Comparing the Efficacy of Specs Loop and T Loop for En Masse Anterior Retraction - A Finite Element Study

Abstract

ABSTRACT Purpose T loop is one of the most commonly used loops for space closure. But the previous literature shows that T loop produces a moment to force ratio of less than the ideal value with high load deflection rate. Thus, a newly designed Specs loop was designed which produced a moment to force ratio of 10:1. The present study was aimed to compare the efficacy of Specs loop and T loop in en-masse anterior retraction. Materials and Methods A finite element maxillary model for en-masse anterior retraction was made. The Specs loop and T loop were designed with preactivation bends of 30 degree alpha bend and 45 degree beta bend. The horizontal and vertical forces and moments at both the alpha and beta nodes and overall moment to force ratio, horizontal and vertical movement of crown and root tip of all the individual teeth and stress acting on the teeth and bone were calculated for each loop for a horizontal activation of 3 mm using Abaqus software. Results T loop produced a moment to force (M/F) ratio of 9:1, whereas Specs loop produced M/F ratio of 10:1. The Specs loop produced more distal crown tipping of anterior and posterior teeth, whereas the extrusive vertical movement seen was almost the same for both the loops. Conclusion Within the limitations of the present study, the Specs loop was more efficient than the T loop for en-masse anterior retraction.