MEASURING EQUIPMENT FOR EVALUATION OF THE ELASTIC BEHAVIOR OF VARIOUSCONFIGURATIONS OF ORTHODONTIC ALLOY WIRE

The paper describes devices which enable the orthodontist (oral surgeo n) to accurately determine the forces produced by orthodontic wire or spring constructions. An apparatus was developed with which the force applied by bent wires - various materials and bending methods - could be assessed. This device uses strain gauges arranged in the form of a semi-bridge as sensors. Measurements showed that the smallest applicat ion of force was achieved with braided stainless steel wires. With res pect to the consistency of the force applied, nickel-titanium alloys ( so-called Japanese Ni-Ti) proved the best material for wires bent with electric current. A second device was constructed which permits the e valuation of the compression and tensile forces applied by springs as a function of movement. Here, too, strain gauges were used as sensors. The freely adjustable range can be determined using a digital distanc e meter with an accuracy of 0. 1 mm. Measurement of the elastic behavi our of these spring configurations revealed that in comparison with st ainless steel, nickel-titanium alloys were much more consistent in ter ms of force applied. Using these devices, the orthodontist can fit cal ibrated configurations, thus avoiding unsuitable forces.