If eruption is inhibited, where does root growth occur at the expense of?

• A. Apical bone resorption
• B. Cervical bone deposition
• C. Cementum deposition
• D. PDL expansion

Answer: (A)

To understand this, remember that eruption relies on two coordinated processes: root growth lengthening the tooth and remodeling of the surrounding bone to make space for the tooth to move. The bone remodeling that matters here is resorption of bone in the eruption path, especially near the apex, to allow the tooth to progress occlusally.

If eruption is inhibited, the tooth cannot move into that eruption pathway. The resorptive activity in the apical bone isn’t needed for movement, so it decreases. Meanwhile the tooth’s root continues to form and lengthen. In other words, ongoing root growth proceeds at the expense of the apical bone resorption that would normally accompany eruption.

Cementum deposition and PDL expansion still occur, but they don’t explain the trade-off described—the key trade-off when eruption is blocked is between root elongation and apical bone resorption.