At what age does tetracycline use MOST likely cause staining of the central incisors (teeth 8, 9, 24, 25)?

Correct answer: A. Up to approximately 3 years of age (during calcification of permanent central incisors)

• A. Correct. Tetracycline (and related antibiotics like minocycline, doxycycline) stain teeth DURING CALCIFICATION. The permanent central incisors (teeth 8, 9, 24, 25) begin calcifying around birth and complete crown calcification around age 3–4. Therefore, tetracycline taken in the first 3 years of life would cause staining of these specific teeth.
• B. During birth — while the calcification is just beginning, the risk persists throughout the calcification period (up to ~3 years for central incisors).
• C. Tetracycline DOES affect permanent teeth — it is contraindicated in children <8 years old (and pregnant women) for this reason.
• D. After age 8 — crown calcification is complete by then; tetracycline use after this age would not cause intrinsic staining of the central incisors.