Evaluation of force system of T-loop retraction pré-activated with UNESPAraraquara pattern

Ricardo Sampaio de SOUZA, Ary dos Santos PINTO, Roberto Hideo SHIMIZU, Maurício Tatsuei SAKIMA, Luiz Gonzaga GANDINI JÚNIOR

Closure of spaces is a routine procedure in Orthodontic practice. There are many ways of performing this, but in some of these the force system is not known. In this research the force system of T-loop is described according to the pre-activation used in the Orthodontic Discipline of Araraquara’s Dental School - UNESP. Traction tests were performed using an universal machine for trials and a moment transductor with a digital indicator for extensiometry. The loop was positioned centered in the space between the brackets and a initial activation of 5mm was done. The loop was deactivated for each 0.5mm, and the horizontal force reading and the moment was observed. The results showed an initial horizontal force of 253.6g and a moment/force rate of 7.6, and the translation occurred after 1.5mm of deactivation, and root correction with 2mm of deactivation. According to the obtained results, this loop is indicated for cuspids or incisors retraction and total retraction, and must be reactivated for each 2,5 mm of deactivation.

Keywords: Biomechanics. Corrective orthodontics. Space closure.

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