A panoramic radiograph shows a dark radiolucent band superimposed over the apices of the maxillary anterior teeth, obscuring them. What instruction to the patient corrects this?

Correct answer: D. Place the tongue firmly against the hard palate during exposure

• A. Incorrect. Tucking the chin down produces an exaggerated 'smile' curve of the occlusal plane and superimposes the hyoid over the mandible — also a different error.
• B. Incorrect. Biting properly into the bite block controls anteroposterior positioning (ghosting, magnification, narrow/wide teeth) — not the palatal air shadow.
• C. Incorrect. Raising the chin produces a 'reverse smile' occlusal plane, flattened or upwardly curved, and superimposes the hard palate over the maxillary roots — a different error.
• D. Correct. Failure to place the tongue against the palate leaves an air space between the dorsum of the tongue and the palate — the PALATOGLOSSAL AIR SPACE. This appears as a dark radiolucent band running horizontally across the maxillary apices and obscures them. The patient must swallow and hold the tongue flat and firm against the roof of the mouth throughout the exposure.