Guidelines for shade selection- Part 1

1. The Value, Hue and Chroma require the fresh eyes and should be evaluated prior to starting a procedure, with proper light source.(James Fondriest,2003,Shade matching in restorative dentistry: the science strategies)

2. Value is determined before, hue and chroma.

3. Chromatic portion of Value(brightness) must be evaluated with a Value guide in dim light conditions. Value comes from the Chroma of the tooth and the surface reflectivity (Glick KL, 1995 Colour management of cosmetic restorations).

4. The rods in the eyes are sensitive to lightness/darkness, or the value scale, even with small amounts of light. The cones only become activated with higher light levels. When the cones are functioning, the Hue and Chroma seen will confuse Value discrimination.

5. Once the chromatic portion of value is measured, change to normal light conditions for further value evaluations.

6. View teeth with the lips relaxed (indirect light) and reflected (with direct light at 90 degrees). If there is a great value drop due to the upper lip shadow, or with a polarized light filter, the predominant brightness source is superficial, caused by high surface reflectivity.

7. Environmental conditions are critical to the proper selection of hue and chroma. Create a neutral-coloured environment. Extra orally, bright clothing and the colour of the walls in the operatory and lab can alter color perception.

8. Peri- and intraorally, lipstick and the red oral tissue background fatigue the cones and form afterimages.

9. The best extra- and intraoral backgrounds for hue and chroma selection are neutral gray. (Lemire P,1975, Color in dentistry; Jun S, 1997)

10. Neutral gray has no complementary colour and is restful to the cones. This is even more critical with aged teeth that have a glossy surface that reflects the shade of any color placed in close proximity. (Ray NJ,1994 Some aspects of colour and colour matching in dentistry).

11. Use a gray bib or towel to cover the patient’s clothes,(Jun SK, 1999 Shade matching and communication in conjunction with segmental porcelain build-up. Pract Periodontics Aesthet Dent) and remove, retract, or cover any lipstick.