Which statement best describes rodent incisor growth?

• A. Open rooted and continuously growing
• B. Closed rooted and do not grow
• C. Open rooted but do not grow
• D. Closed rooted and grow continuously

Answer: (A)

Rodent incisors are open rooted and continuously growing, a design that matches their constant gnawing lifestyle. An open root means the apex is not closed, so the tooth can keep producing tissue from the root end. Growth occurs at the apex from stem cells in the cervical loop, driving eruption as the front surface wears down from gnawing. The enamel covers the labial (front) surface and remains hard, while dentin on the other side wears away, so new tooth material must be added continuously to maintain length. This ongoing production—often described as aradicular hypsodont growth—keeps the incisors growing throughout life. Closed-rooted teeth, by contrast, finish development and stop growing, which does not describe rodent incisors.