A blue articulating-paper mark appears near the INCISAL edge on the labial aspect of the maxillary left central incisor (tooth 11 in FDI notation), with corresponding wear. What does this indicate?

Correct answer: C. Wear from protrusive movement

• A. A debonded restoration would show as a marginal defect or a shadow, not as an articulating-paper contact mark with wear.
• B. Working-side contacts in lateral excursion occur on the CANINES in a canine-guided occlusion, or across the posterior teeth in group function — not at the incisal edge of a central incisor.
• C. CORRECT. A mark at the INCISAL edge of a maxillary incisor is produced during PROTRUSION. As the mandible moves forward, the mandibular incisors slide up the palatal surfaces of the maxillary incisors and across their incisal edges — anterior guidance. Excessive or repeated protrusive contact here produces incisal wear, and in a bruxist it produces matching wear facets on the maxillary palatal and mandibular labial surfaces.
• D. A non-working interference occurs on the posterior teeth of the side OPPOSITE the direction of movement, and is the most destructive interference of all — but it is not an anterior incisal contact.

Note: Mandibular movements and where to look: PROTRUSIVE — anterior incisal and palatal surfaces; WORKING side — canine, or canine plus posterior teeth in group function; NON-WORKING side — should have NO contact at all. Articulating-paper colour convention is usually red for centric and blue for excursive marks.