Ein rechnergesteuerter Biegemeßplatz zur Bestimmung der Elastizitätsparameter hochflexibler orthodontischer Drähte

Abstract

Metals are the most commonly used materials in the construction of orthodontic appliances designed for the correction of malocclusions. Knowledge of the force systems at work is a prerequisite for judging the functionality of these appliances. The elasticity parameters (Young's E-moduli, strain limits) of the alloys employed can be drawn upon to calculate numerically forces and torsional moments. Both tensile tests and bending experiments are used to determine the E-moduli and strain limits of standard steel and highly flexible NiTi wires frequently used in orthodontics. However, parameters obtained by tensile tests are less suited for studying the mechanical properties of orthodontic appliances. Since bending deformation prevails, bending experiments should be preferred method for ascertaining the relevant parameters. This study, therefore, presents a new experimental method for testing the bend ability of highly flexible materials and the determination of the underlying material parameters. A comparison of calculated force systems with direct measurements revealed that bending parameters lead to an appropriate description of forces and moments generated during clinical treatment, whereas calculations based on tensile test parameters differ substantially. The bending test proposed here is, thus, a suitable means for dependably predicting the force systems produced by an orthodontic appliance and the test therefore can contribute to an accurate design of new types of therapeutic devices.

Experimental Analysis of Torque Characteristics of Orthodontic Wires

“…The wire's torsion was measured in the Flex measurement set-up [16] specially constructed for measuring orthodontic wires. The Flex was originally developed for testing the bending properties of highly flexible wires.…”

“…This measurement system consists of two rotary units that can be turned toward each other. One rotary unit is equipped with a torque sensor that can be used to measure the torque generated with a resolution of 0.1 Nmm [16]. Both rotary units were carefully adjusted so that no additional transverse forces were generated during the measurements.…”

“…Die Torsion des Drahtes erfolgte in dem für Messungen an kieferorthopädischen Drähten speziell konstruierten Messaufbau Flex [16]. Das Flex wurde ursprünglich für die Biegeprüfung an hochflexiblen Drähten entwickelt, konnte certain cross-section ratios [9].…”

“…Those wires revealed an obvious dependence on the manufacturer that was also statistically significant. The lowest torquing moment (0.2 ± 0.1 Nmm) was generated by the Tensic ® wire with a cross-section of 16 Figure 8 shows the values calculated at the end of the loading plateau for these NiTi wires: they range from 6.9 (±1.9)° (ODS 17 × 25) to 13.1 (±5.6)° (ODS 16 × 22). Here too, there are very large standard deviations that yielded statistically significant differences in very few comparisons.…”

Praktische Aspekte der Verwendung von “superelastischen” Drahtbögen in der Edgewisetechnik

“…Endgtiltige Annahme des Manuskripts: 16.9.i994. Infolgedessen werden schwache und kontinuierlich wirkende Krfifte zur kombiniert schonenden und effektiven Zahnbewegung propagiert [5,6,12,19,21,22]. Auf der anderen Seite ist die Notwendigkeit der Gewebeschonung durch viele histologische Untersuchungen belegt [9,16,20,23].…”