Tooth Shade Determination - Semmelweis

Tooth Shade Determination

Dr. Judit Borbély

•The American Academy of Cosmetic Dentistry completed a study regarding tooth brightness and appearance. An overwhelming majority (90 percent) of those surveyed viewed people with whiter teeth as healthier and more attractive,” •In fact, further studies by the American Academy of Cosmetic Dentistry show that 96 percent of adults believe an attractive smile makes a person more appealing to the opposite sex, and 74 percent of adults feel an unattractive smile can hurt a person’s chances for career success.

Color and Shade Selection

Esthetics-patients satisfaction!

De gustibus et coloribus non est disputandum

• Raffaello Santi: Scuola di Atene

NO LIGHT NO SIGHT!

• Everything that we see is reflected light

• Visible light is portion of the electromagneticspectrum

• Light enters the eye, and reaches the retina: rods, cones

• Electrical impulses transmitted to the brain

• Visual perception: interaction of light, eyes, brain

• Patterns of illumination on the retina,other senses, past experiences

Color Vision

Color perception:subjective!

Metamerism:Similar colors appear different under different conditions

•Geometric:Different angle/different color

•Simple:Different lightning source/different color

Normal Color vision:•1 million

different colors

Color vision deficiency :inability to perceive differences between some or all colors•1 in 200 females

•1 in 12 males

•Ishiara test

Observer metamerism: Every individual perceives color slightly differently

I. Comparison method with Shade guides

Shade Determination

II. MeasurementInstruments for color measurement

Classical shade guide:practical experience

A-orangeB-yellow orangeC-grey orangeD-brown orange

Shade selection keys• Use correct environment and lightning• Select shade at the beginning of appointment• Patient sitting upright• Patient’s teeth/dentist’s eyes at same level• Look for variance between gingival ,middle and

incisal thirds of teeth

•gingival -higher chroma

•middle -higher value

•incisal -higher translucency

Control of the environment• Must surround teeth with colour

that aids color perception• Use neutral colors in operatory• Window light-daylight• No lipstick• Always use a bibCover brightly-colored clothingNatural teeth-orange/compliment

of orange is blueUse gray patient bibs

Dilemma of the method:number of color samples available in theshade guide:

more samples - human eye tiressmall number of samples-random factors

color perception is subjective and variesbetween individuals :lightning conditions, experience, age, physiological variables such as colorblindness lead to inconsistencies

• Visual color match !

• Vita-Vita teszt• Evaluation of visual and instrument shade

matchingScott R. Okubo, School of Dentistry, West Virginia University Morgantown, J Prosthet Dent 1998;80:642-648

•Isia Leviant Enigma 1981

•Proceedings of the National Academy of Science U S A. 2008

•CIE Lab tooth color space• Grassmann/ Munsell:

• Value degree of lightness or darkness of a color relative to a series of grays

• Chroma the difference between the colorand a gray having the same brightness

• Hue physical wavelength of light, represented asan angle ranging from 0° to 360°.

VALUE

•Chroma

VITA

1M1

5M3

2M1

*

*

3M1

4M1

L-yellow

1.5M1

3D-MASTER Toothguide

R-red

• Introduced in 1988• Systematic and

equidistant coverage of the natural tooth shade spectrum

• Exactly defined mixed colors:52 interpolated colors

• Reflects distribution of tooth shades in nature

•Classical Shade Guides

Limitations:•Not uniformly positioned throughout tooth color space•No standard difference between adjacent shades•In-between shades (eg.”A2.5” ) are inaccurate

• Chroma represented by a number (1- 3)within each value group: pale to intensive

•5 Value Groups (1-5) left to right

•Hue represented by L,M, R left to right

Systematic precision of shade matcing :

3D Master Tooth Guide

Value:

The proper Value is the most important dimension in the shade determining process!Black GV. A work on operative dentistry. Chicago: Medico-Dental Pub Co; 1908. p. 347.

brightness of the color (high value-brighterlower value-darker)

Chromaintensity, saturation, purity of the color (low chroma=weak,high chroma=highly saturated, pure colors)

Chroma

HUEthe color itself dependent upon wavelengthThe attribute of a color by which we distinguish red from green, blue from yellow, etc.

HUE

• ValueFirst step:Value level from the five value groups (levels 1 - 5) that is closest to the value of the tooth to be compared

• ChromaSecond step:Chroma (levels 1 2,3) is determined, color sample of the selected M group that is closest to the tooth to be compared.

• HueThird step:hue (L, M, R) is determined,whether the natural tooth displays a "more yellowish" (L) or "more reddish" {R) shade than M-group

• Linearguide

1. Value2. Chroma/Hue

Digital color determination

• Printing house-press

• Textile industry

• Interior decorators

• Paintwork on cars

• Technological Shade Systems

• Measurement data analyzed by computers

• Color quantified using numerical values

• Objective,consistent,reproducible color measurement

Digital Tooth Shade Determination

•Spectrophotometer:

•Easyshade Compact, Vita•Shadepilot, Degudent

•Colorimeter: •ShadeEye SHOFU Inc., Japan•Digital Shade Guide DSG 4 PLUS, Rieth

•RGB device: •ShadeScan, Cynoprod, Canada•ShadeVison System, x-rite

• RGB Devices• Colorimeter• Spectrophotometer

Dental spectrophotometers

Vita Easyshadedental spectrophotometer

Measure reflected wavelength

Placement of probe tipCorrect placement: (probe tip perpendicular and flush on tooth surface)

Incorrect placement: (probe tip not flush on surface of tooth)

Incorrect incisal placement:(probe tip must be have a minimum distance of 2 mm to the incisal edge)

Incorrect cervical placement:(probe tip too close to gingival tissue.Maintain minimum distance of 2 mm to tissue margin.),

Lab communication

Tooth color: BASIC SHADE and :

• Tooth surface

• Bluish, whitish, greyish incisal edge

• Inclusion of perykimata

• Glossy, matt surface

• Mamelons

• Longitudional and transverese lines

• Hairline cracks and stains

• Transparency zones trans/appearance

• Translucency trans/lucence• Individual characteristics• Anatomic differences

Digital Photography

•Overall appearance ( face, lips, full smile)•Translucency, opacity •Tooth surface characteristics•Color map•Shape and form•Adjacent information

Lab technicianrequires adequat toothcolor information tomake a matching, lifelike restoration!

Best solution: several methods combined!

Thank You for Your Attention!