Objective: To determine how gap opening is affected by the activation intervals of expansion screws in removable orthodontic appliances and which gap widths are achievable during therapy.
Materials And Methods: In this retrospective study, the increases in gap widths for transverse and distalizing screws activated at 7- and 14-day intervals were calculated. These estimates were based on measurements taken with a caliper of the gap widths of 242 screws integrated in the plates of 137 patients examined during 4-5 follow-up visits over a 6- to 7-month therapy period.