color and shade

color

— creates atmosphere, defines space and proportion, establishes order and exudes emotion

color sense

the ability to make the right color choice

isaac newton

he found that a beam of white light could be separated into component colors, or wavelengths, by passing it through a prism

spectrum

newton described resulting continuous series of colors as q —

roy g biv

colors in the spectrum

light source, the object, the observer

color triad

natural light

the ideal light source is — occurring around mid-day for accurate color comparison

time of the day, month, weather

the —, —, and — conditions affect the color of sunlight

perceived

if the light source changes, then the light reflected from an object changes too; in that case, a different color is —

color temperature

A measurement used to determine how closely a light source reproduces standard daylight

standard daylight

The light source that approximates — is ideal for shade matching.

incandescent

Dental unit lights are usually — lights that emit light high in the red–yellow spectrum and are low at the blue end

cool white fluorescent

Regular — lights are high in the green–yellow spectrum

transparent medium

A — will allow visible light to pass through almost unaltered

cornea, crystalline lens on the retina

Visible light enters the eye through the transparent area of the — and is focused by the —

retina

The — is composed of two types of specialized photosensitive cells and is the receptor system for vision

rods and cones

These specialized receptor cells are called — and they contain photosensitive pigments

Munsell

Color is usually described according to the — color space in terms of hue, value and chroma

value, chroma

When color is determined using the Munsell system, — is determined first followed by —

hue

When color is determined using the Munsell system, — is determined last by matching with shade tabs of the value and chroma already determined

hue

is the quality that distinguishes one family of color from another.

value

is defined as the relative lightness or darkness of a color or the brightness of the object

white‐to‐black gray

Munsell described the value as a — scale

lower

Munsell described the value as a white‐to‐black gray scale

• Bright objects have — amounts of gray

higher

Munsell described the value as a white‐to‐black gray scale

• low-value objects have — amounts of gray

chroma

is defined as the saturation, intensity or strength of hue

decreased

As chroma is increased, the value is —; chroma and value are inversely related

pigment colors, dimensions of color

The important concept of shade matching includes — and the —

pigment colors

are inherent hues of an object

red, yellow, blue

The primary pigment colors are similar to subtractive primaries, but they are referred to as —

orange

Secondary colors are formed by combining two of the primary colors

• red + yellow = —

green

Secondary colors are formed by combining two of the primary colors

• yellow + blue = —

violet

Secondary colors are formed by combining two of the primary colors

• blue + red = —

complementary colors

— are those that, when combined in equal proportions, will form a dull gray that absorbs and reflects/transmits all wavelength in equal amounts.

blue/orange, red/green, yellow/violet

Complementary pigment color pairs are —

metamerism

occurs when the perception of color of two objects is different because one of the variables of the color triad (object, light source, or observer) is altered while the other two remain the same.

object metamerism

type of metamerism

• occurs when the two items appear the same in one lighting condition, but appear differently when the light source is changed

object metamerism

type of metamerism

• example: In dental terms, it occurs when crown is matched to the natural dentition under incandescent light, but, when viewed under color‐corrected or fluorescent light, appears not to match the natural teeth.

spectral reflectance curves

to prevent metamerism, objects should have the same —, since only materials with identical spectral energy distribution curves will match under all light sources.

daylight, corrected light, dim light.

to obtain an acceptable shade determination, it is advisable for the viewer (technician, clinician and assistant) to observe the color matching under three different lighting conditions —

observer metamerism

type of metamerism

• occurs when the light source remains the same and the observer changes, caused by either human visual stimulus or instrumental stimulus

third observer

type of metamerism

• observer metamerism - it is recommended that a — (assistant, technician, friend, or family member) evaluate the selected color prior to cementation of any final restoration.

visual, instrumental

Color determination in dentistry can be divided into two categories:

visual

category of color determination

• A popular system for — determination of color is the Munsell color system, the parameters of which are represented in three dimensions

value, chroma, hue

category of color determination

• A popular system for visual determination of color is the Munsell color system, the parameters of which are represented in three dimensions

white to black

Value ranges from —

achromatic or gray to a highly saturated color

Chroma ranges from —

2.5 to 10

Hue is measured on a scale from — in increments of 2.5 for each of the 10 color families

shade matching tools

are called color standards or shade guides.

tooth color standard

type of color standards for dentistry

• color standards for oral soft‐tissues and color standards for facial prostheses‐commonly known as dental, gingival and facial shade guides, respectively ‐ are possible

Clark

— introduced a custom shade guide in 1931 based on visual assessment of human teeth, recorded in Munsell hue, value and chroma

Sproull

—, in the early 70s, suggested that an ideal shade guide should consist of shade (color) tabs that are well distributed and logically arranged in color space, preferably based on the Munsell color system

Vita 3D‐Master shade guide

The — features a systematic colorimetric distribution of 26 shade tabs within the tooth color space

most color‐sensitive

certain principles that should be followed during shade selection

• patient should be viewed at the eye level so that the — part of the retina will be used
  

natural daylight

certain principles that should be followed during shade selection

• Shade comparison should be made under different lighting conditions. Normally, the patient is taken to a window and the color is confirmed in — after initial selection under incandescent and fluorescent lightening
  

clean

certain principles that should be followed during shade selection

• The teeth to be matched should be —
  

start

certain principles that should be followed during shade selection

• Shade comparison should be made at the — of the patient visit
  

removed

certain principles that should be followed during shade selection

• Brightly colored clothing should be draped and lipstick should be —
  

quickly

certain principles that should be followed during shade selection

• Shade comparison should be made —, with the color samples placed under the lip directly next to the tooth being matched
  

digital cameras, spectrophotometers, colorimeters

Technology based shade matching devices

spot measurement

devices measure a small area on the tooth surface

complete-tooth measurement

devices measure the entire tooth

digital cameras

— is extremely efficient and easy to use. Instead of focusing light on the film to create a chemical reaction, this capture images using charged coupled devices, which contain millions of microscopically small light‐sensitive elements

spectrophotometers

measures and records the amount of visible radiant energy reflected or transmitted by an object one wavelength at a time for each value, chroma and hue present in the entire visible spectrum

colorimeters

generally use three or four silicon photodiodes that have spectral correction filters

normal axis

three step shade matching procedures

• A tooth should be viewed along its — (the line of sight perpendicular to the surface), using a diffuse light source

parallel

three step shade matching procedures

• The shade tab should be placed — to the tooth being matched and with the same relative edge position

first

three step shade matching procedures

• The — impression is frequently the best match and shade matching trials should be limited to 5 s, at a time to prevent eye fatigue and the recommendation to relax the eyes by observing a blue card between two trials.

Color blindness

— is caused by a deficiency in or absence of one or more of the three types of photosensitive pigments able to detect red, green and blue.

achromatism

Complete lack of hue sensitivity

dichromatism

Sensitivity to only two primary hues usually either red or green is not perceived

trichromatism

Sensitivity to all three hues with deficiency or abnormality of one of the three primary

pigments in the retinal cones

yellowed

Aging is detrimental to color‐matching abilities because the cornea and lens of the eye become — with age, imparting a yellow‐brown bias

systemic, local or mental fatigue

Tired eyes cannot perceive color as accurately as alert eyes. Compromised visual perception is due to —

Color

— can function as a language. For, e.g., many places in world, red suggest anger, yellow represents joy, blue is associated with sadness.

emotion

— can affect papillary diameter, causing dilation or constriction and this has a direct effect on color discrimination.

binocular difference

is the perception difference between the left and the right eye