A patient had a crown made and returned to the office after 1 week complaining that the crown was too white. Which of the following factors may explain the error when selecting the crown color, EXCEPT:

Correct answer: A. The color was taken before preparation

• A. CORRECT (EXCEPT answer) — Taking the shade BEFORE preparation is actually recommended practice and PREVENTS errors. Prepared teeth can dry out and appear lighter. Shade selection before prep, when the tooth is hydrated and natural, is correct technique — it does NOT cause a too-white crown.
• B. INCORRECT — A mismatch between the clinic's shade guide and the lab's shade guide is a well-known source of color discrepancy and would cause the crown to appear too white or too dark.
• C. INCORRECT — Artificial light (especially cool-toned dental chair lights) distorts color perception and is a documented cause of shade-selection errors. Natural or color-corrected light is preferred.
• D. INCORRECT — Eye fatigue is a real cause of shade-selection error. After prolonged exposure to bright colors, the eye's photoreceptors become desensitized, leading to inaccurate shade perception.