Peg-shaped maxillary lateral incisors are MOST commonly associated with:

Correct answer: B. Impacted or palatally displaced maxillary canines

• A. Third molar impaction relates to arch length deficiency and is not linked to lateral incisor form.
• B. CORRECT. A small, peg-shaped or congenitally MISSING maxillary lateral incisor is a well-established risk marker for PALATAL DISPLACEMENT AND IMPACTION OF THE MAXILLARY CANINE. The proposed mechanism is the guidance theory: the erupting canine normally travels along the DISTAL ROOT SURFACE of the lateral incisor, which acts as a physical guide. When that root is absent or malformed, the canine loses its guide and deviates palatally. There is also evidence of a shared genetic basis.
• C. Ankylosis of primary molars is a separate eruption disturbance with no relationship to lateral incisor morphology.
• D. Mandibular second premolar impaction is not associated with maxillary lateral incisor anomalies.

Note: Clinical action: in any child around age 9–10 with a peg or missing lateral incisor, PALPATE the buccal sulcus for the canine bulge. If it is not palpable by age 10–11, image the site. Timely extraction of the primary canine resolves a substantial proportion of palatally displaced canines without further intervention.