Photoelastic study of the vertical control with double key loop archwire in the Straight wire technique

Adriano DOBRANSZKI, José Henrique VUOLO, Flamínio LEVY NETO, Hideo SUZUKI, Jurandir Antônio BARBOSA, Nara Pereira D´Abreu Cordeiro DOBRANSZKI

Introduction: There are clinical situations in which the extraction of bicuspids becomes necessary and, eventually, the extraction spaces are completely closed after aligning and leveling the teeth. The Double Key Loop (DKL) is a stainless steel arch for retraction, with two loops (keys), one mesial and another distal to the canine. Aim: This study aims to study the area where the force is exerted after the activation of the distal loop, the activation of the loops among themselves and the distal loop, and the activation with Gurin®. Methods: Nine photoelastic models of the inferior arch were made, without the first bicuspids and the third molars, with In-Ovation brackets and the DKL. With the interposition of polarizing filters, pictures of incisors canines and posterior teeth were taken, after the activation of the arch. Results and Conclusions: Based on the analysis of the photoelastic model, we concluded that the activation in the distal loop can produce an anterior retraction movement without an extrusive component, while the activation with Gurin® produces an extrusive component; besides that, the activation of the keys among themselves and the distal loop activation can produce an anterior retraction movement with an intrusive component.

Keywords: Photoelasticity. Vertical control. Retraction. Double-key archwire. DKL. Suzuki´s tie.

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