Year : 2017

Volume : Volume 7

Issue : Issue 2

Address for correspondence :
Dr. Reddeppa Reddy Badepalli
ReddeppaBadepalli@gmail.com

Abstract

Aim:  To investigate the horizontal forces, vertical forces, moments and M:F ratios generated on anterior and posterior segments during deactivation of closing loops (7 mm - 0 mm) constructed from NiTi and TMA alloys with 3mm off-centering towards beta segment and incorporating preactivation bends of 300 on both alpha and beta segments using finite element method.  Materials and methods: To perform 3-dimensiosnal finite element analysis, finite element model of maxilla with MBT bracket system, segmented 0.019 × 0.025 inch SS wires, 0.036 inch diameter transpalatal arch connecting first molars, 0.010 inch SS ligature wire consolidating anterior and posterior segments individually and standard 0.017 × 0.025 inch T-loop retraction systems made of TMA and NiTi were generated by ANSYS software.  Results: Both NiTi and TMA alloy T-loops shows decrease of horizontal and vertical forces, alpha and beta moments during their deactivation ranges, whereas both α and β M:F ratios are increased during deactivation. During some point of deactivation both TMA and NiTi T-loops achieve α M:F ratio > 7 and α M:F ratio > 10 which can be useful for movement of teeth.  Conclusion: Instead of its low stiffness and flexibility, NiTi T-loops are producing M:F ratios of such type that can be used for control tipping and root torquing during some point of deactivation. So usage of NiTi alloy loops in clinical situations can be applicable after recommending further modification in biomechanics for type of tooth movement needed.

Keywords: Finite element method, Moment -to -force ratio, Nickel-Titanium alloy (NiTi), Off- centered position, Titanium-Molybdenum alloy (TMA), T-loop.