What does peg-shaped lateral incisor indicate in development?

• A. Early eruption.
• B. Disturbance in morphodifferentiation during crown formation.
• C. Disturbance in root formation.
• D. Excess enamel deposition.

Answer: (B)

Peg-shaped lateral incisors reflect a disturbance in morphodifferentiation during crown formation. The crown’s final outline is set during the cap-to-bell stages when signaling between the enamel organ and the dental papilla shapes the crown. If this process is disrupted, especially in the region of the lateral incisor, the crown becomes narrow and conical, producing the classic peg shape. This is a localized form of microdontia and is most often seen in the maxillary lateral incisor.

This pattern isn’t about when the tooth erupts, nor about how the root forms, nor about excess enamel. Early eruption would change timing, not the crown shape; root formation disturbances affect the root and its morphology; excess enamel deposition would alter enamel thickness or surface, not produce a slender, peg-like crown.