# Typically rapid palatal expansion is done with a jack screw that is activated at the rate of:
a) 1.0 to 2.0 mm/week
b) 1.0 to 2.0 mm/day
c) 0.5 to 1.0 mm/week
d) 0.5 to 1.0 mm/day
The correct answer is D. 0.5 to 1.0 mm/day.
Rapid expansion typically is done with two turns daily of the Jackscrew (0.5mm) activation. This creates 10 to 20 pounds of pressure across the mid palatal suture, which is enough to create microfractures of interdigitating bone spicules. In slow palatal expansion, approximately 0.5mm per week is the maximum rate at which the tissues of the midpalatal suture can adopt.