BY Dr.For Third year studentsAcademic year 2013/2014September 19,2013

COLOR Is a phenomenon of light or visual perception that enables one to differentiate between otherwise identical objects It is measured in three dimensions Hue, Chroma, and Valuemghazy@mans.edu.eg

mghazy@mans.edu.egWithout light you cannot see

Without light, color does not exist Light It is that part of the spectrum of electromagnetic radiation to which human eyes are sensitive.

It is a form of energy

Measured in nanometers (nm)

The eye is only sensitive to the visible portion of the spectrum (380 750nm)

Different wavelengths constitute the different colors we perceive

mghazy@mans.edu.eg

Relatively 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 wavelengthsPure White Light380nm750nm + + + + + + =

Electromagnetic energy spectrumA nanometer (nm) is 10 -9 meter

DESCRIPTION OF LIGHTlight is described as visible electromagnetic energy whose wavelength is measured in nanometers (nm) or billionths of a meter. The eye is sensitive only to the visible part of the electromagnetic spectrum, a narrow band with wavelengths of 380 to 750 nm.

Is quality of color which distinguishes one color family from another e.g red, green, blue, etc.It is determined by the wavelength of the lightThe shorter WL the closer to the violetThe longer WL the closer to the red Characteristics of color

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

Determined by wavelength of observed light within the VLS

Reflected wavelength determines hue

Hue

The attribute of a color by which we distinguish red from green, blue from yellow, etc

The Munsell Hues include 5 principle hues (Y, R, P, B, G)Which further subdivided into (Y, YR, R, RP, P, PB, B, BG, G, GY)Each for example R is divided into (R1, R2, R3,..R10)

Most natural teeth fall into a range between yellow and yellow-red. mghazy@mans.edu.eg

The intensity, purity or saturation of a distinctive hueCharacteristics of colormghazy@mans.edu.eg

Low Chroma High Chroma

Low Chroma High Chroma

Purity of a color refers to its freedom from white, black, or gray.

Munsell ChromaIt has an open-end scale from 0 (achromatic color) to maximum depending on the hues

Natural teeth are found with Chroma ranges from 0.5 to 4.

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The quality by which a light color is distinguished from a dark color orIt is the dimension of color that denotes relative blackness or whiteness how much light appears to be reflected from a surfaceCharacteristics of colormghazy@mans.edu.eg

High ValueLow Value

High value = brighter (more white)Lower value = darker

Value of 10 = whiteValue of 0 = black

Munsell ValueThe brightness of any object is a direct consequence of the amount of light energy the object reflects or transmits.

mghazy@mans.edu.egIt runs from 0 (black) to 10 (white).

Natural teeth range in Value from 5.5 to 8.5

ValueWhite added to a hue creates a tint.Gray added to a hue creates a tone.Black added to a hue creates a shade.Value is the lightness or darkness of a hue achieved by adding white, gray, or black.

THE color of an object is influenced by three factors.The physical properties of the object.Absorption, reflection, transmission, or refraction

The nature of the light to which the object is exposedNatural, incandescent, and fluorescent

The subjective assessment of the observerColor deficiency : Blindness,Achromatism, Dichromatism, Anomalous Trichromatism

Quality of Light / 3 TypesIncandescent LightHigher concentration of yellow light wavesFluorescent Light higher concentrations of blue wavesNatural Daylight Closest to emitting the full spectrum white light

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

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Metamerism Is when two (2) objects match in color under one (1) light source and not under another. The best solution is to use several light sources and make shade comparisons more than one. Metamerism should be explained to patients as an occurrence and not a fault or an error mghazy@mans.edu.eg

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 BlindnessAbnormal color vision or the inability todiscriminate certain colors, most commonly along the red-green axisDefect in color vision male (8 %) > female (0.5%)Types:- achromatism .complete lake of hue sensitivity dichromatism.sensitive only to tow hues trichromatism sensitive to three with abnormality of one of the three Dentists should have their color vision evaluated. If any deficiency is detected, a dentist should seek assistance when selecting tooth shades.

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mghazy@mans.edu.eg

mghazy@mans.edu.eg

Red deficient will see 2 blackBlue-deficient will no see LRed-Green-deficient cannot see the number on the right sideCOLOUR DEFICIENCY

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.

mghazy@mans.edu.eg

Prior shade matching, the dentist must have an understanding to that the human tooth and dental porcelain transmit light waves differently

It is their physical composition that determines the differences in light-wave transmission, absorption, reflection, refraction, scattering and surface gloss.

The manner in which light strikes an object determines the total appearance of the material.

Transparent materials allow for the passage of light with little change.

Translucent materials scatter, transmit and absorb light.

Opaque materials reflect and absorb; however they do not transmit.

Surface characteristics, such as gloss, curvature and texture, will affect the degree of light diffusion when striking the particular object.

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

mghazy@mans.edu.egHue selectionThe recommended technique is to select the nearest hue first and then select the chroma and valueTabs of similar hue are clustered into letter groups A, B, C, and d ShadesChroma is designated with numerical valuesA3 = hue of red-brown, chroma of 3

Reddish brown Reddish yellow Reddish gray Grayish

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mghazy@mans.edu.egArrange the Vita shade guide in the following order: B1*A1*B2*D2*A2*C1*C2*D4*A3*D3*B3*A3.5*B4*C3*A4*C4. Now, note how this arrangement goes from the brightest (B1) to the darkest (C4), or from the highest to the lowest value as you move from left to right.It's a good idea to keep an extra shade guide in this arrangement, and to mark it as your "value" reference shade guide.

1- Use porcelain shades matches that of the technician

2- Always match before preparation

3- Patient should remove all distraction before matching

4- Clean and brush the teeth before matching

Shade selection sequencemghazy@mans.edu.eg

1- Use porcelain shades matches that of the technician2- Always match before preparation3- Patient should remove all distraction before matching4- Clean and brush the teeth before matching5- Patient position at the operator eye level6- Dentist position between patient and light source

7- Observation made quickly to avoid fatiguing of the cones in the retina8- Scan the entire shade guide quickly and eliminate the worst matchShade selection sequencemghazy@mans.edu.eg

1- Use porcelain shades matches that of the technician2- Always match before preparation3- Patient should remove all distraction before matching4- Clean and brush the teeth before matching5- Patient position at the operator eye level6- Dentist position between patient and light source7- Observation made quickly to avoid fatiguing of the cones in the retina8- Scan the entire shade guide quickly and eliminate the worst match9- To make a choice between two closely matching taps, hold them on either sides of the tooth being matched

10- If no tabs permit a good match, concentrate on the gingival portion then the incisal

11- Draw the pattern of translucency and characteristic features Shade selection sequencemghazy@mans.edu.eg

mghazy@mans.edu.eg

VITA 3D-MASTER With

&

Without neck Colors

VITAPAN 3D-MASTER SHADE GUIDEmghazy@mans.edu.eg

mghazy@mans.edu.eg

5 value levels (1-5) arranged left to right

Value selectionSelect the value level from the 5 value groupsmghazy@mans.edu.eg

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

3 chroma levels (1-3) in each value group, arranged top to bottom

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

Chroma selectionSelect the chroma level from the 3 available levels

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(up to) 3 hue levels (L,M,R) for each chroma level, arranged left to right

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

Hue selectionSelect the hue level from the (L,M,R)mghazy@mans.edu.eg

Vita-3D Step 4For more precise shade, intermediate levels for value, and chroma, and hue 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

Bleached shades now available0M1, 0M2, 0M3Bleached shades occupy the leftmost (brightest) value group (group #0) on the 3D-Master guide.

Dentin Shade GuideWhen 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 guide It is unfortunate that certain teeth may be impossible to match commercial shade samples.

The extensive use of surface staining has sever drawbacks; as it increase surface reflection and prevent light from being transmitted through porcelain.

One approach to this problem is to extend the concept of commercial shade guide by making custom shade guide.

Infinite number of shade samples can be made using combination of porcelain powders in varying distribution. But it is time consuming and is confined to specialty practice.

Limitations of current shade guides Retinal fatigue

Background effects

Color blindness

Age of the receiver

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Recent shade-communication technologies The dental market has demonstrated in recent years a number of new devices engineered to aid us in color communication.

These systems are divided in two categories :

1-Dot capture system. (Vita easyshade and Shofu shadeeye NCC)

2-Whole tooth capture systems. (X-Rite Visionscan and Cynovad shadescan)

Shofu shadeeyeCynovad shadescan

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mghazy@mans.edu.eg

Shade taking with VITA Easyshade Procedure for determining the tooth shades of natural teeth

Clean the tooth Stop the measuring probe and press the handpiece switch

Tooth shade is displayed on the Easyshade screen

Check the tooth shade using the Tooth guide mghazy@mans.edu.eg

mghazy@mans.edu.eg

mghazy@mans.edu.eg

Shade distribution chart The tooth divided into three regions (cervical, middle and incisal ).

Each region is matched independently, either to the corresponding area of a commercial shade sample or to single color porcelain chip.

The junctions between these areas are normally fairly distinct and can be communicated to the laboratory in the form of diagram. Individual characteristics on such a sketch will allow the ceramist to mimic details like hairline fractures, hypocalcifcation, and proximal discoloration.

Shade distribution chart

As a tooth ages, its shade can change from:

a. Shade A3 or A3.5 to shade A2 or A1.b. Shade A2 or A1 to shade A3 or A3.5.c. Both a and b.d. Neither a nor b.

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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

Appearance of AgingNote the indentation on the incisal edge to give the affect of wear into the dentinNote the stain applied in the incisal edge groove to simulate stained dentinNote dark cervical staining to show age Note stained craze line

Translucency is the appearance between complete opacity (like ivory) and complete transparency (like glass).

Teeth, especially incisal edges, show intense characteristics integrating the wide range of effects defined by translucency and transparency.

Figure 6 An example of documenting the 2 closest chromas.

Colour temperature is a characteristic of visible light and is a very important consideration for lighting applications. Colour temperature is normally expressed in the unit of absolute temperature, the kelvin, having the unit symbol K.Colour temperature is used to indicate the warmth or coolness of a light source. Colour temperatures over 5000K are called Cool colours (blueish white), while lower colour temperatures (27003500 K) are called Warm colours (yellowish white through red).

The following is a general guide to selecting LED lamps in consideration of colour temperature (K):

2700K > Homes (Living rooms, halls, bedrooms), Restaurants, Hotels (lobbies, corridors, bedrooms), Boutiques3000K > Offices, Work areas, Retail stores, Outdoor lighting, Bathrooms4100K > Showrooms, Display areas, Office areas5000K > Jewellers, Hospitals, Museums5600K > When outdoor/daylight simulation is required

TOOTH SHADE DETERMINATIONA light source has 3 main characteristics: colour temperature, spectral curve, and colour rendering index.Colours that are apparently the same may be generated by different spectral curves, and may or may not appear to be the same under different lighting conditions.METAMERISM

A light source has 3 main characteristics: colour temperature, spectral curve, and colour rendering index.The colour temperature of a light source is defined in degrees Kelvin. A candle glows with a colour temperature of 2000K At about 5000 - 5500K the colour spectrum produced is fairly balanced, and that is the colour temperature of the slightly overcast sky of "standard daylight". TOOTH SHADE DETERMINATIONTherefore a light source for shade matching should have a colour temperature of 5,500K and a CRI of at least 92.

The colour rendering index (CRI) is derived from a chromaticity diagram. The "equal energy point" is where all hues are perfectly balanced and therefore would be the perfect colour matching source. It is therefore given a maximum score of 100. A CRI of 90 or greater is required for shade matching.TOOTH SHADE DETERMINATION

Primary & Secondary Colors

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

**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.*Hue 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?)**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 100**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. *(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 daylight*Farbtafeltest der Fahrschule*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. ***Intermediate values should be noted on the laboratory communication form*Most 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.*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 makeup**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