What is the rate for rapid palatal expansion activation?

• A. 0.5–1.0 mm per week
• B. 0.1–0.2 mm per week
• C. 2.0–3.0 mm per week
• D. 1.5–2.0 mm per week

Answer: (A)

Rapid palatal expansion relies on applying controlled, gradual widening as the screw is turned. The activation rate you aim for is about 0.5 to 1.0 mm per week. In practice this often means making small activations regularly—roughly a quarter-turn (about 0.25 mm) a couple of times per week—which totals about 0.5 mm per week, with some clinicians allowing up to about 1.0 mm weekly depending on how the sutures respond. This range balances moving the midpalatal suture open while giving surrounding tissues time to adapt, reducing the risk of adverse effects like unwanted tipping or tissue damage. Slower rates would slow progress, while much faster rates increase complication risk, so 0.5–1.0 mm per week is the best target.