Measurement of edgewise torque force in vitro.

The construction of a model for the measurement of palatal root torque is described. It was demonstrated that: 1. Halfway between the apex of a tooth and the arch wire the force was double that which was delivered at the apex. 2. The lateral incisors were subjected to appreciably more force than the central incisors. 3. The smaller the number of teeth acted upon, the greater the force they received.