The T-loop in details

Abstract

Introduction: The T-loop as designed by Burstone is a space closure spring used in the rational application of orthodontic biomechanics. Despite the diversity of studies, there is still no consensus on the optimal parametric characteristics for its conformation. Objective: This study aimed at reviewing the literature on the force systems released by different conformations of the T-loop, according to the type of anchorage and the main characteristics and factors that influence them. Results: Comparing the studies, the need for standardization was perceived in the methodology to shape the loops, regarding the variables that influence the force system. Most of the experimental studies with this loop do not report the vertical movement, nor the steps and angles that occur in the brackets. Clinical studies have obtained more variable results in relation to vertical acting forces, considering the influence of chewing. Conclusion: There is great potential for future studies with this type of loop, especially using nickel-titanium alloys, in order to achieve a pure translational movement without friction, with optimal and constant levels of force.

Stress distribution analysis in anterior teeth caused by several retraction mechanics

“…The analysis of the four retraction techniques evaluated in this study revealed interesting results for understanding the behavior of the strains generated during the correction of malocclusions where orthodontic retraction of anterior teeth is indicated. This procedure is greatly studied in the orthodontic literature, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]22,23 however none of the previous investigations made a linear comparison among the application of these four mechanics.…”

“…30 When intending to create a final force vector for tooth body movement, the retraction force applied to the anteroinferior teeth was complemented by an additional vertical control, to generate an opposite intrusion moment of force, which attempted to annul the extrusion moment of force caused by the resistance to the retraction in relation to the tooth resistance center, suggesting a final resultant force without intrusion or extrusion of the anterior segment (Fig 5). 4,5,[10][11][12][13][14][15] For this reason, in the sliding mechanics long hooks were added to the archwire to activate the system close to the tooth resistance center [6][7][8] . For the mechanics applying loops (teardrop loop spring and T-loop spring), a Gable bend was incorporated for each respective loop.…”

“…For the mechanics applying loops (teardrop loop spring and T-loop spring), a Gable bend was incorporated for each respective loop. [5][6][7][8][9][10][11][12][13][14][15] For the mechanics using the DKL archwire, the mesial loops were tied aiming a deflection of the anterior segment. [16][17][18] For effective retraction, a correct load of force applied to the anterior teeth is essential.…”

“…The ideal approach is identified during treatment planning, aiming at achieving an effective dental movement. 5 Among the existing techniques to retract the anterior teeth, the following techniques can be cited: sliding mechanics, [6][7][8] teardrop loop spring, [9][10][11][12] T-loop spring 5,[13][14][15] and double key loop archwire. [16][17][18] Photoelasticity is one of the available methods for stress analysis over teeth roots.…”

“…19 Domingos RG, Lima Júnior A, Laganá DC, Rino Neto J, Abrão J, Paiva JB -Stress distribution analysis in anterior teeth caused by several retraction mechanics Numerous studies in orthodontics have used this laboratory method to analyze the strain fields created on the structures of interest after a mechanical load. 17, [19][20][21][22][23][24][25][26] Despite the frequent evaluation of retraction mechanics by several studies, 1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18] it is difficult to find articles that have compared the effects of the stress produced in periodontal tissues on anterior teeth with several space closing techniques. Therefore, this investigation aimed at analyzing and comparing the stress distributions in the following four anterior retraction techniques: sliding mechanics, teardrop loop spring, T-loop spring and double key loop archwire.…”