shade selection

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Presentation Transcript

k : 

k GOOD AFTERNOON

The Science of Color and Shade Selection : 

The Science of Color and Shade Selection Presented by Gaurav Tripathi P.G. Student Dept. of Prosthodontics

The theory or philosophy of taste; the science of the beautiful in nature and art; especially that which treats of the expression and embodiment of beauty by art.[Websters]. : 

The theory or philosophy of taste; the science of the beautiful in nature and art; especially that which treats of the expression and embodiment of beauty by art.[Websters]. Esthetics

Esthetics : 

Esthetics It is not absolute but extremely subjective

Earlier it was thought as : 

Earlier it was thought as

Hegel’s Statement : 

Hegel’s Statement “Beauty is substance of imagination and feeling, cannot be an exact sign”

Outline : 

Outline Light and Color Description of Light Quality of light Description of Color Munsell Color System Hue, Chroma, Value Factors influencing perception The eye (rods and cones) Shade selection Techniques for determining shade / Shade guides Shade mapping

Slide 9: 

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

Without Light Color Does Not Exist : 

Without Light Color Does Not Exist Without Light Color Does Not Exist

Slide 11: 

We are going to understand the basic relationship of light ,color and visual perception

Slide 12: 

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

Main sources of light : 

Main sources of light The Sun The Fire

Slide 14: 

Principle sources of artificial light

Slide 15: 

Incandescent light Florescent Tube Photographic Flash

Pure White Light : 

When passed through a prism we see component colors of white light Shorter wavelengths band more than longer wavelengths Pure White Light 380nm 750nm

Quality of Light / 3 Types : 

Quality of Light / 3 Types Incandescent Light Fluorescent Light Natural Daylight Most dental offices are outfitted with incandescent and fluorescent lights

1. Incandescent Light : 

1. Incandescent Light Emits high concentration of yellow waves Not suitable for shade matching

2. Fluorescent Light : 

2. Fluorescent Light Emits high concentration of blue waves Not suitable for shade matching

3. Natural Daylight : 

3. Natural Daylight Northern daylight considered the best Closest to emitting the full spectrum of white light Used as the standard by which to judge other light sources

Color Rendering Index : 

Color Rendering Index CRI = (0-100) Shade selection is done with a light having more than 90 CRI Northern daylight (hence CRI) affected by Time of day Cloud cover Humidity Pollution

CRI and Time of Day : 

CRI and Time of Day Morning and evening Mid-day

Slide 24: 

Color is the subjective impression formed in a specific portion of brain owing to the specialization of certain cells-rods and cones distributed in retina of the eye Color

Color : 

Color Influenced by three main factors 1. Physical properties of the object 2. Assessment of the observer 3. Nature of incident light Relationship to other colored objects

Slide 27: 

A surface of an object appears red for an example when it reflects long waves but absorb light or the complementary color blue

“Light that enters the human eye from that object” : 

“Light that enters the human eye from that object” Dimensions of Color VALUE CHROMA HUE Color

Slide 29: 

Numerous scientist came with the approach to tell about the part of the color but it was Munsell’s(1961) system which best serves to rank the color coz it view differences between neighboring color at regular interval Hue, value, chroma are very well presented in Munsell's’ color scale

Slide 31: 

This system was intended for evaluation of opaque surface and therefore not fully applicable for teeth whose surface are translucent

Slide 32: 

Therefore 4th dimension that of translucency has to be added in the system Hence 4 dimension of color –hue, value, chroma and translucency – should be quantified as clearly and accurately as possible in defining the natural tooth or ceramic color

Translucency : 

Translucency The degree to which light is transmitted rather than absorbed or reflected Highest translucency is transparent While lowest is opacity

Perception of Color : 

Perception of Color

Color Perception : 

Color Perception Rods Scotopic (gray scale) vision, interpret brightness Cones Highest concentration on central retina (macula), most color perceptive area of eye

Color Adaptation : 

Color Adaptation Color vision decreases rapidly as object is observed Leads to retinal Fatigue Viewing a pale blue or gray surface between shade matching will restore color vision

Metamerism : 

Metamerism Two colors that appear to be a match under a given lighting condition but have different spectral reflectance = metamers, the phenomenon is metamerism. 1st Light source 2nd Light source 3rd Light source

Slide 38: 

Shade Selection

Shade selection : 

Shade selection Mainly includes three things Object Observer Light

Shade Selection : 

Shade Selection Timing Lighting Patient preparation Shade guides Conventional Custom made Technology based shade guide systems

Principles of Shade Selection : 

Principles of Shade Selection Teeth to be matched must be clean Remove bright colors from field of view - makeup / tinted eye glasses - bright gloves - neutral operatory walls View patient at eye level

Principles of Shade Selection …… : 

Principles of Shade Selection …… 4. Evaluate shade under multiple light sources 5. Make shade comparisons at beginning of appointment 6. Shade comparisons should be made quickly to avoid eye fatigue

Commercial Shade Guides : 

Commercial Shade Guides Most common method of making shade selections Guides consist of shade tabs Metal backing Opaque porcelain Neck, body, and incisal color Select tab with the most natural intraoral appearance

Commercial Shade Guides : 

Commercial Shade Guides Vita Classic Vitapan 3D –Master Extended Range Shade Guides

Vita Classic Shade Guide : 

Vita Classic Shade Guide Very popular shade guide A3 = hue of red-yellow, chroma of 3

Slide 46: 

Red/Yellow Yellow Grey Grey Red/Yellow A B C D

Vita Classic – Step 1 (Hue Selection) : 

Vita Classic – Step 1 (Hue Selection) Operator should select hue closest to that of natural tooth

Chroma : 

The intensity or saturation of a hue Low Chroma High Chroma Chroma

Vita Classic – Step 2 (Chroma Selection) : 

Vita Classic – Step 2 (Chroma Selection) Hue selection has been made (B) Chroma is selected from gradations within the B tabs-B1, B2, B3, B4 Several comparisons should be made Avoid retinal fatigue Rest eyes between comparisons (blue-gray)

Value : 

Value The relative darkness or lightness of a color, or brightness of an object Low Value High Value

Vita Classic – Step 3 (Value Selection) : 

Vita Classic – Step 3 (Value Selection) Value oriented shade guide B1, 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 light Diminishes cone sensitivity, increases rod sensitivity

Slide 52: 

- Equal in Chroma / Variation in Value - Variation in Chroma / Equal in Value Chroma Value

Vita Classic – Step 4 (Final Check / Revision) : 

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

VITAPAN 3D-MASTER Shade Guide : 

VITAPAN 3D-MASTER Shade Guide 1 2 3 4 5

Vita-3D – Step 1 : 

Vita-3D – Step 1 Determine the lightness level (value) Start with darkest group moving right to left Select Value group 1, 2, 3, 4, or 5

Vita-3D – Step 2 : 

Vita-3D – Step 2 Select 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 3 : 

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

Vita-3D – Step 4 : 

Vita-3D – Step 4 For more precise shade, intermediate levels for hue, value, and chroma can be given 2.5M2 = value between 2M2 and 3m2 3M1.5 = chroma between 3M1 and 3M2 3M2 / 3L2.5 = hue between 3M2 and 3L2.5

Extended Range Shade Guides : 

Extended Range Shade Guides Some porcelain systems extend the typical range Bleached shades Dentin shades Custom shade guides

Slide 61: 

Vita Easy shade. Shade Eye Shade Scan. Advancements in Shade selection Spactroshade.

Importance of luting agent : 

Importance of luting agent Luting agent shade is also important consideration for the imparting proper shade As it imparts color through the restoration

Range for natural teeth : 

Range for natural teeth Value in natural teeth 4 - 8 Chroma in natural teeth 0 - 7 Hue in natural teeth 6 YR - 9.3YR

Limitation of shade guide : 

Limitation of shade guide Don’t tell about the complete tooth color. Shade guide is prepared by different materials and crowns are of different. Problem we face for selecting shade for porcelain fused to metal crown.

Shade Mapping : 

Shade Mapping Tooth is divided into Three regions Nine segments Each region is matched independently Further characterizations are sketched on diagram, may include… Craze lines Hypo calcifications Proximal discolorations Translucency

Summary : 

Summary An understanding of the science of color and color perception is crucial to the success esthetic restorative dentistry. Although limitations in materials and techniques may make a perfect color match impossible, a harmonious restoration can almost be achieved. Shade selection should be approached in a organized manner. This will enable the practitioner to make the best choice and communicate it accurately to the laboratory.

References : 

References Contemporary Fixed Prosthodontics Rosenstiel (3rd edition) Esthetics in dentistry Ronald E Goldstein Esthetics dentistry; a clinical approach to technique and materials Barry G Dale, Kenneth W Aschheim Esthetic dentistry and ceramic restoration Martin Dunitz Tylman’s Theory and practice of FPD Natural Color Concept: A Systematic Approach to Visual Shade Selection Bernhard Egger Shade selection By Christopher CK Ho, BDS Hons (Syd),

Slide 69: 

What we say till now is just the tip of ice berg Greater knowledge is still awaiting to be discovered and practiced about esthetics

Thank You : 

Thank You Have a nice day