Color Science, Esthetics, & Shade Selection-4th Year Lecture

Color Science & Shade Selection

Wael Al-Omari

Light & Color

Without light, color does not exist Factors influence an object’s color:1. Physical properties of the object.2. The nature of incident light.3. Relationship to the colored objects4. Subjective assessment of the

observer

Light & Color Light is a visible

electromagnetic energy

Reflected light wavelength determines the particular color of an object

Description of Light: 380-750 nm

Light & Color Sources of light in dental

office:(1) Incandescent: yellow light waves(2) Fluorescent: blue waves

(3) Northern daylight. Ideal light, Northern Ideal light, Northern

daylight around the noon daylight around the noon hour on a bright dayhour on a bright day

Never select shades in direct sun light

Light & Color

Color Rendering Index (CRI) 100 Color Temperature: color of

standard black body when heated Use a color corrected fluorescent

light (CRI > 90)

Description of Color Three color attributes:(1) Hue: Particular variety of a color(2) Chroma: Saturation or intensity of a hue(3) Value: Relative lightness and darkness of

a color or brightness of an object

Munsell Color Order System

Hue: 10 gradations, most natural teeth in a range between yellow and yellow-red.

O’Brien et al (1997): average Hue for anteriors; ging. 1/3 = 1.2Y middle 1/3 = 1.3 Y, incisal 1/3 = 1.4Y

Chroma: Natural teeth 0.5 to 4.

Value: Value from 5.5 to8.5

CIELAB Color System

CIELAB: L*, a* & b* L* = Value

Color-Measuring Instruments Spectrophotomete

r and colorimeter

Perception of Color Retina (rods+cones) Optical

Centre in the brain Scotopic Vision: under low

lightning conditions. Rods used. Brightness interpretation

Photopic Vision: under higher lighting. Cones used. Color vision

Central field of vision is more color perceptive.

Perception of Color Color Adaptation: Color vision decreases as

an object is observed, and intensity of complementary color appears greater. Pale gray-blue object should therefore be glanced during shade matching.

Deceptive Color Perception: influenced by surrounding colors, like brightly colored clothing and lipstick

Metamerism: Two matching colors differ by changing the light source. Select shade and confirm it under different lighting conditions.

Perception of Color Fluorescence: Reemitting absorbed

radiant energy in visible color of lower frequency. In practice, not significant in color matching of dental restorations

Opalescence: Light scattering effect, Bluish-white scattering similar to opal-gem. Incisal edges

Color Blindness: Achromatism, Dichromatism, or Trichromatism. Affect males more than females

Esthetics Defined as the study of beauty. Anatomy of a smile1. Influenced by culture2. Extensive smile showing anteriors and

teeth posterior to first molar is perceived as attractive and youthful

3. Incisal edges parallel to lower lip

Esthetics Proportion: Based on what is found in nature. Golden proportion: Ration between

succeeding terms converge on approximately 1.618 or 1.

Golden Ration (1.618): A Wonder of God's Creation

Pleasing proportion: central incisors width to length

ration of 75% to 80%

Esthetics Balance: Balance arrangement

implies stability and permanence. Symmetry around the midline

Midline: Coincidence between facial and dental midline.

Minimal lack of coincidence between maxillary midline and central incisor midline is aesthetically acceptable

Shade Selection

Shade matching is subjective, thus consistency is difficult to achieve

Restoration should blend with the teeth to produce a lifelike appearance.

Shade Selection Principles:1. View the patient

at the eyelevel.2. Shade comparison

under different light levels

3. Teeth to be matched should be clean

4. Compare at the beginning of the visit

5. Operatory not bright, bright colors & lipstick removed

6. Quick comparison, with samples under lip level

7. Rest eyes on gray-blue surface

8. Select higher value (lighter) if in doubt

9. Select surface luster

Shade SelectionCommercial Shade Guide: Pickup the shade tap most natural Chose the nearest hue first, then chroma and value Region of highest chroma should be used Value is best chosen with the aid of another commercial shade guide, hold it away, squinting the eyes to reduce light effect on the Retinal cones.

Vita Lumina: A=reddish brown, B=reddish yellow, C=grey, D=reddish grey

Selecting value using classical

guide

Selecting chroma using classical

guide

Shade Selection

Vitapan 3D Master Shade Guide: Shade taps are arranged in 6 groups according to their value Recommended to Chose the lightness level first, then chroma and finally the hue

Shade Selection

Extended Range Shade Guides: Dentin Shade Guide: Custom Shade Guide:

Shade Selection

Shade Distribution Chart: