COLOR AND SHADE SELECTION

In any aesthetic cases, color selection is the most important and first step

• Shade has to be selected before starting the preparation or application of rubber dam. Because this is the only time when teeth is fully hydrated.
• Teeth dehydrate very quickly when mouth is open. Dehydration happens in around 3 minutes.
• Immediately after rubber dam isolation enamel starts dehydrating and loses translucency.
• A dramatic change of colour happens within 3 minutes and tooth becomes white opaque
• Maximum tooth dehydration occurs after 30-45 minutes Complete rehydration occurs only after 24 - 48 hours
• A dry tooth will be atleast 2 shades lighter than it actually is

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Munsell's Colour Wheel and the three dimensions of colour - hue, chroma and value �

• Value or Luminosity is basically how much dark or bright a colour is.
• Higher the value, brighter or more whiter is the colour.
• Lower the value, the colour tends to be darker.

Hue �value �or chroma?

Rods are responsible for vision under low light conditions. They are responsible for detecting the value of an object. �Cones are sensitive to hue, the colour �Human eye has approximately 120 million rod cells and 6-7 million cone cells �Human eye has approximately 120 million rod cells and 6-7 million cone cells. �So comparing the relative number of rods to cones, we can understand that humans are incredibly more sensitive to value of an object rather than its hue ��

Even small differences between value of a restoration and the tooth being matched can be readily detected and may appear to be a mismatch in shade. ��This is why achieving a good value match is much more important �

As a Dentist, we are most concerned about the value (lightness or darkness) of a restoration. �Then comes chroma which is equally important.�And we are least bothered about hue.�If value and chroma are perfect human eye can't appreciate a �hue difference. �Value > Chroma > Hue �

Metamerism

Either you can take shades in bright day light near the window or use a colour corrected light source. �Any colour corrected illumination source like Rite lite or Base light can be used -5500 kelvin�

Shade is selected in 5,500 K. �  First select in bright daylight. �  Then recheck in different condition. �  Take shade with minimum makeup. �  With a dark background (with contrasters) to get an idea of translucency and opalescence, dentin and enamel shades �

Shade guides

VITA CLASSIC

Most common,

4 basic/major groups

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based on hue

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it is divided into four groups A, B, C & D based on hue.

Each group is subdivided based on the chroma. �So A1 - A4 has the same hue and only the depth of colour increases from A1 to A4 ie, the chroma will increase �

PROBLEM?

• value Which is the most important parameter and it is not addressed correctly in this system.
• Hue, which is the least important is given the most importance in this system

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• Arranged accdng to value

VITA 3D MASTER

It is a value based shade guide hence is a more organized and scientific one. �In 3D Master, we select value first from all the 5 groups �So first we have to consider only 5 tabs namely 1M1, 2M1, 3M1, 4M1 and 5M1. �These tabs are representatives of their group. �All the tabs in one group will have the same value ��

First select the most appropriate tab with matching value from 1M1 to 5M1� �As we move from 1M1 to 5M1, value reduces, ie, 1M1 has more value than 5M1� �After selecting the value, say a 3M1, take that tab alone leaving back the rest��Now you have only 3 tabs in hand ie, 3M1 3M2 and 3M3�These 3 tabs have the same value��Only chroma increases as we go down ��

Select the closest matching chroma from these 3 tabs and you are around 90% correct.

Now you can select the R or L group.

When coming to the R group it is more reddish and L is more yellowish when compared to your M counterparts

Opalescence is the ability of a translucent material to appear blue in reflected light�� Translucency conveys depth and vitality� �Excessive translucency leads to a grayish restoration. Inadequate translucency make the restoration lifeless or opaque ��

SHAPE,ANATOMY,SURFACE CHARACTERS

SHADE MAPPING�STUMP SHADE

SHADE GUIDES FOR COMPOSITES

DENTIN CHROMA�ENAMEL VALUE

• Composites which are meant to replace the dentin part is placed more cervically as the thickness of the enamel is least at the cervical region.
• The composite meant to replace enamel area is placed near the incisal edges.
• Any body shades used should be placed in the middle