What term describes the phenomenon where two colors match under some lighting conditions but not under others?

What term describes the phenomenon where two colors match under some lighting conditions but not under others?

• A. Metamerism
• B. Opalescence
• C. Fluorescence
• D. Gamma phase

Answer: (A)

Metamerism is the phenomenon where two colors look identical under one lighting condition but appear different under another. This happens because each color has a unique spectrum of reflected light, and lighting sources vary in how much red, green, and blue they emit. Under one illuminant, the two materials can stimulate the eye’s color receptors in the same way, making them look the same; under a different illuminant, the spectral differences become evident and the colors no longer match. In dentistry, this is why shade matches should be checked under multiple lighting conditions to ensure the chosen shade remains consistent. The other terms describe different optical effects—opalescence is light scattering in translucent materials, fluorescence is light emission after excitation, and gamma phase is not a relevant dental color phenomenon.

Metamerism is the phenomenon where two colors look identical under one lighting condition but appear different under another. This happens because each color has a unique spectrum of reflected light, and lighting sources vary in how much red, green, and blue they emit. Under one illuminant, the two materials can stimulate the eye’s color receptors in the same way, making them look the same; under a different illuminant, the spectral differences become evident and the colors no longer match. In dentistry, this is why shade matches should be checked under multiple lighting conditions to ensure the chosen shade remains consistent. The other terms describe different optical effects—opalescence is light scattering in translucent materials, fluorescence is light emission after excitation, and gamma phase is not a relevant dental color phenomenon.