A bitewing radiograph of a young patient shows abnormally thin enamel covering all teeth. Clinically, the teeth appear yellow-brown. What is the most likely diagnosis?

Correct answer: D. Amelogenesis imperfecta (hypoplastic type)

• A. Fluorosis presents as white opaque spots or brown staining of enamel that is normal thickness on radiograph — not generalized thinning of enamel. It has a diffuse, bilateral, symmetrical distribution.
• B. Nursing caries (ECC) causes demineralization of visible labial/buccal enamel, not a generalized thin enamel on bitewing radiograph. It typically affects the maxillary anteriors first.
• C. Dentinogenesis imperfecta affects the DENTIN, not enamel. Radiographically, it shows obliterated pulp chambers and bulbous crowns. Teeth appear opalescent/blue-gray, not thin enamel with brown color.
• D. CORRECT. Amelogenesis imperfecta (AI) is a hereditary developmental enamel defect affecting the quantity or quality of enamel. The hypoplastic form shows thin enamel radiographically (insufficient quantity) — the contrast between enamel and dentin is reduced on bitewing. Yellow-brown tooth color with thin enamel on bitewing in a young patient is classic for AI.