorb and reflect light differently). Normally purple objects will reflect purple light, but some may actually absorb purple light and reflect blue and red. To the observer the blue and red combination may appear purple. But when the lighting changes the 3 objects no longer appear to match. They become metamers.

(LESSON samples that appear to match under the operatory light may not be satisfactory matches in daylight)The problem can be avoided by selecting and confirming shade under different lighting conditions. (i.e.- natural light and daylight)

(LESSON samples that appear to match under the operatory light may not be satisfactory matches in daylight)The problem can be avoided by selecting and confirming shade under different lighting conditions. (i.e.- natural light and daylightColor Blindness A defect in color vision affecting 8% of the male population and less of the female population. Several types of color blindness exist,Achromatism complete lack of hue sensitivityDichromatism sensitivity to only two primary hues, usually red or green are not perceivedAnomalous trichromatism sensitivity to all three hues with deficiency or abnormality of one of the three primary pigments in the retinal conesDentists should have their color vision evaluated. If any deficiency is detected, a dentist should seek assistance when selecting tooth shades.SHADE SELECTIONBecause shade selection is a subjective evaluation, consistency is difficult to achieve. Considerable variation among dentists exist and even dentists selecting a restoration for the same patient on multiple occasions may not be consistent in his/her final shade selection. Fortunately, an inexact shade may not break the balance of the smile. There can be subtle variations without much notice, if tooth contour and value are meticulously recreated. The overall shade must blend well with the contralateral and adjacent teeth. Shade selection can be improved by applying the principles of light and color in dental ceramic techniques.General Principles regardless of which system is used, the principles for shade selection do not change.1. Teeth to be matched should be cleaned of all debris and stains. If necessary ad prophy should precede tooth shade selection. 2. Brightly color lipstick/makeup should be removed and bright clothing draped. Protective gloves of bright colors should be swapped out for a neutral color. The operatory walls should not be brightly painted.3. Patient should be viewed at eye level, so the most sensitive part of the retina will be used.4. Shade comparisons should be made under different lighting conditions. Initial shade may be taken under a color corrected fluorescent light and then reevaluated or confirmed in natural daylight. (taking patient to an operatory window).5. Shade comparisons should be made at the beginning of a patients visit. Teeth increase in value, particularly if a rubber dam is used. (DESSICATION)6. Shade comparisons should be made quickly (REMEMBER COLOR FATIGE), with shade tabs placed just under the lip and adjacent to the teeth to be matched. This ensures that the background of both the shade tab and the tooth to be matched are the same essential to shade matching.

Commercial Shade Guides The most convenient method for selecting shade is with a commercially available shade guide. Each shade tab has a metal backing coated with an opaque porcelain backing, color , neck color, body color and incisal color. Shade selection consists of selecting the tabs that looks most natural in the mouth. It is reproduced by using the techniques and materials recommended by the manufacturer to replicate the colors seen in the tab. Common shade guide are grouped into categories of the same hue (A, B, C, D). To increase the color possibilitiesIn the past shade guide were created to meet the demand for denture teeth. More recently, shade guides have covered the color space occupied by natural teeth (VITA-PAN MASTER 3D).Commercial Shade Guides The most convenient method for selecting shade is with a commercially available shade guide. Each shade tab has a metal backing coated with an opaque porcelain backing, color , neck color, body color and incisal color. Shade selection consists of selecting the tabs that looks most natural in the mouth. It is reproduced by using the techniques and materials recommended by the manufacturer to replicate the colors seen in the tab. Common shade guide are grouped into categories of the same hue (A, B, C, D). To increase the color possibilitiesIn the past shade guide were created to meet the demand for denture teeth. More recently, shade guides have covered the color space occupied by natural teeth (VITA-PAN MASTER 3D).Common shade guide are grouped into categories of the same hue (A, B, C, D). To increase the color possibilitiesIn the past shade guide were created to meet the demand for denture teeth. More recently, shade guides have covered the color space occupied by natural teeth (VITA-PAN MASTER 3D).Hue Selection In the popular Vita Lumin shade guide there are four hue categories. A1,A2, A3. A3.5, A4 are similar in hue, while the B shade are similar in hue. The same holds true for the C and D tabs. An operator may chose the nearest hue and then go on to select the appropriate chroma. If the intensity of chroma is low, it will be more difficult to select the proper hue. If this is the case, on should use the region of the tooth with the most intense chroma to select hue.Chroma Selection- Once hue is selected, chroma match is chosen. For example, if a B hue is selected as the best color variety, hue is selected from the four gradations within the B tabs: B1, B2, B3, and B4. Several comparison s are usually necessary to determine the most appropriate hue and corresponding chroma. Between comparisons, glancing and a light blue object will rest the operators eye and help avoid retinal fatigue. Hue consistency among shade guides has not been proven and remains on of the main difficulties in maintaining a consistent shade from the shade taking appointment to placement of the final restoration. Value Selection Final value is selected by using a second shade guide whose samples are arranged in order of increasing lightness. The dentist can then determine if the value of the tooth is within the shade guides range (HIT BLEACH SHADES) Attention is then focused on the range of the shade guide that best represents the value of the tooth that relates the hue and chroma. Value is most easily determined by observing the guide and teeth to be matched at a distance, standing slightly away from the chair and squinting. ( COLOR VISION IN THE DARK) Squinting reduces the amount of light that reaches the retina. Therefore stimulation of the cones is reduced while rods become more sensitive to the increasingly achromatic conditions. The dentist should concentrate on which disappears first - the tooth of the shade tab. The one the fades first has the lower value. After value selection has been made it is more likely that the previously selected hue and chroma will not be found in the shade tab of the value selected. One must then consider whether to revise previously selected shade sample.(SHOW BLEACH SHADE GUIDES)If the value of the shade tab is lower (darker) than that of the natural teeth, a change is usually necessary (WHY?) Because increasing the value of a restoration is not possible by means of staining. An increase in opacity will result with inadequate end result for shade. If the value of the shade tab is higher than the natural teeth on must decide whether to decrease the value by selecting a new shade tab or if the difference can be bridged the addition of intrinsic (internal) or extrinsic (external) staining.(HOW LONG DOES EXTRINSIC STAINING LAST?)Value oriented shade guideB1, A1, B2, D2, A2, C1, C2, D4, A3, D3, B3, A3.5, B4, C3, A4, C4, After value selection has been made it is more likely that the previously selected hue and chroma will not be found in the shade tab of the value selected. One must then consider whether to revise previously selected shade sample.(SHOW BLEACH SHADE GUIDES)If the value of the shade tab is lower (darker) than that of the natural teeth, a change is usually necessary (WHY?) Because increasing the value of a restoration is not possible by means of staining. An increase in opacity will result with inadequate end result for shade. If the value of the shade tab is higher than the natural teeth on must decide whether to decrease the value by selecting a new shade tab or if the difference can be bridged the addition of intrinsic (internal) or extrinsic (external) staining.(HOW LONG DOES EXTRINSIC STAINING LAST?)Value oriented shade guideB1, A1, B2, D2, A2, C1, C2, D4, A3, D3, B3, A3.5, B4, C3, A4, C4, VITAPAN 3D-MASTER SHADE GUIDEManufacturer claims this guide covers the entire tooth color space. Shade samples are grouped in 6 lightness levels, each of which has hue and chroma variations in evenly spaced steps of 4 CIELAB units of lightness. Dimension and 2 CIELAB units of hue and chroma.. Because the tabs are evenly spaces intermediate shades can bee predictably formulated by combining porcelain powders. Manufacturer recommends selection value, hue and chroma in that order. (MAY NEED TO ELABORATE)In the past shade guide were created to meet the demand for denture teeth. More recently, shade guides have covered the color space occupied by natural teeth (VITA-PAN MASTER 3D).

Al shade samples belonging to one lightness level (1- 5) have the samevalue (see black and white photograph). Differences within one lightnesslevel are only with regard to the chroma and hue. These are determinedin stage 2 and 3.In step 1 we are only concerned with determining the correct value(lightness level), i.e. not a single shade sample tooth (1 out of 26),but a group of shades with the same value (1 out of 5).Al shade samples of an M-group feature the same hue and lightness.They only differ in the chroma.Tips forIntermediate values should be noted on the laboratory communication formMost shade guides cover a more limited range of colors than is found in the natural, and altered dentition. Some porcelain systems are available which extend this range. Using two shade guides is a practical way to extend the range of the traditional commercial shade guides. (EXAMPLE BLEACH SHADES)

Dentin Shade Guides (STUMP GUIDE)When using translucent all-ceramic system for a crown or veneer (FEDLSPATHIC PORCELAIN OR IPS EMPRESS), communicating the shade of the prepared dentin is very helpful to the laboratory. One system provides specifically colored die materials that match the dentin shade guide and enable the technician to better judge restoration esthetics.

Custom Shade GuideUnfortunately, some teeth can be impossible to match to commercial shade guides. It can also be difficult to exactly match the final restoration with the shade tab. The extensive use of extrinsic surface staining has severe drawbacks,Stains increase surface reflectionsPrevent light from being transmitted through the porcelainOne approach to this dilemma is to extend the concept of a commercial shade guide with the creation of a custom shade guide. An infinite number of samples can be made by using different combinations of porcelain powders in varying distributions. This is a very time consuming procedure and typically limited to specialty practices.Shade Distribution Chart (SHADE MAPPING)A shade distribution chart is a practical approach to accurate shade selection. IT is recommended even when a fairly good shade match is available from the custom shade guide. Method - The tooth is divided into 9 segments ( three regions: cervical, middle and incisal) Each region is matched independently, either to the corresponding area of a shade tab or to a single color porcelain chip (SAY WITH A CUSTOM SHADE GUIDE) Because only a single color is matched, intermediate shades can usually be estimated rather easily and duplicated by mixing porcelain powders. The junctions between these areas are normally distinct and can be communicated to the lab in the form of a diagram. The shade distribution and thickness of the enamel porcelain are particularly important. Individual characteristics are marked on such a sketch and will allow the ceramist to mimic details like hairline fractures, hypocalcifications, and proximal discolorations.SUMMARYAn understanding of the science of color and color perception is crucial to the success in the ever expanding field of esthetic restorative dentistry. Although limitations in materials and techniques may make a perfect color match impossible, a harmonious color match impossible, a harmonious restoration can almost be achieved. Shade selection should be approached in a methodical and organized manner. This will enable the practitioner to make the best choice and communicate it accurately to the laboratory. Newly developed shade systems and instruments may help the practitioner achieve a reliable restoration match. An understanding of the science of color and color perception is crucial to the success in the ever expanding field of esthetic restorative dentistry. Although limitations in materials and techniques may make a perfect color match impossible, a harmonious color match impossible, a harmonious restoration can almost be achieved. Shade selection should be approached in a methodical and organized manner. This will enable the practitioner to make the best choice and communicate it accurately to the laboratory. Newly developed shade systems and instruments may help the practitioner achieve a reliable restoration match.