Analysis of the forces produced by loops: mechanical testing

Milton SANTAMARIA JR., Antonio Beleño DIAZ, Carlos Nelson ELIAS, Margareth Maria Gomes de SOUZA

Aim: the aim of this work was to assess the force applied by the vertical loop, divergent boot loop and convergent boot loop, made with 0.016” arch wire, during the leveling phase in function of the produced deformation and of the tie back in the posterior extremity of the arch wire. Methods: a special experimental model was built for this study, and a Universal Test Machine EMIC-DL10.000 was used to evaluate force levels. Results and Conclusions: The produced deformation varied of 0.5 to 2mm and the force produced varied from 75.1 to 268.5gf for vertical loop, 69.7 to 241.0gf for the divergent boot loop and 67.0 to 220.4gf for the convergent boot loop, in the condition of not tying back the wire. When wire was tied back the force varied from 105.0 to 311.6gf; 70.8 to 251.4gf and 69.4 to 243.4gf; respectively. It was applied Student t test and it was verified that the vertical loop produces larger force in agreement with the deformation followed by the divergent boot loop and convergent boot loop (p<0.05). This force is greater when the arch wire is tied back in the posterior extremity of the wire in the three types of studied loops (p<0.05).

Keywords: Loop. Leveling. Extrusion.

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