Space closure effect on force system in the segmented arch: an experimental-numerical study

Objective: To perform an experimental-numerical analysis to study the influence of the interbracket distance (IBD) on the spring's mechanical behavior and on the resulting force system during space closure in the segmented arch technique (SAT).Material and Methods: Twenty delta springs (DSs) made of beta-titanium alloy, 0.017 x 0.025 inch, were tested on a platform transducer. A Young's modulus (E) of 69 GPa (10 x 10(6) psi) and Yield's strength (s(e)) of 1240 MPa (180 x 10(3) psi) were used. The springs were activated considering different IBDs. The spring was modeled in autodesk Inventor software and its behavior was simulated using the finite element (FE) code Ansys Workbench.Results: The ANOVA showed a significant difference in the studied variables with a reliability of over 95% (only for the activation variable there was an effect upon the horizontal forces (Fx). The Tukey HSD and the Games-Howell post hoc multiple comparisons tests were applied to identify differences between the treatments for heterogeneous variances.Conclusions: The IBDs do not significantly affect the force system during space closure, even though there was an increase in the Mz/Fx ratio as spring deactivates. Activation can cause a statistically significant effect on the force system even though the force showed safe levels. At 4mm activation (19mm IBD), the spring wire starts yielding, i.e. plastic deformation occurs near the anterior attachment due to the shorter IBD.