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Questions and Answers
What determines the color of an object?
What is the role of light in perceiving color?
What is essential for perceiving color?
What happens to light when it encounters an object?
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What is the result of light interacting with an object?
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What is responsible for the color of an object?
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What is the role of the human eye in perceiving color?
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What is the relationship between light and color?
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What is necessary for color perception?
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What happens to color when viewed for a prolonged period?
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What is the effect of viewing a pale blue or gray surface between shade matching?
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What occurs when the chroma of a color is affected?
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What is the result of adaptation to a particular color?
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What is the purpose of viewing a pale blue or gray surface during shade matching?
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Study Notes
Shade Selection Principles
- Position of the operator is between the patient and light source to evaluate shade accurately.
- Evaluate shade under multiple light sources to ensure accuracy.
Principles of Shade Selection (cont'd)
- Carefully examine the tooth to determine the pattern of translucency and unique characterizing features such as craze lines, areas of hypo-calcification, etc.
Shade Selection Systems
- Commercial Shade Guides:
- Most convenient and common method of making shade selections.
- Guides consist of shade tabs with metal backing, opaque porcelain, and neck, body, and incisal color.
- Select tab with the most natural intraoral appearance.
Vita Classic Shade Guide
- Very popular shade guide.
- Tabs of similar hue are clustered into letter groups:
- A (red-yellow)
- B (yellow)
- C (grey)
- D (red-yellow-gray)
- Chroma is designated with numerical values (e.g., A3 = hue of red-yellow, chroma of 3).
- Manufacturer recommended sequence for shade matching:
- The more dentin fluoresces, the higher the chroma.
Opalescence
- Is a phenomenon in which the material appears to be of one color when light is reflected from it and of another color when light is transmitted from it.
- In human enamel, it renders bluish in reflected color and orange brown in transmitted color, although it is colorless.
Color and Light
- The color of an object is determined by the light that is reflected from an object and entered the human eye.
- Factors affecting perception of color include shade guide system and selection of tooth shade.
Shade Consistency in Dentistry
- Hue consistency among shade guides has not been proven and remains a significant challenge in maintaining a consistent shade from appointment to final restoration.
Auxiliary Light Sources in Shade Matching
- Ambient lighting in the dental operatory may not be ideal for visual shade matching.
- The use of auxiliary lighting is recommended in such cases.
Factors Affecting Crown Translucency
- Increasing the translucency of a crown lowers its value due to less light returning to the eye.
- Enamel translucency is affected by: • Angle of incidence • Surface texture • Wavelength
Human Visual Perception
- Rods are located at the periphery and are few in the center of the retina.
- Rods are activated with low light, resulting in a duller color view (value).
- Chroma, on the other hand, is related to color intensity.
Color Vision Restoration
- Viewing a pale blue or gray surface between shade matching can restore color vision.
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Description
This quiz covers the principles of shade selection in dentistry, including the position of the operator and evaluating shades under multiple light sources.
