The Quantitative Measurement of Orthodontic Force by the Experimental Arch Model with Strain Gauges

Characteristics of Orthodontic Force Generated by Various Bended Wires

Abstract

To investigate the magnitude and direction of orthodontic force generated by the various arch forms, we proposed the quantitative measurement of orthodontic force by experimental arch model with strain gauges. The comparison of orthodontic force was evaluated with (1) plane arch wire, (2) toe-in bend, (3) tip-back bend, (4) crown lingual torque, and (5) step bend. The size of wires is 016″×016″,016″×022″ and 017″×025″ and made of stainless steel. Furthermore the magnitude of orthodontic force and force/root area ratio was calculated.
From the results, the force magnitude and direction were determined by relation of arch form and placement of neighboring brackets, but the effect of bending wire changed with size of wires. The maximum force/root area ratio of 2026.2 mN/cm². These results suggested that possibility of applying stronger than optimum force, and take notice to select size of wires, in orthodontic practice.